An international research group investigated the changes in DNA methylation after consumption of a standardized meal and found that alterations in white blood cell amounts account for 99% of the changes in DNA methylation.
DNA methylation is a process that results in gene regulation so the cell can adapt to extracellular effects. Environmental factors can cause DNA methylation by triggering proteins to regulate DNA expression in cells. Studies have been able to link specific methylation of cytosine (one of the four bases that is found in the DNA) in CpGs (a link between a cytosine and a guanine base) to diseases and characteristics, such as hair or eye colour. CpG methylation has a potential to be used as a biomarker to assess disease risk, progression and response to treatment.
In an article recently published in The American Journal of Clinical Nutrition, an international research group investigated how a standardized meal affected DNA methylation in the peripheral blood. 26 healthy men participated in the study in 2013-2014. All participants were between 18-40 years of age with normal diet and of northern ancestry. After an overnight fast, blood samples were collected and the participants consumed a standardized breakfast in 15 minutes. A second blood sample was drawn 160 minutes after the first one, in order to let the meal to be digested and nutrients to enter the bloodstream.
140828, approximately 30%, of the total amount of probes were methylated differently, and 1832 were analysed after correction. After the meal there was an alteration in white blood cell (WBC) amounts that influenced the results. After adjusting for WBC fractions, only 541 CpG sites could be observed that were differently methylated, thus these changes in methylation were independent of WBC counts. Further analysis showed that the changes in methylation in the non-adjusted sample mainly occurred in genes that were related to immune response, cell activation and response to wounding, and also genes that are linked to hormones that affect appetite and digestions were altered.
It seems that after food intake alterations in WBC numbers account for more than 99% of the observed changes in DNA methylation. More available nutrients, altered secretion of appetite and metabolic hormones and immune response to food antigens may be responsible for these changes. This study underlines the importance of meal-standardized sampling procedures in further studies that assess CpG methylation.
Written By: Dr. Fanni R. Eros