Does intake of dairy products negatively impact cardio-metabolic health?

The research revealed that a higher dietary intake (regardless of fat content) had no detrimental effects on anthropometric outcomes, blood pressure, or lipids. However, full-fat and low-fat dairy improved systolic blood pressure but may impair glycemic control. Yoghurt, compared to milk, improved triglycerides, waist circumference, and HDL-C.

Due to inconsistent findings across trials, the health effects of dairy products are still debatable; and no network meta-analysis has been conducted to date to simultaneously compare the isocaloric results of different dairy products types and different amounts of fat on blood lipids, anthropometric outcomes, systolic blood pressure, or glycemic control. Considering this, Eva Kiesswetter, University of Freiburg, Freiburg, Germany, and colleagues aimed to compare the effects of different dairy products on cardio-metabolic health markers in a systematic review and network meta-analysis (NMA).

For this purpose, the researchers systematically searched three electronic databases. RCTs (randomized controlled trial) with ≥ 12-week intervention comparing any two of the eligible interventions (e.g., high dairy [≥ three servings/day or an equal amount in g/day], low-fat dairy, full-fat dairy, low dairy/control [0-2 servings per day or usual diet], naturally fermented milk products) were included.

A pairwise meta-analysis and NMA were conducted for ten outcomes (BMI, body weight, waist circumference, fat mass, systolic blood pressure, glycosylated haemoglobin, fasting glucose, triglycerides, HDL-cholesterol, LDL-cholesterol). Pooling of continuous outcome data was done using mean difference (MD). Dietary interventions were ranked using the surface under the cumulative ranking curve (SUCRA). Nineteen RCTs comprising 1427 participants were included.

The authors reported the following findings:

• High dairy intake (irrespective of fat content) demonstrated no harmful effects on blood lipids, anthropometric outcomes, and blood pressure.
• Both full-fat and low-fat dairy improved systolic blood pressure (BP) (MD: -5.22 to -7.60 mmHg; low certainty) but, concomitantly, may impede blood sugar control (fasting glucose [MD: 0.31 to 0.43 mmol/L] and glycosylated haemoglobin [MD: 0.37 to 0.47%]).
• Full-fat dairy may increase HDL cholesterol compared to a control diet (MD: 0.26 mmol/L).
• Yoghurt improved waist circumference (MD: -3.47 cm, low certainty), triglycerides (-0.38 mmol/L, low certainty), and HDL-cholesterol (MD: 0.19 mmol/L) compared to milk.

"Overall, it seems that current recommendations for dairy intake did not negatively impact markers of cardio-metabolic health," the researchers wrote. "However, as available RCTs focused mainly on total dairy intake, future studies should compare the effects of specific dairy products to generate more robust evidence."

Reference:

Kiesswetter E, Stadelmaier J, Petropoulou M, Morze J, Grummich K, Roux I, Lay R, Himmelsbach L, Kussmann M, Roeger C, Rubach M, Hauner H, Schwingshackl L. Effects of dairy intake on markers of cardio-metabolic health in adults - a systematic review with network meta-analysis. Adv Nutr. 2023 Mar 11:S2161-8313(23)00273-9. doi: 10.1016/j.advnut.2023.03.004. Epub ahead of print. PMID: 36914032.