Are Vitamin Supplements Killing Us?

Health

Written by Danny Penman

Vitamin and mineral supplements are widely touted by the multi-billion pound health food trade as the panacea for a long and active life. Vitamin C is presumed to fight off colds, betacarotene is touted as a cancer-beating drug, and vitamin E is supposed to defeat ageing and reduce the risk of a heart attack.

Alarming new evidence, however, suggests that rather than helping us fight off disease, certain supplements may actually increase the risks of cancer and a range of debilitating diseases.

The idea that vitamin supplements are healthy comes from the discovery that eating plenty of foods rich in the antioxidant vitamins A, C and E dramatically lowers the risk of cancer, heart disease and stroke. Scientists had assumed that fortifying the diet with antioxidant containing vitamin pills would have the same positive impact. But when the scientists looked a little closer, they found the opposite to be the case. By the time the scientists had discovered their error, the genie was out of the bottle and huge numbers of people had started taking mega-doses of vitamins and minerals.

“As with all things, too much of a good thing can be bad for you,” says Dr Derek Shrimpton, a consultant nutritionist to the Ministry of Agriculture and the food industry.

“Water is essential to life but if you drink seven litres of water in half an hour then the result is likely to be fatal.”

Professor Joseph Lunec, Director of Chemical Pathology at Leicester University, is also concerned about the possible dangers of taking large quantities of highly purified vitamin supplements. He warns: “Taking vitamin supplements in high doses may shunt the body’s biochemistry off in the wrong direction. The truth is we don’t know if this is what happens. That’s why we’re conducting our research.”

Scientists are especially worried about people taking high doses of the antioxidant beta-carotene, which the body converts into vitamin A. One study conducted by the US National Cancer Institute found that smokers taking 20 milligrams of beta-carotene increased their cancer risk by 16 per cent. Another study found that taking high levels of beta-carotene increased the cancer risk in smokers by 28 per cent. The US National Academy of Sciences is so concerned about the possible adverse effects of betacarotene that they refused to set a safe upper limit for daily consumption. Supplements containing “risky” levels of beta-carotene are freely available over the counter. The good news is that typical multi-vitamin pills contain only about one fortieth of the risky levels so even smokers can improve their health with a general supplement.

Professor Katherine Rice-Evans, Director of the International Antioxidant Research Centre at London’s Guy’s Hospital, says that people should be aware of the research but not alarmed. She says: “Smokers should not take more than about six milligrams of beta-carotene per day. Non-smokers should take about 6-10 milligrams per day.”

Vitamin A, closely related to beta-carotene, can also be highly dangerous if taken in excess. Pregnant women are especially vulnerable because vitamin A toxicity can cause birth defects and liver damage. Experts recommend that people limit their consumption to a maximum of about 3,000 micrograms a day - about four times the recommended daily allowance or RDA.

Even vitamin C may have a darker side. It has been known for many years that the vitamin can make certain forms of arthritis worse. The National Academy of Sciences recommends that you should not exceed 2,000 milligrams per day. And recent work published in the highly respected science journal, Nature, showed that as little as 500 milligrams per day produces DNA damaging and cancer inducing free radicals. Half a gram of vitamin C is only about eight times the RDA.

Professor Lunec, who conducted the vitamin C research, says that although his studies proved that the nutrient damages DNA it could, in the long run, end up protecting the body.

“It could be a bit like a vaccination. The vitamin C appears to damage certain genes. This primes the body’s repair mechanisms and encourages it to heal itself. High levels of vitamin C in the short term are damaging but in the long term it’s protective.”

Professor Lunec is now trying to discover the optimum vitamin C intake. He estimates that it is likely to be between 200 and 500 milligrams per day which is about 3 to 5 times the RDA.

Vitamin E, long touted as the premier anti-cancer and anti-ageing nutrient, is also under fire. Finnish researchers recently discovered that smokers taking more than 50 milligrams per day (five times the RDA) are more likely to suffer a stroke. Experts are now advising the French government to recommend a maximum vitamin E intake of 40 milligrams per day. The National Academy of Science is not so churlish and says that you can safely take up to 1,000 milligrams per day.

But Professor Rice-Evans says that vitamin E is not only safe but also dramatically improves life expectancy. She says: “Those who supplement their diets with about 75 mg of vitamin E per day show a decrease in coronary heart disease of about 40 per cent. You can’t get that sort of vitamin E level from the diet. You have to take a supplement and there’s no evidence of any toxicity associated with it.”

Massive doses of vitamin B6, used by many women to ease pre-menstrual syndrome, may also wreak havoc on the body. Experts estimate that sustained long term consumption of more than 200 milligrams per day - about 100 times the RDA - risks inflicting lasting damage on the nervous system.

High dose vitamin supplements may also interfere with the absorption or use of other nutrients. The vitamin folic acid, for example, can interfere with the action of vitamin B12 and possibly B6 if taken in excess.

Even minerals may not be safe enough to pop with impunity. High doses of iron can lead to deficiencies of the equally vital minerals zinc and calcium. Molybdenum can destroy the effectiveness of copper, vital for the body’s energy producing machinery, and selenium can damage the nervous system. In fact, the National Academy recommends that you should not take more than 400 micrograms per day of selenium.

In response to the concerns over nutrient supplements, many European countries have laid down maximum limits for vitamin tablets. In Britain, the Ministry of Agriculture has just set up a committee to see if high dose supplements pose a significant health risk. A similar American committee will report its findings in the near future.

Scientists are unsure exactly why vitamins, which are so essential to health, can be toxic in high doses. The most likely explanation is that the body is only equipped to deal with the levels found naturally in the environment. If the intake is too far outside normal range, then the body’s internal chemistry can be shunted out of alignment.

Another possible explanation is that the vitamins sold commercially are often subtly different to those provided by nature. This may interfere with the body’s internal chemistry by ‘crowding out’ the more natural and beneficial forms of the nutrients. The vitamins obtained from food are also allied with a host of other substances which may moderate or augment their activity in the body.

Despite the slowly accruing evidence that certain vitamins in high doses can be damaging, scientists working in the field take just as many as the rest of us. They feel that the optimum intake for a long and healthy life is likely to exceed that which can be obtained from food alone. They are virtually unanimous in recommending - and taking - a general low dose multi-vitamin supplement containing about 100 per cent of the RDA of each vitamin and mineral.

Dr Shrimpton, a consultant nutritionist to the Ministry of Agriculture and the food industry, says: “Overall there’s a lot of evidence that vitamins and mineral supplements can improve health.”

“My advice is first of all eat the best diet of complete wholesome foods that you can and then use supplements if it makes you feel better. You may say it’s psychosomatic or you may say its real but the truth is nobody knows for sure.”

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