How many of you remember taking vitamins as children? Doled out by my mother as I trotted off to school, I loved their orange tang. Vitamins were not to every child's taste, however. A colleague in The Irish Times remembers systematically stashing then behind sofas and bookcases, her mother blissfully attributing her rude good health to the phantom doses of daily Vitamin C.
Vitamins are substances needed by the body for various essential metabolic functions. Metabolism is the term used to describe chemical reactions that take place inside our bodies. It refers to the never-ending cycle of ingesting food, converting it to energy and eliminating waste products.
Many of the body's essential chemical reactions can only take place in the presence of vitamins. Basically, they act as catalysts, speeding up the natural process of cellular functioning. Vitamin A, D, E and K are fat-soluble. With the exception of K, the body can store fat-soluble vitamins for long periods. People taking supplements of these vitamins need to be careful, as high doses can be toxic.
The B Vitamin groups (a complex of different substances) and Vitamin C are water soluble. In theory, the risk of toxic build-up is unlikely since any excess will be flushed out by the kidneys. These vitamins are chemically unstable and are easily destroyed by exposure to light and by cooking.
Vitamins are a huge industry, worth more that £360 million in the UK. Clint Eastwood takes them religiously, convinced they will extend his life and keep him cancer-free. Sylvester Stallone reportedly swallows 65 different vitamins and nutrients a day. Should those of us of more modest means continue to spend more and more on supplementing our diets with vitamin pills?
The short answer is no. With a little attention to detail, it is possible for everyone in the western world to ensure an adequate intake of vitamins by diet alone. A balanced diet with fresh fruit, vegetables, fish and lean meat will give most people all the vitamins they need. Supplements taken on top of this will simply be got rid of by the body. According to Prof Ben Sacks, a neurologist in the UK, "people who take very high doses of Vitamin C get the most expensive urine in the world".
But can supplementation with Vitamin C cause any harm? A paper at this year's American Heart Association Conference was the first to suggest that Vitamin C supplements could be linked to heart disease. In a preliminary report on his research, Prof James Dwyer of the University of Southern California described a study of 573 workers at a utility company aged between 40 and 60. Researchers measured the thickness of the walls of arteries in their neck at the start of the trial and 18 months later.
Workers who took up to 480mg of Vitamin C per day had a thickening of the arteries twice that of non vitamin users. Those who smoked had a thickening five times that of smokers that took no Vitamin C.
The EU and the US differ in the recommended daily allowance (RDA) levels for Vitamin C. The American National Academy of Science recommends a dose of 90mg a day of Vitamin C for men and 75mg a day for women. The EU recommends a daily dose of 60 mg for both sexes.
Interestingly, the European Commission has just announced plans to move from the system of RDAs to a more flexible measurement called Upper Safety Levels (USL). The draft directive states that bottle labels must include a daily dosage recommendation, a warning about possible health risks in case of excessive use and a statement that the tablets should not be used as a substitute for a varied diet.
In addition, claims that a product can prevent, treat or cure illness will be prohibited. The proposed legislation also promises to establish a scientific assessment of the USLs of vitamins and minerals.
Vitamin C is a proven antioxidant; oxidative damage by chemicals called "free radicals" has been linked to heart disease, dementia and the development of cancer in humans. As the name suggests, Vitamin C (and other minerals) protect the cells by combatting the harmful effects of oxidation. They literally mop up the free radicals circulating in the body.
SO where does all this leave the healthcare consumer? A Dublin cardiologist refused to condemn Vitamin C on the basis of Prof Dwyer's study, preferring to wait for more evidence to emerge on possible cardiac side effects.
We can certainly reach one definite conclusion in the debate about vitamins. There is no need for you to take regular supplements provided you eat a balanced diet of fish, fresh fruit and fresh vegetables.
And just to reinforce the point, last week's British Medical Journal reports a novel approach to the treatment of heart disease. A doctor in Stromness in the Orkney Islands is prescribing tubs of marinated herring for patients with existing heart problems.
Funded by the NHS, Dr Andrew Trevett prescribes two portions a week of the oily fish as well as encouraging his patients to give up smoking and to take more exercise. It sounds like an eminently sensible approach to the whole question of vitamins and health.