Recently, food processors can apply high pressure processing (HPP, up to 800 MPa) to inactivate microorganisms. By this way, nutritional attributes of food products can be kept at the most.

The best thing is to classify foods into 3 categories:

1. Foods in which cooking destroys important nutrients (fruits, non starchy vegetables, etc)

2. Foods in which cooking destroys some of important nutrients (starchy vegetable, milk, meat, etc)

3. Foods in which cooking has no effect on nutrients (most of the cereals)

So we start from the third category, we can see that there is almost no effect of cooking on nutrients so we dont need to tailor new methods. For the second category we need to optimize existing methods or develop new methods to prevent nutrient spoilage. For the first category its always better to go for minimal processing.

It depends on the type of food you are dealing with. You have to be specific. If it is vegetable, blanching for few minutes will be appropriate.

Cooking is required not only for destroying microorganism but it also denatures many natural toxicants, enzymes, facilitates chemical reactions and enhances food palatability - taste, texture, flavor, digestibility and assimilation, which are most vital for proper nutrition. Yes we can reduce nutrient loss caused by cooking to a certain extent by adopting appropriate methods of cooking.

Just joining the discussion so must give some thought to the quesion, but first wanted to comment that the science of nutrition of late has seemed more to focus on food as if vitamins and minerals in any form are the main considerations, when we show in Behavioral Medicine that delivery to the cells is much dependent upon on trace minerals, co-factors, enzymes, amino acids, and other factors for which there are almost no routine measures. I agree with Aman that there are at least main categories of food and the grains are a good place to start. In the US, at least 90-95% of grains have been degerminated, affecting the most essential components of grains for the body, namely wheat germ, oat germ, etc. rendering most grain consumption so sterile that increasing levels of food sensitivities and deficiencies are a problem in the nation's public health.

Whole grains in terms of organic qualities are almost non-existent and almost all of it is consumed in overprocessed form. Adding synthetic nutrition does not, in my opinion, even begin to replace what has been taken out of the public food supply, and as a result we left with skyrocketing levels of diabetes type 2, cardiovascular disease, and cancer at unprecedented levels. Our healthcare costs are approaching $3.5 trillion per annum or about 20% of our entire GDP in a nation of only 320 million people.

Getting back to bioavailable nutrition, including the more critical but lesser recognized components mentioned above, and delivering in more organic form seems to me to be ideal. I appreciate the question being posed here and will try to contribute in a substantive way in terms of ideal goals in the science of nutrition.

I am not certain the basis or application of that 30 - 40% figure. Unless we are speaking of a culture or region with a limited access to a variety of foods, it us questionable whether there is cause to be overly concerned about such losses. As correctly stated above, there are important assets to consider, such as cooking as important adjunct to food safety, and cooking can also enhance bioavailability of various nutrients. Also to be considered is that there are usually other foods that provide these nutrients, and often times these other foods represent the primary sources. For example, cooking vegetables may destroy levels of vitamin C, but it is fruits, not vegetables, that tend to be the major source in most diets. This reinforces the recommendation for variety in food selection.

Yes, at our clinic we ask all patients to stop microwaving their food and go to convection, steaming, stovetop, etc. and always their health status improves dramatically. Method of cooking does matter. All research on microwaving and food safety was arbitrarily stopped by governments, for the early research was not looking good for the future of microwaving.

High pressure processing, reduction time of cooking and large pieces of food during cooking can somewhat protect food quality.

Many books have been written on this topic. In the popular press a good and recent example is 'Cooked' by Michael Pollan. Cooking, or food preparation using heat, is considered by anthropologists to be a positive influence in human evolution. Nutritionally, cooking techniques are very different. While some nutrients are heat sensitive, particularly those in fruit, slow cooking at low heat improves bioavailability of various essential nutrients, e.g. preformed vitamin A from meat, and beneficial phytochemicals, e.g. carotenoids from vegetables and leafy greens, particularly in the presence of fat or oil, such as olive oil.

Furthermore, as mentioned in Munira Husain's excellent response to your comment and query 'Cooking is required not only for destroying microorganisms, but it also denatures many natural toxicants, enzymes, facilitates chemical reactions and enhances food palatability - taste, texture, flavor, digestibility and assimilation, which are most vital for proper nutrition.'

However, some domestic cooking techniques - browning, smoking and charring - create undesirable by-products, such as advanced glycation products. Many industrial cooking techniques have created foods with high concentrations of undesirable products, such as trans-fats and high-fructose corn syrup.

In summary, nutritional value of legumes, meats, fish, grains/cereals, and vegetables [with oil] is improved by slow cooking. By contrast, nutritional value of most fruits is not improved by cooking. One cuisine that embodies these cooking concepts is the traditional Greek Mediterranean diet, as explained in the recent book 'The Mediterranean Diet' by Catherine Itsiopoulos.

You hit a lot of nails on tbeir proverbial head, Laima. And Ensiyeh's suggestion is well taken. The key word in Laima's comments, to me, is "carotenoids", for it is these elements of nutrition that are often overlooked. One of the follies of modern life has been the destruction of the acid barrier of the human stomach--hence, the exponential and almost universal rise of the grossly misunderstood "acid reflux" or GERD. The acid barrier is there to take care of many unfavorable micro-organisms, and when it is not, for public health reasons, it has to be accomplished at the processing, storage, and cooking end of the equation, thereby reducing bioavailablity of some of the needed nutrients.

Also, something we have not talked about, but to which I think Laima was alluding, is cooking oils. I have long advocated against use of the plasticized canola oils and advocated for the more organic extra virgin olive oil for the same reasons we advocate for better quality foods and cooking methods: the difference in terms of human health are marked. This is a wonderful and needed discussion and I thank all of you for your great insights.

To avoid cooking losses of mictronutrients:

- Wash vegetables before cutting.

- Avoid washing after vegetables are cut (it is the general practice in India).

- Pressure cook to the extent possible.

- Avoid deep frying to the extent possible.

- If lime juice is used, to add the same at the end of cooking and when the food - - preparation is not too hot (to preserve Vit. C, as it is thermolabile). [Same is the case with iodized salt].

- Avoid reheating of oils used for frying (it is Common practice in India

whenever possible

In order to enhance the nutritive value:

- germination of grains

- fermentation of dough (common practice while making idli/dosa etc.,)

- malting.....

To avoid nutrient loss some more good cooking practices are:

1. Avoid reheating of cooked food by consuming them first hand or cook food just before consumption.

2. Cook in covered pan.

3. Avoid excess of roasting or pan frying.

4. Use oils with higher smoke points like rice bran, peanut oil for frying.

5. Soak grains and pulses just in sufficient water before cooking.

6. Try to cook food in neutral medium; add acid or alkaline ingredients at the end or after cooking or at the time of serving.

It depends on the type of food in question, type of nutrient being addressed and the method of food preparation applied. e.g boiling, steaming and blanching of vegetables have different effects on different types on nutrients and amounts of nutrient loss. In the case of vitamin C., blanching minimizes its loss while boiling maximizes the loss. The same methods have different effect on micro elements e.g boiling increases iron availability and does not lead to iron loss in the vegetables. Therefore each food type, cooking method applied, and nutrient in question should be addressed separately rather than generalization.

Any cooking method that shatters the DNA, kills the amino acid chains, or in anyway changes the organic structure should be discouraged. To me and my colleagues, microwaving fills the bill as a cooking method that ought to be avoided. Someone commented a while back that this sounded "so 1980s", which I replied, "Sure it does, because that is when the US Government and others following banned all research relative to microwaving and public health consequences". Now, some 3 decades of assuming microwaving is safe at the macro level of public health, we find in the US every conceivable form of learning disorder and developmental delay grown by hundreds of times in young (1970s to today) and diabetes mellitus, cardiovascular disease, and cancer exploding manifold in the adult population. So, I repeat that any cooking method that changes the organic structure of the food so that the body has to exert more effort to synthesize the nutrition and accept it as "food" should be avoided. Does anyone else see this as a concern?

In brief, note the following

1. Cooking is essential for many foods, to make them edible, hence you cannot avoid cooking altogether. Cooking has many benefits in terms of making food more palatable, safe, and increases digestibility and availability of many nutrients. It also reduces anti nutrients in many foods.

2. Contrary to popular notion, cooking does not destroy all nutrients, only some of them, that too partially. For example vitamin C and thiamin are partly destroyed if high temperatures are employed. Time and temperature [ method of cooking] determines the extent of losses, higher the temperature, greater is the loss.

3. The cooking losses are generally taken into consideration, while recommending nutrient intakes, hence, if healthy meal pattern is followed, there is no need to worry about smaller quantity of nutrients lost in cooking.

4. Nutrient loss in cooking can be minimized by using appropriate temperature and time, not wasting the cooked or soaked water [ if applicable], and not storing the cooked food for too long a time.

high temperatures denature amino acids and the duration of exposure to the heat is another problem. all the comments made have a few things in common, we all concede that high temperature and long duration of cooking is detrimental to some nutrients in feed particularly vitamin C. Now a question that is left in my mind is, which temperature and duration is the best in minimizing cooking losses?

Almost all food preparation process reduces the amount of nutrients in food. In particular, processes that expose foods to high levels of heat, light, and/or oxygen usually cause the greatest nutrient loss. Nutrients can also be "washed out" through leaching of foods (specifically leafy vegetables and roots/tubers) by fluids that are introduced during a cooking process. For example, boiling Spinach or a potato can cause much of the potato's B and C (water soluble) vitamins to migrate to the washing or boiling water. You'll still benefit from those nutrients if you consume the liquid that is if the vegetable or potato and water are being turned into vegetable or potato soup. Similar losses also occur when you broil, roast, or fry in oil, and then drain off the drippings. In contrast, certain cooking processes may in some cases increase the availability of certain nutrients. Such is the case of lycopen and carotenoids, both of which are easier for our bodies to use once the foods sources rich in these nutrients have been exposed to heat. Cooking may also make our foods safer by killing microbes or making it difficult for them to grow and multiply which have a longer shelf life due to the lack of water available for bacteria to grow. And, simply put, cooking usually turns plain ingredients into a palatable meal. This is owing to the fact that during cooking, the cells of the food will soften which generally makes the food easier to digest. Some foods, such as carrots and tomatoes have a reaction during cooking which increases the quantity of essential nutrients such as beta carotene and lycopene, making it healthier to cook them before eating.

The exact amount of nutrients lost during cooking will vary depending on the characteristics of the foods and the processes followed. As long as they are safe to eat, try consuming your foods raw as often as possible or cook them in a way that will reduce the nutrient loss to a minimum (opinion).

The method of cooking will have a great impact on the foods nutritional value. As a general rule, the longer you cook your food, the more nutrients will be lost. This is also true for foods cooked on a very high heat. Over boiling vegetables will cause the most nutrients to leach out. The vegetables should be firm when cooked and retain their colour. If they are soft and the colour has faded they have been overcooked and lost most of their nutrients. You can try to combat this by using less water and cooking for a shorter period of time. You can also try using the leached vegetable water to make gravy although the nutrient content will be greatly reduced. A much healthier alternative to boiling vegetables is steaming them. You can either use an electric steamer or a steamer on the hob, this method of cooking helps to retain more nutrients. There is no water for the vitamins and minerals to leach out into and it is less harmful to the cells in the food than boiling. Also, some people opined that microwave cooking is one of the fastest cooking methods, so it helps the food to retain vitamins and minerals due to the short heating time. Stir frying vegetables is also a healthy option provided you do not cook them for too long.

Please don't forget most toxin are heat resistant and we should cook to increase proteins efficiency ratio and digestibility.

In the wellness clinics for which we provide consultation, many chronic inflammatory and metabolic conditions are routinely reversed, in part, by making basic changes in dietary and cooking methodology: Steaming vegetables to replace boiling, using small convection in place of microwaving, avoidance of GMO where possible, most especially strict avoidance of GMO high fructose, at least one-third of the diet of (non-irradiated) fresh fruits and vegetables, using only organic (non-irradiated) whole grains in cereals and baked goods, convection cooked fish, chicken, pork, beef (in moderate quantities), etc. Typically, diabetes mellitus type 2 moderates (A1C score

I think that most important facts to approach a better nutrition is eat as much as possible raw (fish or meat) and use as much as possible steam or pressurised food (press cooker). TRy to avoid oil, olive oil is sales and least possible fried food. Avoid prepared frozen food and NEVER eat fast food. Food preservatives like EDTA are harmful. 125 mg per day are toxic, and EDTA are in almost everything is prepared from candy lollipops, canned food, dry snacks, etc.

what scares me the most about raw meat is that there are lots of micro organisms that might be there and some parasites use animal meat as vectors. for example Helminths in pork.

Yes, Sipho, new e Coli strains are ever on the rise, because of it.

That is also true. However we were talking about digestibility. On how much the cooking process harm the protein to be assimilated

Yes, Maria, a close consideration in the digestibility department is the falling stomach acid levels in the population, which also brings on increasing acidosis and metabolism-related conditions. We find in our research and work that cooking methods have a great deal to do with this, adding another layer of issues with the loss of the acid barrier in the stomach that would normally eliminate many of the organisms over which so many public health programs are concerned. So the issue becomes a double edged sword, reduce the acid in the stomach (medicine's current false solution to GERD), requiring overcooking of food to assure safety from unsafe organisms AND decreasing food to nutrition synthesis bringing more chronic disease and deficiencies. I am attaching here two of my monographs that may help fill in the blanks on the issue of digestive disorders.

one more.. cooking degrades around 30-40% of nutrition. It means cooking helps to reduce the nutritive value food there by reduce obesity. one approach to reduce obesity is by reducing the biological value of nutrients.

why not decrease the amount of colesterol in food to avoid obesity. its like Max said, we need to find a balance between not losing nutrients and also the safety. Same with obesity, we need to fight obesity without degrading the nutrition of the food. what you sugesting Kalkidan has some logic but i think it will just create another problem of an unhealthy society thats suffering from nutrient deficient diseases instead of obesity.

We need cholesterol to form our cells. Lots of it actually, and certainly more than many people realize, but we don't need it from saturated fats or transfats. Instead, we need monosaturated fats (extra virgin olive oil, etc.) and certain polyunsaturated fats (Omega-3/Omega-6). And I say this with all due respect. We need the kind the body makes, but not the VLDL, which is really one of the main culprits for CVD albeit a secondary one--it would not exist if our livers were not so alkaline and stomachs so short of HCL and pepsin. When we try to bypass the underlying cause by taking statins we only make the body work harder at making the wrong kind of cholesterol and never win the battle. What's on paper for a test score is relatively meaningless in terms of gauging "success" with synthetic statins. Success is when our bodies make the right kind of cholesterol on its own, and an abundance of it to meet our needs.

The problem is the rise in acidosis in the population from dietary and hydration anomalies, and the terrible empty calories the population is eating. Today, in the US, we have a population starving for nutrients with no sense of satiation to tell them when they've had enough. The low fat diets (Pritikin comes to mind) are dangerous.

The sterilization of the food supply has gone overboard and has forced society to add synthetic nutrients that in and of themselves are harmful to the body. The body is begging for organic nutrition, so that when metabolic needs are met, we go to our natural body weight. But when the diet is sterile and synthetic--wearing out immunology and metabolic functions--added to sedentary lifestyle, we find unprecedented rises in diabetes and obesity.

In our research we find changing to an organic diet, avoidance of high caffeine and other harmful substances, with adequate hydration and exercise and sleep, that bodies return to their ideal health state and weight level...everytime.

In my opinion, the best method of cooking is that the highest to preserve the nutritional value of the food and also to enhance the bioavailability of nutrients in food which depends on the type of food. However, one of the best methods of cooking could be achieved by semi-cooking of the food in which the digestability is increased & the nutrients loss will become minimized. This can be applied especially for fruits & vegetables. But for meat, fish, ....one of the proper methods is to marinade them to soften the texture. And then, barbecue, grill, roast them but with lower flame called

What about high-pressure processing of foods? Since, the process preserves maximum amount of nutrients and it has been proved that the process retains colorants and nutrients at the maximum levels. Certainly, the process is expensive and only currently practiced for premium foods like fresh squeezed orange juice, dairy and meat products.

While high-pressure processing of foods may preserve nutrients better than other industrial food processing methods, an orange is nutritionally superior to its juice, regardless of the quality of the juice extraction method or the freshness of the juice. It is encouraging that improved, albeit expensive industrial food processing methods, such as high-pressure processing are emerging. Currently, industrially processed meat products rank poorly in nutritional quality and health benefits when compared with traditionally cooked fresh meats. This may relate to the difference in objectives that underpin traditional/home and industrial food processing methods.

Laima and Jasim, and Mahnaz, all excellent and well considered comments! Keywords, home, organic, whole foods, say it all.

If the overall concern is achieving 'total nutrition' then I would not worry about cooking losses or gains. As long as the total daily diet drawn from a variety of food groups is consumed as per age and gender needs, the human is capable of optimizing nutritional need. On the contrary, deficient diets [anorexia or poverty] leads to nutritional deficits.

Tilakavati, appreciate your comments. In the United States, one can have marked nutritional deficiencies bringing a large range of chronic conditions just from eating the typical food available in our supermarkets. Irradiated, degerminated, over-processed, toxic additives, genetically modified, synthetically fortified, microwaved, and what we have are pandemics of every imaginable chronic disease--typically treated with more toxins we call medicines. We are a nutrient-starved population suffering the consequenes of such short-sighted modernization. So, this brings us back to how can we get the mass produced food supply back into the organic, live, whole food category, where we find almost instantaneous improvements in every category of public health?

I wonder what you all think about the work of Nora Gedgaudas (http://www.primalbody-primalmind.com/ ) and the wider movements against grain based diets?

I've not read her book, but after reading most of her website about it I just placed it on my To Do List, Martin. Particularly, I found her Top 10 Nutritional Mistakes right in line with our own findings. I might add that heavy metals play a far greater role in today's chronic and developmental conditions for people of all ages than most professionals realize, especially since the amount of lead (and other metals) in the soils where the food is grown has become so proliferate. We address the heavy metal issue in our consultation firm but find a virtual blackout in the clinical community. Rather allopathic approach has accepted the terrible practice of using pharmacological management of the symptoms of heavy metal toxicity instead of getting rid of the metals from the human body. Of course, the latter holds far less promise of profits compared to the former approach. Thanks for bringing this book to our attention.

Max, we should take the -Where is the evidence?- approach. Supermarket aisles in the US may be filled with processed food of every denomination [even organic foods] BUT our physiology cannot differentiate these differences at 1st action- absorption. The dietary role of non-communicable diseases [NCDs] is only implicated at this stage in relation to carbohydrates, saturated fats, salt, sugar , low fibre etc. The other aspect to consider is lack of physical activity.

There is much to what you say, Tilakavati, but we see the effects of irradiation, etc. which the body can differentiate by virtue of the missing co-factors that identify the nutrients and in its attempt to convert the nutrients into a useful form. The food additives are troubling, even the added synthetic nutrients. The evidence is buried from the standpoint of big dollar research, which is almost always conflict of interest. The lesser research-demonstrating efficacy of truly organic nutrition--is underfunded and of small populations. The Pied Piper of biased research marches on telling us that the huge pandemics we see in cancer, diabetes, and cardiovascular disease are caused by caloric consumption and lack of physical exercise, yet we see case after case of those who diligently follow the food pyramid, exercise regularly, and limit caloric consumption and STILL number among the chronically ill. The burden of proof is actually on the big dollar research to begin to differentiating between what their backers claim (that there is nothing wrong with pharmaceuticals and what the mass food industry is providing) and that these do not link to the huge increases of chronic disease in our population. On a case study basis, in the cases for which we are called upon to consult, we see solid and repeatable evidence that changing the diet away from the current paradigm and away from pharmaceutical solutions ALWAYS brings dramatic improvements in metabolism and the diseases related to it. In our thinking there is so much wrong with the current mass food provisions and with pharmaceutical treatments for long-term chronic conditions that we see the need for changing the entire system to that that is more organic, less dependent on synthetics, and for sure refraining from the irradiation process that plagues the American market.

We need to avoid generalisations and stick to available science as it evolves. The problem with the diet approach is there are too many variables and difficult to pin down a direct cause-effect and too expensive. This area is not like pharma research. Yet there is some evidence from observational studies. On a case-based approach I treat my patients [diet] using the evidence-based approach- their individual dietary patterns titred against clinical outcomes.

With the amounts of chemicals used in cultivation of food crops and in animal products it is important to cook the food slightly prior to consume and the processing method should be able to enhance the bio accessibility of the major nutrients available in the commodity while minimizing the toxic substances.

Dr. Max, that was the great issue in nutrition & health which you mentioned. Unfortunately, this is an ugly fact that we are surrounded by the toxins and chemicals even in colorful food items rich in phytonutrients, nutraceuticals,... which are reported to be healthy & useful for the body!

So, the only way to keep our body healthy is to eat wisely & moderately, being aware of hazardous sides of healthy foods & meanwhile, try to detoxify the body regularely by nutritional detoxifications & of course physical activity which acts as a pump to remove the toxins from the human body.

That is the mission of nutritionist & health scientists to warn people of both ththe beauty & ugly facts about the today's food & nutrition.

I realize that, Tilakavati, am traveling overseas & attempting to stay in the discussion with no resources at my fingertips. What is complex to us in research is really quite uncomplicated to the body. Amazingly many serious conditions from autoimmune disease to neuropathies to metabolic disorders clear up almost spontaneously in the patients that follow the pattern I mentioned earlier. It will be for science to explain it and so far the most accepted evidence to date denies it happens. When I am in a more resourceful situation I will share aspects of evidence but at this point can only provide general direction to the curious. The study done by my colleagues at Princeton found for instance that every rat gained weight & developed fatty tissues around the heart when given equivalent quantities of HFCS vs cane sugar. Yet HFCS completely inundates the US food supply & obesity is exploding unabated. Bromulated vegetable oil permeates huge swaths of the food supply and while the research shows detriment to many individuals it continues without protest from the scientific community. Aspartame permeates artificially sweetened food products of which the science demonstrates serious toxic effects and caffeine studies shows the incredible increase of high caffeine drinks portends conditions from hypertension to adrenal depletion and proliferate intoxication effects. Yet all this evidence is ignored by mainstream food scientists. These are not generalities but represent serious public health threats that have exploded incidence of chronic disease across the nation. Diabetes & prediabetes have grown by 13 times since 1970s in the US, CVD by 17 times, cancer if all kinds by 25 times. And. The costs of heAlthcare reflect same. The food supply while not the sole culprit is by by the largest driver behind the pandemics if our population while we wait for the (accepted) science to catch up to the reality.

Scientists have to build the evidence. I am not a layman. For instance I work in the area of interesterified fats and trans fats. IE is now the replacement for trans fat in the food supplu. We exchange more as we go on. I am leaving for Melbourne to attend the World Diabetes Conference.

Great work, Tilakati, we will catch up on the topic at hand in time Developing models on the development of diseases and as a behavioral medicine consultant is my work. So we see the real life results of current trends and are hoping for bold changes in the current trends that have brought us where we are today. Thank u for the cordial exchange.

Great discussions and discourse about this important topic. My concern given social impact of this topic is that this is "Research"gate and to me comments and discourse need to be supported by research and there seems to be a lack of scientific evidence provided in this discussion. I hold my students to a standard of referencing statements, and I would expect that in a research forum. I think this thread would be improved if we discussed the science about these issues (e.g., processing on bioavailablity). For example, if something is undesirable does that make it unhealthy? Is dose important? What about the type of methods used to test, in vivo human, in vivo genetic-specific rodent, in vitro, etc? I am sorry I did not read all of the responses to note whether these were incorporated in the thread, but -- as noted by Florence -- methodolgy is important.

For example, this study by Bugianesi et al (2004) http://www.ncbi.nlm.nih.gov/pubmed/15309458 reported that cooking cherry tomatoes increased the bioavailability of specific polyphenols compared with raw, and eating the raw vegetables did not elicit increased bioavailability of any of the nutrients studied. Thus, according this evidence, cooking actually increases the nutrition of cherry tomatoes (relative to nutrients assessed). Granted, a limitation is that this outcome may only occur in cherry tomatoes, and/or may only pertain to certain nutrients. Maybe cooking/processing disrupts the cell membrane of plants thereby making the nutrients within the plant more bioavailable. Is there research to support this? Or, put another way, if nutrients do end up in the waste water (if boiled) does that mean that we would absorb them? I would need to see evidence that the bioavailability from the raw food was superior to the cooked food - this was not the case in the cherry tomato study. Also, noted in the study's discussion, was a study by Stahl and SIes where cooking tomato juice increased lycopene concentration in plasma. Again, maybe tomatoes are the exception.

Steam boiling and microwave heating are generally seen as the best ways to preserve sensitive micronutrients.

There are many negative views on microwaves, so not sure what "generally" refers to?

Here are some:

The majority of studies on microwaves and nutrition were conducted prior to 2000, I suspect because the focus of radiation research of late has shifted toward a more ominous threat: environmental radiation from electromagnetic devices, such as cell phones and computers, which has mushroomed into a gigantic cloud of electrosmog worldwide over the past decade.

Nevertheless, some excellent scientific data has been gathered regarding the detrimental effects of microwaves on the nutrients in your food:

•A study published in the November 2003 issue of The Journal of the Science of Food and Agriculture[5] found that broccoli "zapped" in the microwave with a little water lost up to 97 percent of its beneficial antioxidants. By comparison, steamed broccoli lost 11 percent or fewer of its antioxidants. There were also reductions in phenolic compounds and glucosinolates, but mineral levels remained intact.

•A 1999 Scandinavian study of the cooking of asparagus spears found that microwaving caused a reduction in vitamin C[6] .

•In a study of garlic, as little as 60 seconds of microwave heating was enough to inactivate its allinase, garlic's principle active ingredient against cancer[7] .

•A Japanese study by Watanabe showed that just 6 minutes of microwave heating turned 30-40 percent of the B12 in milk into an inert (dead) form[8] . This study has been cited by Dr. Andrew Weil as evidence supporting his concerns about the effects of microwaving. Dr. Weil wrote:

"There may be dangers associated with microwaving food... there is a question as to whether microwaving alters protein chemistry in ways that might be harmful."

•A recent Australian study[9] showed that microwaves cause a higher degree of "protein unfolding" than conventional heating.

•Microwaving can destroy the essential disease-fighting agents in breast milk that offer protection for your baby. In 1992, Quan found that microwaved breast milk lost lysozyme activity, antibodies, and fostered the growth of more potentially pathogenic bacteria[10] .

Quan stated that more damage was done to the milk by microwaving than by other methods of heating, concluding:

"Microwaving appears to be contraindicated at high-temperatures, and questions regarding its safety exist even at low temperatures."

•Another study about breast milk/infant formula by Lee in 1989[11] found vitamin content becomes depleted by microwaving, and certain amino acids are converted into other substances that are biologically inactive. Some altered amino acids are poisons to the nervous system and kidneys. (Numerous authors mention this study, yet I was unable to find the original article/study, so I cannot personally validate.)

Although many of the above studies are not new, there is certainly ample evidence that microwaving is NOT good for your food.

From: http://www.huffingtonpost.com/dr-mercola/microwave-cancer_b_684662.html

which also goes into the health problems of simply having that monstrosity running in your house:

"Even when the microwave oven is working correctly, the microwave levels within the kitchen are likely to be significantly higher than those from any nearby cellular phone base-stations. Remember also that microwaves will travel through walls if the microwave oven is against an inside wall."

A recent study examining the effects 2.4 GHz radiation (which is the frequency of radiation emitted by Wifi routers and microwave ovens) on the heart was just completed. The study found "unequivocal evidence" that microwave frequency radiation affects the heart at non-thermal levels that are well below federal safety guidelines, according to Dr. Magda Havas of Trent University [4] .

Dr. Havas says:

"This is the first study that documents immediate and dramatic changes in both heart rate and heart rate variability caused by an approved device that generates microwaves at levels well below (0.3 percent) federal guidelines in both Canada and the United States.

===============================================================

So, *generally*, I think you can say that nuking food is not *generally* considered very good.

At any rate, one needs to find a balance between - on the one hand - reserving nutrients and - on the other - treat them so that that the body can digest and absorb them. If a food is full of this and that according to a laboratory microscope, then that does not mean that it will end up in your system. There can be anti-nutrients interfering, sugars that feed bad bacteria and slows digestion, and uncooked (or otherwise untreated) food from plants might have such a strong cell wall that we can't get to it. Grains, for instance, are a difficult thing to digest, After millions and millions of years evolution shaped certain plants with seeds that are so attractive looking, but strong and durable that all the plants had to do to commence their world take over operation was to invent animals to distribute them. As Terence McKenna said:

“Animals are something invented by plants to move seeds around. An extremely yang solution to a peculiar problem which they faced.”

A grain has been shaped by evolution so as to endure the digestive apparatus of mammals that move them around for transplantation.

A very different tangent is careful techno-treatment: the vegan raw food biohacker/alchemist movement also offers some useful insights. Here is a good introduction:

"Harmony with Living Raw Foods & Chinese Medical Diet Therapy: The Spleen Qi connection" - from http://rawfoodsolution.com/harmony-with-living-raw-foods-chinese-medical-diet-therapy-the-spleen-qi-connection-2412.html

I have my papers on this somewhere at home from my chemical nutrition course, I will try to find them and see what they say.

HI guys....i am agree with Florence, too. The cooking methods is really important to evaluate the nutrition composition of a food. In addition there are some compounds that are bio-available only after cooking....and others that are inhibit after any kind of cooking.

I have some papers regarding both situations. I will post some of them.

After that, we can continue the discussion :)

Answer to Martin

"The effect of microwaves on nutrient value of foods"

DOI:10.1080/10408398209527340

In this paper is reported that the effect of microwaves on food nutrient is minimal, especially for vitamin.

I think that a serious problem is the "heterocyclic amine", that can occur when, for example, meat is cooked on direct fire (barbecue) for a long time. These substances are responsable for cancer risk.

So, please help me here, I am lost. The response to current studies is a 1982 study with the conclusion that "no significant nutritional differences exist between foods prepared by conventional and microwave methods. Any differences reported in the literature are minimal"? And this paper refutes papers with different conclusions written twenty years later? And a paper written by someone with close relations to a "professional organization for the advancement of food science and technology"?

Since I don't have access to this evergreen gospel paper, I also cannot consider what "conventional" here refers to - conventional in which culture, in which era, and so on?? - but for argument's sake, let say that "conventional" here refers to peasant style vegetable cooking, which takes place in a large pot always on the fire with an eternal soup/broth/stock in the making, where largely all the nutrients are in the stock. Should I fish out a broccoli from such a medium, then it seems plausible that nuking it at, say, 2,450 MHz might not be worse in terms of what can subsequently be found in a broccoli examined in a lab. (The difference here being that in the former case, of course, you eat the stock).

At any rate, twenty years later we get:

"•A study published in the November 2003 issue of The Journal of the Science of Food and Agriculture[5] found that broccoli "zapped" in the microwave with a little water lost up to 97 percent of its beneficial antioxidants. By comparison, steamed broccoli lost 11 percent or fewer of its antioxidants. There were also reductions in phenolic compounds and glucosinolates, but mineral levels remained intact."

and there was also this:

•A 1999 Scandinavian study of the cooking of asparagus spears found that microwaving caused a reduction in vitamin C[6] .

•In a study of garlic, as little as 60 seconds of microwave heating was enough to inactivate its allinase, garlic's principle active ingredient against cancer[7] .

In other words, I might argue that the earth is flat because someone once upon a time said so, notwithstanding what we've learned since?

Ok, granted, sometimes old discoveries (like the gut/brain connection for instance) disappear from view and have to be rediscovered, so I set about investigating the author of the paper further. It appears that he is closely associated with IFT:

“Founded in 1939, the Institute of Food Technologists is a nonprofit scientific society with 28,000 members working in food science, food technology, and related professions in industry, academia and government.... [that] advances the science and technology of food through the exchange of knowledge.” (http://www.ift.org/inside/; accessed 10/02/02)

So, according to http://www.cspinet.org/integrity/nonprofits/institute_of_food_technologists.html - Integrity in Science,

Sponsors of the IFT’s annual World Congress of Food Science and Technology included:

Gold Sponsors

Procter & Gamble

U.S. Department of Agriculture

Coca-Cola Company

Silver Sponsors

Kerry Ingredients

Monsanto

Silver Contributor

Archer Daniels Midland Company

Bronze Sponsors

Land O’Lakes, Inc.

(http://www.worldfoodscience.org/worldcongress/sponsors.html; accessed 10/02/02)

My confidence is to say the least rather low now. And I think I will stick with steaming and boiling and frying.

"The effect of cooking methods on mineral and vitamin contents of African catfish"

Beyza Ersoy, Akif Özeren, Food Chemistry, 2009

...you should accept that the litterature is controversial.....

anyway it depends on kind of food and way of cooking....there is not a "general roule"

The theme is interesting but the microwave process is similar at the convectional on the vitamins. But is more quickly and it's a "convenience"process.

Martin, I'm with you. Many people may not realize that further research into microwaving and food safety was stopped in about 1989 by I believe NIH. In our practice we found so many cases of diabetes 2 and other conditions clear up almost spontaneously when microwaving was stopped and better methods used that we ourselves stopped microwaving 12 years ago and my own diabetes cleared up, we both lost weight, my asthma disappeared, my bad heart valves from years of rheumatic fever went back to normal within about two years. Seeing these kinds of things repeatedly with hundreds of patients we decided to add avoidance of microwaved food to the list of "what to do if you really want to get well". Squelched science is not good science as you well know and the absence of proof is not necessarily proof of anything. We see the ridicule of those who say microwaving is healthy. But they have yet to see an honest discourse on the topic. Our view is nothing live survives the DNA shattering of microwaving. Dead, lifeless food is a cause of acidosis and a host of metabolic diseases.

Instead, we advocate to our patients: fresh foods, slow cooking, steaming, convection, some stovetop (never boiling if nutrition is what is aimed for), baking, some grilling. Microwaving changes the food quality too much for our liking & encourages use of over processed foods that have little healthful value. Emerging evidence through testing for carotenoids all but eliminates microwaving as a cooking method and processed foods as a food source of choice. Now, I understand that the science is not yet robust in these statements (politics and economic interests too often dictate where science goes) but anecdotal evidence and common sense are sufficiently strong for informed individuals to take pause amidst the pandemics in metabolic disease, obesity, CVD, and the exploding rates of cancer we see from current dietary trends.

@ Francesco, who said: ...you should accept that the litterature is controversial.....

anyway it depends on kind of food and way of cooking....there is not a "general roule"

I completely accept that. Most science is controversial, because nothing emerges from a socio-cultural vaccum. There are always agendas, ulterior motives or mindless parroting possible. From large corporate interests in food processing through producers of electrical appliances to drug pushers of all kinds - including socalled alternative drugs and herbs - there are potential influences for which a keen reader must correct - or against which one must contemplate.

So in this case, as often, we can follow the money, for instance, and the 1982 paper leads straight back to some of the world's most damaging industries and generally to food processing and technology interests. When you have such interests mingling with the scientists writing the paper, then all alarm bells go off and that paper hits the bin in my assessment of the controversy. It is advertising, not science to me.

And, guess what, as Max has noted above indirectly, there is a common rule and that is commons sense: eat good food and good food is not nuked, processed and filled with additives. If that is too controversial for you, then good luck with sticking to Monsanto food, which might in fact be better nuked, for who knows what it contains?!?

Variety is the spice of life. Try different foods in different combinations and of course with different cooking methods and even raw, as some vegetables. Currently the traditional cooking methods and ways to prepare foods are safer and of course, the best. Do not believe in myths...

Usually to preserve the nutrition of food, it is better to cook the food in a pressure cooker and on a low temperature.Vitamins especially water soluble are stable during cooking at low temperature. Avoid using too much of microwaves to cook the foods, because it will change the structure of water molecules and other compounds and convert them to active substances like free radicals which are harmful for body functions.

An interesting discussion, diverse opinions and many useful suggestions, and Ali, good input on the topics of interest to Arvind - firstly, his view on the impact of heat processing [cooking] on food and, secondly, his question on ‘the way’ to preserve the ‘nutrition of food’.

Arvind, your assumption that cooking [or heat processing] degrades about 30-40% of ‘nutrition’ in [all] food is incorrect and not a useful view to cling to. At this stage of the discussion it may be apparent that NUTRIENT losses in foods due to applied heat/cooking are dependent on many factors, including the type, intensity and duration of applied heat as well as the food type, variety and size. It can be minimised in many ways, as already well discussed.

To directly answer your question about ‘the way’ to preserve the ‘nutrition of food’ requires some terminology correction/clarification, Arvind. While your interest in preserving NUTRIENT LEVELS in foods is important, more relevant to health is the NUTRITIONAL VALUE of a food to an individual. This depends not only on the level of all nutrients in a food, but also on the portion size consumed [collectively known as NUTRIENT INTAKE]. Once consumed, the bioavailability of the nutrient [which may be improved by cooking, as with lycopene in tomatoes, or by the consumption of synergistic nutrients, such as iron and vitamin C], the metabolism of the nutrient [which is tissue-specific and can be influenced by other compounds [nutrient interactions]] and an individual’s nutritional status (replete, depleted or deficient in specific and related nutrients) all influence NUTRIENT UPTAKE. Nutrients, both macronutrients and micronutrients, form the substrate from which other compounds important for health are manufactured in the body e.g. enzymes, endogenous antioxidants etc.

OPTIMIZING NUTRIENT INTAKE AND UPTAKE PROMOTES HEALTH. This is the basis of NUTRITION SCIENCE. Non-nutrient and toxic compounds in [and on] foods that can affect an individual’s health are a part of this science and of great interest, but not directly related to your question on ‘the way’ to preserve the ‘nutrition’ [I think you meant ‘nutrient levels’] in food. The effect of processing on foods is FOOD SCIENCE, and this is only one, but important, component of nutrition science.

I hope defining some basic terms and concepts in the science of nutrition may be of assistance to some, while acknowledging that many in this discussion take these basics for granted.

For simple but valuable guidance in a minefield of many and conflicting nutrition messages, my favourite is Michael Pollan’s statement: 'Eat food. Not too much. Mostly plants.' [Food defined as minimally processed].

I said before, variety is the spice of life!.

Laima, thank you for contributing a remarkably insightful post here. You are correct that the percentage of nutrient loss is so variable and may not even occur with certain kinds of nutrients and preparation methods. In fact, once we have eliminated questionable methods (microwaving, boiling vegetables) from the discussion, conversion to more useful forms of the nutrient enter the bioavailability stage and we find that cooking ADDS to the quality of the foods and its digestibility. One of my long standing concerns is that we need to refine how we label or identify a given nutrient, for the stripped down models now used in science are much oversimplified compared to what the body greets upon intake as the nutrient in its much larger universe of components. Just because we can measure the survivability of the simpler structure via a given cooking method does not mean we are home safe for the larger schemata of bioavailable nutrition, or we could look elsewhere for the culprit that is responsible for increasing prevalence of chronic diseases in modern societies. But nutrition is still where it's at, as any informed observer will note, if we are ever to improve the health state of the population. Thanks again for your most cogent input and thanks to all of you who've brought out important considerations in the discussion.

Yes, Ana Maria, variety is indeed the spice of life and of health. Having a larger variety of food sources and forms, indeed, correlates with better health in my observation.

Glycation is non-enzymatic covalent bonding of a sugar residue to amino groups of proteins .But glycosylation is enzyme-controlled addition of sugars to protein or lipid molecules.Glycosylation occurs at defined sites on the target molecule and is required in order for the molecule to function.

BMI ranges do not depend on genetics human. It can be applied to all the population in the world .But it depends on type of nutrition and environment.

I would just like to add a comment to Martin. I eat a large bowl of microwaved (steamed from the inside out, which is how a microwave works by creating friction btwn the water molecules and therefore heat) colored peppers, carrots, broccoli, asparagus, bok choy, tomatoes and kale (all organic and mostly local) 5 nights a week and I'd like to know why this is considered processed food? Someone please send me a stitch of evidence that microwaving is harmful and/or causes nutrient loss? Don't throw the baby out with the bathwater please!

....one of the last paper in literature about the quality of raw milk....

Boiling or microwave?....of course microwave...

Check out an answer to a similar question I posted in my weekly newspaper column. http://t.co/PuSZ2DZrc2

Also be sure to check out the cited article in Scientific American that covers this issue.

EB

Nowadays high amount of pesticides are used in agriculture especially in the developing countries. similar situations may exist in the other parts due to high demand for agricultural commodities. Even though a substantial level of nutrient loss is reported due to cooking it is advisable to cook or heat treat the fresh vegetables and fruits prior to consume.Or else should think of minimal processing of food stuffs which will have a positive impact on nutrient preserve and at the same time the method employed should be able to remove the pesticide residues that may remain in the food. My opinion is to increase the level of organic farming and if not if we still have to consume the contaminated food rather than worrying about the nutrition loss, to avoid the resulting diseases we must always cook the food efficiently before use.

Some protein may be lost if vegetables are cooked in water containing salt and the cooking water is discarded. There causes considerable loss of minerals, especially Sodium, Potassium and Calcium due to leaching. It is therefore advisable either to cook in a minimum amount of water or to use the cooking water in soups and gravies.

Some protein may be lost if vegetables are cooked in water containing salt and the cooking water is discarded. There causes considerable loss of minerals, especially Sodium, Potassium and Calcium due to leaching. It is therefore advisable either to cook in a minimum amount of water or to use the cooking water in soups and gravies.

It is best to steam vegetables that must be cooked. We advise patients at our clinic to help reverse chronic disease conditions to make sure that at least 50% of the quantity of their daily diet consists of fresh fruits and vegetables and nuts. We call food "nature's vitamin delivery system". Supplementation should only be used to deliver that which is not available in food or for well defined therapeutic purposes.

Cooking of foods is generally done to increase their shelf life or to increase the palatability of the food.

1.For Fruits and vegetables it is always suggested to eat them raw and fresh or to subject them to minimal processing like blanching to increase the palatability and reduce the nutrient loss.

2.For Milk, it is really surprising that even after knowing that boiling results in the depletion of nutrients we have tendency to reboil the milk whenever we consume. It is good to consume sterilized milk directly without reboiling it as the microbial load is already controlled by the sterilization of milk.

3.For meat and meat products, it is always good to boil them at low temperatures for softening of tissue and helps in the proper availability of the nutrients.

4. For legumes it is always good to boil them with the required amount of water and the excessive water can be utilized for other foods without draining them out.

Eventhough we know the fact that cooking results in loss of nutrient we should also ensure that food we consume is safe. So it would be always better to consume foods by minimally processing them or with a combination of methods to ensure safety and quality.

It is always good to have foods which form a balanced diet. So, as we cannot control the loss of nutrients completely it is always good to have a combination of foods for necessary nutrition.

Good points, all, Kollu. Being ever conscious of the nutritive residuals of what is cooked is one way not to unncecessarily waste that which can benefit one's health.

The degradation of nutrition of food depend on the way of cooking and also the condition of food you are cooking. Therefore food knowledge, Food ingedient, Interaction of food components will help you to choose the best cooking methods you want to use in trying to minimize the degradation of nutrition

I believe the 30-40% figure is for vitamin C, not for all nutrients. Many nutrients, especially minerals and flavonoids, are MORE bioavailable if food is cooked. Anthropologists believe that cooking is what allowed our species to evolve large brains that have metabolic demands.

On the button, Paul. Good points. The amount of glucose burned by the human brain is phenomenal and sometimes rivals that of the rest of the body (when the body is in resting state and the brain is busy). I thought this an interesting explanation on the brain/glucose connection and humans' unique evolved ability to keep the brain going when everything is about shut down: http://io9.com/5941883/how-your-body-fights-to-keep-you-alive-when-youre-starving.

Cooking is essential for certain products before it can be used for food purposes, it enhances organoleptic acceptance of that food and also enhance digestibity of the food by human body. During that heat processing surely some of the nutrients specially vitamins get lost. Researchers are now using the concept of minimal processed food to avoid or lessen these losses, that may use include techniques like, HTST, irradiation, high pressure processing etc. HTST is very common in dairy industry where milk is heating for 3-4 seconds only at very elevated temperature. That will cause the killing of bacteria but vitamin will not destroy at this time temperature processing.

Nutrients are lost from foods due to leaching out from the foods or being destroyed by heat applied in the process of preparation. Heat brings about many changes in constituent molecules of the raw food. The effects are directly related to intensity of applied heat and duration of treatment. Mild heating usually causes only slight loss. High temperature may be considerably destructive. Common methods of preparing foods by heat treatment in the households are grilling, baking, stir and deep frying, and heating in an aqueous medium (cooking). Of these, grilling, baking, and frying involve high temperature treatment. Food stuff at these temperatures may caramelize, or produce Maillard reaction products. Maillard reaction is a conjugation between aldehyde group of sugars and free amino group (also imino nitrogen of proline) of proteins. The epsilon amino group of lysine is conjugated, rendering this important amino acid nutritionally useless. In short treatment this usually affects only the surface of foods. Hence, loss is usually insignificant. However, some East Asian cuisines marinate food with good amount of palm sugar before heat treatment. In the process of marinating, considerable amount of sugar can seep into the food. Loss in such preparations may be substantial. Cooking is a low temperature process. Maximum temperature that can be attained is near boiling temperature of water, with exception of pressure cooking. However, leaching out of unbound water soluble nutrients in the cooking medium occurs in this method of food preparation. Discarding the cooking medium causes a loss of the nutrients that leaches out. On the other hand, consuming the fluid as soup/gravy or as Indian curry mixed with staple will retrieve the nutrients. One most discussed nutrient loss is the loss of vitamin C. I would like to refer you to vitamin C content of potatoes prepared by heating in different environments/conditions in the USDA-ARS nutritive values of foods table. Potatoes cooked without skin are much lower in vitamin C than those cooked in skin. I guess this difference is due to not taking into account the amount lost to the cooking medium, which is the usual practice. Pressure cooking may not be a good choice. Pressure cooking accelerates changes brought about by the ordinary cooking method by applying high temperature, which may also accelerate changing of the labile nutrients. Water soluble nutrients are also lost in dripping. Another factor that causes significant loss of vitamins, particularly B vitamins, is the pH of the cooking environment. They (especially thiamine) are labile in an alkaline medium. This happens when sodium bicarbonate is used to soften unleavened breads (e.g., chapattis in India). Sodium hydroxide left behind after the carbon di oxide is driven out by heat makes an alkaline microenvironment in the dough. This can be avoided by using baking powder, in which phosphate controls pH, or preheating the flour with water to make dough that makes soft chapattis, instead of using sodibicarb. For rice eaters, it better to use parboiled rice. Nutrients from the outer layers seep into the endosperm during parboiling. This drastically reduces loss nutrients in milling and later cooking.

Excellent and valuable information, Moududur. We generally advocate that at least 50% of one's diet should be fresh vegetables and fruits if one wants to enjoy optimal health from their diet. Also, steaming instead of stove top for vegetables that must be cooked. The pH information is excellent, also. Thank you.

As I mentioned in our previous discussions though cooking reduce the levels of certain nutrients, on the other hand it increase the bio availability and digestibility level of some other nutrients. The important thing is it can efficiently reduce certain anti-nutrient factors naturally available in the food itself as well as the toxic additives which are present in the food due to various factors (deliberate and in deliberate adulteration,etc). As discussed food processing condition depends on the type, nature and the requirement regarding the food stuff and it is better to go for composite food mixtures. In order to compensate the nutrient loss during cooking and increase the more efficient availability of the existing nutrients can apply various post cooking steps. For example when you cook green leaves prior to consumption you can add lime , etc in order to make vitamin C available and it also can enhance the available Iron absorption of the food stuff. Therefore should use the correct art of cooking that should be able to make food more palatable and nutritive as well as eradicating the harmful effects.

But unknown to many, lots of veg's & some fruits are more nutritious when cooked! Eg. red peppers, carrots, tomatoes: crack that cell wall with heat & boost your carotenoid/lycopene boost from these foods! Steamed spinach for eg also lowers oxalates, which can interfere with iron or calcium bio-availability. Boiling can leach out water soluble vitamins so best to steam or microwave (which is steaming from within through water molecule friction, no need to add water)

A cocção deverá ser realizada com o corte, temperatura , tempo e quantidade de água devidamente analisados. A cocção a vapor e à seco, como ao forno, continuam sendo maneiras de reter nutrientes. O remolho para as leguminosas e alguns cereais é indicado.

I differ with this concept that Food cooking degrades around 30-40% of nutrition. In Ayurveda for famous formulation Chywanprash where Amla is 50 % to other ingredients & is a very rich and natural source of Vit - ‘C’. The value of Vit - ‘C’ is well recognized in the finished product. But it is preserved during the boiling of Amla. In this preparation, we maintained the heat between 800 degrees C - 1000 degrees C during the process of decoction preparation. The active principle of other herbal drugs may bind Vit - ‘C’ as well as the action of amla. Vitamin - ‘C’ may be in some bound form with tannins and this complex is not destroyed easily Similarly in our Indian foods if we prepare as per the SOP, the essential nutrients is well recognized.