Indian spice with an important kick
There’s another element of the epigenome that seems to be influenced by nutrition: microRNAs. These tiny molecules appear to regulate the process by which genes make vital proteins. Usually their expression and activity is perfectly normal, but sometimes they malfunction. “Recent evidence suggests that microRNAs can leave the tissue of origin and land in distant sites,” says Sharon Ross, PhD, a scientist in the Nutritional Science Research Group at the National Cancer Institute. This migration may play a role in the development of cancer.
Scientists are investigating the influence of nutrients on the concentration and activity of microRNA. In several recent studies, curcumin (which provides yellow color to the Indian spice turmeric) was shown to manipulate microRNA in a manner that helps suppress the proliferation of pancreatic- and lung-cancer cells. There’s also a wealth of data (from studies done in laboratories on isolated human cells) indicating that curcumin may decrease the proliferation of cancer cells, Ross says.
And it’s not just cancer that curcumin affects. In January a team of researchers from China and the U.S. Department of Agriculture’s Human Nutrition Research Center on Aging reported that curcumin reduces the expression of five genes known to regulate the aging process in fruit flies, which have a genetic profile similar to that of human beings.
When researchers fed elderly mice a diet high in a derivative of curcumin, they lived longer than mice that ate regular kibble. The scientists concluded that curcumin regulates protein expression so as to reduce oxidative stress, a type of cell damage caused by free radicals, pollution, smoking and other harmful forces. Oxidative stress has been implicated in many diseases, including cancer, Parkinson’s, Alzheimer’s and heart failure. How much curcumin should we eat to reap benefits? No one knows, because the appropriate studies have not yet been conducted on humans.
Life-extending benefits of coffee and tea
Polyphenols are naturally occurring chemicals found mostly in plants. In addition to ameliorating oxidative stress, polyphenols may protect our DNA in a way that helps us live longer.
Using data collected from regions of the world where green tea is popular, researchers have shown that a polyphenol in the tea (it’s called -epigallocatechin-3-gallate) might provide protection from age-related diseases. For example, a 2008 study of elderly people on several Mediterranean islands found that as green and black tea consumption increased, the likelihood of diabetes declined.
Coffee, which also contains polyphenols, may be beneficial, too. In January 2013, the Tufts Nutrition Research Center released a study showing that older rats fed the equivalent of 10 cups of coffee performed better on tests of motor function and memory than did rats on the standard diet. Tufts University nutrition and genomics professor Jose Ordovas, PhD, says there’s good evidence coffee may have a “significant effect” on memory and cognition, but researchers are not sure that polyphenols are the main cause. Another possible factor is the caffeine in coffee, Ordovas notes.
Although scientists disagree about just how much coffee you should drink, a 2012 study sponsored by the National Institutes of Health suggests that more than one cup a day provides benefits. The research, which tracked more than 229,000 men and 173,000 women for 12 years, showed that drinking two or more cups of coffee a day was associated in men with a 10 percent lower risk of dying and in women with a 15 percent lower risk. If green tea is your beverage of choice, Tollefsbol suggests drinking two or three cups a day.
Protecting DNA with vitamin D and selenium
Another epigenetic phenomenon that plays into aging is DNA methylation. During this chemical process, hydrogen and carbon atoms are added onto DNA, altering its structure, which changes the way genes are expressed. Methylation usually works to our benefit—it’s vital for normal development and cell physiology—but evidence suggests methylation patterns become disturbed as we age.