Thiamine (Vitamin B1): ICMR-NIN Requirement, Polished Rice, Beriberi and Alcohol

Thiamine, also written thiamin and numbered vitamin B1, is the vitamin the body needs to draw energy from carbohydrate. ICMR-NIN's Nutrient Requirements for Indians 2020 sets the recommended allowance at 1.4 mg a day for a sedentary man or woman and raises it with physical work, to 1.8 mg and 1.7 mg at moderate activity. The body keeps very little in reserve, and polishing strips most of it from rice, which is why a rice-heavy plate needs dal, whole grains or nuts beside it. This entry in the vitamins section of the handbook sets out the figures.

What does thiamine do in the body?

It works as a helper to enzymes that process carbohydrate. The joint FAO and WHO expert consultation on vitamin requirements describes thiamine as a co-enzyme in the metabolism of carbohydrates and branched-chain amino acids, and notes that when it runs short, carbohydrate metabolism slows with severe consequences, among them less acetylcholine for nerve function. The classic signs of deficiency accordingly appear in the nerves, the brain and the heart.

Thiamine cannot be banked the way vitamin B12 can. A 2018 review for the New York Academy of Sciences states that the body makes none of its own, that thiamine has a short half-life of 1 to 12 hours, and that body stores are limited, so a regular dietary supply is required. The eight B vitamins are set side by side in the list of the 13 vitamins.

How much thiamine do Indians need under ICMR-NIN's 2020 values?

A sedentary adult needs 1.4 mg a day on the recommended allowance, which covers nearly every healthy person. The report also gives an estimated average requirement, 1.2 mg for a sedentary man and 1.1 mg for a sedentary woman, for judging the diets of groups. Both rise with activity, pregnancy and lactation. The expert group set no tolerable upper limit for thiamine: its table of upper limits has no thiamine column.

The values climb with activity because thiamine is spent in using energy. The same report puts a man's energy requirement at 2,110 kcal when sedentary, 2,710 kcal at moderate work and 3,470 kcal at heavy work, and his thiamine allowance at 1.4, 1.8 and 2.3 mg. Divide one by the other and each level comes to about 0.66 mg for every 1,000 kcal. The additions for pregnancy and lactation were made, the report says, on the basis of the extra calorie allowance for those stages.

Which Indian foods supply thiamine in a normal portion?

Pulses, whole wheat, millets, groundnuts and oilseeds do most of the work on an Indian plate. No single helping is large: the best everyday portions give 0.15 to 0.25 mg, so the allowance is met by several of them across the day. The portions below are worked out from the Indian Food Composition Tables 2017, and grains and pulses are weighed raw. The ranked figures are in the thiamine table of Indian foods.

Milk and eggs add little, so a vegetarian loses nothing here by leaving out meat; the pulses and grains carry it. ICMR-NIN's 2024 Dietary Guidelines put the average thiamine content of pulses at 400 mcg per 100 g, nuts at 390 mcg, millets at about 356 mcg and cereals at about 238 mcg, against roughly 35 mcg for fruits and 80 mcg for milk. The article on millets and their nutrition covers the grains in more detail.

Polished rice: where the thiamine goes

The FAO and WHO consultation says that excessive refining and polishing of cereals removes considerable proportions of their B vitamins, and that beriberi occurs in adults whose high carbohydrate intake comes mainly from milled rice. The Indian tables show the size of the loss. Since the requirement follows energy, the fair comparison is thiamine per 1,000 kcal of the grain, set against the roughly 0.66 mg per 1,000 kcal implied by the adult man's allowance.

Raw milled rice keeps under a fifth of the thiamine of brown rice, and supplies about a fifth of what its own calories call for. Parboiling before milling holds on to more: parboiled milled rice has over three times the thiamine of raw milled rice. The full panels are in the comparisons of brown rice and white rice and of rice and wheat atta.

What is beriberi, and does it still occur in India?

Beriberi is the disease of thiamine deficiency, and it is still reported from India. The FAO and WHO consultation describes a dry, paralytic form and a wet form with oedema, and adds that it occurs in breastfed infants whose mothers are deficient. Recent Indian reports are of that kind. A one-year hospital study from Srinagar followed 50 exclusively breastfed infants with thiamine-responsive brain illness; 80 per cent of the mothers followed traditional food avoidance after delivery, on a diet of polished rice, and 10 per cent of the infants died.

A second Srinagar series found that 58 of 145 infants admitted with encephalopathy between November 2014 and March 2015 had the thiamine-responsive kind. A 2019 review by children's doctors in Jammu and Kashmir warned that the diagnosis is frequently missed because awareness is low and the tests are costly. Among adults, a National Institute of Nutrition study of 270 apparently healthy people aged 30 to 70 in Hyderabad found low blood thiamine in 11 per cent, the least common of the B vitamin deficiencies it measured, and judged only 59 per cent likely to have an adequate intake.

Why does alcohol raise the risk of thiamine deficiency?

Alcohol works against thiamine from two directions. The 2018 review states that chronic alcoholism impairs the absorption of thiamine in the intestine and increases the amount needed for metabolism, and the FAO and WHO consultation adds the third factor, that heavy drinkers often eat little. The result in adults is Wernicke's encephalopathy, marked by abnormal eye movements, an unsteady gait and confusion. Its most severe form includes Korsakoff's psychosis, with profound loss of memory. These are medical emergencies.

Food habits can also interfere. The same review lists betel nut and tea leaves as carrying thiamine antagonists and raw fish as carrying enzymes that break thiamine down, and says populations that consume them regularly are more likely to have deficiency disorders when the diet is already poor. It is frank about the limit of this knowledge: how much has to be consumed to affect thiamine status is not known.

What does the evidence say about thiamine supplements?

For deficiency itself, the benefit is plain and the trials are few. Infants in the Kashmir series recovered when given thiamine by their doctors, and the 2018 review concludes that fortification and supplements for mothers or infants have raised thiamine status and reduced infantile beriberi where deficiency is prevalent, while noting that trial data are limited. A Cochrane review of thiamine for Wernicke-Korsakoff syndrome in people dependent on alcohol found only two trials, one usable, with 107 participants, and judged the evidence insufficient to guide dose, route or duration.

For people who are not deficient, trials have so far shown little. A 2023 meta-analysis of 6 randomised trials with 298 participants found that thiamine did not change heart function, hospital admission or deaths in heart failure, with heart rate the only measure that moved. A second 2023 meta-analysis, of 8 trials with 1,572 patients, found that thiamine combined with hydrocortisone and vitamin C did not reduce deaths in sepsis. The trials are small, so the reading is no demonstrated benefit, not proof of none.

A worked example: a white-rice day against the requirement

This is an illustration, not a real person. Take a 28-year-old office worker in Kolkata, sedentary, who needs 1.4 mg on the allowance and 1.1 mg on the average requirement. Her day holds poha at breakfast (60 g, 0.07 mg of thiamine), then rice (75 g raw, 0.04 mg), masoor dal (30 g, 0.10 mg) and potato (100 g, 0.06 mg) at lunch, a glass of milk (0.06 mg), and rice (0.04 mg), moong dal (30 g, 0.11 mg) and an egg (0.03 mg) at dinner. The total is about 0.5 mg, under half the average requirement, before any loss in washing and cooking.

Four swaps change the picture. Dalia made from 60 g of broken whole wheat in place of poha adds about 0.20 mg, using the whole wheat figure of 0.46 mg per 100 g. Parboiled rice at lunch adds 0.09 mg. Two chapatis in place of the dinner rice add 0.21 mg, and a small handful of groundnuts adds 0.17 mg. The day now reaches about 1.2 mg: above the average requirement, still short of the allowance. A dalia porridge is one way to make the first swap.

Common mistakes and myths about thiamine

The second mistake is to wash rice until the water runs clear and then pour off the cooking water, which removes part of the little thiamine that milling left. The third is to assume that a diet with enough calories has enough B1: white rice delivers the calories with about a fifth of the thiamine they call for. The fourth is the custom of holding a new mother to rice and thin soup, the pattern behind the Kashmir cases; her allowance is 2.1 mg, half as much again as a sedentary woman's. The pregnancy diet guide covers eating in those months.

Too much thiamine, safety and when to see a doctor

Excess from food is not a concern. ICMR-NIN lists no upper limit, the FAO and WHO consultation says toxicity is not a problem because the kidneys clear thiamine quickly, and the 2018 review reports no known adverse effects of high intakes. That does not make a tablet the answer to symptoms. Deficiency is diagnosed and treated by doctors, often by injection in hospital, and the Hyderabad study found several B vitamins low in the same adults, a point taken up in the article on B-complex tablets.

FSSAI's fortification standard for thiamine

India's food regulator allows, but does not require, thiamine in fortified staples. Under the FSSAI fortification regulations, fortified atta, maida and raw rice must carry iron, folic acid and vitamin B12, and may also carry thiamine at 1 to 1.5 mg per kg, as thiamine hydrochloride or mononitrate. The arithmetic is modest: 75 g of rice fortified at that level would add about 0.08 to 0.11 mg to the 0.04 mg in the grain. Every fortified pack must name the fortificant on its label beside the fortification logo.

Learning this properly

Thiamine is taught under vitamins, cereal processing and deficiency diseases. The subject sits inside the teaching of NNWA, a private skill academy based in Kolkata whose classes run online in English and in Hindi. Its courses train people to coach healthy clients and to send medical cases to a doctor; none of them is a degree or a dietitian qualification. The Diploma in Nutrition, Dietetics and Public Health covers requirements and diet planning, and the Public Health Nutrition course looks at fortification and surveys.