When I first arrived in Tokyo from London with my young children, it was midwinter. The school that I had enrolled my son at had many children off with seasonal coughs and colds, and although I had moved thousands of miles away from home, the sight was a familiar one: tired and strained parents who had been up all night with their unwell children.

As a doctor and mother, I was asked by many an exhausted parent at the school gates what they could do to prevent their child succumbing to repeated infections. I was also often asked if supplements would help.

We know that vitamins and minerals that are sourced from food (and, in the case of vitamin D, from the sun) are essential for good health. There are some supplements that are well documented to be beneficial: folic acid for expectant mothers, for instance, and antioxidant supplements for people who have, or who are at risk of, certain eye conditions, such as age-related macular degeneration. As doctors, we regularly diagnose and treat people with vitamin and/or mineral deficiencies, and the effectiveness of treating them with specific supplements is well known. But what about their role in healthy individuals — in those who are well nourished and without any known deficiency? Vitamin and mineral supplements are big business in Japan, but are they really any use?

There have been hundreds of studies evaluating the benefits and risks for healthy people of taking various vitamins. With the wealth of information now available on the Internet, it is hard to separate fact from fiction, and advice can be conflicting.

Recently the British Medical Journal looked at over 2,000 different pieces of research and collated the results. It concluded that there was no decrease in the risk of developing high blood pressure, heart attacks or strokes in a healthy, well-nourished person taking vitamin supplements. This was echoed in another reputable journal, The Annals of Internal Medicine, which, after collating the work of three major review studies, concluded they could find no positive benefit in taking supplements in otherwise healthy adults in terms of cardiovascular health, cancer risk, cognitive health or mortality. Some recent evidence has also suggested some high doses of vitamins may be harmful — for example, for smokers who take high doses of vitamin E.

But what about the role of vitamin supplements in more minor conditions? Take, for example, the common cold, a condition we are all familiar with. Research published in a 2012 Cochrane review (which collaborates all recent high-quality evidence) found that taking zinc supplements reduced the duration and severity of the common cold. It also found that giving children zinc supplements for at least five months during winter cut the likelihood of a cold by a third, and reduced the need for antibiotics.

Another 2012 Cochrane review demonstrated that taking daily vitamin C did not reduce the likelihood of developing a cold in the normal population, but did in those individuals who undertook high levels of exercise (e.g., marathon runners). Daily vitamin C supplements did, however, reduce the severity of cold symptoms, and research showed that for those prone to colds, there were benefits in taking daily vitamin C throughout the year. There was, however, no benefit if the supplements were only taken after the onset of a cold.

The case for giving multivitamins to children is more definitive. Britain’s Department of Health recommends all children be given vitamin A, C and D supplements from the age of 6 months to 5 years, on the presumption that in these growing years their dietary intake may be inadequate.

With the Fukushima disaster throwing food safety into the spotlight, people living in Japan are more conscious than ever of what they are putting into their bodies. For those adults who are otherwise healthy and well nourished, research has shown that the optimum way of getting the vitamins and minerals you need for good health is by eating a balanced and varied diet. But as for many things with young children, when it comes to vitamins, research has shown that they may still need a helping hand.

Dr. Roopa Gill qualified as a doctor in the U.K. She holds qualifications in both internal medicine and general practice, and currently lives in Tokyo with her husband and two young children. Foreign Agenda offers a forum for opinion on issues related to life in Japan. Your comments and story ideas: community@japantimes.co.jp

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