The effect of high compared with low dairy consumption on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults: a randomized crossover trial.
Study Goal
The researchers aimed to investigate the effects of high versus low dairy intake on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults.
Results Summary
The study found no significant differences in metabolic flexibility or postprandial glucose metabolism between high and low dairy diets, though fasting insulin concentrations were lower after the low-dairy diet. The high-dairy diet resulted in a higher HOMA-IR, indicating reduced insulin sensitivity.
Population
Overweight men and postmenopausal women aged 45-65 years (mean age 58.9 ± 4.3 years, BMI 27.9 ± 1.9 kg/m²).
Effective Dosage
High-dairy diet (HDD): 5-6 portions daily (200 g semi-skimmed yoghurt, 30 g reduced-fat cheese, 250 mL semi-skimmed milk/buttermilk); low-dairy diet (LDD): ≤1 portion daily.
Duration
6 weeks per diet, with a 4-week washout period.
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
high dairy intake diet (HDD) | no change | fasting RQ and ΔRQ, reflecting metabolic flexibility | overweight adults (aged 45-65 y) | - | did not differ | #1 |
high dairy intake diet (HDD) | no change | fasting glucose concentrations | overweight adults (aged 45-65 y) | - | were similar | #2 |
low dairy intake diet (LDD) | decrease | fasting insulin concentrations | overweight adults (aged 45-65 y) | 8.1 ± 2.8 mU/L (LDD) vs 8.9 ± 3.3 mU/L (HDD) | were lower | #3 |
high dairy intake diet (HDD) | increase | HOMA-IR | overweight adults (aged 45-65 y) | - | resulted in a higher | #4 |
high dairy intake diet (HDD) | no change | postprandial glucose and insulin responses as well as glucose kinetics | overweight adults (aged 45-65 y) | - | were similar | #5 |
the amount of dairy intake during a 6-wk period | no change | metabolic flexibility or postprandial glucose metabolism | middle-aged overweight subjects | - | had a neutral effect | #6 |
BACKGROUND: Dairy products contain many nutritious components that may benefit metabolic health. There are indications that glucose metabolism and insulin sensitivity, which are generally disturbed in overweight and obese individuals, may improve by increased dairy intake. This may also affect one's metabolic flexibility. OBJECTIVE: The aim of this study was to investigate the effects of high compared with low dairy intake on glucose metabolism, insulin sensitivity, and metabolic flexibility in overweight adults (aged 45-65 y). METHODS: In this randomized intervention study, subjects consumed a high- and a low-dairy diet [HDD (5-6 dairy portions) and LDD (≤1 dairy portion), respectively] for 6 wk in a crossover design, with a washout period of 4 wk. Dairy portions were 200 g semi-skimmed yoghurt, 30 g reduced-fat (30+) cheese, and 250 mL semiskimmed milk and buttermilk. After 6 wk, a 75-g oral-glucose-tolerance test (13C-labeled) and a subsequent fasting challenge were performed. Metabolic flexibility was studied by determining the respiratory quotient (RQ) using indirect calorimetry. Fasting and postprandial plasma concentrations of glucose and insulin were analyzed. The dual isotope technique enabled calculation of glucose kinetics. RESULTS: The study was completed by 45 overweight men and postmenopausal women [age 58.9 ± 4.3 y, BMI 27.9 ± 1.9 kg/m2 (mean ± SD)]. Fasting RQ and ΔRQ, reflecting metabolic flexibility, did not differ after both diets. Fasting glucose concentrations were similar, whereas fasting insulin concentrations were lower after the LDD (LDD: 8.1 ± 2.8 mU/L; HDD: 8.9 ± 3.3 mU/L; P = 0.024). This resulted in a higher HOMA-IR after the HDD (P = 0.027). Postprandial glucose and insulin responses as well as glucose kinetics were similar after both diets. CONCLUSIONS: The amount of dairy intake during a 6-wk period had a neutral effect on metabolic flexibility or postprandial glucose metabolism in middle-aged overweight subjects. More trials are needed to study the effects of specific dairy types and to differentiate between metabolic subgroups. This trial was registered at trialregister.nl as NTR4899.