We all have our own unique genetic blueprint, so doesn’t it make sense that we all have a unique nutrition blueprint as well? We know that diet and health are interrelated, but did you know that your genes can affect how your foods are being processed, which has a big impact on your health and possibly weight loss journey? The concept of nutritional genomics have been around for a while, but recently started to gain more attention from several companies offering personalized nutrition testing based on an individual’s DNA. The idea is that these tests could help you optimize your health so that you can have a “DNA-diet” specifically catered to you.
Then why isn’t everyone pouncing to order these tests?
Although official government agencies, such as the Food and Drug Administration, does support tests "that may provide consumers with direct genetic information that can inform health related decisions,” it’s important to note they are not actively regulating these products. This means it’s very hard to validate the accuracy of these take-home tests as it may also vary between companies. Ambry Genetics, a certified genetic diagnostic lab, found that 40% of consumer genetic tests yielded false positives for genetic variants. Not only that, these personalized nutrition brands hasn’t been tested in a single clinical trial.
So what exactly do you have to do for these DNA-diets?
The procedures are pretty uniform between these companies that offer these services: they provide you with an at-home test kit to gather information on your height and weight, activity level, waist size, as well as blood and DNA samples. What’s different from other genetic test kits is that they also have a metabolism test, which requires you to take blood samples before and after drinking their sugary high-fat test drink. After all that, you send off the kit to the lab for analysis and a 3-4 weeks later, you’ll receive your personalized reports about your body handles different nutrients. Voila! You’re one step closer to being your best self. You’re basically an expert of your own body now. The world is your oyster.
You’re given all this information but… is it actually accurate?
Ironically, as scientific and evidence-based as this whole concept sounds, it’s actually, well, not really that scientific at all. In fact, there is little research on validating the usage of personalized nutrition advice based upon individual genetic information. Although the concept of nutritional genomics is definitely not new, evidence of understanding the diet-gene-health relationship is still immature. Yes, there is compelling evidence that common diet-related diseases such as cardiovascular disease, type 2 diabetes, osteoporosis, are modulated by certain genetic variants and can affect an individual’s biological responses to nutrients, this knowledge, however, is incomplete and only a few diet-gene-health relationships identified. In fact, genes can only explain 5-10% of the risk linked to these diet-related diseases. One study in 2011 attempted to study the relationship between the impact of genetic makeup to fish oil-cardiovascular disease risk in a randomized controlled trial (which is one of the gold standard scientific designs) and concluded that “considering single genes (or gene variants) may be too simplistic” to establish genotype-based dietary advice. Furthermore, the Academy of Nutrition and Dietetics stated that personalized dietary interventions require not only advanced knowledge in genetics but also additional information such as family history and personal risk factor like the environmental in which you live in.
How important is genetics in diet?
Another reason why these DNA-diets are not a huge breakthrough in the scientific community is because there is no proof that this increase in knowledge will motivate appropriate behavioral changes. “DNA is important, but it plays a pretty minor role in making personal decisions about food” says Dariush Mozaffarian, cardiologist and dean of Friedman School of Nutrition Science and Policy at Tufts University. We all know that highly processed foods are bad for you, and that healthy eating includes nutritionally-dense foods like fruits and vegetables, but it’s hard for us to make these choices if we don’t change our mindset and mentality. “For basic healthy living, it’s not about your genes, it’s about your behavior,” Mozaffarian says.
In a systematic review done in 2010, only 14 papers were found looking at the effectiveness of DNA-based advice in changing behavior with respect to reducing disease risk. From those 14 studies, only two assessed the effects on dietary behavior. One study by Marteau et al 2004 showed that “genetic testing that confirmed the clinical diagnosis of familial hypercholesterolemia weakened the participants’ belief in the effectiveness of dietary change.” The same authors proposed that larger, better-quality randomized controlled trials should be done as “claims that receiving DNA-based test results motivates people to change their behavior are not supported by evidence.” Another review in 2016 showed that there were no significant effects of genetic-testing on behaviors such as quitting smoking, improving diet, and increasing physical activity.
The bottom line
Doing a genetic test can be be helpful, especially if you find out you have a genetic variant for a certain disease, like Celiac disease. However, the thing with DNA-diets is that there is still so much research to be done to find specific diet-gene-related interactions since well, diet and health are complicated subjects - it’s not black-and-white. That being said, behavior is everything. Try a few days sticking to the simpler stuff like eating more greens and drinking more water and maybe that in itself could be a revelation too!