Adjusting your diet based on your genes, also known as the DNA diet. According to German researchers, there is no clear evidence that it can work.
“DNA diet is futuristic”
This is one of those topics that will continue to be discussed for years to come. Last year, I wrote two articles about the DNA diet as well. Different reactions from different people to the same diet are a very old phenomenon. Scientists have been trying to link these differences in recent years to genetic variations. To do this, you need to know which genetic variations, single nucleotide polymorphisms (SNPs), can cause different reactions to the amount of food eaten in general, or specifically fats and carbohydrates. Then you need to look at who has these variations in order to adjust the right diet. Oddly enough, this latter is already happening while we’re still somewhere at the beginning of that first step. Only a (relatively) small number of genetic variations have been shown to be associated with certain reactions to a diet. However, some parties already let you pay a few hundred euros to test whether certain genetic variations occur in your case. Based on this, the ‘ideal diet’ could then be determined. Based on the research, my conclusion was that it is still far too early to link DNA to a diet in practice. Simply because we still know too little about the different variations and their influence. So, it’s futuristic.Genes affecting food processing or food intake?
Researchers at the Technical University of Munich (TUM) recently came to the same conclusion:Hence, to date there exist no indications that certain genetic factors are associated with the total intake of calories, carbohydrates, and fat. The current state of knowledge is still too limited for deriving individual nutritional recommendations based on genetic information, e.g. for weight management, Christina Holzapfel, TUMHowever, the Germans examined a very different genetic influence than the studies I discussed in the earlier articles. The TUM researchers looked at the genetic influence on the amount of food you consume. The studies I discussed earlier looked at the influence of genes on the processing of the already ingested food. These are two completely different starting points with completely different implications. This research looks at how much energy is coming in, while the earlier studies looked at what happens to that energy. For example, the Germans want to know if some people eat more because of their genes. The previously discussed studies wanted to show the influence of genes when the same diet was consumed. Why do some people gain weight on the same diet that leads others to lose weight? An important difference.
“DNA has no influence on food intake”
The Germans conducted a systematic search through the relevant literature of more than 10,000 scientific articles. Ultimately, there were 39 articles that looked at the relationship between genetic factors and total energy, carbohydrate, and/or fat intake. Among those thousands of other articles, there could also be studies looking at food processing instead of intake.In all studies, we most frequently encountered the fat mass and obesity (FTO) associated gene as well as the melanocortin 4 receptor gene (MC4R). There are indications of a relationship between these two genes and total energy intake.These are just two of about a hundred genes suspected to be related to BMI/weight. They were the most studied in the 39 articles examining the role of a total of 86 genetic variations. The German study found that the 39 articles did not paint a uniform picture of the influence of these two genes.
There is only limited evidence for the relationship between the FTO gene and low energy intake as well as between the MC4R gene and increased energy intake.
DNA unknown
The Germans therefore conclude that it is still too early for advice on diet based on personal genetic characteristics. Many more studies based on these variations would have to be conducted for more insight. In my opinion, they should mainly look at the other correlation: Especially looking at the effect of genes on how food is processed. That seems to me to be much more practical information for dietary advice. What use is it to know that you eat more than average (carbohydrates and fats) thanks to your DNA? “Due to a genetic variation, you tend to eat more. My advice: Eat less”. That doesn’t help you, does it? You now only know that it will be more difficult for you to eat less, whether it’s carbohydrates, fats, or in general. Not very encouraging. The earlier discussed studies showed that genetic variations can cause different people to react differently to the same diet. I think that’s the path that needs to be further explored. If you already have trouble eating less, you want to be sure that you get the most out of the effort you make. Then you want to know especially whether you should lower your fats or carbohydrates. Then your effort is at least targeted.References
- Theresa Drabsch, Jennifer Gatzemeier, Lisa Pfadenhauer, Hans Hauner, Christina Holzapfel. Associations between Single Nucleotide Polymorphisms and Total Energy, Carbohydrate, and Fat Intakes: A Systematic Review. Advances in Nutrition, 2018; 9 (4): 425
- https://academic.oup.com/advances/article/9/4/425/5055951
