Who would have thought the sunshine vitamin would have such a dark side to it? But doctors say over consumption of vitamins - especially vitamin D - can tip them from tonic to toxic.
"I've come across many people who eat healthy and have no need to supplement their diets with pills. Yet, they insist on taking vitamin, omega-3 fatty acids, iron and folic acid supplements," says endocrinologist Dr Jayashree Gopal, senior consultant at Apollo Hospitals.
She adds that while some vitamins like B1, B2, B6 and C are water-soluble, which means people are naturally protected against an overdose, vitamins A, D, E and K are fat-soluble (meaning stored in fat and released slowly) and so an overdose can be toxic, causing anything from renal failure to intracranial hypertension, or even death, as in the recent case of a 10-year-old boy from New Delhi.
Dr R Bharath of the Arka Centre for Hormonal Health says studies have shown Vitamin E too, though sometimes prescribed for leg cramps, may not be good for the heart when taken in high doses.
The safe upper limit of vitamin D consumption, say doctors, is around 1000-2000 International units (IU) per day, but even that can be taken only after consultation. Only in cases of serious deficiencies, patients are prescribed doses of 60,000 IU or even 6 lakh IU.
"A dose of 60,000 IU is recommended only once a week or month until the deficiency is overcome, a 6 lakh IU injection is recommended once in six months. But people feel energetic almost as soon as they have a 6 lakh IU shot so they take it every day to feel better," says Dr Gopal. In fact, the 10-year-old boy who died of vitamin D overdose was reportedly on a continuous dose of 6 lakh IU of vitamin D against the prescribed limit of 1,000.
What people sometimes don't realise, says nutritionist Shiny Chandran, is that in medical terms, Vitamin D is considered more a hormone than a vitamin. "It's the only vitamin with a dual role, and that's why one needs to be careful about dosage," she says.
"As a nutritionist I never give my clients long-term dosages of vitamin D but ask them to consult a physician," she says, adding that many clients get their dosage recommendations from fitness trainers, which is unsafe.
Dr Gopal says she had two cases of acute renal failure in adults recently because of over-consumption of vitamin D pills. "Unfortunately, there is no antidote for a vitamin D overdose. The body just has to flush out the excess vitamin D on its own, and it can sometimes take up to six months," she adds.
One of the biggest concerns, says Dr Bharath, is that though vitamin D level tests are expensive, pills or injections are cheaper and can be bought over the counter. "So people keep dosing themselves without ever finding out if they have a deficiency," he says, adding that vitamins are best in their natural form - in fruits, vegetables, meats and sunshine -rather than as supplements. So the next time you reach for a pill, learn your ABCDs first.