Does Science Support DNA Diets?

Photo Credit: © University of Toronto. All Rights Reserved.

Photo Credit: © University of Toronto. All Rights Reserved.

Can a blood test tell you what diet is best for your body? 

That's what some companies are claiming. Currently trending in an era of personalized nutrition are diets tailored to a patient's DNA. A myriad of companies now offer blood tests aimed at helping consumers determine the ideal ratio of carbs, fats, and proteins for a person's genetic makeup.  

Neil Grimmer, the founder of personalized nutrition company Habit, said in a recent CNBC interview that crafting a dietary plan based on his genetics helped him lose 25 pounds in just six months. "My journey led me to figure out that a lot of the answers to what foods we should eat, is actually inside of us," he said.

Yet the idea that DNA testing can find the perfectly tailored diet for every person is a distant reality. Gene mapping for diet is nowhere near having the ability to deliver, as recently reported in the New York Times and Medium. As one article's subhead reads, "many consumers don't understand that their results are not conclusive." Moreover, as CNBC reports, there are real risks in sharing one's highly personal data with a private company, including the fact that law enforcement agencies could pressure these companies to release this data without your consent. 

Additionally, a recent, randomized 12-month clinical trial conducted by Stanford University researchers on 609 overweight adults found no significant weight loss differences between participants eating diets that "matched" their genome versus those who didn't. 

The Centers for Disease Control and Prevention (CDC) is weary as well. The agency published an article last year advising consumers to "think before you spit" when it comes to genetic testing, explaining that "there is no evidence for clinical validity or utility" of personal genomic tests.  

Dr. Zak Kohane, a biomedical informatics professor at Harvard University, said with regard to consumer genetic testing, "we really have a perfect storm of insufficient data and insufficient competence."    

Even Ambry Genetics, a certified genetic diagnostics lab, found that 40 percent of consumer genetic tests yielded false positives for genetic variants. 

It's worth noting that such DNA products aren't subject to FDA regulations, which would require scientific testing to prove their validity. Habit's product, for example, hasn't been tested in a single clinical trial to date. Even the company's own website states: "Recommendations regarding diet provided to you may or may not be beneficial to you and may cause or exacerbate certain medical problems."

Still, that hasn't stopped companies like Habit and Profile, another personalized nutrition brand, from selling consumers customized meal plans based on DNA tests. 

Given that the jury is still out on the effectiveness of gene mapping for diet, our belief is that consumers should base their dietary decisions on the most promising data available, not something that may or may not show benefit decades down the road.