Modulation of gut microbiota by dietary supplementation with tuna oil and algae oil alleviates the effects of D-galactose-induced ageing.

Previous studies have shown that dietary supplementation with tuna oil and algae oil can alleviate the effects of ageing on learning and memory in mouse models, but the mechanism of this effect remains unknown. This study aimed to determine whether dietary oil supplementation alters the composition of the gut microbiota during the prevention of age-related effects on cognition. Ageing mice received dietary oil supplementation continuously for 12 weeks. The supplementation was found to improve the animals' learning and cognition, and this effect was most marked in the TO200AO400 group, which received a 1:2 mixture of tuna oil and algae oil at 600 mg kg-1 day-1. Next-generation sequencing of the 16S rRNA gene present in faecal samples showed that the gut microbiota varied in the groups that received different oil treatments; the TO200AO400 treatment most closely restored the composition of the D-galactose-altered gut microbiota to that of the control. Moreover, 83 altered operational taxonomic units (OTUs) responsive to dietary oil supplementation were identified; five of these differed in one or more parameters associated with host ageing. In conclusion, this study confirmed the effect of dietary oil supplementation on the alleviation of age-related decline in cognitive function and showed that oil supplementation results in alterations in the composition of the gut microbiota. Further research will be needed to elucidate the causal relationship between the reversal of age-related cognitive decline and gut microbiota modulation and to explore the potential of gut microbial communities as a diagnostic biomarker and a therapeutic target in ageing.

Modulation of the gut microbiota by the mixture of fish oil and krill oil in high-fat diet-induced obesity mice.

Previous studies confirmed that dietary supplements of fish oil and krill oil can alleviate obesity in mice, but the underlying mechanism remains unclear. This study aims to discern whether oil treatment change the structure of the gut microbiota during the obesity alleviation. The ICR mice received high-fat diet (HFD) continuously for 12 weeks after two weeks of acclimatization with a standard chow diet, and the mice fed with a standard chow diet were used as the control. In the groups that received HFD with oil supplementation, the weight gains were attenuated and the liver index, total cholesterol, triglyceride and low-density lipoprotein cholesterol were reduced stepwise compared with the HFD group, and the overall structure of the gut microbiota, which was modulated in the HFD group, was shifted toward the structure found in the control group. Moreover, eighty-two altered operational taxonomic units responsive to oil treatment were identified and nineteen of them differing in one or more parameters associated with obesity. In conclusion, this study confirmed the effect of oil treatment on obesity alleviation, as well as on the microbiota structure alterations. We proposed that further researches are needed to elucidate the causal relationship between obesity alleviation and gut microbiota modulation.