Does intake of bread supplemented with wheat germ have a preventive role on cardiovascular disease risk markers in healthy volunteers? A randomised, controlled, crossover trial

Wheat germ supplementation has modest effects on gut health markers but improves glucose homeostasis markers in adults classified as overweight: A randomized controlled pilot study

Wheat germ (WG), a by-product of flour milling, is rich in bioactive substances that may help improve health complications associated with increased adiposity. This study investigated the effects of WG on gut health, metabolic, and inflammatory markers in adults classified as overweight. We hypothesized that WG, because of its many bioactive components, would improve gut health and metabolic, and inflammatory markers in overweight adults. Forty adults (18-45 years old) and with a body mass index between 25 and 30 kg/m2 participated in this single-blinded randomized controlled pilot study. Participants consumed the study supplements containing 30 g of either cornmeal (control, CL) or WG daily for 4 weeks. Primary outcome variables were gut health markers including gut microbiota, gut integrity markers, and fecal short-chain fatty acids, whereas secondary outcome variables included metabolic and inflammatory parameters assessed at baseline and at the end of supplementation. Thirty-nine participants (n = 19 and 20 for CL and WG group, respectively) completed the study. The genus Faecalibacterium was significantly higher in the WG group compared to CL post-supplementation but no significant changes in other gut health markers, short-chain fatty acids, inflammatory markers, and lipid profiles were observed. Compared with baseline, WG improved markers of glucose homeostasis including insulin (P = .02), homeostatic model assessment of insulin resistance (P = .03), glycated hemoglobin (P = .07), and the pro-inflammatory adipokine, resistin (P = .04). However, these parameters after intervention were not different with control. Our findings suggest that WG supplementation have modest effects on gut health but may provide an economical option for individuals to improve glycemic control.

The Effect of Regular Consumption of Reformulated Breads on Glycemic Control: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Bread is a major source of grain-derived carbohydrates worldwide. High intakes of refined grains, low in dietary fiber and high in glycemic index, are linked with increased risk for type 2 diabetes mellitus (T2DM) and other chronic diseases. Hence, improvements in the composition of bread could influence population health. This systematic review evaluated the effect of regular consumption of reformulated breads on glycemic control among healthy adults, adults at cardiometabolic risk or with manifest T2DM. A literature search was performed using MEDLINE, Embase, Web of Science and the Cochrane Central Register of Controlled Trials. Eligible studies employed a bread intervention (≥2 wk) in adults (healthy, at cardiometabolic risk or manifest T2DM) and reported glycemic outcomes (fasting blood glucose, fasting insulin, HOMA-IR, HbA1c, and postprandial glucose responses). Data were pooled using generic inverse variance with random-effects model and presented as mean difference (MD) or standardized MD between treatments with 95% CIs. Twenty-two studies met the inclusion criteria (n = 1037 participants). Compared with "regular" or comparator bread, consumption of reformulated intervention breads yielded lower fasting blood glucose concentrations (MD: -0.21 mmol/L; 95% CI: -0.38, -0.03; I² = 88%, moderate certainty of evidence), yet no differences in fasting insulin (MD: -1.59 pmol/L; 95% CI: -5.78, 2.59; I² = 38%, moderate certainty of evidence), HOMA-IR (MD: -0.09; 95% CI: -0.35, 0.23; I² = 60%, moderate certainty of evidence), HbA1c (MD: -0.14; 95% CI: -0.39, 0.10; I² = 56%, very low certainty of evidence), or postprandial glucose response (SMD: -0.46; 95% CI: -1.28, 0.36; I² = 74%, low certainty of evidence). Subgroup analyses revealed a beneficial effect for fasting blood glucose only among people with T2DM (low certainty of evidence). Our findings suggest a beneficial effect of reformulated breads high in dietary fiber, whole grains, and/or functional ingredients on fasting blood glucose concentrations in adults, primarily among those with T2DM. This trial was registered at PROSPERO as CRD42020205458.

Antioxidant Effect of Wheat Germ Extracts and Their Antilipidemic Effect in Palmitic Acid-Induced Steatosis in HepG2 and 3T3-L1 Cells

Wheat germ (WG) is a by-product of wheat milling and comprises many bioactive compounds. This study aimed to compare the antioxidant and antilipidemic effects of different WG extracts (WGEs) by analyzing candidate bioactive compounds such as carotenoids, tocopherols, γ-oryzanol, and biogenic amines by reversed-phase high-performance liquid chromatography. Antioxidant activity was determined using the ABTS, DPPH, and FRAP assays. The antilipidemic effect was evaluated in palmitic acid-induced steatosis in HepG2 hepatocytes and 3T3-L1 adipocytes. Cellular lipid accumulation was assessed by Oil Red O staining and a cellular triglyceride content assay. All analyzed WGEs showed significant antioxidant potential, although some bioactive compounds, such as carotenoids, tocopherols, and γ-oryzanol, were the highest in the ethanol extract. Correlation analysis revealed the antioxidant potential of all identified biogenic amines except for spermidine. Ethanol and n-hexane extracts significantly inhibited cellular lipid accumulation in cell models. These results suggest that WGEs exhibit promising antioxidant potential, with a variety of bioactive compounds. Collectively, the findings of this study suggest that bioactive compounds in WGEs attenuate plasma lipid and oxidation levels. In conclusion, WG can be used as a natural antioxidant and nutraceutical using appropriate solvents and extraction methods.

Effect of wheat germ on metabolic markers: a systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis aim to evaluate the association of wheat germ interventions and metabolic markers. An electronic search was performed by mid-May 2019 in the PubMed, Google Scholar, and Web of Science databases. Quality was evaluated using the risk of bias assessment tools. Thirty-three randomized controlled trials (RCTs) were identified, among which ten were suitable and systematically reviewed based on biomarkers (cholesterol, triglycerides, glucose, and oxidative stress). Three biomarkers in five eligible studies were investigated by meta-analysis. Total cholesterol showed non-significant results (p = 0.98), with standard mean difference (SMD) of − 0.01 (95% confidence interval; − 0.17, 0.16). The SMD was − 0.06 (95% CI − 0.41, 0.29, n = 4) for triglycerides and − 0.09 (95% CI − 0.62, 0.45, n = 2) for glucose. No biomarkers showed heterogeneity (0%). This review revealed non-significant association between wheat germ interventions and metabolic markers. Sensitive analysis with high-quality RCTs may be worth trying.

The effects of wheat germ supplementation on metabolic profile in patients with type 2 diabetes mellitus: A randomized, double-blind, placebo-controlled trial

The aim of the present trial was to examine the effects of wheat germ (WG) consumption on metabolic control and oxidative stress status of type 2 diabetes mellitus (T2DM) patients. Eighty participants with T2DM were randomly allocated to receive 20-g WG (n = 40) or placebo (n = 40) in a randomized double-blind clinical trial for 12 weeks. Serum lipid profiles, glycaemic indices, total antioxidant capacity, and malondialdhyde (MDA) were assessed. A total of 75 subjects completed the trial. Compared with the placebo, WG consumption led to significant reduction in total cholesterol (TC) concentrations (p = .04). There was a trend regarding TC to high density lipoprotein ratio (p = .08) following 12 weeks WG consumption, although they were not statistically significant after correcting for multiple testing. In addition, within-group comparison revealed a significant rise in total antioxidant capacity concentration (p = .001) in WG group. We observed no significant effects of WG intake on glycaemic status, blood pressure, MDA, triglyceride, and low density lipoprotein levels. WG consumption for 12 weeks could decrease serum TC levels and had no significant effects on other metabolic variables and MDA in patients with T2DM. Though observed health benefit effects were small, it might lead to a major impact on wider public health.

Daily intake of wheat germ-enriched bread may promote a healthy gut bacterial microbiota: a randomised controlled trial

PURPOSE

Wheat bran fibre has a beneficial effect on gastrointestinal function, but evidence for wheat germ is scarce. Accordingly, we evaluated the effects of daily intake of wheat germ on gastrointestinal discomfort and gut microbiota by adding wheat germ to refined (white) wheat bread, the most consumed bread type. We hypothesised that an improvement in the composition of refined bread could beneficially affect intestinal health without compromising consumers' acceptance.

METHODS

Fifty-five healthy adults were recruited for a randomised, double-blind, crossover, controlled trial comprising two 4-week intervention periods separated by a 5-week washout stage. During the first 4-week period, one group consumed wheat bread enriched with 6 g of wheat germ and the control group consumed non-enriched wheat bread.

RESULTS

Wheat germ-enriched bread was well-appreciated and the number of participants that demonstrated minimal gastrointestinal improvements after wheat-germ intake was higher than in the control arm. Importantly, intake of wheat germ-enriched bread decreased the perceived gastrointestinal discomfort-related quality of life (subscale worries and concerns) over refined white bread. The improvements in the gastrointestinal function were accompanied by favourable changes in gut microbiota, increasing the number of Bacteroides spp. and Bifidobacterium spp.

CONCLUSIONS

Adding wheat germ to industrially made white bread without altering sensory properties may promote a healthy gut bacterial microbiota and the gastrointestinal health.