If men make sure they consume sufficient selenium they can considerably reduce their chances of developing a fatal form of prostate cancer. This is suggested in a Dutch study published in 2013 in the Journal of the National Cancer Institute. As in many other countries, most men in the Netherlands consume less selenium than nutritionists recommend. Study The researchers analysed data on nearly sixty thousand men, which had been collected during the Netherlands Cohort Study. When the study began in 1986 the participants were aged between 55 and 69. The project continued until 2003. For 79 percent of the men data was available on the amount of selenium in their toenails. During the study nine hundred men developed a severe form of prostate cancer. The researchers compared the selenium status of these men with that of men who did not have prostate cancer. Results The more selenium there was in the men's toenails, the smaller the chance of them having a severe form of prostate cancer. Stage III prostate cancer means that the tumour is malignant and has spread to the epithelium of the organ. Stage IV means that the prostate cancer has spread throughout the body. Conclusion "Our results further support that selenium intake may be an important modifiable factor that reduces the risk of advanced prostate cancer," the researchers wrote. "We specifically evaluated advanced prostate cancer because these cancers have a poor prognosis and are, therefore, clinically relevant." "Several studies have provided evidence that the relationship between selenium and cancer may be U-shaped, with a higher risk associated with levels both below and above an optimal selenium range." "The Nutritional Prevention of Cancer trial showed that selenium supplementation was associated with a reduced risk of total and prostate cancer risk. The association, however, was only present among participants with baseline plasma selenium concentrations in the lowest two tertiles; those in the highest tertile (more than 122 micrograms/l) showed a nonstatistically significant increase in risk." [BJU Int. 2003 May;91(7):608-12] [Cancer Epidemiol Biomarkers Prev. 2002 Jul;11(7):630-9.] "In our study, quintile medians of toenail selenium ranged from 0.43 to 0.67 micrograms/g. This range of toenail selenium was estimated to be equivalent to (quintile medians) 64 to 100 micrograms/l plasma selenium. Based on results of the Nutritional Prevention of Cancer trial, selenium levels in our study are in the range where additional selenium is expected to be beneficial, in the proposed U-shaped curve." "In conclusion, our large prospective analysis showed that higher toenail selenium was associated with a substantial decrease in risk of advanced prostate cancer. If our results are confirmed, a prevention trial of selenium and prostate cancer in a low-selenium population may be justified." Source: J Natl Cancer Inst. 2013 Sep 18;105(18):1394-401.
I was told it was almonds (laetrile) but I think that any nuts are good for you if you eat enough. But Brazil nuts are good too! Unless I missed something, how many units of selenium are we supposed to be consuming? The story illustrated the amounts found in the toenails but how much do we have to consume to get to the desired level?
Without telling us what the optimum dosage is, this study is worthless. If you take too much it is just as bad as not taking enough.
A couple of online sources say the safe upper limit of selenium is 400 mcg per day. The actual amount of selenium in a brazil nut seems to vary quite a bit, but based upon what I've read, I'm estimating there's probably 50 - 75 mcg per brazil nut. So I figure if I eat 3 per day plus whatever I get from my multivitamin and diet, I should be near that upper limit of 400 mcg.