Second Opinion: Diet and exercise leave no need for supplementary help

No one needs vitamin D supplements unless they stay indoors or wear clothes that cover every inch of skin. Photgraph: Getty Images

No one needs vitamin D supplements unless they stay indoors or wear clothes that cover every inch of skin. Photgraph: Getty Images


Winter has arrived and we can look forward to 10-12 weeks of cold, damp weather with a maximum of eight hours of light a day. Many people take vitamin and mineral supplements, particularly vitamins C and D (the sunshine vitamin) and calcium, in the hope of getting through the winter unscathed health-wise. Do these extra supplements improve health or are they a waste of money?

Vitamin C, advertised as an effective treatment for the common cold, has been the subject of controversy for more than 70 years. The latest research from the Cochrane Collaboration, based on 29 studies involving more than 11,000 participants, shows routine vitamin C supplements do not reduce the incidence of colds in the general population and have no effect on whether or not a person will catch a cold.

However, taking vitamin C every day seems to reduce a cold’s severity and duration. When taken therapeutically after the onset of symptoms, neither severity nor duration is affected.

The authors conclude: “Given the consistent effect of vitamin C on the duration and severity of colds in the regular supplementation studies, and the low cost and safety, it may be worthwhile for common cold patients to test, on an individual basis, whether therapeutic vitamin C is beneficial for them.”

Adults need 80-90mg every day and should never take more than 2,000mg a day, no matter what the labelling and advertising says.

A shortage of vitamin D and calcium, combined with lack of exercise, particularly during the winter months when the weather is miserable and exercising in the dark may be unsafe, can lead to osteoporosis (fragile, porous bones that break easily) and many years of pain and disability.

In fact, osteoporosis can start in childhood and more than a third of Irish children do not get enough calcium.

Nearly three-quarters of adults and 88 per cent of primary school children get less than half the recommended daily amount of vitamin D because they spend so much time indoors.

About 300,000 people in Ireland have osteoporosis and more than half a million are receiving treatment to either prevent or treat it. One in two women and one in five men develop osteoporosis during their lifetime.

In women, the one-in-six lifetime risk of hip fracture is greater than the one-in-nine risk of developing breast cancer yet few people talk about osteoporosis and the disease is often seen as an inevitable consequence of getting older.

Women are more at risk because of constant dieting and worries about their weight from their teenage years onwards, thus setting themselves up for weak bones later on. Boys are encouraged to drink pints of milk whereas a pint of milk for girls is considered unladylike by some.

The best way to build healthy bones and prevent osteoporosis is regular exercise, calcium in the diet and vitamin D. Calcium is useless without vitamin D and both are metabolised more efficiently when combined with physical activity.

People of all ages need lots of calcium. Children from one to eight years of age need 700-1,000mg per day depending on age; those from nine to 18 years need 1,300mg, and men and women aged 19-50 need 1,000mg. Adults over 70 need 1,200mg every day.

To get enough calcium an adult should each day consume, for example, a pint of milk and two natural yogurts; or two tins of sardines; or nearly two pounds of spinach; or a combination of all these foods.

Contrary to popular belief no one needs vitamin D supplements unless they stay indoors all day or wear clothes that completely cover every inch of skin.

The World Health Organisation concludes that 10-15 minutes of sunlight a day on any part of your body – hands, arms, legs, face – especially during the summer months, enables the body to store enough vitamin D to take people through the winter.

Vitamin D is also found in oily fish, eggs, and fortified milks and yogurts. No one should take more than the recommended dietary reference intakes (DRIs).

Taking vitamin D and calcium supplements when sunshine and diet already provide enough of these nutrients is bad for health.

People with a healthy diet who get out and about and take enough exercise do not need any vitamin or mineral supplements. They are a waste of money and can do a lot of harm. More is not better.

There is no getting away from fresh air, physical activity and a healthy diet, especially during the winter.

Dr Jacky Jones is a former HSE regional manager of health promotion.

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