High-Dairy Food Patterns and Gut-Brain Axis

Official title

Longer-term Effects of High-dairy Food Patterns on the Gut-brain Axis in Adults With Overweight or Obesity

Overview

Disturbances in brain insulin sensitivity are associated not only with obesity and type 2 diabetes, but also with brain aging and cognitive decline. Longitudinal studies suggest that dietary patterns, particularly those high in dairy intake, may impact brain function via the gut-brain axis. Indeed, dairy foods are known to modulate gut microbiota and may, through this pathway, not only improve brain insulin sensitivity and cognitive performance, but also mental health and appetite regulation. However, underlying mechanisms remain largely unexplored. The primary objective of this study is to evaluate, in older adults with overweight or obesity, the effects of a high-dairy food pattern (4-5 daily servings of (butter)milk, cheese, yogurt, or cottage cheese) compared to a low-dairy food pattern (≤1 serving daily) on (regional) brain vascular function and insulin sensitivity. These outcomes will be quantified using the non-invasive MRI perfusion technique Arterial Spin Labeling (ASL), which assesses cerebral blood flow (CBF) in response to intranasal insulin, a validated physiological marker of brain insulin sensitivity. Secondary objectives include changes in cognitive performance (via the CANTAB neuropsychological test battery), gut microbiota composition (via shotgun metagenomic analysis of fecal samples), and appetite-related brain reward activity (via BOLD-fMRI with food cues). Exploratory analyses include conventional cardiometabolic risk markers (blood pressure, lipid and glucose metabolism), and perceivable (consumer) benefits.

Interventions

• Dietary supplement High-dairy food pattern
  During the high-dairy period, participants will be instructed to consume 4-5 daily servings of dairy products, including: 1-2 servings of yogurt or cottage cheese (200 mL per serving, ≤1.5% fat), 1-2 servings of milk or buttermilk (250 mL per serving, ≤1.5% fat), and 1-2 servings of cheese (20 g per serving, 20+ or 30+ reduced-fat options).
• Dietary supplement Low-dairy food pattern
  During the low-dairy control period, participants will restrict dairy intake to a maximum of one serving per day

Primary outcome measures

• Brain Insulin Sensitivity [Time frame: Change in brain insulin sensitivity (difference in CBF [mL/100 g tissue/min] before and after intranasal insulin) at the end of an 8-week high-dairy food pattern and an 8-week low-dairy food pattern]
• Brain vascular function [Time frame: Change in brain vascular function (CBF in mL/100 g tissue/min) at the end of an 8-week high-dairy food pattern and an 8-week low-dairy food pattern]

Secondary outcome measures (3)

• Cognitive Performance [Time frame: Change in cognitive performance (test-specific standardized scores) at the end of an 8-week high-dairy food pattern and an 8-week low-dairy food pattern]
• Gut microbial composition [Time frame: Change in gut microbial composition (shannon index indicating α-diversity) using gene relative abundance profiles at the start and end of an 8-week high-dairy food pattern and an 8-week low-dairy food pattern]
• Appetite-related brain reward activity [Time frame: Change in appetite-related brain reward activity (functional connectivity [BOLD signal changes]) at the end of an 8-week high-dairy food pattern and an 8-week low-dairy food pattern]

Eligibility criteria

Inclusion criteria

• Men and postmenopausal women (≥ 2 years since last menstruation);
• Aged between 40-75 years;
• BMI between 25-35 kg/m2 (overweight or obese);
• Low-to-moderate habitual dairy consumption (≤ 3 servings/day);
• Fasting serum total cholesterol < 8.0 mmol/L;
• Fasting serum triacylglycerol < 4.5 mmol/L;
• Fasting plasma glucose < 7.0 mmol/L;
• Systolic blood pressure < 160 mmHg and diastolic blood pressure < 100 mmHg;
• Stable body weight (weight gain or loss < 3 kg in the past three months).

Exclusion criteria

• Left-handedness;
• Milk protein allergy or lactose intolerance;
• Current smoker, or smoking cessation < 12 months;
• Familial hypercholesterolemia;
• Abuse of drugs;
• Alcoholic intake >3 standard drinks/day;
• Use of medications, food products or dietary supplements affecting glucose, lipid, or blood pressure regulation, gut microbiota or mental or neurological function, judged by the principal investigator;
• Use of antibiotics within the previous month;
• Use of other biomedical investigational products within the previous month;
• Participation in another clinical trial within the past month;
• Severe medical conditions including type 2 diabetes, epilepsy, asthma, kidney failure, COPD, inflammatory bowel disease, autoimmune diseases, or rheumatoid arthritis;
• History of cardiovascular events (e.g., heart attack, stroke) or active cardiovascular disease;
• Contra-indications for MRI imaging (e.g. pacemaker, metal implants, claustrophobia);
• Willing to donate blood starting from 8 weeks before the study begins, throughout the study, and for 4 weeks after its inclusion;
• Difficult to venipuncture as evidenced during the screening visit.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Double blind

Primary purpose

Prevention

Study locations

Netherlands · 1 center

• Maastricht University — Maastricht

Identifiers

NCT: NCT07355309 · METC25-043

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗