So far, the targets of micronutrients set by HarvestPlus and other projects for rice, wheat maize and pulses etc. are yet to achieve. There seems some physiological barriers needed to be addressed in available germplasm.
Article The challenges of food fortification
https://www.nutritionintl.org/content/user_files/2018/02/Team-Folate-LargeScaleFortification-FinalReport.pdf
I think, this might help
Article Biofortified crops for tackling micronutrient deficiencies -...
Over 30% of the world's population is deficient in essential vitamins and minerals, especially those known as the "Big 4": iron, iodine, vitamin A and zinc.
Micronutrient deficiencies disproportionately affect infants, young children and women, preventing them from reaching their full potential in life.
The consequences of this deficiency can be devastating, leading to mental deficiencies, poor health, poor productivity and in severe cases, death. Even a mild to moderate deficiency can affect a person's well-being and development.
Ideally, these nutrients should come from a balanced and varied diet, but this is not always possible, especially in developing countries.
Theoretically, we have both the responsibility and the opportunity to improve the nutritional status of people at risk by adding important micronutrients to foods and beverages regularly consumed by vulnerable populations.
Thus, biofortification can be done through the process that contributes to increasing the concentration of nutrients in the diet based mainly on staple foods.
Nutrient crops are obtained by selecting and creating varieties of cereals that are naturally rich in micronutrients. This process can contribute to the nutrient density of the diet for those who may not have access to fortified processed foods.
Also, fortifying cereals and milk provides additional sources of food for vulnerable groups, such as school-age children and pregnant mothers. In total, 83.5% of affordable products that have gained popularity among low-income consumers have been fortified with at least the "Big 4" elements: iron, iodine, vitamin A and zinc.
Also, through the collaboration with the agricultural research institutes and through special programs, the development and creation of the supply chains for the biofortified crops is pursued. In Nigeria, biofortified corn is combined with provitamin A with normal corn and we reserved over 1,000 tons of grain in 2016 for use in grain puree.
The research and development Centre in Abidjan, Ivory Coast, is also exploring opportunities for wheat, rice and maize, along with partners from Madagascar, Turkey, Brazil and India.
At the level of consumers, the fortification of food, cereals and milk is very easily accepted because the technological processes for obtaining finished products use monoglutamate that give a sweet taste to the products, but also give addiction that is not good for human health.
The question is? Isn't biofortification cereal always natural?
I agree that
Over 30% of the world's population is deficient in essential vitamins and minerals, especially those known as the "Big 4": iron, iodine, vitamin A and zinc.
Micronutrient deficiencies disproportionately affect infants, young children and women, preventing them from reaching their full potential in life.
There are several attempts to add micronutrients by bio-fortification. Success was less. In Japan, researchers struggled hard to add iron while the plant is growing. They did not succeed. In my opinion, one should make attempts by permutation and combination, one fine morning , there may be a success.
From my point of view, this is a holistic issue. Breeding for biofortification is a worthy task but are the commercial soils in which the crop will be grown, sufficiently equipped to provide the nutrient. Zinc deficiency in soils occurs in many areas of the globe.
In the biofortification process, I believe we need to also consider root configurations and increased phosphorus use efficiency by the plant. With increased root size and increased P efficiency, often zinc levels are elevated.
To some extent we can get micronutrients by consuming whole grains, wherever possible. In all grains, it is not possible to consume whole grains, as in the case of some millets , some of them need to be used only after removing outer layers. Similarly whole grains in the case of brown rice or dehusked rice, needs up to 2-3% degree of polish, otherwise cent percent brown rice consumption is not possible, as it causes health problems like indigestion, chewing is difficult, rice grain opens while cooking.
Attempts have been made to increase iron content in paddy rice, while growing paddy plants. With some limitations, the work have been carried out . Some of the studies are in progress on adding micronutrients during planting or during growing the cereal plants.
By testing the soil for some of the micronutrients, micronutrients could be added to soil and by growing cereal crops , these micro nutrients may enter with different concentrations in different cereals .