Otago University scientists say that eating two Brazil nuts everyday may help reduce the risk of a wide range of conditions, including cancer and heart disease.
Professor Christine Thomson says that Brazil nuts may provide such beneficial health effects by helping maintain the levels of selenium, a trace mineral essential for producing antioxidant enzymes and other proteins that protect cells from damage.
The researcher, who led the first ever research into how much of the essential micronutrient people can obtain from Brazil nuts, pointed out that people in New Zealand generally had "marginal" selenium levels because the soil was deficient in selenium.
"There is mounting evidence that a marginal selenium status can lead to an increased risk for a range of conditions, including cancer and cardiovascular disease," stuff.co.nz quoted her as saying.
During the study, described in the American Clinical Journal of Nutrition, 60 volunteers were divided into three groups - one ate two Brazil nuts a day, one received a 100 microgram selenium supplement, and one was given a placebo.
After 12 weeks, the researchers observed a 64.2 per cent increase in the blood selenium concentrations among participants who ate Brazil nuts, compared with 61 per cent in the selenium supplement group.
Upon measuring the activity levels of a key antioxidant, the researchers noted that the Brazil nut eaters' levels went up by 13.2 per cent, compared with 5.3 per cent in the supplement group.
The study report says that research is underway to investigate the link between low selenium levels and higher rates of cancer and heart disease.
"Kiwi farmers have been feeding selenium supplements to their cattle for years ... but it's only in the past few years that people have cottoned on to the fact it might be good for them too," Wellington Nut Store co-owner David Upchurch said.