The one nutrient I wonder about is your selenium intake limit – is it really 900mcg per day, and if so why?

As I’m sure you’re well aware, Clyde, the usual daily supplement dose recommended for men to prevent and/or fight prostate cancer is 200 mcg (some comes from food depending on where it was grown). Recommendation of 200mcg is based on Larry Clarke’s double-blind trial at the University of Arizona Cancer Center (JAMA. 1996; Br. J. Urol, 1998). Designed to find the effect of selenium on skin cancers (and finding zero effect there), the study chanced to show “a 63% reduction in the secondary endpoint of prostate cancer.” The selenium-treated group developed fewer prostate, colorectal and lung cancer. They had a nearly 50% decrease in total cancer deaths and a 17% decrease in overall mortality compared to those taking placebo.

400 mcg is considered “hazardous” level by one source (Beloit University). That may be exaggerated. The Institute of Medicine of the National Academy of Sciences has set a tolerable upper intake level for selenium at 400 micrograms per day for adults.

You may already be consuming some selenium from your foods, especially vegetables and sea food. I’ve seen an estimate of 800 mcg in 3 Brazil nuts.

True, senior adults may absorb less selenium from dietary sources than younger people do.

For all of us — a good listing of foods high in selenium (depending on where they were harvested) is at Unversity of Pittsburgh. They say that for cancer “Many studies that have examined selenium intakes and blood selenium levels have suggested that people with greater intakes of selenium are less likely to develop cancer or to die from cancer if they already have it.”

Types of cancer that selenium may help prevent include, they say, include:< br/>
lung cancer
colorectal cancer
prostate cancer
skin cancer, nonmelanoma
stomach cancer
breast cancer

They say "Selenium’s effects on cancer are believed to be due to its action as an antioxidant. In addition, selenium helps to stimulate the immune system, making it better able to fight cancer.” Just stay in the safe zone.

The most recent study on selenium and prostate cancer risk comes from NCI and a large group of researchers at US centers:
Serum selenium and risk of prostate cancer – a nested case-control study, Am Jour of Clinical Nutrition, Vol. 85, No. 1, 209-217, January 2007).
They come to a mixed conclusion: "Greater prediagnostic serum selenium concentrations were not associated with prostate cancer risk in this large cohort, although greater concentrations were associated with reduced prostate cancer risks in men who reported a high intake of vitamin E, in multivitamin users, and in smokers."

Short term high-dose selenium (1000 mcg per day given intravenously) is used for a period of days in some critical care centers to reduce oxidative stress in burn patients and people with sepsis. Results have been called mixed although a 1000 mcg dose does appear to have some benefit for these critical care patients. A study preceding this with a 4000 mcg loading dose on day 1 reports that more people died who received IV selenium compared with those who did not.

Mark Moyad at the University of Michigan wrote in 2002: “Selenium supplements provided a benefit only for those individuals who had lower levels of baseline plasma selenium. Other subjects [i.e. patients], with normal or higher levels, did not benefit and may have an increased risk for prostate cancer.”

Some people might be interested in New Selenium Test for Prostate Health (2006)