How supplements can endanger your health

Dietary supplements are widely marketed as an essential complement to our diet, to ensure we get nutrients our body needs to fend off disease.

It is a vast, global industry, and its popularity has gone from strength to strength.

And while many supplements are based on good science, with positive effects on your body and mind, some make claims which are not fully supported.

Indeed, you should be aware that even some important supplements which are considered as safe and effective can have a negative impact on your health.

We've looked at the recent research for three widely used supplements - calcium, selenium, and folic acid - and here is the suprising news.

Calcium

Calcium supplements, which are commonly taken by older people to help fend off brittle bone disease osteoporosis, have been found to be associated with a 30 per cent increased risk of heart attack, as well as increases in the risk of stroke and mortality.

In a different study, scientists found that the widespread use of over the counter calcium and vitamin D supplements has led to the resurgence of a century old disease called calcium-alkali syndrome, which occurs when too much calcium is present in the blood. This can cause high blood pressure and can even lead to kidney failure.

Selenium

The mineral selenium, which has anti-oxidant properties, is marketed as effective in reducing the risk of cancer and other diseases, despite a lack of definitive evidence about its efficacy.

Your body naturally absorbs selenium from vegetables, meat and seafood. However, if you take supplements, your body might absorb too much selenium, which can lead to adverse effects.

Indeed, a recent study has found that taking too much of this essential mineral in your diet can actually increase your cholesterol by almost 10 per cent.

An increase in cholesterol can cause heart disease.

Folic Acid

Folic acid is widely recommended as a supplement for women early in their pregnancy to prevent birth defects.

Now a new study has found that taking the supplement in late pregnancy can actually increase the risk of asthma in the child between the ages of 3 and 5.

The study findings may offer an explanation for the rise of childhood asthma in recent decades.

In a separate study, Swedish scientists found that folic acid can increase the risk of breast cancer in certain women.

In most women folate, a type of B vitamin, reduces the risk of breast cancer. However, in women with a certain genetic make-up it was found to have done the opposite.

This has led scientists to suggest exercising caution before taking multi-vitamin supplements that contain folic acid.

So should I take supplements?

Eating a balanced diet that includes all the major food groups will give you all the vitamins and minerals you need - so there should be no need to take supplements.

However, if you are on a diet which excludes major food groups, then supplements might be a way to complement your diet - though that is no substitute for balanced nutrition.

If you do take supplements, make sure you follow the recommended daily allowance.

You should know that the Department of Health only recommends taking supplements for three vitamins - A, D and folic acid.

• Women who are pregnant are advised to take folic acid in the first trimester.

• Children between the ages of 6 months and 5 years may need vitamins A, C and D, unless they have a good, varied diet.

• Children who do not get sufficient exposure to the sun may need vitamin D supplements.

Before taking supplements it is a good idea to get advice from your GP or a pharmacist.

This article was published on Fri 17 September 2010