Nutritional advantages of millets are offset by presence of phytic acid; cultivation yield also poor compared to wheat and rice
The United Nations has declared 2023 as the Year of Millets. It is being extensively promoted for its healthfulness and climate resilience, but its health effects and economic viability needs to be studied as well.
In India, the use of millets as staple food can be traced back to Vedic times. China is said to have used millets for over 4,000 years. It is widely available in Chinese stores across the United States. It is usually grown in rain-fed, dry land regions in Indian states and tribal belts.
Its importance as staple food was replaced by wheat and rice, thanks to the Green Revolution. Various reasons have been cited for bringing back millet, including climate resilience, excessive rice and wheat production, health benefits and economic benefits to the farmers.
Millets are being promoted as climate resilient in contrast to rice and wheat, which require high carbon inputs. Several chief ministers have commented that grain production has become excessive.
However, this is a myth. Rice or wheat production may come down with an erratic monsoon, which turns the tables to the other side.
The high buffer stock of these is misleading. People cannot purchase as per their requirements because of high prices in the open market and the ration supply does not meet their needs. the entire buffer stock may vanish if the quota of grains in rations is doubled.
It is also not wise to convert rice and wheat-growing lands to millet.
This could lead to the 1966 to 1968 type grain shortage when we heavily depended on American wheat under Public Law 480 for our daily needs. The United States’ President can authorise the shipment of surplus commodities to “friendly” nations, either on concessional or grant terms under the law.
Today, with modern technology, the per acre yield of rice is 35 to 40 quintals. The yields for major millets jowar (sorghum), bajra (pearl millet) and ragi (finger millet) vary from five quintals to 10 quintals — standing in no comparison to 35 to 40 quintals of rice.
Current agronomy practices, which include pesticide and fertiliser treatment, are well-stabilised for major millets. Its growth is dependent on one or two irrigation times in the last phase.
Thus, cultivation of major millets will not provide climate resilience since the yields are very low and require high acreage if it were a staple crop.
Another reason cited for millet revival is that they have immense health benefits, such as the slow release of glucose to the bloodstream during digestion.
A low glycaemic index is favourable for diabetic patients. Further, millets have been said to have high traces of mineral micronutrients such as iron and are rich in fibre.
There is also a strong belief that it reduces obesity with regular usage. This is because 100 grams of sorghum has 11 grammes of proteins, 28 milligrammes of vitamin C, micronutrients like iron 8 mg, zinc 2.5 mg, calcium 10 mg, magnesium 23 mg and a fat content of 10 per cent.
However, there are some antinutritive concerns regarding the uses of millets.
The advantages of millets are offset by the presence of phytic acid (inositol phosphate), an undesirable antinutritive compound. On eating food made of millets, phosphate-containing phytic acid reacts to form several complexes. It chelates with micronutrients such as calcium, magnesium, zinc and iron present in millet.
The micronutrients and minerals, therefore, cannot be absorbed by our intestines. Phytic acid or its metal chelates also will not be absorbed by our body.
The result is anaemia and fatigue and it is probably the reason behind the high incidence of these illnesses among tribals and poor villagers depending on millet for food exclusively. This is a serious health concern.
Unfortunately, high phytic acid is found in all major millets — sorghum (900 mg to 2,200 mg per 100 g of raw jowar), pearl millet (~700 mg per 100 g bajra) and finger millet (570 mg per 100 g ragi).
The presence of high phytic acid is a negative aspect of the promotion of millet as an exclusive staple food. In addition, some millets, such as pearl millet, contain high oxalates that bind to calcium and may form kidney stones.
Further, the millets contain protein inhibitors, called protease- and trypsin-inhibitors, that retard the mineral micronutrient absorption in the body. Millets also contain high levels of tannins and polyphenols that may form chelates with micronutrients.
Read more: Are millets safe from biopiracy?
Thus, all the factors prevent micronutrient bioavailability in our bodies. No doubt phytic acid is also found in other foods like rice, wheat, nuts, legumes and grains, etc, but our modern food processing practically removes phytic acid.
For example, milled white rice contains 0.2 per cent phytic acid, while brown rice 0.9 per cent and wheat 0.4 -1.4 per cent.
For consumption of the millets, high phytic acid content needs to be reduced, which involves dehusking, soaking for 24 hours, removing excess water and then cooking.
These methods are not being followed widely at present. The usual practice includes powdering the millet and boiling it or making it into chapattis, which may not remove phytic acid.
Malting or fermentation with curd or yoghurt also removes the acid. Several cultures around the world practice fermentation techniques. Examples include Hausa Koko as porridge from Ghana and our own Jawar Ambali. These techniques should be adapted to our cooking with some training to reduce phytic acid content.
Another worrying factor with millet is that it is goitrogenic and known to have anti-thyroid effects. Studies reveal that millet, particularly pearl millet, contains goitrogenic compounds such as C-glucosyl flavones like vitexin.
Although goitrogens can be destroyed by cooking, it is better to avoid goitrogenic food like pearl millet for those with iodine deficiencies. Similar studies of goitrogenic effects don’t seem to have been studied for other millets.
Talking about the economic considerations, the yield of millet is uniformly poor compared to rice or wheat. Millets cannot be grown in the Rabi season as a summer crop since it is dependent on rainfall. Further, there are no dehusking or grinding machines available for millet processing.
The government offers no minimum support price on millet either. It is a clear disadvantage to farmers and most would not accept millet cultivation given the economic challenges. Larger areas are required for millets, given the yield is low.
Biodiversity envisages preserving all species, cultivars and varieties, including food crops like millets. In addition to major millets, there are many minor millets like foxtail, kodo, barnyard, proso and brown-top.
The storage life of millets is also short and cannot be stored for two-three years like rice and wheat. This is due to the presence of fats in the millets.
Agronomy status, phytic acid and other antinutritive constituents must also be studied extensively. Right now, farmers of tribal areas cultivate some of these millets and sell them in small quantities in the weekly markets.
The task of agricultural scientists and government institutes is to stabilise agronomy, devising processing machinery, storage practices and cooking methods like fermentation. The main challenge is retaining high micronutrients and reducing antinutritive phytic acid through suitable processing methods.
The biodiversity can be preserved by seed banks, deoxyribonucleic acid or DNA barcoding, DNA profile and Real-Time Reverse Transcription – Polymerase Chain or RT-PCR methods to identify varieties of each millet.
Cryopreservation and continued cultivation can help preserve posterity and propagate it.
Going through the antinutritive literature on millets, it is advisable not to overdo millets and eat no more than 60g of millets a day. It may be mixed with rice or wheat. The antinutritive effect of phytic acid will be felt only if one eats millets as staple food continuously.
Phytic acid doesn’t get too absorbed in the body. Therefore, there is no long-term effect of phytic acid antinutritive effect if one discontinues phytic acid high-content millet food. Research activity millets need to prioritise scientific research over publicity and promotion of millets.
It is desirable to wait for the results rather than introducing them in the public distribution system (PDS), residential schools and mid-day meals. Wide publicity needs to be given to the side effects of the millets also.
K Nagaiahi is chief scientist, CSIR-IICT, Hyderabad; G. Srimannarayana is retd professor for department of chemistry, Osmania University, Hyderabad and Phaniraj G is a IT Professional, Boston, USA.
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.