Diet And Cancer – DNA Methylation

Many epidemiological studies have shown the dietary patterns of those who live the longest, have the lowest amount of heart disease, and the lowest risk of cancer. Many of these have shown that high potassium foods are in the diets that lead to these results. How do they do it? A recent study sheds some light on the question.

The study (1) looked at the diet of people coming down with head and neck cancer. It specifically looked at a process called DNA methylation in tumor suppressor genes, which is associated with development of cancer. When a methyl group attaches to DNA, it results in the DNA being less stable and less able to be repaired. If enough abnormalities accumulate in certain genes, eventually cancer will result.

There are two major groups of cancer genes – those that promote cancer and those that suppress it. The study looked at over twenty of the tumor suppressor genes to determine if methylation in these genes was associated with certain specific micronutrients or types of foods.

The study found several correlations. The people developing these cancers with increased methylation were found to have eaten less cruciferous vegetables. Other findings were that they ate more refined grains, less vitamin B12, less folate and less vitamin A. Leafy green vegetables, meats, and whole grain seemed to make no difference one way or another, although there was a tendency for them to have positive effects of protection. But it may well be that the study was too small to show significant differences, and with a larger study these foods would show significant effects.

True, this is a small study looking at a small aspect of cancer. It is not a big, sweeping study. But there are plenty of those kind of epidemiological studies. Now is the time for the real work to be done. Thousands of smaller studies like this one to examine the details of how diet produces its effects.

This is the first study to look at the diet cancer patients were on before they developed cancer and correlate the diet with a specific change in DNA that makes the DNA more susceptible to cancerous change. Undoubtedly there are many other dietary factors and many other specific DNA changes that can be examined. With enough such studies, eventually what aspects of various foods provide what benefits will be known.

We know that high potassium foods protect against hypertension, osteoporosis, and kidney stones, and that they reduce the likelihood of many cancers. Little is known of how they do this. Many more studies like this one will help us to find out how various foods provide these benefits. Then even better diets can be devised to prevent diseases in people who are more susceptible to those diseases.

For tables of foods high in potassium and their potassium and other nutrient content see the “Links To Food Potassium Tables” tab at the top of the page. The page links to multiple tables organized by food category, such as vegetables, fruits, poultry, etc.
1. Pretreatment dietary intake is associated with tumor suppressor DNA methylation in head and neck squamous cell carcinomas.
Colacino JA, Arthur AE, Dolinoy DC, Sartor MA, Duffy SA, Chepeha DB, Bradford CR, Walline HM, McHugh JB, D'Silva N, Carey TE, Wolf GT, Taylor JM, Peterson KE, Rozek LS. Epigenetics. 2012 Aug;7(8):883-91. doi: 10.4161/epi.21038. Epub 2012 Jun 22.

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