TOPLINE:

A fiber supplement also found in beans and other foods may lead to weight loss and improved insulin sensitivity in people with excess body weight, partly due to changes in the gut microbiota.

METHODOLOGY:

In animal studies, resistant starch (RS), a kind of dietary fiber, has shown a potential to reduce body fat along with other metabolic benefits, but human dietary studies of RS have been inconsistent, especially with a high-fat diet.
Researchers conducted a crossover, randomized trial to study the effect of RS as a dietary supplement on 37 individuals with overweight or obesity (average age, 33.43 years; 15 women; body mass index > 24 or higher waist circumference).
Participants were fed a similar background diet and either 40 g of RS (high-amylose maize) or an energy-matched placebo starch daily for 8 weeks and then switched between the two in a separate 8-week period.
The primary outcome was body weight, and the secondary outcomes were visceral and subcutaneous fat mass, waist circumference, lipid profiles, insulin sensitivity, metabolome, and gut microbiome.
RS’s impact on gut microbiota composition and function was assessed with metagenomics and metabolomics, and RS-modified gut microbiota’s effect on host body fat and glucose was confirmed by transferring from select average participants to mice.

TAKEAWAY:

Participants showed a mean weight loss of 2.8 kg after consuming RS for 8 weeks (P < .001), but there was no significant change in body weight in those on placebo starch.
RS improved insulin sensitivity in people to a greater extent than placebo starch (P = .025) and showed a greater reduction in fat mass, waist circumference, and other obesity-related outcomes.
The abundance in the gut of the microbe Bifidobacterium adolescentis increased significantly following RS intervention, an increase that exhibited a strong correlation with decreased BMI, suggesting a role of RS in reducing obesity.
The levels of pro-inflammatory cytokines, such as serum tumor necrosis factor-alpha and interleukin-1 beta, were significantly lower in participants who consumed RS than in those who had placebo starch.

IN PRACTICE:

“Our study provided an effective dietary recommendation using RS as a supplement (40 g/d with a balanced background diet containing 25%-30% fat), which may help to achieve significant weight loss,” the authors wrote.

SOURCE:

This study was led and corresponded by Huating Li, Shanghai Clinical Center for Diabetes, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China, and University of Hong Kong, Pok Fu Lam, and published online in Nature Metabolism.

LIMITATIONS:

This study was limited by the small sample size and stringent inclusion criteria for participants. The use of database-driven and taxane-based methodology might have led to difficult-to-classify sequences being discarded and strain-level functional diversity being overlooked. The authors also acknowledged the need to validate the findings of this study in larger and more diverse cohorts.

DISCLOSURES:

This work was supported by the National Key Research and Development Program of China, Shanghai Municipal Key Clinical Specialty, National Natural Science Foundation of China, and other sources. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

High-Fiber Gut Microbe Makeover Aids Weight Loss

DISCLOSURES: