Warning - taking high dose supplements over a long period of time could be harmful to your health. Wynnie Chan reports

Over 50 per cent of UK households bought dietary supplements in 2001, spending around £350 million. Yet this trend could be set to change. A recent report by the Food Standards Agency (FSA) found that people taking large doses of certain vitamins and minerals might permanently damage their health. FSA proposed that a balanced and varied diet gives a person all the necessary vitamins and minerals they need. So, where does that leave the consumer?

Why do we take dietary supplements?
We use supplements for a variety of reasons, from improving our health and wellbeing to preventing and treating specific conditions, and maintaining general health. The body needs an optimum amount of vitamins and minerals to function healthily and stave off illness and disease - and with today's busy lifestyle, it's not always possible to get all your vitamins from diet alone.

What is a dietary supplement?
Dietary supplements can be divided into several categories, as follows:

• Single vitamins or single minerals such as vitamin C or calcium
  
• Multivitamins and/or multi-minerals
  
• Natural oils such as essential fatty acids (cod liver or halibut liver oils), and evening primrose oils
  
• Natural substances such as ginseng, Royal Jelly and garlic, which are often marketed for their health-promoting benefits
  
• Natural substances such as phytonutrients, which are not essential nutrients, e.g. flavonoids
  
• Natural substances - herbal compounds such as echinacea, St John's Wort.
  
  

Vitamin warning
Current intakes of most vitamins and minerals are not said to be harmful, but the FSA has given specific recommendations on the following vitamins and minerals:

1. Chromium picolinate supplements. Consumers are advised not to take chromium in this form, because this has potential to cause cancer. However, having 10mg a day or less in total of chromium in the form of supplements or food is unlikely to cause any harm.
2. Vitamin C supplements. Doses of over 1,000mg a day can cause abdominal pain and diarrhoea.
3. Calcium supplements. Doses of over 1,500mg a day can cause abdominal pain and diarrhoea.
4. Iron supplements. Doses of over 17mg a day can cause abdominal pain and diarrhoea.
5. Beta-carotene, nicotinic acid (a B vitamin), zinc, manganese and phosphorous supplements. High doses above the RDAs guidelines, taken over long periods, may have an irreversible harmful effect.
6. Vitamin B6 supplements. No more than 10mg a day should be taken. High intakes can lead to a loss of feeling in the arms and legs.

'Vitamin pills are a waste of time'. This was the conclusion Rory Collins, Professor of Medicine and Epidemiology at Oxford drew, after leading a five-year trial to establish the effects of supplementing the diets of over 20,500 individuals with a high risk of developing cancer, heart disease and strokes, with high doses of antioxidant vitamins - vitamin C, E and Beta carotene. The study conducted by the Medical Research Council and the British Heart Foundation, published in the Lancet, found no evidence to suggest that these vitamins had beneficial effects in protecting against cancer or heart disease. Professor Collins concluded that eating fresh fruit and vegetables was a better way of protecting the body from disease.

Vitamin pills - a waste of money or worth their weight in gold?
Certainly, vitamin and mineral supplements can be useful companions to the diet of certain individuals, during certain periods of their lives. Hectic lifestyles can make it difficult to follow a balanced diet. Taking a one-a-day multivitamin and mineral supplement, in amounts close to 100 per cent of their RDAs, is a good way to maintain health and prevent disease. This advice extends to individuals on restricted diets, such as slimmers, those who are ill, and fussy eaters. Remember that some vitamins, for example vitamin C and B are water soluble, so the body cannot store excess amounts. High doses of these vitamins will be excreted in the urine.

The following groups of people can benefit from vitamin and mineral supplements.

1. Young children. Vitamins A and D supplements in the from of drops should be given to children between the ages of 6 months to 5 years, unless their diets are normally balanced and varied. Iron supplements may also be needed if meat, or iron-fortified formula milk is not included in the diet.
2. Women planning to become pregnant or are pregnant. Folic acid supplements are needed to reduce the risk of neural tube defects in the unborn child. A daily 400ug folic acid supplement should be taken at least 3 months prior to becoming pregnant and until the 12th week of pregnancy. (Note: no other vitamin and mineral supplements should be taken, unless advised by a GP or antenatal clinic)
3. Breastfeeding women. Extra vitamin D (10ug vitamin D a day) can be taken to meet the additional needs caused by lactation.
4. Older people. Extra vitamin D is needed after the age of 65 because this cannot usually be met by diet or exposure to sunlight. A daily supplement of 10ug vitamin D is advisable. Vitamin B12 supplements may also be needed.
5. Vegans. Individuals who don't eat meat, fish, milk, dairy products or eggs have lower intakes of calcium, iodine, vitamin B12, and vitamin D. Usually, if fortified products are eaten, then supplements may not be necessary.
6. Smokers. People who smoke heavily may need additional vitamin C as they often have a higher turnover of vitamin C than non-smokers.

My top vitamin and mineral supplements

• Sanatogen Gold A-Z
  
  
• Sanatogen Classic 50+
  
• Centrum A-Z
  
• Multibionta probiotic multivitamin and mineral
  
• Boots Mum multivitamin (to be taken before and after pregnancy and up to the 12th week during pregnancy - see guidelines above)
  
• Abidec multivitamin drops (1-5 years)
  
• Tesco complete multivitamin and minerals
  
• Seven Seas multispectrum multivitamin and mineral capsules (suitable for vegetarians and vegans)