Effect of 12 wk of resistant starch supplementation on cardiometabolic risk factors in adults with prediabetes: a randomized controlled trial

Effects of the resistant starch on glucose, insulin, insulin resistance, and lipid parameters in overweight or obese adults: a systematic review and meta-analysis

Background

The role of resistant starch (RS) in glucose, insulin, insulin resistance or sensitivity, and lipid parameters have been reported in several studies and remained controversial. A pooled analysis which assessed these parameters has not been performed. Thus, we conducted a meta-analysis to sum up existing evidence about the issue.

Methods

We searched in MEDLINE and PUBMED for studies that were published before November 2018. Meta-analysis of diabetics and nondiabetics trials were performed by use of a random-effects model.

Results

A total of 13 case–control studies that included 428 subjects with body mass index ≥25 were identified. RS supplementation reduced fasting insulin in overall and stratified (diabetics and nondiabetics trials) analysis (SMD = –0.72; 95% CI: –1.13 to –0.31; SMD = –1.26; 95% CI: –1.66 to –0.86 and SMD = –0.64; 95% CI: –1.10 to –0.18, respectively), and reduced fasting glucose in overall and stratified analysis for diabetic trials (SMD = –0.26; 95% CI: –0.5 to –0.02 and SMD = –0.28; 95% CI: –0.54 to –0.01, respectively). RS supplementation increased HOMA-S% (SMD = 1.19; 95% CI: 0.59–1.78) and reduced HOMA-B (SMD =–1.2; 95% CI: –1.64 to –0.77), LDL-c concentration (SMD =–0.35; 95% CI: –0.61 to −0.09), and HbA1c (SMD = –0.43; 95% CI: –0.74 to –0.13) in overall analysis.

Conclusions

This meta-analysis has provided evidence that RS supplementation can improve fasting glucose, fasting insulin, insulin resistance and sensitivity, especially for diabetic with overweight or obesity. However, owing to potential sophistication, individual difference and composition of intestinal microbiota, this result should be carefully taken into account.

Impact of Diet-Modulated Butyrate Production on Intestinal Barrier Function and Inflammation

A major challenge in affluent societies is the increase in disorders related to gut and metabolic health. Chronic over nutrition by unhealthy foods high in energy, fat, and sugar, and low in dietary fibre is a key environmental factor responsible for this development, which may cause local and systemic inflammation. A low intake of dietary fibre is a limiting factor for maintaining a viable and diverse microbiota and production of short-chain fatty acids in the gut. A suppressed production of butyrate is crucial, as this short-chain fatty acid (SCFA) can play a key role not only in colonic health and function but also at the systemic level. At both sites, the mode of action is through mediation of signalling pathways involving nuclear NF-κB and inhibition of histone deacetylase. The intake and composition of dietary fibre modulate production of butyrate in the large intestine. While butyrate production is easily adjustable it is more variable how it influences gut barrier function and inflammatory markers in the gut and periphery. The effect of butyrate seems generally to be more consistent and positive on inflammatory markers related to the gut than on inflammatory markers in the peripheral tissue. This discrepancy may be explained by differences in butyrate concentrations in the gut compared with the much lower concentration at more remote sites.