Alleviation Of Metabolic Endotoxemia In Adults With Metabolic Syndrome With Milk Fat Globule Membrane

Background and hypothesis:

Our preclinical evidence shows that phospholipid-rich milk fat globule membrane (MFGM) attenuates lipopolysaccharide-induced increases in gut permeability and pro-inflammatory cytokines. MFGM also attenuates inflammation in association with a prebiotic and/or antimicrobial activity that modulates microbiota composition. Our central hypothesis is that MFGM-enriched dairy milk compared with a matched milk beverage containing soy lecithin (control) decreases metabolic endotoxemia and improves glucose tolerance in metabolic syndrome (MetS) adults by increasing gut barrier integrity in association with alleviating gut dysbiosis and inflammation.

Study Design:

The investigators will enroll male and female MetS adults (n = 24; 18-65 y) to complete a 2-arm, double-blind, randomized controlled, crossover trial. They will be randomized in 4-unit blocks to receive, for 14 days, a controlled diet with dairy milk (3.5% fat; 3 servings/d) enriched with MFGM-derived phospholipid or a matched dairy milk that instead contains coconut and palm oil (control). The investigators will provide all foods during each study period to ensure weight maintenance and to increase homogeneity of gut and host responses.

Subjects:

Participants will be recruited from Columbus, Ohio area. Participants having no history of liver or cardiovascular disease or cancer will be enrolled. They will have ≥3 established criteria for MetS: i) glucose (100-126 mg/dL), ii) waist circumference (>89 or >102 cm for F/M), iii) HDL-C (<50 or <40 mg/dL in F/M), iv) triglyceride >150 mg/dL, and iv) blood pressure >130/85 mmHg. Major exclusion criteria include: unstable body mass (±2 kg over prior 3-mo) vegetarian; food allergies or lactose intolerance; user of dietary supplements or probiotics (within past 1-mo); pregnancy, lactation, changes in birth control (within 6-month); any gastrointestinal disorders; chronic diarrhea; smoker; excess alcohol (>2 drinks/day); excess aerobic exercise (>7 h/week); recent antibiotic or anti-inflammatory agent use; blood pressure >140/90 mmHg.

Dietary Control:

The intervention will be performed in the Human Nutrition Metabolic Kitchen under the auspice of a registered dietitian (PI Bruno). In each 2-wk intervention, participants' diet will be rigorously controlled. All foods will be prepared, packaged, and provided every 3-4 days to supply a weight maintenance (i.e. eucaloric) diet. To assess compliance, participants will return MFGM/coconut/palm oil milk bottles for counting and any uneaten food portions for weighed measurement. Milk beverages will also be formulated to contain para-aminobenzoic acid (PABA; 80 mg/milk serving). Spot urine samples will be collected 4 times during each study arm coinciding when participants pick up test foods. Urinary PABA will be measured by spectrophotometry. Separate from this, participants will also keep food logs to document any dietary deviation. Diets will be standardized at 50-60% of energy from carbohydrate with low fiber intakes (~15 g/day) similar to Americans' diets to prevent potential masking of the benefits of MFGM, 15-20% from protein, and 25-30% from fat. Importantly, other than test beverages provided as part of the eucaloric diet, diets will be otherwise devoid of significant amounts of dairy foods, fermented products, and probiotics to prevent confounding effects.

Measurements:

Anthropometrics and blood pressure will be assessed at days 0, 7, and 13. Prior to (day 0), at day 7 and after each 2-wk arm (day 13), a fasting blood sample will be collected to assess serum endotoxin and metabolic chemistries (glucose, insulin, lipids (triglyceride, total and HDL cholesterol), and TLR4/NFκB-dependent genes from whole blood. A breath sample will be collected to assess the correlation analysis of plasma metabolic biomarkers. After the 2-week intervention, from fecal samples collected on day 13, the investigators will assess microbiota composition and function, SCFAs, and intestinal inflammatory markers (calprotectin, myeloperoxidase). During this period, participants will also record daily stool characteristics using a 7-point Bristol Stool scale. On day 13, participants in the fasted state will receive a high-fat/high-glucose meal challenge to induce gut-derived endotoxin translocation. At 30-minute intervals for 3 hours, the investigators will evaluate circulating endotoxin, glucose, and insulin; TLR4/NFκB-dependent genes will be assessed from whole blood at 0 hour and 3-hour. Gut permeability probes will be co-administered with the test meal challenge, and 24-hour urine will be collected to assess gut barrier integrity. Participants will then undergo a 2-week washout prior to receiving the alternative treatment and completing all procedures in an identical manner.