If one enters “individual diet” into a search engine, hundreds of websites with tips, comments, and recommendations will pop up. Scientists also confirm the advantages of the trendy tailored balanced diets. However, the exact influence of such diets on the gut microbiota and the time during which the content of the microbiota changes were unknown until recently. A team of scientists from BFU and their colleagues from other Russian higher educational establishments carried out a large scale experimental study to find out if a 2-week long diet is enough to change the content of microorganisms in the gut microbiota.
“The idea of the study was developed by our collaborators, and we carried out the technical implementation of certain study stages including the preparation of samples and high throughput sequencing,” said Alexey Korzhenkov, a co-author of the study, and an employee of the Institute of Living Systems, IKBFU.
The study was divided into several stages. First of all, over 200 respondents filled in a questionnaire developed by the authors. They specified how often they ate certain products (e.g. carrots every day or sausages twice a week, and so on) and also indicated whether they smoked or drank alcohol, how many hours a day they slept, and what medications they took. After that the team carried out clinical stool tests and developed an individual diet for each respondent. After two weeks of the diet the researchers took stool samples again and compared test results. In turned out that even within such a short period of time the diet had its impact on the gut microbiota.
Major changes in the gut community structure of the volunteers after following the dietary recommendations.
Source: Klimenko, N.S. et al. Microbiome Responses to an Uncontrolled Short-Term Diet Intervention in the Frame of the Citizen Science Project. Nutrients 2018.
The research included 207 respondents (110 males and 97 females) 18 to 64 years of age. The diets developed by the authors of the study for each of them consisted of a basic part and an individual part. All participants were recommended to eat less sugar, salt, and saturated fats, reduce the consumption of “empty calories” (soda drinks, pastry, mayonnaise, etc), drink more water, and so on. The individual part was based on the responses from the questionnaire. For example if a respondent ate potatoes more than once a day, he or she was recommended to reduce its consumption to two times a week.
The researchers analyzed the content of gut microorganisms (over 600 species) before and after the diet. To compare the results the scientists calculated the so-called Bray-Curtis dissimilarity. It is used to determine the likeness of species composition in two groups of animals and is calculated based on the number of species that are unique or similar for both groups. Bray-Curtis dissimilarity values may range from 0 (completely identical content) to 1 (completely different content). The similarity coefficient between the gut microbiota before and after the 2-week diet amounted to 0.45. In the control group (the respondents that did not change their diets during these 2 weeks) the value was almost two times smaller - 0.26. The researchers believe that the results of their work may become the basis for the development of efficient tailored diets based on the gut microbiota data.
The work was carried out in collaboration with the scientists from Knomics LLC, ITMO University, Moscow Institute of Physics and Technology, Novosibirsk State University, Atlas Biomed Group and Atlas Medical Center, Research Centre of Medical Genetics, George Mason University, University of Groningen and Winogradsky Institute of Microbiology.