Selenium is a trace element found in the soil. Selenium is only required in very small amounts, but plays a number of vital roles in our body. In particular it helps protect cells against the effects of free radicals and prevents the development of chronic diseases such as cancer. Selenium is also essential for normal functioning of the immune system and can help people living with HIV/AIDS minimise the damage caused to their immune system.
Selenium deficiency can lead to muscular weakness and fatigue therefore it is incredibly important to ensure you are getting enough selenium in your diet via either food or supplementation.
Which foods provide selenium?
Plant foods are the major dietary sources of selenium in most countries throughout the world. The amount of selenium in soil, which varies by region, determines the amount of selenium in the plant foods that are grown in that soil.
Selenium also can be found in some meats and seafood. Animals that eat grains or plants that were grown in selenium-rich soil have higher levels in their muscles. Some nuts, in particular Brazil nuts and walnuts, are also very good sources of this vital mineral.
All cells contain selenium. The highest concentrations are found in sexual glands and semen. Sperm cells are particularly dependent on selenium, as this nutrient is required for proper functioning of proteins in the tail that enables the sperm cell to swim forward. For this reason sexually active men need more selenium, as each ejaculation consumes a large quantity of selenium.
Selenium contains antioxidants that help in sperm formation and also increases sperm’s mobility, giving it the ability to swim and fertilise. Therefore adequate levels of selenium increase the sperm’s chances of fertilizing the egg. Blood selenium levels have been found to be lower in men with low sperm counts. Results of a study by Hawkes and Turek (2001) found supplementation of selenium to have positive effects on sperm mobility. Selenium can also help to prevent chromosome breakage, which is known to be a cause of birth defects and miscarriages.
Fights against thyroid cancer
Standard daily intake of selenium helps to maintain normal development and production of thyroid hormones. However, selenium may also prove effective in reducing thyroid cancer cell growth. Preliminary research reported by the American Thyroid Association suggests that selenium inhibits the growth of cancer cells. Clinical trials are underway to determine the long-term effectiveness of selenium for preventing thyroid cancer development.
Lowers the risk of heart disease
Collectively, heart and circulatory diseases cause more than one in three of all deaths in the UK, accounting for more than 191,000 deaths each year at an estimated cost of £30 billion to the economy. This figure is also on the rise due to lifestyle changes that allow people to spend less time exercising, leading to an increase in the amount of fat stores within the body. Regulating the amount of selenium reduces the risk of heart disease by lowering oxidation of harmful cholesterol and unnecessary clotting of the blood.
The recommended daily allowance (RDA) is 55 mcg for men, however it is considered safe to take up to 400 mcg daily.
Note: Supplements must not be used as a substitute for a varied and balanced diet and a healthy lifestyle. If you are pregnant, breastfeeding or taking any medications, please consult a doctor before use. Discontinue use and consult a doctor if adverse reactions occur.
- American Thyroid Association: Dietary Supplement May Be Future Treatment for Thyroid Cancer
- The British Heart Foundation. http://www.bhf.org.uk. Our heart disease facts (visited October 2012).
- Hawkes, W. C., &amp; Turek, P. J. (2001). Effects of dietary selenium on sperm mobility in healthy men. The Journal of Andrology. 22 (5): 747 – 772.