Effects of whole-grain wheat, rye, and lignan supplementation on cardiometabolic risk factors in men with metabolic syndrome: a randomized crossover trial.
Study Goal
The researchers aimed to investigate the effects of whole-grain rye (with and without lignan supplements) and whole-grain wheat diets on glucose tolerance, cardiometabolic outcomes, enterolignans, and gut microbiota composition in men with a metabolic syndrome risk profile.
Results Summary
The study found that whole-grain rye (with or without SDG supplementation) did not affect glucose metabolism compared to whole-grain wheat but caused a transient reduction in LDL cholesterol. It also altered gut microbiota composition, increasing Bifidobacterium and decreasing Clostridium.
Population
40 men with a metabolic syndrome risk profile.
Effective Dosage
280 mg SDG (secoisolariciresinol diglucoside) supplemented with the rye diet at weeks 4-8.
Duration
8 weeks (crossover study).
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
WG rye diet (± SDG supplements) | no change | OGTT | men with MetS risk profile | no significant change | did not affect | #1 |
WG rye diet (± SDG supplements) | no change | glucose metabolism | men with MetS risk profile | no significant change | did not affect | #2 |
WG rye diet | decrease | total cholesterol | men with MetS risk profile | -0.06 mmol/L | lowered | #3 |
WG rye diet | decrease | LDL cholesterol | men with MetS risk profile | -0.09 mmol/L | lowered | #4 |
WG rye diet | increase | Bifidobacterium | men with MetS risk profile | fold-change = 2.58 | resulted in higher abundance | #5 |
WG rye diet | decrease | Clostridium genus | men with MetS risk profile | fold-change = 0.54 | resulted in lower abundance | #6 |
WG rye diet, alone or with SDG supplementation | decrease | LDL-cholesterol | men with MetS risk profile | - | caused transient reduction | #7 |
BACKGROUND: A whole-grain (WG)-rich diet has shown to have potential for both prevention and treatment of the metabolic syndrome (MetS), which is a cluster of risk factors that increase the risk of type 2 diabetes and cardiovascular disease. Different WGs may have different health effects. WG rye, in particular, may improve glucose homeostasis and blood lipids, possibly mediated through fermentable dietary fiber and lignans. Recent studies have also suggested a crucial role of the gut microbiota in response to WG. OBJECTIVES: The aim was to investigate WG rye, alone and with lignan supplements [secoisolariciresinol diglucoside (SDG)], and WG wheat diets on glucose tolerance [oral-glucose-tolerance test (OGTT)], other cardiometabolic outcomes, enterolignans, and microbiota composition. Moreover, we exploratively evaluated the role of gut microbiota enterotypes in response to intervention diets. METHODS: Forty men with MetS risk profile were randomly assigned to WG diets in an 8-wk crossover study. The rye diet was supplemented with 280 mg SDG at weeks 4-8. Effects of treatment were evaluated by mixed-effects modeling, and effects on microbiota composition and the role of gut microbiota as a predictor of response to treatment were analyzed by random forest plots. RESULTS: The WG rye diet (± SDG supplements) did not affect the OGTT compared with WG wheat. Total and LDL cholesterol were lowered (-0.06 and -0.09 mmol/L, respectively; P < 0.05) after WG rye compared with WG wheat after 4 wk but not after 8 wk. WG rye resulted in higher abundance of Bifidobacterium [fold-change (FC) = 2.58, P < 0.001] compared with baseline and lower abundance of Clostridium genus compared with WG wheat (FC = 0.54, P = 0.02). The explorative analyses suggest that baseline enterotype is associated with total and LDL-cholesterol response to diet. CONCLUSIONS: WG rye, alone or with SDG supplementation, compared with WG wheat did not affect glucose metabolism but caused transient LDL-cholesterol reduction. The effect of WG diets appeared to differ according to enterotype. This trial was registered at www.clinicaltrials.gov as NCT02987595.