vitamins deficiency symptoms

Selenium and cancer

Many studies indicate that death from cancer, including lung, colorectal, and prostate cancers, is lower among people with higher blood levels or intake of selenium. In addition, the incidence of nonmelanoma skin cancer is significantly higher in areas of the United States with low soil selenium content.

The effect of selenium supplementation on the recurrence of different types of skin cancers was studied in seven dermatology clinics in the U.S. from 1983 through the early 1990s. Taking a daily supplement containing 200 μg of selenium did not affect recurrence of skin cancer, but significantly reduced the occurrence and death from total cancers. The incidence of prostate cancer, colorectal cancer, and lung cancer was notably lower in the group given selenium supplements.

Research suggests that selenium affects cancer risk in two ways. As an anti-oxidant, selenium can help protect the body from damaging effects of free radicals. Selenium may also prevent or slow tumor growth. Certain breakdown products of selenium are believed to prevent tumor growth by enhancing immune cell activity and suppressing development of blood vessels to the tumor.

However, not all studies have shown a relationship between selenium status and cancer. In 1982, over 60,000 participants of the Nurse’s Health Study with no history of cancer submitted toenail clippings for selenium analysis. Toenails are thought to reflect selenium status over the previous year. After three and a half years of data collection, researchers compared toenail selenium levels of nurses with and without cancer. Those nurses with higher levels of selenium in their toenails did not have a reduced risk of cancer.

Two long-term studies, the SU.VI.MAX study in France and the Selenium and Vitamin E Cancer Prevention Trial (SELECT) in the United States and Canada, investigated whether selenium combined with at least one other dietary supplement could reduce the risk of prostate cancer in men.

The SU.VI.MAX study examined the effects of a supplement package containing moderate doses of vitamins E and C, beta-carotene, zinc, and selenium versus placebo on the risk of chronic diseases such as cancer and cardiovascular disease. Among the 5,141 men enrolled, those randomized to the supplements that began the study with a normal PSA (prostate specific antigen) level at baseline had their risk of prostate cancer reduced by half. Among the men whose PSA levels were elevated at baseline, however, use of the supplements was associated with an increased incidence of prostate cancer of borderline statistical significance compared to placebo.

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) was a very large randomized clinical trial begun in 2001 specifically designed to determine whether 7-12 years of daily supplementation with selenium, with or without synthetic vitamin E (400 IU), reduces the number of new prostate cancers in healthy men (PSA ≤4 ng/ml at baseline).

The trial, which had enrolled >35,000 men, was discontinued in October 2008 when an analysis found that the supplements, taken alone or together for an average of 5.5 years, did not prevent prostate cancer. Study staff members will continue to monitor participants’ health for an additional 3 years.

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Selenium decrease the risk of cancer

Selenium is part of an important antioxidant, glutathione peroxidase. Selenium is also found in another antioxidant, selenoprotein P. Recent researches have shown that selenium can be a powerful cancer-prevention supplement. Several studies show that supplementation with selenium decrease the risk of colon and prostate cancer. Unfortunately, the risk of one type of skin cancer (squamous cell carcinoma) was found to be increased by selenium supplementation. Selenium may also help protect us against heart disease. It also helps our immune system work effectively and helps remove heavy metals such as lead from our body. Vitamin E works better and longer in our body when we have plenty of selenium. All that makes selenium pretty important for a mineral we need only in micrograms.

seleniumDeficiency of selenium is uncommon, but may occur in those with poor diets, those who live in areas where the soil is depleted in selenium, Crohn’s disease, and malabsorption syndromes (celiac disease). Selenium deficiency symptoms are muscular weakness and wasting, cardiomyopathy (infl ammation of the heart), pancreatic damage, and impaired immune function.

Selenium food sources

Natural sources of selenium are whole-wheat bread, oatmeal, spaghetti noodles, ground beef and canned tuna. Fruit and vegetables grown in selenium-rich soil also contained selenium.

Selenium side effects and toxicity

Doses of over 1000 mcg/day of selenium can be toxic. Even at doses greater than 400 mcg/day it can occur hair and nail brittleness and loss, upset stomach, skin rash, fatigue, and irritability Symptoms of toxicity can include also vomiting and diarrhea, and skin problems.

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