Immunity is Not in Your Genes
’Tis the season for the flu, colds, and whatever else is making people sick in mid-winter. From stomach viruses to respiratory infections, there’s something about winter that seems to tax even the strongest of immune systems. Some people get the flu vaccine every year, but experts at the Centers for Disease Control and Prevention are telling us that this year’s anti-influenza concoction is only about 25% effective. Turns out, the strains of flu circulating this year are even more virulent than experts anticipated.
Some folks seem to never get sick, while others seem to come down with any number of illnesses, with distressing regularity. It’s probably about genetics, right? Some people are simply dealt a better disease-fighting hand from birth, genetically speaking. Aren’t they? Not so much. According to intriguing new research on identical and fraternal twins, one’s environment plays a far larger role in the effectiveness of one’s immune system than one’s genes.
I think this is really interesting, because it underscores what I’ve been saying for years: If you want to be healthy, you need to avoid environmental toxins, eat toxin-free whole foods, exercise regularly, and avoid unhealthy behaviors, like smoking, or getting too many x-rays, or working with pesticides.
Mark Davis, PhD, is a professor of microbiology and immunology and director of Stanford's Institute for Immunity, Transplantation and Infection. He and colleagues wondered about the wide variability in immunity that is observable among different people. “…When you examine people's immune systems, you often find tremendous differences between them…But what we found was that in most cases, including the reaction to a standard influenza vaccine…there is little or no genetic influence at work, and most likely the environment and your exposure to innumerable microbes is the major driver,” said Davis, in a press release.
Regardless of genetic similarity, or diversity, about three-fourths of the differences in immunity between twins appear to be related not to genes, but to environmental influences, such as previous exposure to microbes or toxins, vaccinations, diet, and dental hygiene. These environmental influences were more important when accounting for differences within a given pair of twins. The older the twins, the more these differences were likely to have manifested. This is also consistent with the supremacy of environmental—rather than heritable—influences on the strength of the immune system.
To put it simply: environmental influences accumulate over the decades to reshape a given person’s immune system. The new research should finally convince experts that the immune system is remarkably adaptable, and subject to significant outside influences. “A healthy human immune system continually adapts to its encounters with hostile pathogens, friendly gut microbes, nutritional components and more, overshadowing the influences of most heritable factors,” said Davis.
All of which underscores the importance of a healthy lifestyle if you’d like to have a robust immune system capable of fighting off disease. Eat right, exercise, avoid toxins (including cigarette smoke) and get plenty of sleep. What you do—or don’t do—really does matter.
Petter Brodin, Vladimir Jojic, Tianxiang Gao, Sanchita Bhattacharya, Cesar J. Lopez Angel, David Furman, Shai Shen-Orr, Cornelia L. Dekker, Gary E. Swan, Atul J. Butte, Holden T. Maecker, Mark M. Davis. Variation in the Human Immune System Is Largely Driven by Non-Heritable Influences. Cell, 2015; 160 (1-2): 37 DOI: 10.1016/j.cell.2014.12.020