Several diseases, including Alzheimer’s and cancer, have been tied to abnormal methylation, and that has prompted scientists to search for nutrients that can normalize the process. Last December a study coauthored by Nigel Belshaw, PhD, of the Institute of Food Research in Norwich, U.K., showed that people with low levels of vitamin D and the mineral selenium in their blood had higher rates of a particular type of methylation that increases the risk of colon cancer. Interestingly, “normal levels of selenium seemed to be more beneficial for women than men,” says Belshaw. The mineral has also been tied to a reduced risk of bladder cancer.
A variety of foods are rich in selenium, including seafood and Brazil nuts. You can easily meet the recommended daily allowance (RDA) of selenium, 55 micrograms, by eating three ounces of tuna (92 mcg) or six to eight Brazil nuts (544 mcg). The best source of vitamin D is sunshine, but there’s no harm in taking a supplement if you live in an area that gets little sunlight in the winter, says Belshaw. The RDA of vitamin D is 600 international units for women 70 and under.
Belshaw’s group also found a correlation between high body weight and a bad type of DNA methylation. “We know that obesity is a significant risk factor for colorectal cancer development,” he says. “So I would advise anyone obese to lose weight.”
Exercise and epigenetics
The Cooper Institute, a Dallas-based nonprofit research house, has been collecting data on 110,000 individuals for the past 40 years and recently embarked on a plan to identify biological markers associated with cardiovascular fitness.
There’s no doubt that fitness allows you to live longer and stay healthier. In February the Cooper Clinic published research in the Annals of Internal Medicines howing that high fitness is associated with a 36 percent reduced risk of developing dementia later in life. In May, Cooper scientists followed up with a study concluding that those who do aerobic exercise regularly have a 20 percent lower risk of being hospitalized for heart failure than do couch potatoes. “People who are fitter have lower mortality, from both cardiovascular and all causes,” says Laura DeFina, MD, the Cooper Clinic’s chief scientific officer. “Fitness appears to have an independent benefit outside of reducing your risks for hypertension and type 2 diabetes.”
Why? One clue can be traced to the epigenetic changes that take place when people work out. A study published last year in the journal Cell Metabolism showed that a onetime high-intensity exercise session (20 to 35 minutes on an exercise bike) changed the methylation status of genes in the muscle cells, setting the stage for muscle growth and improved metabolism (after exercising, you might burn more fat and sugar than usual during the day). Another report, which appeared this July in PLOS Genetics, determined that a six-month workout routine (for example, Spin or aerobics classes twice a week) produced beneficial changes in genes linked to type 2 diabetes and obesity.
So how much exercise is sufficient to produce these benefits? For now, researchers cite the standard advice for staying fit: 30 to 60 minutes of moderate-intensity exercise five days a week or 20 to 60 minutes of vigorous-intensity exercise three days a week.
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