Novel findings: Mouse study shows annatto tocotrienols may impact gut microbiota, benefit metabolic health
Supplementing a high-fat diet with annatto tocotrienols led to a decrease in the Firmicutes to Bacteroidetes ratio in the murine gut. The Firmicutes/Bacteroidetes ratio is reportedly a good biomarker for obesity, with data from a 2005 study indicating that obese mice had lower levels of Bacteroidetes and higher levels of Firmicutes, compared with lean mice.
“[Annatto tocotrienols] supplementation significantly reduces T2DM [type 2 diabetes mellitus] or obesity-related hormones (eg, resistin and leptin) and a proinflammatory cytokine (eg, IL-6),” wrote scientists from Texas Tech University in Nutrition Research.
“To our knowledge, this is the first study to demonstrate the potential role of AT in modifying the gut microbiome, and at the same time, we observed improvements in insulin resistance and glucose tolerance.”
Vitamin E forms
Vitamin E is a family of eight separate but related molecules: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Tocotrienols are derived from three major sources, including rice, palm and annatto.
The new study used annatto tocotrienols from DeltaGold, which is free from tocopherol, and was supplied by US-based manufacturer American River Nutrition.
Commenting on the research, Dr Barrie Tan, President of American River Nutrition, said: “The importance of a healthy gut is fully appreciated by consumers and those with chronic conditions. The unusual finding that tocopherol-free DeltaGold annatto tocotrienol affects a positive change in gut microbiota is simply remarkable.
“We recognize the novelty and importance of this research, and are currently examining similar parameters in an ongoing obesity clinical trial, with results forthcoming within the next year or two,” added Dr Tan.
The Texas Tech scientists performed a 14-week study in high fat diet-induced T2DM mice. Lab mice were fed either a low-fat diet, a high-fat diet, or the high-fat diet supplemented with annatto tocotrienols at 800 mg/kg, which is equivalent to a human dosage of about 320mg/day. A fourth group consumed the high-fat diet with 200 mg metformin/kg.
Results showed that, at the end of the study, animals in the annatto tocotrienol supplemented group displayed significant reversal in the high-fat diet-induced alterations in the gut microbiome profile, resulting in enhanced insulin sensitivity, reduced obesity-related hormones, and decreased inflammatory cytokines.
At the gut microbiome level, significant decreases were recorded within the Firmicutes phylum, notably for Ruminococcus lactaris, Dorea longicatena, and the Lachnospiraceae family in the tocotrienol-supplement group, compared to the control high-fat diet group. Both R. lactaris and the family of Lachnospiraceae have been reported to be highly abundant in obesity and T2DM.
An increase in Akkermansia muciniphilla was also recorded compared to the low-fat diet group, but there were no differences between the high-fat diet groups – with or without tocotrienol supplementation.
The scientists did not measure any significant differences between the high-fat groups for body weight and fat mass, but they did record significant inhibition of obesity-related hormones, including resistin and leptin, as well as the pro-inflammatory cytokine interleukin-6, in white adipose tissue. This indicated a decrease in overall inflammation.
Improvements in glucose homeostasis by enhancing insulin sensitivity were also recorded in the tocotrienol-supplemented animals.
“[Annatto tocotrienol]supplementation not only modulated gut microbiota profile with significant changes in bacteria (ie, A. muciniphila, D. longicatena, and R. lactaris) but also improved glucose and insulin homeostasis and decreased proinflammatory adipokines, diabetes, and obesity-linked hormones,” wrote the researchers.
“Our results expand current knowledge on the importance of dietary supplements, such as tocotrienols, on gut health.”
Source: Nutrition Research
Volume 77, May 2020, Pages 97-107, doi: 10.1016/j.nutres.2020.04.001
“Metabolic benefits of annatto-extracted tocotrienol on glucose homeostasis, inflammation, and gut microbiome”
Authors: E. Chung, et al.