There is a lot of focus on personal nutrition, but perhaps we should focus on taking personal responsibility for our health.
“Personalized nutrition (PN) is based on the idea that one size does not fit all,” and who does not want to think that they are special? The idea of personalized nutrition is naturally attractive to our person; that is why simple messages that recognize individual differences resonate deeply with us and why such messages are popular in marketing and sales. This focus on uniqueness has inspired the creation of personalized food, and the proposal that “3D Food Printing seems to be a good candidate for food customization.”
Now, there are some legitimate differences between people. Some have peanut allergies and keel over when they eat nuts, some have celiac disease and need to avoid gluten, and some are genetically lactose intolerant. There is an enzyme mutation common in some parts of Asia that protects against alcoholism because people with the mutated enzyme do not metabolize alcohol efficiently, so toxic metabolites build up. I published an interesting video about fast vs. slow caffeine metabolizers and the difference in health benefits that carry over to athletic performance. Caffeine is ergogenic—it improves performance—but only for fast metabolizers, shaving more than a minute off 10 kilometers (about 6 miles) of cycling, while slow metabolizers get no benefit or caffeine actually slows them down, adding two minutes to their cycling time, depending on which genes break this enzyme. You can see these results below and at 1:24 in my video How Useful Is Personalized Nutrition?.
But for most people, in most cases, we are more alike than different.
Although there is a certain minority of people who need a more personalized approach to nutrition, there is currently not enough evidence to support truly personalized nutrition for the general population. Yet a surprising number of consumer-oriented genetic testing companies have proliferated, offering personalized nutrition advice. For example, there are supplement-hawking companies that claim to help consumers improve micronutrient status based on a few genetic variants, even though most variants explain only a few percent of the difference in levels between people.
Personalized nutrition is part of a broader movement toward personal medicine, also known as personal medicine precision medicine. There is a “massive cultural allure” of personal control over diagnosis, treatment, and prevention, fueling demand and greater sales. But unlike rare genetic diseases—rare genetic diseases caused by a single malfunctioning gene, such as hemophilia or sickle cell anemia—most diseases are caused by complex interactions between multiple genes and environmental factors, posing “a major challenge for personalized medicine.”
Take something like an adult’s head, for example. Researchers have found at least 40 locations on our chromosomes that are associated with human height, which is largely inherited. Genetics from parents account for about 80% of the variation in height between individuals, yet those most identified genes explain only 5% of the variation in height between individuals.
Researchers find those genetic links by using genome-wide association studies, where entire chromosomes are scanned to look for statistical associations between diseases and any specific segments of DNA. That’s interesting, but companies that advertise genetic susceptibility testing reinterpret this data as if it predicts individual risks. But all you get is a modest genetic association with a small increase in disease risk and little predictive power compared to the more important contributions of things we already know, like lifestyle behavior. Currently, the practice of using a person’s DNA to predict disease “has been viewed as providing little or no useful information.”
For example, let’s say that a person’s genetic analysis indicates that they have a higher risk of a certain serious condition compared to others in their ancestral group. This person is advised to exercise, lose weight, not drink too much alcohol, eat fruits, vegetables and grains. It’s smart advice, but we should be living this way regardless of our genetic vulnerability. And we know—at least we should know—these simple, basic strategies for reducing the risks of common chronic diseases. “Yes, the problem is that very few people live this way. Actually, to be more precise, almost no one lives this way.” That’s not an exaggeration—a national survey shows that nearly everyone in the United States eats a diet that doesn’t meet the recommended recommendations of the Dietary Guidelines.
Indeed, almost “no one in the United States eats a healthy diet.” Findings like that remind us that when it comes to public health, “concerns about making our prevention strategies based on genetic risk information border on irrational.”
Doctor’s Note
Here’s a video I mentioned about fast vs. slow caffeine metabolizers and the difference in health benefits that carry over to athletic performance: Friday Favorites: Do the Health Benefits of Coffee Apply to Everyone?.
To find out more about lifestyles, see the related posts below.
