Keto diet increases cholesterol, reduces beneficial gut bacteria | Science News

The health benefits of ketogenic low-carbohydrate diets may be overhyped.

A Keto breakfast served at a restaurant. (Image Credit: Alexander Spatari/Moment/Getty Images).

New Delhi: Researchers from the University of Bath have been able to determine that the ketogenic low-carbohydrate diets can increase cholesterol levels, and decimate populations of a beneficial genus of bacteria ubiquitous in the digestive track, called Bifidobacterium. The research was conducted by tracking 53 healthy adults over a period of 12 weeks, with the control participants following a moderage sugar diet, a low-sugar diet where less than five per cent of the calories were derived from sugar, and a ketogenic low-carbohydrate diet where less than eight per cent of the calories were derived from carbohydrates.

The key findings were that the keto diet raised cholesterol levels, as well as specifically apolioprotein B, which restricts blood flow by causing plaque buildup in arteries. The low-sugar diet significantly reduced cholesterol. The keto diet also altered the composition of the gut microbiome, including decreasing Bifidobacteria which is commonly used in probiotic formulations. This bacteria produces vitamins, inhibits pathogens, attacks harmful bacteria, and reduces cholesterol. Restricting sugar was not found to have a significant impact on the composition of the gut microbiome.

Keto diets also reduced glucose tolerance

The keto diets also made the adults less efficient at handling carbohydrates. Both the diets resulted in fat loss, with the keto diet reducing an average of 2.9 kg of fat mass per person, while the sugar restriction diet reducing an average of 2.1 kg of fat mass per person, over the study period of 12 weeks. The keto diets also caused a significant shift in the lipid metabilism as well as muscle energy use, shifting the fuel preference of the body from glucose to fats. Both the diets were found to have a minimal impact on physical activity levels.

A paper describing the findings has been published in Cell Reports Medicine. One of the study authors, Dylan Thompson said, “The ketogenic diet is effective for fat loss, but it comes with varied metabolic and microbiome effects that may not suit everyone. In contrast, sugar restriction supports government guidelines for reducing free sugar intake, promoting fat loss without apparent negative health impacts.” According to the academics, a low-sugar diet is better than a keto diet over the long term.

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