What selenium is: Selenium is a necessary hint mineral—that’s, it’s wanted in small quantities to take care of good well being and should be consumed, for the reason that physique doesn’t manufacture it. The Really helpful Dietary Allowance (RDA) is simply 55 micrograms a day (a microgram is one-thousandth of a milligram). It’s plentiful in meals resembling entire grains and nuts and in baker’s yeast. When first found in 1817, selenium was thought of a poison as a result of it’s poisonous in giant quantities.
Claims, purported advantages: Prevents cancers—notably prostate most cancers—and wards off many persistent ailments and circumstances, together with coronary heart illness, diabetes, rheumatoid arthritis, Alzheimer’s illness and pregnancy-related issues.
What the research present
Prostate most cancers. Early research noticed that in areas the place meals are richer in selenium, there are fewer cancer-related deaths; researchers additionally discovered an affiliation between low blood selenium ranges and an elevated threat of a number of cancers. Some research have discovered associations between greater selenium ranges in toenails (a measure of long-term selenium consumption) and a decrease threat of sure cancers, together with bladder most cancers.
Within the Dietary Prevention of Most cancers Trial in 1996, selenium (200 micrograms a day from baker’s yeast) dramatically lowered the danger of prostate most cancers, principally in males with low preliminary selenium ranges. And within the Physicians’ Well being Examine, males with the very best blood selenium ranges had been solely half as more likely to develop superior prostate most cancers as males with the bottom ranges.
However the necessary Selenium and Vitamin E Most cancers Prevention Trial discovered no profit in opposition to prostate most cancers from both complement; these taking selenium had a barely elevated threat of diabetes. For that reason, the examine was halted in late 2008. A examine within the Journal of Scientific Oncology in 2009 discovered that greater selenium ranges within the blood may very well worsen prostate most cancers in some males who have already got the illness. A 2011 examine discovered that males at excessive threat for prostate most cancers who took selenium dietary supplements, in tandem with vitamin E and soy, had been as liable to develop invasive most cancers as males who took a dummy tablet, or placebo.
On the subject of dietary selenium, a 2011 assessment of 55 research by the Cochrane Collaboration found that within the majority of observational research, males who received probably the most dietary selenium had been at lowered threat for a number of cancers. However the high quality of the research was questionable.
The Meals and Drug Administration (FDA) has authorized this extremely certified well being declare concerning selenium and prostate most cancers: “Selenium could scale back the danger of prostate most cancers. Scientific proof regarding this declare is inconclusive. Primarily based on its assessment, FDA doesn’t agree that selenium could scale back the danger of prostate most cancers.”
Coronary heart illness. A analysis assessment revealed within the American Journal of Scientific Vitamin discovered no cause to advocate selenium dietary supplements to stop coronary heart illness. A 2011 Annals of Inside Drugs examine discovered solely minor declines in ldl cholesterol, which do not warrant the usage of selenium dietary supplements, significantly in international locations the place residents devour sufficient selenium (just like the U.S.). A 2013 assessment by the Cochrane Collaboration concluded that selenium dietary supplements don’t scale back the danger of heart problems and should barely enhance the danger of sort 2 diabetes.
Diabetes. A 2012 Harvard examine revealed in Diabetes Care linked greater toenail selenium with a lowered threat of sort 2 diabetes, however solely 4 % of the topics took selenium dietary supplements. Nevertheless, based on a 2012 assessment article within the Lancet, some research counsel that greater selenium consumption enhance diabetes threat.
Unwanted effects: The secure higher restrict for adults is 400 micrograms a day. Dosages of 1,000 micrograms or extra a day may cause nausea, vomiting, hair loss and different issues. As talked about, a number of research have discovered that selenium (200 micrograms each day) could elevate the danger of diabetes. And two latest research linked excessive blood ranges of selenium with modest will increase in levels of cholesterol.
Backside line: Go for selenium-rich meals and depart the dietary supplements on the cabinets. Most People already get greater than the RDA. Should you do take a selenium complement, don’t take greater than 200 micrograms a day.