Selenium, which is largely obtained from cereals, fish and meat, plays a vital part in a range of metabolic functions and in the body’s defence against antioxidant damage.
Previous studies have sought to examine the effect on chronic disease of differing levels of selenium consumption.
Such studies have reported conflicting results, but research in this area has been limited by problems in accurately assessing participants’ dietary consumption of selenium.
Dr Darius Mozaffarian and colleagues from Harvard School of Public Health in Massachusetts, in the US, instead analysed selenium levels in participants’ toenails. This analysis was designed to provide a valid and objective biomarker of long-term selenium consumption.
The researchers studied 3,630 women from 1982-83 until 2008 and 3,535 men from 1986-87 until 2008.
The risk of developing type 2 diabetes was 24% lower among the fifth of patients with the highest levels of selenium, compared with the fifth of patients with the lowest levels.
The researchers said that the dose-response relationship appeared to be generally linear, but that a raised risk at the highest levels of consumption could not be excluded.
They commented: ‘Our results provide the best evidence to date of how habitual selenium intake from dietary sources may influence the onset of type 2 diabetes.’
Dr Mozaffarian and his team said further studies would now be needed to consider how dietary and higher doses of selenium affect metabolic pathways and risk factors for type 2 diabetes.
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