Full-fat dairy products and cardiometabolic health outcomes: Does the dairy-fat matrix matter?

Dairy intake, plasma metabolome, and risk of type 2 diabetes in a population-based cohort

BACKGROUND

Whether dairy intake is related to type 2 diabetes (T2D) remains unclear, as does potential metabolic mechanisms for this association.

OBJECTIVES

We aimed to examine the association between high dairy intake and risk of T2D and identify plasma metabolites reflecting dairy intake.

METHODS

This prospective cohort study included 26,461 Swedish individuals recruited between 1991 and 1996 and followed up until 31 December, 2020, with available data on dairy intake at baseline and linked registers. Plasma metabolites were measured in a subsample (n = 893) using mass spectrometry. Associations of dairy intake with risk of T2D were assessed using Cox proportional hazards models, with results presented as hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

A total of 4552 new-onset incident T2D cases were documented during a median follow-up of 24.3 y. Increased risk of T2D was observed among participants consuming high nonfermented milk (>1000 g/d compared with <200 g/d; HR: 1.40; 95% CI: 1.12, 1.74) and cheese (>100 g/d compared with <20 g/d; HR: 1.23; 95% CI: 1.07, 1.41), although decreased risk of T2D was observed among those with high fermented milk (>300 g/d compared with 0 g/d; HR: 0.88; 95% CI: 0.74, 1.03), cream (>50 g/d compared with <10 g/d; HR: 0.77; 95% CI: 0.64, 0.92), and butter (>50 g/d compared with 0 g/d; HR: 0.82; 95% CI: 0.71, 0.94). Such associations were slightly attenuated after additional adjustment for BMI. In addition, we identified metabolite profiles for nonfermented milk (n = 45), fermented milk (n = 48), cheese (n = 12), cream (n = 27), and butter (n = 46); no overlap between metabolites was found.

CONCLUSIONS

In this cohort of Swedish adults, high intakes of nonfermented milk and cheese are positively associated with risk of T2D, although high intakes of fermented milk, cream, and butter are inversely associated. Metabolomics provides novel insights into understanding the metabolic pathways of these associations.

Associations between Saturated Fat from Single Dairy Foods and Body Composition in Young Canadian Children

Purpose: To examine the associations between dairy-derived saturated fat from fluid cow's milk, cheese, and yogurt, and body composition [body mass index z-scores (BMIz), fat mass index (FMI), and waist-to-height ratio (WHtR)] in children aged 1.5-5 years. Methods: This cross-sectional study used baseline data from 267 children (3.5 ± 1.2 years) from the Guelph Family Health Study. Dairy-derived saturated fat intake (g/1000 kcal) was assessed via one 24-hour dietary recall completed by parents using the web-based Automated Self-Administered 24-Hour Dietary Assessment Tool 2016 - Canadian version. Linear regression using generalized estimating equations explored associations between dairy-derived saturated fat intake and BMIz and FMI, adjusted for physical activity, household income, parent education, and child ethnicity; WHtR was additionally adjusted for age and sex. Results: Total dairy- and milk-derived saturated fat were not associated with any body composition outcomes. Cheese-derived saturated fat intake was positively, but marginally associated with BMIz (B̂ = 0.03, 95% CI: 0.01 to 0.06, p = 0.013), while yogurt-derived saturated fat was inversely associated with FMI (B̂ = -0.19, 95% CI: -0.34 to -0.04, p = 0.015). Conclusions: These cross-sectional findings may inform dietary guidelines to recognize the neutral or potentially beneficial effects of saturated fat from dairy products on body composition in young children. Longitudinal studies are warranted.

Full-fat versus non-fat yogurt consumption improves glucose homeostasis and metabolic hormone regulation in individuals with prediabetes: A randomized-controlled trial

Dietary guidance recommends consuming low- or non-fat dairy foods for metabolic health, yet observational research indicates full-fat yogurt intake may not detrimentally affect type 2 diabetes risk. Randomized-controlled trials are needed to further explore this relationship. Our aim was to evaluate the effect of substituting full-fat (3.25%) yogurt for non-fat yogurt on type 2 diabetes risk in individuals with prediabetes. We hypothesized beneficial effects on measures of glucose homeostasis, insulin sensitivity, and metabolic hormone response following short-term consumption of 3 full-fat yogurt servings daily. Thirteen individuals completed the 8-week randomized, double-masked crossover controlled-feeding trial comprised 2, 3-week experimental diet periods in which participants consumed 3 daily servings of full-fat or non-fat yogurt; a 1-week control preceded each diet period. Following each diet period, changes in whole-body glucose handling and metabolic hormone concentrations were measured using mixed meal and oral glucose tolerance tests. Our primary outcome measure was the blood glucose concentration at the 120-minute time point during the oral glucose tolerance test. Though differences in the primary outcome measure were not observed, the full-fat yogurt diet resulted in lower concentrations of blood fructosamine, a marker of average blood glucose concentrations over 2 to 3 weeks. Further, fasting glucagon-like peptide-1 and post-prandial glucose-dependent insulinotropic polypeptide concentrations were greater following the full-fat yogurt diet. Our preliminary results indicate that short-term consumption of full-fat relative to non-fat yogurt beneficially affected aspects of glucose homeostasis and metabolic hormone regulation in individuals with prediabetes, warranting further randomized-controlled research. This trial is registered at clinicaltrials.gov (NCT03577119).

Decrypting the messages in the matrix: The proceedings of a symposium on dairy food matrix science and public health opportunities

Although food matrix research is still in its infancy, there is an emerging understanding of the important role of the food matrix on human nutrition and physiology, as well as for public health. This understanding has largely been propelled forward by research involving different milk and dairy food matrices which has revealed that in addition to their distinct array of nutrients and bioactive compounds, milk and dairy foods also contain complex food matrix microstructures that act as nutrient and bioactive delivery systems that set them apart from the other food groups. Due to these distinct food matrix properties, milk and dairy foods may be uniquely positioned to help Americans meet many of their nutrition and health needs. The aim of this manuscript is to describe the activities and findings from a National Dairy Council-sponsored symposium focused on connecting the science on milk and dairy food matrices with opportunities for improving public health. This proceedings paper summarizes and communicates the symposium presentations and panel discussions, key insights, and next steps to help leverage the evidence on different dairy food matrices (e.g., milk, yogurt, cheese) to develop science-backed strategies to support public health and health equity.

Redefining Protein Quality: Integrating Health Outcomes and Environmental Impacts in the Plant-Animal Protein Debate

There is an ongoing debate about the relative merits of plant-based versus animal-based protein sources in terms of human health outcomes and environmental impacts. This viewpoint article reviews and synthesizes the current evidence comparing plant and animal protein sources on measures of human health like cardiovascular disease, cancer, and mortality risk, as well as environmental factors like greenhouse gas emissions, water use, and land requirements. Overall, greater consumption of plant protein sources like legumes, nuts, seeds, and whole grains is associated with reduced risks of cardiovascular diseases, some cancers, and mortality, especially compared to red and processed meats. Crucially, these health benefits align with the dramatically lower environmental footprints of plant proteins across measures like emissions, water use, and land use. However, evidence is mixed for some health outcomes, and more research is still needed. While blanket recommendations should be avoided, the convergence of health and environmental advantages suggests future dietary guidance should emphasize shifting toward more plant-based protein sources. However, evaluations must consider specific foods rather than broad categorizations. New protein production methods like precision fermentation may also reduce environmental impacts while maintaining adequate nutrition.

Study Protocol for a Randomized Controlled Trial Investigating the Effects of the Daily Consumption of Ruminant Milk on Digestive Comfort and Nutrition in Older Women: The YUMMI Study

BACKGROUND

Age-related changes can lead to dietary insufficiency in older adults. The inclusion of high-quality, nutrient-dense foods such as ruminant milks can significantly improve health outcomes. However, many older adults worldwide do not meet daily milk intake recommendations because of digestive discomfort and health concerns. Ovine and caprine milks are increasingly popular for their perceived digestive and nutritional benefits. While preclinical studies suggest differences in milk digestion, human studies investigating acute postprandial responses remain inconclusive, and the impacts of sustained milk consumption remain uncertain.

OBJECTIVES

Hence, we present a randomized controlled trial investigating how the sustained consumption of bovine, caprine, or ovine milk influences digestion, nutrition, and metabolism in older women.

METHODS

A total of 165 healthy older women were randomized to receive bovine, caprine, or ovine milk, or no milk, twice daily for 12 weeks. The primary outcome is the impact of milk consumption on digestive comfort assessed via the Gastrointestinal Syndrome Rating Scale (GSRS). Secondary outcomes include changes in nutrient intake, plasma amino acid and lipid appearance, bowel habits, the gut microbiota, cardiometabolic health, physical function, physical activity, sleep, mood, sensory perception, and emotional response.

CONCLUSIONS

The findings could inform dietary recommendations for older women and facilitate the development of targeted functional food products.