Health & Wellbeing

According to University of Otago researchers, eating 1-2 brazil nuts each day could lead to added health benefits and raise the average New Zealander's selenium intake to internationally recommended levels and Department of Human Nutrition Professor Christine Thomson and colleagues carried out the first-ever study (recently appearing in the American Clinical Journal of Nutrition) to look at how much selenium people can obtain from Brazil nuts and the resulting levels of antioxidant activity in their blood.

Over a 12-week period around 60 volunteers were divided into three groups, one of which ate two Brazil nuts a day, while the other groups were given either a 100 mg dose of selenium or a placebo to take daily.

At the outset, the researchers analysed the study members' blood for selenium concentrations and the activity of a key antioxidant, known as glutathione peroxidase (GPx).

After 12 weeks, the blood selenium concentrations of the Brazil nut group were found to have increased by 64.2 per cent, while blood GPx activity went up by 13.2 per cent.

In the selenium supplement group the increase was 61 per cent and 5.3 per cent respectively.
"These results indicate that including a couple of Brazil nuts a day in the diet could ensure a greatly enhanced selenium status without needing to fortify other foods or take supplements."

New Zealanders have a marginal selenium status compared to many other Western countries to soils here being generally low in the mineral, and there is mounting evidence that a marginal selenium status can lead to an increased risk for a range of degenerative conditions, including cancer and cardiovascular disease. At the same time, there is growing scientific support for the idea that higher intakes may provide additional health benefits, such as enhancing the body's immune system and assisting the body in fighting off free radicals.

Professor Thomson cautions that while New Zealanders' low selenium intakes need addressing, too much of the micronutrient can be toxic and people should be careful to limit themselves to no more than a few Brazil nuts per day, otherwise selenium could potentially accumulate to toxic levels in body tissues.

Source: University of Otago website, News at Otago, 2008 archive, March 2008