Effects of dietary components on intestinal short-chain fatty acids (SCFAs) synthesis in healthy adult persons following a ketogenic diet.

Background: The ketogenic diet (KD) has been used for almost 100 years in the treatment of drug-resistant epilepsy in children - and adults. The intestinal microbiome has a climax character, and the main factor changing its composition and functions is the diet. Both increased biodiversity and the production of short-chain fatty acids (SCFAs) are important indicators of gut barrier function. SCFAs are synthesized by microorganisms through the fermentation of dietary fibre provided with the diet. They are an important element in signal transduction from the digestive system to other tissues. To date, there is little research to determine how the use of KD alters the SCFAs profile of the human stool.

Objective: To assess the SCFAs profile in the stool of healthy and active KD users.

Material and methods: Study group: amateur athletes following KD. Control group: amateur athletes following a regular diet (carbohydrates min. 50%); gender: men and women aged 18-60. Material: stool sample (1x10 g). SCFAs content was determined in stool samples using gas chromtography method. Participants completed a Food Frequency Questionnaire (FFQ) and a 72-hour food diary.

Results: There research has shown differences in the amount of SCFAs, as far as the results obtained from the two groups are concerned. The discrepancies referred to the levels of acetic, butyric, iso-butyric, valeric, and isovaleric acids. Spearman's rank correlation analysis showed a strong relationship between the consumption of selected dietary components (vegetables, fruits, red meat, poultry, fish, nuts and seeds, sugar, sugar substitutes, fats) and the SCFAs content in the stool of the study group.

Conclusions: High consumption of cruciferous and leaf vegetables, berries and nuts on a ketogenic diet may have a positive effect on the profile of short-chain fatty acids produced by the gut microbiome. Changing the diet towards a greater supply of plant products may prevent proteolytic fermentation and reduce the negative effects of microbiome changes caused by an oversupply of protein and fat in the ketogenic diet.