- Why the Correct Diagnosis is Important
- Should Supplements be Used?
- Diet and Cancer
- Exercise after Cancer
- Stage Four is not always Terminal
- Immunotherapy, Targetted Therapy, Is there a Difference?
- Soy Products and Breast Cancer
Although epidemiology studies link the intake of vegetables rich in beta-carotene with lower risks of cancer, there are several studies that suggest that supplements are not for everyone.
The ATBC (Alpha-Tocopherol Beta-Carotene) study comprised 29,000 male smokers from Finland who were given either alpha-tocopherol (a form of Vitamin E), or beta-carotene (a type of Vitamin A), or alpha-tocopherol plus beta-carotene or placebo. During a 5 to 8 year follow-up period, 876 new lung cancers were diagnosed. The group receiving beta-carotene had 18% more lung cancers than the groups not receiving beta-carotene. The groups taking alpha-tocopherol had no change in incidence of lung cancer.
In the CARET (beta-CArotene RETinol efficacy) study 18,000 people who were at high risk for lung cancer, either because they smoked or because of asbestos exposure, were either given daily beta-carotene plus retinyl palmitate (a type of Vitamin A), or a placebo. The study was stopped when it was found that new lung cancer cases were 28% higher in the group receiving the supplements.
VITAL (VITamins And Lifestyle) was a study of men and women aged 50 to 76 years living in Washington State in the USA. 364,400 questionnaires with a list of brand name vitamins and supplements were mailed out and 79,300 questionnaires were returned. Respondents were asked how many of the brand name vitamins and supplements were taken over a 10-year period. Respondents were followed up to determine how many developed cancer. 56% of respondents were never smokers.
It was found that using beta-carotene supplements for more than 4 years was associated with an 18% higher risk of lung cancer. Longer duration of retinol (a type of Vitamin A) supplements was associated with 53% more lung cancer, worse for men than for women. Lutein (the pigment found in yellow and red fruits and vegetables) supplements were associated with 102% more lung cancer, worse for women than for men.
The Physicians' Health Study (PHS) studied 22,000 American male physicians. About half the group received beta-carotene supplements and the other half did not. Over a 13-year period, 2,667 cancers were confirmed: 1,117 prostate, 267 colon, and 178 lung cancers. There was no difference in the risk of developing cancer whether or not beta-carotene was taken.
Hence, it would appear that supplements per se do not reduce the risk of cancer and, in certain populations, may even be detrimental.