Reduced levels of folate -- found in dark green leafy vegetables, legumes and whole-grains -- are associated with altered DNA methylation in the liver of people with diabetes, found a new study.
”On the basis of our results, it can be assumed that an insufficient folate intake may lead to epigenetic changes in the liver, which in turn may contribute to the pathogenesis of type 2 diabetes,” says Jussi Pihlajamäki, Professor of Clinical Nutrition, from the University of Eastern Finland.
Many genes raises the risk of type 2 diabetes but even those genetically predisposed can reduce their risk by changing their lifestyles to eat healthier and become more active .
Epigenetic mechanisms explains how lifestyle affects the genetic risk, as they cause stable, permanent or even heritable changes in gene activity without changing the gene itself. One such mechanism is DNA methylation, the addition of a methyl group to DNA, usually results in reduced gene expression.
In healthy people, the liver plays an important role in maintaining glucose homeostasis, but in type 2 diabetes, it fails to do so.
To test whether this could be attributed to altered DNA methylation, with researchers from Lund University, Pihlajamäki’s research group investigated the genome-wide DNA methylation pattern in the liver of 35 subjects with type 2 diabetes and 60 non-diabetic controls. They also compared the methylation differences to gene expression and erythrocyte folate levels.
Significant differences between diabetics and controls were found at 251 methylation sites. Some 236 of these sites displayed decreased DNA methylation in people with diabetes, including sites in genes previously linked to type 2 diabetes. Twenty-nine genes displayed both differential DNA methylation and gene expression in the liver of people with diabetes. Decreased DNA methylation was also associated with reduced folate levels.
Folate serves as a methyl donor in the methylation cycle, which explains why the lack of folate lowersDNA methylation.