A recent clinical trial report, published Scientific report, compared faecal levels of short-chain fatty acids (SCFA) and serum inflammatory markers in individuals under low-carbohydrate (LCD) and habitual (HD) diets.
Study: A low-carb diet increases faecal short-chain fatty acids in the feces of obese women following a weight loss program: a randomized feeding trial.Image credit: Boontoom Sae-Kor/Shutterstock.com
Background
Diet plays an important role in maintaining health. For example, a Western-style diet has been linked to increased inflammation and gut microbial dysbiosis that promotes obesity and reduces the abundance and diversity of beneficial microbes, e.g. Bifidobacterium sp and Lactobacillus sp In contrast, the Mediterranean diet increases beneficial gut microbiota and promotes a healthy lifestyle.
Obesity is recognized as one of the leading causes of all chronic diseases. Previous studies have shown that obesity is on the rise worldwide due to high consumption of high-fat and high-carbohydrate foods.
The high prevalence of obesity has led to the development of many safe and effective anti-obesity strategies in the health system.
Different dietary interventions have shown varying efficacy in treating obesity and overweight. This variable performance has been linked to many factors, including adherence and nutrient levels.
A low-carbohydrate diet, popularly called a low-carb diet, is a popular dietary intervention for rapid weight loss. However, the effectiveness of these diets for weight loss varies due to variable carbohydrate content and quality. This variability presents difficulties in assessing the true effect of low-carb diets on obesity.
Functional modifications of dietary fatty acids have been linked to the prevention of metabolic complications, usually induced by a high-fat diet. Compared to mono- and polyunsaturated fatty acids (MUFAs and PUFAs), saturated fatty acids (SFAs) are more obesogenic. This is because a diet rich in MUFA and PUFA produces more thermogenesis than SFA.
Studies have shown that low-carb diets improve blood glucose, serum insulin levels, and blood pressure in obese patients. Furthermore, this diet positively affects the homeostasis model assessment of insulin resistance (HOMA-IR).
SCFAs are synthesized by gut microbes using undigested/unabsorbed food material. Because of their role in the intestinal barrier, SCFAs have recently attracted much attention.
About the study
The present study hypothesizes that SCFA, produced by gut microbiota, varies with changes in microbiota composition. This study compared the effects of LCD and HD on faecal levels of inflammatory markers in SCFA and obese women.
Acetate, propionate, and butyrate are the three major SCFAs synthesized by the gut microbiome, present in a 60:20:20 molar ratio in the colon and feces. However, their content depends on the diet and the diversity of the gut microbiota.
This study used a block randomization technique, where the randomization unit was the participant. Here, five blocks of four participants were considered.
Study results
At baseline, no significant differences were observed between the two study groups, i.e., LCD and HD, in total fat, protein, calories, carbohydrates and fiber content.
However, at the end of the study period, a significant difference in weight and waist circumference (WC) was observed in both dietary groups. It must be noted that the mean changes in WC and weight were not statistically significant between the two study groups.
A significant reduction in waist-to-hip ratio (WHR) was observed compared to baseline readings in both study groups. However, the mean change in WHR was significantly greater in the LCD group. Regarding metabolic markers, a greater reduction in serum insulin and HOMA-IR was observed in the HD group than in the LCD group.
A serum inflammatory marker assessment revealed a significant decrease in serum interleukin-6 (IL-6) in the HD group compared to baseline estimates. After the intervention, both groups significantly decreased serum high-sensitive C-reactive protein (hs-CRP) levels.
The serum hs-CRP level was found to significantly influence the faecal level of butyric acid. An increase in serum hs-CRP resulted in a 25% decrease in the percentage of faecal butyric acid.
Faecal propionic acid affects butyric acid levels. Furthermore, serum insulin levels significantly increased faecal levels of acetic acid, i.e., 8.9-fold. Both faecal propionic and butyric acids affect acetic acid.
Gut microbiota characteristics did not reveal any significant differences Firmicutes And Bacteridates levels in the LCD and HD groups before and after the intervention. At the end of the intervention, the positive no-Actinobacteria There were more participants in the LCD group than in the HD group.
Six months after the intervention, faecal acetic acid, butyric acid and propionic acid levels increased significantly in both dietary groups. However, this level was higher in the LCD group than in the HD group.
Conclusion
The present study found that a low-carb diet increased faecal SCFA after a month-long weight loss program. In the future, more research is needed to elucidate the underlying mechanisms and human health consequences of these changes.