Are you getting enough selenium?
Selenium is an incredibly important trace element that is essential to our wellbeing. The body needs it in small amounts for a number of functions including to help regulate thyroid hormones and support a healthy immune system. The importance of selenium in animal nutrition was first discovered in the 1950s, when it was shown that myopathies (neuromuscular disorders) in sheep and cattle could be prevented by adding selenium and vitamin E to their diet.
One of selenium's most important roles from a human nutrition perspective is as an antioxidant, helping to prevent cell damage due to free radicals. Selenium also works alongside other antioxidants such as vitamins E and C, which are essential for a healthy immune system. Studies suggest that a selenium-rich diet can help to protect against skin cancer, sun damage and age spots. It is also incorporated into a range of important proteins in our bodies, called selenoproteins, one of which is a vital part of our antioxidant defence mechanism.
New Zealand soils are low in selenium; subsequently foods grown in New Zealand are also low in this mineral also. On average our blood selenium concentrations remain lower than those in many other Western countries. It has been estimated that dietary intakes of adult women in New Zealand are around 80 per cent of the recommended dietary intake (RDI) for selenium, and adult men get around 95 per cent of the RDI. Too many people don't meet the RDI for selenium, which can lead to significant long-term health consequences.
Since low levels/a lack of selenium deprive cells of their ability to synthesise selenoproteins, many health effects of low selenium intake/status are considered to be caused by the lack of one or more specific selenoproteins. New Zealand research has shown that higher selenium intakes result in increased activity of one of the important antioxidant selenoproteins, glutathione peroxidase. Low levels of glutathione peroxidase have also been associated with an increased risk of cardiac events in patients with coronary artery disease. It's no wonder this essential mineral is the subject of increased interest. Research also suggests selenium could play a role in reducing the likelihood of developing cancer, as it has been shown to inhibit cell proliferation. There is also some evidence to suggest selenium may help protect against prostate cancer.
So how can you get enough selenium? Fish, seafood, poultry and eggs contain small amounts of selenium but perhaps the simplest way to improve our selenium intake is to eat two to four brazil nuts each day, as these are the richest food source of selenium.