Low-quality dietary patterns impair cardiometabolic health by increasing the risk of obesity-related disorders. Cardiometabolic risk relative to dairy-food consumption continues to be a controversial topic, due to recommendations that endorse low-fat and nonfat dairy foods over full-fat varieties despite accumulated evidence that does not strongly support these recommendations. Controlled human studies and mechanistic preclinical investigations support that full-fat dairy foods decrease cardiometabolic risk by promoting gut health, reducing inflammation, and managing dyslipidemia. These gut- and systemic-level cardiometabolic benefits are attributed, at least in part, to milk polar lipids (MPLs) derived from the phospholipid- and sphingolipid-rich milk fat globule membrane that is of higher abundance in full-fat dairy milk. The controversy surrounding full-fat dairy food consumption is discussed in this review relative to cardiometabolic health and MPL bioactivities that alleviate dyslipidemia, shift gut microbiota composition, and reduce inflammation. This summary, therefore, is expected to advance the understanding of full-fat dairy foods through their MPLs and the need for translational research to establish evidence-based dietary recommendations.
Poor diet quality influences cardiometabolic risk. Although potatoes are suggested to adversely affect cardiometabolic health, controlled trials that can establish causality are limited. Consistent with potatoes being rich in micronutrients and resistant starch, we hypothesized that their inclusion in a Dietary Guidelines for Americans (DGA)-based dietary pattern would improve cardiometabolic and gut health in metabolic syndrome (MetS) persons. In a randomized cross-over trial, MetS persons (n = 27; 32.5 ± 1.3 year) consumed a DGA-based diet for 2 weeks containing potatoes (DGA + POTATO; 17.5 g/day resistant starch) or bagels (DGA + BAGEL; 0 g/day resistant starch) prior to completing oral glucose and gut permeability tests. Blood pressure, fasting glucose and insulin, and insulin resistance decreased (p < 0.05) from baseline regardless of treatment without any change in body mass. Oral glucose-induced changes in brachial artery flow-mediated dilation, nitric oxide homeostasis, and lipid peroxidation did not differ between treatment arms. Serum endotoxin AUC0–120 min and urinary lactulose/mannitol, but not urinary sucralose/erythritol, were lower in DGA + POTATO. Fecal microbiome showed limited between-treatment differences, but the proportion of acetate was higher in DGA + POTATO. Thus, short-term consumption of a DGA-based diet decreases cardiometabolic risk, and the incorporation of resistant starch-containing potatoes into a healthy diet reduces small intestinal permeability and postprandial endotoxemia.
Objectives
Preclinical evidence demonstrated that catechin-rich green tea extract (GTE) improves gut barrier function and reduces intestinal and systemic inflammation. Thus, this clinical trial was conducted to test the hypothesis that GTE would alleviate intestinal inflammation relative to cardiometabolic risk in persons with metabolic syndrome (MetS).
Methods
We conducted a randomized, double-blind, placebo-controlled, crossover trial in adults with MetS and age- and gender-matched healthy persons who received confections without (placebo) or with 1 g/d GTE (890 mg catechins) for 28 d while following a low-polyphenol diet. Dietary polyphenols, fasting blood glucose, insulin, and lipids were assessed at d 0, 14, and 28 of each intervention. Intestinal inflammation was assessed by measuring neutrophil-derived calprotectin and myeloperoxidase by ELISA in pooled stool samples collected over the last 3 d of each intervention. Data were analyzed using RM ANOVA and multiple linear regression.
Results
MetS (n = 21; 40 ± 3 y; 35 ± 1 kg/m2) and healthy (n = 19; 34 ± 2 y; 22 ± 0.4 kg/m2) persons completed the study with high compliance (>95%), no adverse effects, or changes in body mass. Participants’ total polyphenol intakes decreased during each intervention compared with baseline (P < 0.001). Fecal calprotectin and myeloperoxidase were lower (P < 0.05) in GTE compared with placebo regardless of health status. Although fasting insulin, triglycerides, total and high-density lipoprotein cholesterol were unaffected by treatment, fasting glucose decreased (P < 0.01) in response to GTE regardless of health status. Age (β = −0.29; P = 0.05) and between-trial changes in myeloperoxidase (β = 0.03; P < 0.04) were predictive of changes in insulin after controlling for sex, waist circumference, and changes in blood lipids and calprotectin.
Conclusions
Dietary intervention with GTE-rich confections in weight-stable healthy and MetS adults decreased fasting glucose and intestinal inflammation, which was associated with improvements in fasting insulin. This suggests that gut-level anti-inflammatory activities of GTE may improve glycemic control with reductions in intestinal inflammation contributing to enhance insulin sensitivity.
Funding Sources
USDA-NIFA, USDA-HATCH, and the Ohio Agricultural Research and Development Center at the Ohio State University.
Full-fat dairy milk may protect against cardiometabolic disorders, due to the milk fat globule membrane (MFGM), through anti-inflammatory and gut-health-promoting activities. We hypothesized that a MFGM-enriched milk beverage (MEB) would alleviate metabolic endotoxemia in metabolic syndrome (MetS) persons by improving gut barrier function and glucose tolerance. In a randomized crossover trial, MetS persons consumed for two-week period a controlled diet with MEB (2.3 g/d milk phospholipids) or a comparator beverage (COMP) formulated with soy phospholipid and palm/coconut oil. They then provided fasting blood and completed a high-fat/high-carbohydrate test meal challenge for evaluating postprandial metabolism and intestinal permeability. Participants had no adverse effects and achieved high compliance, and there were no between-trial differences in dietary intakes. Compared with COMP, fasting endotoxin, glucose, incretins, and triglyceride were unaffected by MEB. The meal challenge increased postprandial endotoxin, triglyceride, and incretins, but were unaffected by MEB. Insulin sensitivity; fecal calprotectin, myeloperoxidase, and short-chain fatty acids; and small intestinal and colonic permeability were also unaffected by MEB. This short-term study demonstrates that controlled administration of MEB in MetS persons does not affect gut barrier function, glucose tolerance, and other cardiometabolic health biomarkers, which contradicts observational evidence that full-fat milk heightens cardiometabolic risk. Registered at ClinicalTrials.gov (NCT03860584).
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