Methylation of DNA is a process by which cells control the expression of genes, effectively turning them on or off. In this way the cell can use signal from the environment to alter the genes expressed, and thus alter their metabolism to adapt to these changes. Epigenetics is the branch of biology that deals with this environmental effect on gene expression. As levels of DNA methylation fall in an organism, there develops an increased risk of cancer, and as diet quality improves the levels of DNA methylation increase. Researchers are therefore interested in the way that diet and lifestyle affect DNA methylation, as it may give clues as to how these behaviours affect cancer risk. To these ends a number of studies have investigated the effects of dietary changes on DNA methylation. For example, one study1 investigated the DNA methylation levels in a group of female breast cancer survivors that underwent lifestyle and dietary changes that was aimed at causing weight loss in the subjects.
The intervention involved increased physical activity and an energy intake of 1200 kcal per day for 2 weeks, followed by 1600 kcal per day thereafter. The macronutrient content of the diet was 45 % protein, 30 % carbohydrate and 25 % fat. In addition, the subjects were advise to eat breakfast, to consume fruit (more than 2 servings) and vegetables (more than 3 servings) and to drink 2 litre of water per day. After 6 months and 12 months DNA methylation levels were significantly elevated compared to baseline. There were also reductions in blood glucose levels and percentage body fat that correlated with the increased DNA methylation levels. At 12 months intakes of protein and total vegetables were also correlated with DNA methylation levels. These results suggest that DNA methylation, and therefore cancer risk, may change significantly over the course of 12 months with some simple dietary changes. This may suggest that a holistic approach to cancer treatment is the most effective long term survival strategy.
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