People who believe a high fat diet is a recipe for good health may be badly mistaken; the evidence is against them.
Consuming a high-fat diet can cause a significantly lower gut microbiome diversity, something that is generally linked to poorer health, weight gain and more body fat.
The study (1) used rats, but researchers felt this was indicative of what took place in humans too. The species Firmicutes also greatly outnumbered the species Bacteroidetes.
The Firmicutes/Bacteroidetes (F/B) ratio is widely accepted to have an important influence in maintaining normal intestinal balance in the microbiome. Increased or decreased F/B ratio is a major factor in ‘dysbiosis’, a term used to indicate the loss of balance in the microbiome.
For example, when the ratio is high, it is normally linked to obesity; when low it can indicate IBS. It is known that the Lactobacillus family can control the F/B ratio (2)
For information: the species Firmicutes tends to include the good bacteria - gram-positive bacteria such as Lactobacillus, Ruminococcus, Bacillus, Clostridium and Enterococcus, whilst the species Bacteroidetes includes over 7000 different species of gram-negative bacteria such as Bacteroides, Alistipes, Parabacteroides and Prevotella (3).
Researchers from the University of Colorado Boulder conducted the study over a nine week period. Rats were fed either a diet where fat was 11 per cent of total calories; or one where fat was 45 per cent.
Interestingly, the high-fat diet group exhibited increased expression of genes related to serotonin production and signalling within the brainstem’s dorsal raphe nucleus, the area of the brain linked to stress and anxiety. Approximately 90 per cent of your serotonin is made by your gut bacteria from tryptophan. It is a crucial precursor in making melatonin in your cells during the day, via the action of Near Infra Red sunlight.
The researchers concluded that people who ate a higher fat diet might exhibit greater levels of anxiety.
Obviously these findings have several implications for people who use a keto diet, and for people with cancer.
Go to: Saturated fat drives cancer
*******
Reference
-
de Noronha, S.I.S.R., de Moraes, L.A.G., Hassell, J.E. et al. High-fat diet, microbiome-gut-brain axis signaling, and anxiety-like behavior in male rats. Biol Res 57, 23 (2024). https://doi.org/10.1186/s40659-024-00505-1
-
The Influence of Probiotics on the Firmicutes/Bacteroidetes Ratio in the Treatment of Obesity and Inflammatory Bowel disease; Spase Stojanov, Aleš Berlec, and Borut Štrukelj; Microorganisms. 2020 Nov; 8(11): 1715.
-
Gibiino G., Lopetuso L.R., Scaldaferri F., Rizzatti G., Binda C., Gasbarrini A. Exploring Bacteroidetes: Metabolic key points and immunological tricks of our gut commensals. Dig. Liver. Dis. 2018;50:635–639.
.