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increased risk of BPH and LUTS whereas increased physical activity and moderate alcohol consumption were beneficial. One can argue that diabetes is not exactly a modifiable factor, but blood glucose control may be an issue here. In two studies that looked at physical activity, walking 2 hours a week or more vs. 0 hours/week yielded a 27% risk reduction. In another study, physical activity greater than 6 times a week resulted in a 51% decrease in risk, whereas when physical activity was quantified in terms of energy used, 862 kcal/day vs. 140 kcal/day gave a 50% reduction in risk. For alcohol consumption, two studies found a 41% decrease in risk, one for 2-3 drinks a day, one for one or more per day. Risk reductions for BPH in a Korean cohort were 74% for those who drank alcohol every day vs. abstainers. The risk reductions in the studies reviewed were with reference to clinical BPH, LUTS and the likelihood of requiring surgical intervention for acute urinary retention and intolerable LUTS. The author points out that it is counterintuitive that alcohol in any amount protects against the development of BPH and LUTS given its potent diuretic effects, but that a potential explanation for the above observations might be by mechanisms similar to those operating to produce the beneficial effects of alcohol on the cardiovascular system. With regard to modifiable factors that increased the risk of BPH and LUTS, diabetes, impaired fasting glucose, hypertension and a large waist circumference (> 109 vs. < 89 cm) produced increases in risk, mainly of LUTS, of approximately a factor of 2 to 3.

MICRONUTRIENTS AND PROSTATE CANCER RISK

Several but not all follow-up studies on the impact of dietary or supplemental vitamin E on the incidence and progression of prostate cancer found a positive benefit, and there is an ongoing clinical trial in this regard

involving the combination of vitamin E and selenium (the SELECT phase III trial). A recent study National Cancer Institute of the NIH and New York University has contributed to this subject [2]. prospective study, Wright et al followed a cohort of almost 300,000 who were cancer free at enrollment.

from the In this Baseline

supplemental questionnaire.

and dietary intakes At the end of 5 years

of alpha-, beta-, gamma- and delta-tocopherols were obtained from a follow-up over 10,000 prostate cancer cases were identified. Supplemental

vitamin E (alpha-tocopherol) intake was not found to be associated with prostate cancer risk even at 800 IU/day. However, dietary gamma-tocopherol was found to be significantly and strongly inversely

intakes related to

prostate cancer risk, median intake in the

with a 32% risk reduction when the highest vs. the lowest quintiles were compared. The highest quintile was 20.8 mg/day with a range of 18.5 to 57.5. Furthermore, this beneficial

effect was particularly evident among men with a low selenium intake.

commonly dressings,

consumed form of fried potatoes, oils

vitamin E in the US diet. The authors (mostly corn) cookies and brownies.

list

as

major

Gamma-tocopherol

sources

margarine,

is the

most

butter,

salad

The potential anti-cancer properties of gamma-tocopherol appear to be under appreciated, given that most people appear to think of vitamin E only in terms of the common supplement, the alpha form. In a recent review titled Gamma-Tocopherol--An Underestimated Vitamin?, Wagner et al [3] discuss a number of studies that relate to this question. One found a 5-fold reduction in prostate cancer risk for the highest vs. lowest quintiles of gamma-tocopherol intake. Another serum level study also found the same 5-fold reduction. However, a large trial involving U.S. physicians that also looked at serum levels failed to find a similar association. In addition, Wagner et al point out that gamma-tocopherol is more effective than alpha-tocopherol in inhibiting prostate cancer cells, reducing oxidative DNA damage and scavenging certain mutagens. Obviously, more studies are needed, but the evidence of the benefits of gamma-tocopherol in regard to prostate cancer is accumulating. In fact, it may occur to some readers that the SELECT trial may not be using the ideal form of vitamin E and that a negative outcome of this trial when it finally reports might well kill interest in vitamin E in general, including the gamma form.

Gamma-tocopherol is also available in supplements, generally as mixed tocopherols. Careful label reading is required since IU may be quoted (conversion 0.15 IU per mg) but it is common for only a total in IUs or milligrams for the beta, gamma and delta combined to be displayed. Products are available that contain 200 or more mg per capsule of the gamma form. Given that many individuals do not eat foods rich in the gamma form of vitamin E, supplements containing this form appear to be of interest.

International Health News

November 2007

Page 19

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