image by: Randen Pederson
Some people choose to undergo genetic tests to determine whether they carry copies of specific genes that put them at higher risk for various diseases. Knowing that one possesses copies of "cancer genes," for example, can lead to some tough decisions about where to go from there.
A bright spot, however, is that what's also become clear in recent years is that genetics is only half of the discussion. Our lifestyles, as doctors are keen on telling us, are important in increasing or reducing our risk of various diseases. Research in the new field of epigenetics is finding that our lifestyle choices -- the foods we put in our bodies, the chemicals we are exposed to, how active we opt to be, even our social environments -- can actually alter our health at the level of the gene. These choices can have big effects on our risk for disease, even if our genes seem to be working against us. So before throwing your hands up and saying, "What can I do? It's all up to my genes," read on.
HOW CHOICES CAN CHANGE MOLECULES
Smoking is a familiar example of how our behaviors can affect our genes. We know smoking is linked to poor health outcomes. But how does this work molecularly-speaking? In this case, the carcinogens in cigarette smoke directly affect the molecules in our bodies, triggering the growth of cancer by mutating our anti-cancer genes so that they no longer function effectively.
But what's found to be equally true is that the positive lifestyle choices we make -- most notably, eating right and exercising -- may have just as powerful an effect on our genetic makeup. Two recent studies illustrate this point. One found that eating well can "turn off" the genes that put one at higher risk for heart problems; the other showed that exercise can persuade stem cells to become bone and blood cells rather than fat cells. Each helps us see just how lifestyle variables work at the genetic level to modify our risk.
YOU (AND YOUR GENES) ARE WHAT YOU EAT
In the first study, people who ate more raw fruits and vegetables had a reduced risk of heart disease, even if they carried copies of the gene that increases one's risk for cardiovascular disease. The researchers divided groups of participants according to the type of diet they ate. They dubbed the diets as follows: a typical "Western" diet included more salty and fried foods, meats, eggs, and sugar; the "Oriental" diet consisted of more soy, pickled foods, eggs, and leafy greens; and the "Prudent" diet, contained more raw fruits and veggies, leafy greens, nuts, and dairy. People who were genetically at the very highest risk of having a heart attack (they had two copies of the specific genes associated with heart attacks) had about double the heart risk if they ate a diet lacking in fruits and vegetables, compared to people who ate a prudent diet.
The study illustrates vividly how eating well will not only help you feel better in an immediate way, but it could actually alter your genes and reduce risk to your heart in a long term way.
EXERCISE CAN SWAY THE FAT(E) OF CELL
Exercise is the other piece of advice that we hear over again. It is strongly linked to a variety of health benefits from heart and vascular health, to warding off Alzheimer's, to extending lifespan. But now researchers are beginning to show that exercise may function, at least in part, by affecting the expression of our genes.
Certain types of stem cells can "choose" how they differentiate, and exercise and environmental factors can actually determine the direction that cells take early in their development. When mice ran on a treadmill for as little as an hour three times a week, the exercise induced these stem cells to become blood-producing cells of the bone marrow, rather than fat cells.
The stem cells of sedentary mice in this study were much more likely to become fat cells. "Some of the impact of exercise is comparable to what we see with pharmaceutical intervention," says author Gianni Parise in a university press release. "Exercise has the ability to impact stem cell biology. It has the ability to influence how they differentiate."
If exercise can influence how stem cells differentiate into mature cells, it is certainly possible that exercise also works on the genetic level as it influences our risk for certain diseases. More research will be needed to map out the molecular changes that exercise brings about. Again, since the evidence is overwhelming that exercise does reduce our risk for physical and mental health problems, it certainly won't hurt to put on your walking shoes and get moving.
THE MOLECULES THAT AFFECT GENE ACTIVITY
Much more work needs to be done to untangle the specific changes that are occurring in the genes exposed to different environments and lifestyles. Researchers do know that it's not the genes themselves that are changed by lifestyle or environmental factors; rather, it's likely the molecules around them, which can affect how active genes are.
Methylation is one example of the molecular changes that may occur in response to environmental factors, and there are other regulatory molecules that could certainly be affected by the foods we eat, the chemicals we come into contact with every day, the viruses we contract, and our level of activity. The addition or subtraction of a methyl group is known to be a cue for whether genes are turned off or on.
A recent study found that in sets of twins, one of whom suffered from schizophrenia or bipolar disorder, there were differences in how methylated certain disease-associated genes were between the two twins. This suggests that for people who share identical genomes, the molecules around the genes may play an important role in whether certain diseases are present or not. Other studies have found similar results regarding methylation as a likely candidate for the changes that are occurring early in development as a result of exposure to the chemical additive BPA, and in the buildup of amyloid-beta precursor protein in response to inflammation in Alzheimer's disease.
BE KIND TO YOUR GENES
That our lifestyles can affect our genes in significant ways is both sobering and encouraging. On one hand, our genes affect our health, since they can put us at varying levels of risk for issues like heart disease, weight gain, and even depression. And on the other, our lifestyles also affect our health in significant ways at the level of the gene. Eating fruits and vegetables can "turn off" the heart attack genes, and exercise can sway the development of stem cells.
We are not completely at the mercy of our genes. In many ways, they are at the mercy of our health and lifestyle decisions and habits. Family history can be a strong predictor of disease, but we have at least some power to change it. Making healthy lifestyle choices may not be foolproof, but for many it could mean the difference between experiencing a significant health issue and avoiding it. So, your doctor's advice is not just rote recitation. Pay attention to it with the knowledge that your genes are paying attention, too."
Source: Alice G Walton, How Health and Lifestyle Choices Can Change Your Genetic Make-Up, The Atlantic, November 6, 2011.