Prescription for plant-based diet overlooks vitamin B12 deficiency

When Basant Manjari, a 65-year-old woman from Rourkela, Odisha, started losing control of her hand, her family members went into a tizzy. She would spill or drop the cup of tea she was holding. Doctors told her she was suffering from vitamin B12 deficiency.

A water-soluble vitamin, B12 is the most critical element in the metabolism of every cell in the human body. Deficiency can cause anemia, weakness of limbs and dementia. Pregnant women who lack this vitamin can give birth to brain-damaged babies, which can lead to autism.

India doesn’t have nation-wide data on B12 deficiency. But there is wide acceptance among the medical fraternity that a large number of people — as many as those suffering from vitamin D deficiency — have this problem.

“About 47 per cent people in northern India are vitamin B12 deficient. It is an endemic problem,” says Rajiv Singla, an endocrinologist at the Kalpavrisksh Health Care, Dwarka in New Delhi.

Now, Manjari is at the centre of a debate over which diet will enable the world to meet the United Nations’ Sustainable Development Goals (SDGs). Earlier this year, the EAT-Lancet Commission on Food, Planet and Health published a report which stated that to meet the SDGs, the world must shift to plant-based diets as it is more sustainable than an animal-based diet.

But this vitamin is only found in animal meat and to a lesser extent in milk products. “There is no source for B12 in the plant kingdom,” says Kamala Krishnaswamy, former director of the National Institute of Nutrition (NIN), Hyderabad.

“It is not a prudent prescription as not just B12, but several other vitamins and nutrients are found only in animal-based diets,” says Bhanuprakash Reddy, a scientist with NIN.

For India, this debate has greater relevance as about 30 per cent of the population is vegetarian, according to an assessment of the National Sample Survey Office in 2014. An Indian eats roughly 4 kg of meat per year, as compared to the global average of 43 kg, according to the Food and Agriculture Organization.

But there is another layer to the curious case of B12 deficiency in India. Even the non-vegetarian population is facing this deficiency. For example, Manjari eats two eggs each week and 3-4 pieces of fish and still she has this deficiency. NIN conducted a survey of 979 pregnant women in Telangana in 2017 and found that 44 per cent of the women were vitamin B12 deficient. Ironically, Telangana has the highest number of non-vegetarians in India (98 per cent).

Singla, who is a co-author of a study on vitamin B12 deficiency, says that what is important is the kind of meat we are consuming. “Most non-vegetarian Indians largely consume chicken, which has very little amount of vitamin B12 as compared to mutton or sea food,” he adds.

At the same time vegetarians — who can get this vitamin through dairy products — have a problem. If the milk is diluted or is over-boiled, the level of vitamin present gets reduced and intake is low, says Krishnaswamy. Moreover, as B12 is water soluble, the vitamin can be lost during the cooking process.

Reddy says there are other factors involved which influence the absorption of the vitamin in the body. A study, published in Nature in June 2017, says when people experience severe acidity or gastric problems, they take antacid tablets. This reduces the secretion of hydrochloric acid and low pepsin activity within the stomach due to which B12 doesn’t get absorbed.

Diabetics are at increased risk. A study on diabetic population consuming Metformin drug over a prolonged period found that 56.52 per cent vegetarians in India were B12 deficient, while 35.71 per cent of non-vegetarians were also deficient. The study was published in International Journal of Advances in Medicine in 2017.

Changing consumption habits have accentuated the problem. “Eating local cuisines, traditional diets and home-cooked meals are rapidly diminishing in our society. This is leading to poor diets that are deficient in micronutrients,” says Shweta Khandelwal, head of nutrition research, Public Health Foundation of India, a research group based in Delhi.

So what is the way out? The daily requirement of B12 for adults is 1 mg. For vegetarians, a balanced diet consisting of cereals and pulses (ratio of 4:1) is necessary.

The diet should also contain one food source rich in calories, one source with high protein and regular intake of fresh milk, curd and vegetables.

Importantly, vitamin B12 test is not prescribed for pregnant women in most hospitals, says Vishakha Munjal, infertility specialist and obstetrician, Apollo Cradle Royale, New Delhi. This should be made mandatory.

The government should also think about fortification as a possible panacea, says Singla. The easiest solution is to inject the vitamin; a one course injection can suffice for a year.

(This article was first published in Down To Earth's print edition dated August 16-31, 2019)

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