Selenium is a trace mineral found in soil, water, and some foods. It is an essential element in several metabolic pathways. Selenium deficiency can occur in areas where the soil content of selenium is low and it may affect thyroid function and cause conditions such as Keshan disease. Selenium deficiency is also commonly seen in patients on total parenteral nutrition (TPN) as their sole source of nutrition. Gastrointestinal disorders may decrease the absorption of selenium resulting in depletion or deficiency. Selenium may be destroyed when foods are refined or processed. Specific dietary sources of selenium include brewer's yeast, wheat germ, butter, garlic, grains, sunflower seeds, Brazil nuts, walnuts, raisins, liver, kidney, shellfish (lobster, oyster, shrimp, scallops), and fresh-water and salt-water fish (red snapper, salmon, swordfish, tuna, mackerel, halibut, flounder, herring, smelts). Selenium is also found in alfalfa, burdock root, catnip, fennel seed, ginseng, raspberry leaf, radish, horseradish, onion, chives, medicinal mushrooms (reishi, shiitake), and yarrow. The role of selenium in cancer prevention has been the subject of recent study and debate. Initial evidence from the Nutritional Prevention of Cancer (NPC) trial suggests that selenium supplementation reduces the risk of prostate cancer among men with normal baseline PSA (prostate specific antigen) levels and low selenium blood levels. However, in this study, selenium did not reduce the risk of lung, colorectal, or basal cell carcinoma of the skin and actually increased the risk of squamous cell skin carcinoma. The ongoing Selenium and Vitamin E Cancer Prevention Trial (SELECT) aims to definitively address the role of selenium in prostate cancer prevention.
Chinese herbalists have relied on rhubarb rhizomes and roots for thousands of years. The rhizomes and roots contain powerful anthraquinones and tannins that act as stimulant laxatives and astringents, respectively. In traditional Chinese medicine, rhubarb is also used to treat gastric ulcers, chronic renal (kidney) failure, and pregnancy-induced hypertension (high blood pressure), pre-eclampsia and eclampsia. European herbalists have recommended rhubarb as a laxative, diuretic, and to treat kidney stones, gout (foot inflammation), and liver diseases. Externally, it is recommended to heal skin sores and scabs. The current practice of using rhubarb to treat cancer (as an ingredient in the herbal Essiac® formula) lacks the support of controlled clinical trials. However, rhubarb is being tested for multiple other conditions, including hyperlipidemia (high cholesterol) and obesity. Use for gingivitis, chronic renal failure and upper gastrointestinal bleeding seem to be the most promising, although more research should be done in these areas, specifically with rhubarb as a monotherapy.