Zinc: ICMR-NIN Requirement by Age, Phytate in Cereal Diets and Zinc with ORS for Diarrhoea

Zinc is a trace mineral needed in milligrams, not grams, yet it is involved in growth, immunity and the working of hundreds of enzymes. ICMR-NIN's Nutrient Requirements for Indians 2020 sets the recommended allowance at 17 mg a day for an adult man and 13.2 mg for an adult woman, with a tolerable upper limit of 40 mg. Both figures rest on the expert group's assumption that only 23 per cent of the zinc in an Indian diet is absorbed. This entry in the minerals section of the handbook explains why.

What does zinc do in the body?

It works mostly out of sight, inside enzymes and the proteins that switch genes on and off. A 2016 expert review for the Biomarkers of Nutrition for Development project counts more than 300 enzymes that need zinc as a catalyst, and describes zinc deficiency as impairing immune function. It recommends height-for-age in growing children as one of three measures of a population's zinc status. The same review lists weight loss, delayed wound healing, changes in taste and mental lethargy among the signs of more severe deficiency, while warning that most of them are non-specific.

That vagueness is the practical difficulty with zinc. The body holds its zinc levels within a narrow range across a wide span of intakes, and the review notes that only about 1 per cent of the body's zinc is in circulating blood. A serum zinc test is therefore useful for judging a population and much less reliable for judging one person.

How much zinc do you need under ICMR-NIN's 2020 values?

An adult man needs 17 mg a day and an adult woman 13.2 mg on the recommended allowance, against average requirements of 14.1 and 11.0 mg. The 2010 edition gave 12 and 10 mg. The expert group added up the zinc lost each day in sweat, urine, stool, semen and menstrual blood, added the needs of growth and lactation, and divided by the share absorbed: 23 per cent for most groups, 25 per cent in pregnancy and 30 per cent in lactation. The allowance is the average requirement multiplied by 1.2.

For people aged 60 and over the report keeps the adult figures, 17 mg for men and 13.2 mg for women. No value is set for the first six months of life. Boys of 16 to 18 have the highest allowance of anyone, 17.6 mg.

Indian food sources of zinc, portion by portion

No everyday Indian food is a concentrated source in the way ragi is for calcium. Zinc arrives a milligram at a time from atta, millets, pulses, nuts, oilseeds and paneer, and in larger amounts from mutton. The table works out household portions from the Indian Food Composition Tables 2017, grains and pulses weighed raw. The ranked list is in the zinc table of Indian foods.

The table explains why zinc is hard to plan for. Goat meat stands well clear of everything else, but chicken breast and rohu give no more than a helping of rice, and vegetables and fruit add little: the 2024 Dietary Guidelines put the average for vegetables at 0.22 mg per 100 g and for fruit at 0.10 mg. A vegetarian plate collects its zinc from the cereal, the dal, the paneer and a spoonful of sesame seeds or nuts.

Why do cereal-based diets deliver less zinc than they contain?

Because of phytate, also called phytic acid, which cereals and legumes carry and which hinders the absorption of minerals. A review of the dietary factors in zinc absorption says phytate has a strong negative effect on zinc absorption from composite meals, and that inhibitors of absorption are probably a commoner cause of poor zinc status than low intake. The expert review cited above grades diets by the molar ratio of phytate to zinc: above 15 means poor zinc bioavailability, 5 to 15 medium, below 5 good. Animal foods contain no phytate. The Indian tables measure phytate in the same foods that supply the zinc.

By weight, the staples in the table carry between about 60 and 280 times as much phytate as zinc. The kitchen can shift the balance. The absorption review reports that germination and fermentation, which break phytate down, markedly improve zinc absorption, and that the amount of protein in a meal has a positive effect.

A sprouted moong cheela uses two of the four at once, and the article on sprouts, their benefits and their safety covers how to sprout without making anyone ill. The same habits help the absorption of iron from plant foods.

Zinc status in India: the survey figures

The first national measurement came from the Comprehensive National Nutrition Survey of 2016-18. Using international cut-offs and adjusting for inflammation, its authors found low serum zinc in 17.4 per cent of children aged 1 to 4, 15.8 per cent at 5 to 9 and 31.1 per cent of adolescents aged 10 to 19. ICMR-NIN's 2024 guidelines tabulate the same survey as 19.0, 16.8 and 31.7 per cent. Low zinc was commoner in rural and poorer preschool children, in the severely stunted, and in those who had had diarrhoea in the previous two weeks: 22.6 against 16.5 per cent.

Those figures come with an honest dispute. A 2022 analysis by many of the same researchers derived cut-offs from healthy Indian children in the survey itself. They were lower than the international ones, and with them the prevalence of deficiency was 2.7 to 5.5 times lower, with no state and no age group reaching the 20 per cent that marks a public health problem. So the size of the problem depends on which line is drawn.

Intake tells a plainer story. ICMR-NIN's own model balanced diet for a sedentary man supplies 9.7 mg of zinc in its vegetarian version and 9.2 mg in the non-vegetarian one, against an average requirement of 14.1 mg. The sedentary woman's diet supplies 7.4 mg against 11.0 mg. A meta-analysis of 26 studies found that vegetarians ate 0.88 mg less zinc a day than non-vegetarians and had lower serum zinc, with a larger gap in developing countries.

What does India's diarrhoea programme give children, and why?

It gives zinc tablets for 14 days alongside oral rehydration salts (ORS). The Ministry of Health and Family Welfare's operational guidelines for its yearly diarrhoea control fortnight state the dose health workers are trained to give: 10 mg a day from 2 to 6 months of age and 20 mg from 6 months to 5 years, continued for the full 14 days even if the diarrhoea stops. This is the programme's schedule for a sick child under a health worker's care, reported as such. It follows the 2004 joint statement of WHO and UNICEF, which recommended 20 mg a day for 10 to 14 days and 10 mg for infants under six months.

Coverage is the weak point. The Ministry's guidelines record zinc use rising from 0.3 per cent of episodes in 2005-06 to 20.3 per cent in 2015-16, against a target of 90 per cent. The National Family Health Survey of 2019-21 found that 61 per cent of children under five with diarrhoea were given ORS, 31 per cent zinc and 24 per cent both. The child nutrition diet chart covers feeding during and after illness.

What does the evidence say about zinc supplements?

For childhood diarrhoea the evidence is real but narrower than the campaign posters suggest. The Cochrane review of 2016 pooled 33 trials in 10,841 children, most of them in Asian countries at high risk of zinc deficiency. In children older than six months zinc may shorten an episode by about half a day, on low-certainty evidence, and probably reduces the number still ill on day seven (risk ratio 0.73). In malnourished children the gain was about a day, on high-certainty evidence. Under six months there was no benefit, and zinc made vomiting more likely at every age.

For colds the answer is weaker still. The Cochrane review of 2024 covered 34 trials with 8,526 participants. Zinc taken to prevent colds made little or no difference (risk ratio 0.93). Taken once a cold had started it may shorten the illness by about two days, but the evidence was of low certainty and the trials disagreed widely. Side effects such as an unpleasant taste and stomach upset were more frequent on zinc, risk ratio 1.34. The zinc gluconate lozenge trials used 45 to 276 mg a day, above the adult upper limit. The article on an immunity-boosting Indian diet looks at what food can do.

A worked example: one vegetarian day against 17 mg

The person here is made up to show the arithmetic. Take a 30-year-old vegetarian bank employee in Kolkata with a desk job. His day holds four chapatis (120 g atta, 3.4 mg of zinc), rice (100 g raw, 1.2 mg), masoor dal at two meals (60 g, 2.2 mg), milk (300 g, 1.0 mg), paneer (50 g, 1.4 mg), a handful of groundnuts (30 g, 1.0 mg) and a palak sabzi (100 g, 0.5 mg). The total is about 10.6 mg, close to ICMR-NIN's own model diet and well short of the 14.1 mg average requirement.

At 23 per cent absorption, 10.6 mg yields about 2.4 mg absorbed, against the 3.9 mg that 17 mg would yield. Adding a tablespoon of black sesame in a chutney (1.3 mg), 20 g of cashew (1.1 mg) and a chana dal cheela at breakfast (30 g, 1.1 mg) takes the day to about 14.1 mg: level with the average requirement, still under the allowance. Fermenting and sprouting work on absorption instead.

Common myths and mistakes about zinc

Too much zinc, side effects and when to see a doctor

ICMR-NIN's tolerable upper limit is 40 mg a day for adults, including pregnant and lactating women, 34 mg from 13 to 18 years, 23 mg at 10 to 12, 12 mg from 4 to 9 and 7 mg from 1 to 3, counted as habitual intake from all sources. Food does not reach these levels; tablets do. The expert review warns that high zinc supplementation over a long period may cause a secondary copper deficiency, and the trials above recorded vomiting, bad taste and stomach upset. Doses above the limit belong only with a doctor who is monitoring the patient.

See a doctor, and do not self-treat, if a child has diarrhoea with blood, cannot drink, is drowsy or passes little urine; if a child is not growing along the chart; if wounds heal slowly or a rash around the mouth will not clear; or if you have been taking zinc tablets for months without medical advice. People with bowel, liver or kidney disease, and anyone on long-term medicines, should ask before taking zinc.

Learning this properly

Zinc comes into NNWA's teaching under trace minerals, child nutrition and public health programmes. The academy is a private skill institution in Kolkata and teaches online, in English and in Hindi. What its courses prepare people for is coaching healthy clients and referring medical cases; not one of them is a degree or a dietitian qualification. The Public Health Nutrition course looks at programmes such as zinc with ORS, and the Diploma in Nutrition, Dietetics and Public Health covers requirements and diet planning.