Vitamins - are they helpful or harmful

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.

How much is too much?
Existing European guidelines specify the recommended daily amount of vitamins or minerals that adults need to maintain health and prevent deficiencies. These guidelines are known as the recommended daily allowance or RDA.
Vitamins   EC labelling RDA

Vitamin A (ug)
Vitamin D (ug)
Vitamin E (mg)
Vitamin C (mg)
Vitamin B1 (mg)
Vitamin B2 (mg)
Niacin (mg)
Folate (ug)
Vitamin B6 (mg)
Vitamin B12 (ug)
Biotin (mg)
Pantothenic acid (mg)

  800
5
10
60
1.4
1.6
18
200
2
1
0.15
6

Minerals     Calcium (mg)
Phosphorous (mg)
Magnesium (mg)
Iron (mg)
Magnesium (mg)
Zinc (mg)
Iodine (ug)   800
800
300
14
300
15
150 Micrograms - ugMilligrams - mg

Often, dietary supplements are available in amounts close to 100 per cent of their RDAs. However, some are sold in high or megadoses of the RDAs, and it's these high dose supplements that can pose problems if taken over a long period of time.