Vitamin boosts may increase death rate of users, report says
By Jeremy Laurance, Health Editor
01 October 2004
Thousands of people could be dying prematurely from vitamin supplements, researchers report today, stating that the pills increase the death rate of those who take them by 6 per cent.
One in three women and one in four men in the UK is estimated to take dietary supplements for health reasons. But a review of 14 trials of vitamin pills taken by 170,000 people found they increased the death rate by 6 per cent. While they offered no explanation as to what caused the deaths, they discovered that the supplements offered no protection against cancers of the gut.
The researchers, writing in The Lancet, estimate that for every one million people taking the supplements, 9,000 would die prematurely as a result. The figure takes account of the background level of premature death in the population.
Dr Goran Bjelakovic, of the University of Nis in Serbia, who led the review, said: "We could not find evidence that antioxidant supplements can prevent gastrointestinal cancers. On the contrary, they seem to increase overall mortality."
Two UK experts described the findings as "somewhat chilling". Professor David Forman of the University of Leeds and Douglas Altman of Cancer Research UK says in The Lancet: "The prospect that vitamin pills may not only do no good but also kill their consumers is a scary speculation given the vast quantities that are used in certain communities."
The Lancet has printed the quote in large type on the cover of its current issue.
Professor Forman said yesterday that supplements could be useful for people such as pregnant women and the elderly, who might be unable to get adequate vitamins from their diet. But they did not offer a short cut to better health.
For the majority of the population who ate a balanced diet, there were no grounds for taking vitamin supplements, he said. "If someone has a good reason for taking these supplements other than to prevent cancer, then they should continue to do so. But I remain sceptical of their overall value."
The Lancet study is the latest to cast doubt on the value of dietary supplements.
A huge trial of betacarotene (the pre-cursor of vitamin A) and vitamin E in male smokers in 2000 found it increased the lung cancer rate by 18 per cent and the death rate by 8 per cent. Smokers are now advised against taking these vitamins pills.
A second trial of multivitamin supplements in people at high risk of heart disease published in 2002, also in The Lancet, found that after five years they had no protective effect against the risk of heart attacks, strokes, cancer or other serious health problems.
Vitamins are organic nutrients essential for normal metabolism and good health. But specialists say there is a difference between the life-long physiological effects of small amounts ingested in the diet from childhood and pharmacological doses of the same micronutrients taken over a few years by middle-aged adults.
For the latest study, the researchers examined the role of vitamins A, C, E and betacarotene (which is converted into vitamin A in the body) and the mineral selenium, taken either singly or in combination.
They investigated their effect against cancers of the oesophagus (gullet), stomach, bowel, pancreas and liver.
The results showed that a combination of betacarotene and vitamin A increased the death rate by 30 per cent and betacarotene combined with vitamin E increased it by 10 per cent. Selenium was associated with a lower risk of cancer, but the authors say this could be due to bias.
A possible explanation for the findings is that people may vary in their need for antioxidants (vitamins) according to the circulating levels of substances known as free radicals in the blood. Those with high levels of free radicals need extra vitamins to neutralise them but in those with low levels, extra vitamins may paradoxically protect cancer cells and have carcinogenic effects.
The researchers acknowledge they did not look at all trials of vitamin supplements in preventing death and their results are preliminary. The Lancet commentary says that the study is a "work in progress" and "does not provide convincing proof of hazard".
It adds: "In the event that a hazard is established from a complete review, these researchers will need to identify which specific interventions are associated with any risk. It is unlikely that all supplements will exert a similar effect and it will be vital to establish the safety profile for those with demonstrated benefits."
The Health Supplements Information Service, said in a statement yesterday that The Lancet findings were of "borderline statistical significance" and involved some vitamin doses above recommended safe levels. It added: "What is important to take away from this piece of research is that these results are preliminary and further investigations into the role of vitamins in cancer are needed."
Vitamins are either fat soluble or water soluble. The fat-soluble vitamins, which include A, D, E, and K, are absorbed by the body using processes that closely parallel the absorption of fat. They are stored in the liver and are used up by the body very slowly.
The water-soluble vitamins include C and the B complex vitamins. The body uses these vitamins very quickly and excess amounts are eliminated through the kidneys. Taking large doses of vitamin C or B, beyond what the body can immediately absorb, only creates expensive urine.
THE PROS AND CONS OF VITAMINS
Essential for growth, bone development, night vision and healthy skin.
Found in liver, dairy products and eggs. Also in dark red, green and yellow vegetables. Deficiency causes skin disorders, eye damage and may increase the risk of cancer.
Toxic in overdose, causing dizziness, nausea, vomiting and can cause damage to the bones, blood, skin and nervous system.
Found in many yellow fruits and vegetables.
Converted into vitamin A in the body (see above).
Essential for the production of collagen, the basic protein in bones, cartilage, tendons and ligaments. May help boost the immune system.
Found in citrus fruits, tomatoes, potatoes, cauliflowers and Brussels sprouts.
Deficiency causes tiredness, weight loss, irritability, bleeding gums, rough skin and wasting away of muscles. In extreme cases, scurvy.
High doses, above 2gms a day, may cause headaches and diarrhoea. Long-term high doses may increase risk for kidney stones.
Helps prevent cell membrane damage. May prevent blood clots and the formation of fatty plaques in the arteries.
Found in vegetable oil, avocados, nuts and soya beans. Also produced by bacteria in the intestines.
Deficiency may result in easy bruising and bleeding. May increase the risk of hip fractures in women.
Large doses may cause bleeding problems, rashes and itching.