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.

DNA methylation
Two White Dots Represent Methyl Groups On Cytosine Nucleotides

The Study

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. Tumor suppressor genes are genes that prevent other genes from causing cancer. When a methyl group attaches to a tumor suppressor gene, it results in the gene being silenced. If enough hypermethylation accumulates in tumor suppressor genes, eventually cancer will result.

There are two major groups of cancer genes – those that promote cancer and those that suppress it. The study did not look at cancer promoter genes. Rather, it looked at over twenty of the tumor suppressor genes. Specifically, the authors examined whether increased methylation in these genes had an association with certain specific micronutrients or types of foods.

The Findings

The study found several correlations. The people developing these cancers with increased methylation ate 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 made no difference one way or another, although they tended to have positive effects of protection. But possibly the study was too small to show significant differences in these food groups. Consequently, with a larger study these foods would possibly show significant effects.

Sadly, the researchers did not look at potassium, sodium, or the potassium sodium ratio. So we have no direct information on the influence of the ratio. But the type of foods that had the favorable effect of suppressing methylation are the type of foods with a high potassium sodium ratio.

This is a small study looking at a small aspect of cancer. It is not a big, sweeping study. But researchers have produced plenty of those large, sweeping kind of epidemiological studies. Now is the time for the real work to be done. We need thousands of smaller studies like this one – small pilot studies to examine the details of how diet produces its effects. From such productive pilot studies, researchers can design bigger studies for more definitive answers.

This Is Early Work

In summary, 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 making the DNA more susceptible to cancerous change. Undoubtedly, there are many other dietary factors, and many other specific DNA changes, to examine. But with enough such studies, eventually we will know what aspects of various foods provide what benefits.

We know that high potassium foods protect against hypertension, osteoporosis, and kidney stones, and that they reduce the likelihood of many cancers. However, 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 investigators can discover even better diets 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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