Findings published in Cancer Causes and Control also showed that carotenoids, niacin, thiamine, and vitamin D may reduce the risk of bladder cancer in older people.
?The effects of vitamin E, carotenoids, vitamin D, thiamin, and niacin in relation to the risk of developing bladder cancer may warrant further investigation,? report the researchers, led by Maree Brinkman from The Cancer Council Victoria in Australia.
?Future studies should focus on optimal doses and combinations of these micronutrients particularly for high risk groups such as heavy smokers and older individuals,? they state.
Bladder cancer is diagnosed in about 336,000 people every year worldwide, and it is three times more likely to affect men than women, according to the European School of Oncology.
Brinkman and her co-workers analysed dietary data from 322 people with bladder cancer and 239 healthy controls. A 121-item food frequency questionnaire was used to estimate dietary intakes.
Results showed that, in general, people with the highest average intakes of vitamin E (at least 193.4 milligrams per day) were 34 per cent less likely to develop bladder cancer. The highest average intakes of phosphorous (1,557 milligrams) were associated with a 51 per cent reduction in bladder cancer risk.
?Although we observed an approximate 50 per cent reduction in the odds of bladder cancer associated with higher dietary intake of phosphorus, it was not statistically significant,? wrote the researchers. ?Given this ubiquitous micronutrient is an important physiological component of DNA, RNA, ATP, and cell membranes, it may be worthy of further consideration.?
When the researchers focused their analysis on smokers, they found that the highest intakes of vitamin E, carotenoids (18 milligrams), and niacin (46.5 milligrams), were associated with a 42, 38, and 34 per cent reduction in bladder cancer risk in heavy smokers.
In older individuals, the highest average intakes of carotenoids, vitamin D (641 International Units), thiamin (3.35 milligrams), niacin, and vitamin E were all associated with a reduced bladder cancer risk.
?Bladder cancer is a disease that typically affects older people, and bioavailability of B-group vitamins may be compromised in this demographic by certain drugs (e.g., acid lowering agents),? stated the researchers. ?Additionally, vitamin E, like carotenoids acts as an antioxidant and, as suggested by our results, could be more beneficial under conditions of the greatest oxidative stress such as smoking and ageing.?
The researchers called for additional study to further examine these potentially protective relationships.
The study was supported by the National Institute of Environmental Health Sciences and the National Cancer Institute at the US National Institutes of Health (NIH).
Source: Cancer Causes and Control
Published online ahead of print, doi: 10.1007/s10552-009-9490-0
?Minerals and vitamins and the risk of bladder cancer: results from the New Hampshire Study?
Authors: M.T. Brinkman, M.R. Karagas, M.S. Zens, A. Schned, R.C. Reulen, M.P. Zeegers