Go easy on the brazil nuts!Too much selenium may increase cholesterol
Eating large amounts of the essential mineral selenium in your diet can boost your blood cholesterol and increase your risk of heart disease, new research suggests.
Researchers from the University of Warwick discovered that taking too much selenium in your diet can increase your cholesterol by almost 10%.
Selenium is a trace essential mineral with anti-oxidant properties, and helps prevent damage to the body's cells and tissues. It is also plays an important role in immune system functions, thyroid hormone metabolism and reproduction.
The body obtains selenium from vegetables, meat, seafood and sometimes bread. Brazil nuts are a particularly rich source of the mineral, containing 0.025mg of selenium per 100g of nuts.
It is already known that taking too much selenium can cause selenosis, or selenium poisoning, which causes hair, skin and nail loss. However, this research suggests it may also cause an increase in blood cholesterol.
High cholesterol levels can lead to narrowing of the arteries, heart disease and stroke.
In the study published in the Journal of Nutrition, researchers measured the concentration of selenium and cholesterol in blood taken from 1,042 people aged between 19 and 64.
After adjusting for lifestyle factors such as diet and exercise, they found a 10% increase in non-HDL cholesterol (the bad type) in people with selenium blood concentrations greater than 1.2umol per litre.
Almost half of the people with the highest selenium levels admitted to regularly taking supplements.
Dr Saverio Stranges, who led the study, said the results were of concern. The consumption of selenium supplements has recently risen in the UK, driven by the belief that the mineral can reduce the risk of cancer and other diseases.
“This use has spread despite a lack of definitive evidence on selenium supplements efficacy for cancer and other chronic disease prevention," Dr Stranges said.
"The cholesterol increases we have identified may have important implications for public health. In fact, such a difference could translate into a large number of premature deaths from coronary heart disease.
“We believe that the widespread use of selenium supplements, or of any other strategy that artificially increases selenium status above the level required is unwarranted at the present time. Further research is needed to examine the full range of health effects of increased selenium, whether beneficial or detrimental.”
The recommended daily amounts in the UK are set at 0.075mg of selenium for men and 0.06mg for women.
This article was published on Fri 13 November 2009
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