Taking selenium supplements may increase cholesterol levels by as much as 10 per cent, according to a new study.
Writing in the Journal of Nutrition, scientists at the University of Warwick Medical School said consuming too much selenium can have adverse effects.
Selenium is considered a health ingredient because of its antioxidant properties, and the perception that it can reduce cancer risks. The body naturally absorbs selenium from vegetables, meat, and seafood but it is also found in higher quantities in supplements.
Health benefits may be linked to selenium but according to a team led by Dr Saverio Stranges at Warwick University, the balance can be tipped and high levels of selenium in the diet are associated with increased cholesterol.
The scientists reached this conclusion after examining the relationship between plasma selenium concentrations (levels of selenium in the blood) with blood lipids (fats in the blood).
A cross-sectional study of the1042 participants in the 2000-2001 National Diet and Nutrition Survey revealed that among those with higher plasma selenium (more than 1.20 µmol/L) there was an increase in the average total cholesterol level of 8 per cent (0.39 mmol/L (i.e. 15.1 mg/dL).
Researchers also found a 10 per cent increase in non-HDL cholesterol levels, which is the bad cholesterol most closely linked to heart disease.
Making the final step linking high selenium intake, supplementation, and high cholesterol, the scientists noted that among the participants, 48.2 per cent admitted they regularly took dietary supplements.
Dr Saverio Stranges said high levels of selenium were not exclusively caused by supplementation, but the conclusions of the study do raise concerns given the increased use of selenium supplements in recent years.
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.” Stranges called for further research to examine the full range of health effects from increased selenium in the diet.
In a recent opinion on selenium, the European Food Safety Authority (EFSA) concluded that it could offer “protection of DNA, proteins and lipids from oxidative damage, normal function of the immune system, normal thyroid function and normal spermatogenesis.” But the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) dismissed claims linking the mineral to normal cognitive function, normal prostate function and normal function of the heart and blood vessels
Source: Journal of Nutrition
November 11, 2009 doi:10.3945/jn.109.111252
“Higher Selenium Status is Associated with Adverse Blood Lipid Profile in British Adults
Authors: S. Stranges, M. Laclaustra, C Ji, F.P. Cappuccio, A. Navas-Acien, J.M. Ordovas, M. Rayman, E. Guallar