Selenium is a naturally occurring essential trace element found in soil, rocks, plants, and water. Its main roles within the body are to promote immune system function and thyroid hormone metabolism.
While selenium deficiency is generally unheard of in healthy individuals, studies are showing intake is decreasing in many parts of the world. The problem with selenium is the content in your food can vary drastically depending on geographical factors such as soil concentration.
In the UK for example, meat contains lower levels of selenium in recent years due to opting for low selenium wheat and animals grazing on low selenium soil. The two leading selenium deficiency-related diseases are Keshan disease and Kashin-Beck disease. These are most commonly found in central and western China and surrounding areas due to their soil containing low selenium levels.
Keshan disease is a chronic disease of the heart muscle (cardiomyopathy) that affects blood flow, abnormalities in the linings of the heart chambers and valves and leakage of enzymes into the bloodstream .
Kashin-Beck disease is a chronic joint disease that can cause decreased muscle strength, the range of joint movement and can cause serious functional limitations or disability . Signs of selenium deficiency include the lowered immune system, fatigue, slower thyroid function, hair loss, infertility, poor concentration and anxiety .
Studies show adequate selenium intake may be preventative against cancer and cancer-related mortality . One particular study shows high selenium intake may reduce the likelihood of bladder cancer by up to 39% and is in line with prior studies linking selenium with reduced rates in breast, prostate, lung, colorectal and skin cancer .
Selenium is also shown to be an antioxidant and prevents oxidative modifications and inflammation as a result. For these reasons, cardiovascular diseases are thought to be prevented by sufficient selenium intakes . As we age, serum selenium levels decrease in our bodies and lower levels are associated with the decreased brain function such as memory loss.
The thyroid is the most selenium concentrated part of our body and plays a vital role in thyroid hormone synthesis and metabolism. Women tend to experience a number of thyroid conditions both during and after birth which had been proven to slow the metabolism. Research shows strong positive results when using selenium supplementation as a cure.
How to Avoid Selenium Deficiency – Good Selenium Sources
Adults generally require 55 micrograms of selenium per day and 200 micrograms has been shown to be preventative against disease while 400 micrograms are thought to be the upper limit. Dried fruits such as apricots and raisins and vegetables such as mushrooms and celery contain a fairly handy serving of selenium.
Beans such as mung beans and soybeans, both white and brown rice and whole-grain bread contain an even greater serving of selenium to help you towards your daily needs. 100g of cashew nuts and a wide variety of white fish such as cod and herring will provide with at least 50% of your daily requirement.
Going even further you’ll find 100g of crab, brazil nuts, shrimp and animal kidney will take you beyond your daily intake so be sure to eat these in moderation if you want to stay below the recommended upper limit.