Can Vitamins Prevent Disease?
The vitamin supplement industry is worth millions of pounds every year, and the Internet is full of suggestions that vitamins can prevent or cure all kinds of diseases. There is research under way all around the world looking at the role of vitamins in health and disease, and while there is some evidence about where vitamins can and cannot help, some claims are just based on anecdote and assumption, and should be taken with a pinch of (vitamin enriched?) salt.
Even where there is scientific evidence, using vitamins to treat specific diseases, especially at doses above recommended daily allowances, should only be done at the recommendation of a doctor.
Vitamins and Cancer/Heart DiseaseFollowing studies of people with diets rich in fruit and vegetables showing lower rates of cancer and heart disease, researchers studied a group of 161,808 women taking multivitamin supplements for eight years and saw no reduction in cancer and heart disease. This might mean that the vitamins in food are ‘better’ than the vitamins in supplements (see ‘Are Vitamins in Food Better Than Supplements?’) or it might mean that the people who ate a lot of fruit and vegetables were also the kind of people who exercised more and ate less meat.
Vitamin B2 and MigraineIn a study, Vitamin B2 (riboflavin) supplements at 400 mg per day halved the number of migraines in some people.
Vitamin B6 and Pre-Menstrual SyndromeVitamin B6 (pyridoxine) at doses of 50 to 100 mg can help with the symptoms of pre-menstrual syndrome. Higher doses are unlikely to be any more effective and vitamin B6 at doses above 200 mg per day can cause tingling in hands and feet and may lead to irreversible nerve damage.
Folic Acid (Vitamin B9) and Neural Tube DefectsTaking folic acid before conception and during pregnancy can reduce the risk of the unborn child having neural tube defects – problems with the spinal cord, skull and brain.
Folic Acid (Vitamin B9) and Heart Disease/StrokeThere is mixed evidence for and against the suggestion that taking a folic acid supplement can reduce the risk of heart disease – some evidence suggests that it could increase the risk. There is some evidence that folic acid can reduce the risk of stroke.
Vitamin B12 and AnaemiaInjected vitamin B12 is used to treat pernicious anaemia, a form of anaemia caused by the inability to absorb B12 from food.
B Vitamins and Diabetic NeuropathySome diabetics are low in B vitamins – this may be related to reduced absorption of B vitamins caused by the antidiabetic drugs. B vitamins, including vitamin B12, may help prevent and treat diabetic neuropathy.
Vitamin C and the Common ColdThere is no evidence that high doses of vitamin C prevent colds, though they may reduce the length and severity slightly. High doses of vitamin C can cause indigestion, diarrhoea and kidney stones.
Vitamin D and Multiple SclerosisResults from research in 2009 suggested that a vitamin D supplement during pregnancy and childhood, or careful exposure to the sun, could prevent multiple sclerosis. However, this is still early research.
Vitamin E and Heart DiseaseThough some studies have shown that vitamin E supplements reduce the risk of heart disease, other studies have not shown the same results.