Technically all organic mater is composed largely of proteins. Even lettuce is full of proteins. Nevertheless, many food products are labeled as containing little to no protein. For instance, lettuce is said to have one gram of protein per serving (1.5 cups shredded).
What counts as "protein" from a nutritional standpoint? Is it only foods which contain all of the essential amino acids?
Hi,
On most/all nutrition labels, "protein" content is often presented in general terms irrespective of compositional and functional differences. Nutritionally, dietary proteins are not the same (composition and functionality); in food systems they occur in different combinations. The protein combination is what makes some foods have complete (e.g. animal food sources and soy), incomplete (e.g. plant food sources) and complimentary proteins. On this basis, "protein" on a nutrition fact label, unless a claim is clearly stated, gives little to no information on composition/functional nature of its inherent protein.
I hope this was helpful.
Thanks.
Dear David,
you said
"Technically all organic mater is composed largely of proteins"
This is wrong fact because organic matter means that a matter contain mostly with atoms of carbon, oxygen, and hydrogen. Not all matters contain protein in amount cover the humans need, for example vegetables contain carbon, hydrogen and oxygen, starch the same. Does starch is a good source of protein? We need first to set a fact that fruits and vegetables are poor sources of protein. why ? the answer is the protein in chicken is about 20g/100g compare that with lettuce 1g/100g so what do you think? secondly the RDA of protein for adults is about 56 g/day so how come vegetables cover this amount? plant sources as a general is limiting sources of amino acids, this means that vegetable sources are limiting in one or more of essential amino acids that never made in the body and must be supplied in the diet.
Best regards
Aly R Abdel-Moemin
Hello Jacob Ojobi Omedi
What kind of information does the 'nutritional fact' label on food products provide then?
I feel we should start from the method of protein analysis which is always proximate. Some analyses are based on just nitrogen content (which is not necessarily protein) and then multiplying with certain conversion factor (6.5) {whereas we all know that all amino acids are unique in their molecular structures and weights}; some analyses are based on dry weight while some on wet basis.
There are many verification papers on nutritional composition of some standard food products that match the company label; we should also bear in mind that some food processing companies just label their products without proper assessment (QC: quality control). I remember vividly the verification of Indomie instant noodles nutritional facts by one of my cited authors, Ejembi et al, in my Article Development of Whole Cassava Based Instant Noodles
Do not also forget that the functionality of proteins comes from their amino acid content; composition is the onus here and as far as I am concerned, the analysis has always been proximate.
Thanks
"Technically all organic mater is composed largely of proteins" ... Yes, this generalization is wrong Aly, but there are vegetables that are quite rich in proteins (Bitter leaf: Vernonia amygdalina is a typical example). The question is,
What classifies "protein" in the context of nutrition facts labeling?
Dear David Schad, I repeat, the key to nutrition facts labeling is the the amino acid composition as revealed by proximate analysis of the food product after all the processing. Irrespective of the raw materials (no matter how rich the the lettuce or bitter leaf is) it is the protein content of its product that would be labeled on the product and not that of the parent source.
Regards.
Protein is a macro nutrient needed for building up of body tissues. It is required for growth and development in infants and older children, and replacement of waste or lost tissues in adults. Proteins are polymers of amino acids. The declaration of protein in the context of nutrition fact labeling depends on the particular food product and value of crude protein content, determined mostly by proximate analysis which involves the determination of total nitrogen content and multiplying the obtained value by a standard factor; 6.25 (NOT 6.5) to arrive at the crude protein content (given in % or g/100 g).
Proximate analysis will not reflex the essential or non essential amino acids composition except through amino acid profile of the product under consideration. Generally, foods of plant origin except soy bean are low in protein content and lacking in some essential amino acids (e.g. tryptophan, lysine, histidine) compared to that of animal source. So, it is not out of place seeing a low percentage of protein being declared in nutrition facts of some food products of plant origin. The protein quality of a food is measured not only by the determination of total essential amino acids content but by many other test methods involving its bioavailability.
Protein in food label is the amount of Protein in 100g of the total component. but in nutritional point of view Protein quality labeling is associated with the number and types of amino acid found that can complement the body amino acid requirement and how much of the amino acid in the particular food is appropriate for body protein formation and this related with biological value, digestibility, efficiency ratio and amino acid ration. Protein in nutrition plays a crucial role in almost all biological processes and amino acids are the building blocks of it. A large proportion of our cells, muscles and tissue is made up of amino acids, meaning they carry out many important bodily functions, such as giving cells their structure.
- Badges
- Science topic
- Similar topics
- Medicine
- Nutrition and Dietetics
- Nutritional Medicine
- Food Science
- Food