Whole grain-rich diet reduces body weight and systemic low-grade inflammation without inducing major changes of the gut microbiome: a randomised cross-over trial

Abstract

ObjectiveTo investigate whether a whole grain diet alters the gut microbiome and insulin sensitivity, as well as biomarkers of metabolic health and gut functionality.Design60 Danish adults at risk of developing metabolic syndrome were included in a randomised cross-over trial with two 8-week dietary intervention periods comprising whole grain diet and refined grain diet, separated by a washout period of ≥6 weeks. The response to the interventions on the gut microbiome composition and insulin sensitivity as well on measures of glucose and lipid metabolism, gut functionality, inflammatory markers, anthropometry and urine metabolomics were assessed.Results50 participants completed both periods with a whole grain intake of 179±50 g/day and 13±10 g/day in the whole grain and refined grain period, respectively. Compliance was confirmed by a difference in plasma alkylresorcinols (p<0.0001). Compared with refined grain, whole grain did not significantly alter glucose homeostasis and did not induce major changes in the faecal microbiome. Also, breath hydrogen levels, plasma short-chain fatty acids, intestinal integrity and intestinal transit time were not affected. The whole grain diet did, however, compared with the refined grain diet, decrease body weight (p<0.0001), serum inflammatory markers, interleukin (IL)-6 (p=0.009) and C-reactive protein (p=0.003). The reduction in body weight was consistent with a reduction in energy intake, and IL-6 reduction was associated with the amount of whole grain consumed, in particular with intake of rye.ConclusionCompared with refined grain diet, whole grain diet did not alter insulin sensitivity and gut microbiome but reduced body weight and systemic low-grade inflammation.Trial registration numberNCT01731366; Results.

Association of whole grain, refined grain, and cereal consumption with gastric cancer risk: A meta‐analysis of observational studies

“…Moreover, whole grain is a major source of dietary fiber, vitamins, and several minerals (Stephen, ). (b) The whole grain diet, compared with a refined grain diet, plays a role in decreasing energy intake and lowering systemic inflammation without significantly altering gut microbiome or gut functionality in terms of intestinal integrity and transit time (Costabile et al., ; Roager et al., ). (c) Refined grain has a higher digestibility than whole grain, resulting in glycemic overload, higher plasma insulin concentration and compensatory increases in insulin‐like growth factor I, an important mitogenic stimulant of tumor cell growth in vitro (Giovannucci, ).…”

“…Moreover, whole grain is a major source of dietary fiber, vitamins, and several minerals (Stephen, 1994). (b) The whole grain diet, compared with a refined grain diet, plays a role in decreasing energy intake and lowering systemic inflammation without significantly altering gut microbiome or gut functionality in terms of intestinal integrity and transit time (Costabile et al, 2008;Roager et al, 2017).…”

Diet‐derived microbial metabolites in health and disease

“…; Roager et al . ). Overall, evidence indicates that changing the gut microbial community structure by diet is not straightforward and may require substantial dietary manipulations and/or long‐term changes in the habitual diet.…”

Coreopsis Tinctoria Modulates Lipid Metabolism by Decreasing Low-Density Lipoprotein and Improving Gut Microbiota

“…However, in recent studies, the improvement in cardiometabolic risk markers following a multifunctional diet was associated with gut microbial taxa in relatively healthy overweight and obese subjects, but dietary interventions did not significantly alter the gut microbiota composition at the phylum or genus levels [47]. Also, compared with a refined grain diet, whole grain diets did not alter insulin sensitivity and gut microbiomes but did reduce body weight and systemic low-grade inflammation [48].…”