Regular-fat and low-fat dairy foods and cardiovascular diseases: perspectives for future dietary recommendations

Abstract

Most current dietary guidelines for the prevention of cardiovascular diseases (CVD) recommend the consumption of low-fat dairy in place of regular-fat dairy foods, one of the main sources of dietary saturated fatty acids (SFAs). Here, we summarize the data presented and discussions held-relating to the validity of such recommendations-between a panel of international nutrition research experts at a high-level closed workshop on "Saturated Fat in Dairy and Cardiovascular Diseases," which took place in Amsterdam on 15-16 April, 2024. The most recent evidence indicates that overall, consumption of milk, yogurt and cheese, irrespective of fat content, is neutrally associated with CVD risk. There is also no evidence yet from randomized controlled trials that consumption of regular-fat milk, yogurt, and cheese has different effects on a broad array of cardiometabolic risk factors when compared with consumption of low-fat milk, yogurt, and cheese. Thus, the body of evidence does not support differentiation between regular-fat and low-fat dairy foods in dietary guidelines for both adults and children. Strategies focusing primarily on reduction of energy-dense, nutrient-poor foods, the main source of SFAs in Western diets, rather than on the fat content of dairy foods, are more likely to benefit the population's cardiovascular health. Future research is needed to understand better the place of regular-fat and low-fat dairy foods within healthy eating patterns.

Keywords: cardiovascular disease (CVD); dietary guidelines; low-fat dairy; regular-fat dairy; saturated fatty acids (SFAs).

FIGURE 1

Dose–response results of large prospective cohort studies and meta-analyses examining the association of dairy food consumption and risk of cardiovascular outcomes; (A) total dairy, (B) regular-fat and low-fat dairy, (C) milk, (D) fermented dairy, cheese and yogurt. Square sizes are proportional to study sample size within each panel. Dehghan et al. [28] reported results from the Prospective Urban Rural Epidemiology cohort study of nearly 140,000 adults from 21 countries in 5 continents over a median follow-up of 9 y. ¹Major cardiovascular disease (CVD) was defined as death from cardiovascular causes, nonfatal myocardial infarction, stroke, or heart failure; ²low dairy intake regions included China, south Asia, southeast Asia, Africa; ³high dairy intake regions included Europe and North America, South America, and the Middle East. Guo et al. [29] reported results from a meta-analysis of 29 prospective cohort studies in over 900,000 adults from North America, Europe, Australia, and East Asia over a mean follow-up of 13 y. Fermented dairy foods included cheese, yogurt, and soured milk. Soedamah-Muthu et al. [30] reported updated results from Guo et al. 2017, including 15 cohort studies for coronary artery disease (CAD), and De Goede et al. 2016, including 20 cohort studies for stroke. Chen et al. [31] reported results from a meta-analysis of 55 studies in over 850,000 adults from North America, Europe, and Asia over a follow-up time of 5–32 y. De Goede et al. [32] reported results from a meta-analysis of 18 prospective cohort studies in over 750,000 adults from North America, Europe, Australia, and East Asia over a follow-up of 8–26 y. Jakobsen et al. [33] reported results from a meta-analysis of 18 prospective cohort studies in over 600,000 adults from Europe, North America, and Asia over a follow-up time of 5–23 y. Yogurt was defined as yogurt or other soured milk products. Across studies, regular-fat and low-fat dairy categories usually included milk, yogurt, and cheese. Low-fat milk/dairy was usually defined as having fat content lower than regular-fat milk/dairy, although for cheese, this could include both reduced-fat cheeses and naturally low-in-fat cheeses.

FIGURE 2

Potential mechanisms linking dairy food consumption and dairy fat to cardiometabolic health. Several mechanisms from cellular and animal models, as well as from clinical studies in humans, have associated components of dairy foods to beneficial cardiometabolic changes [[61], [62], [63], [64]]. Potential benefits on biological and signaling functions include contribution to acylation processes that are essential to some protein/enzyme functions (notably those involved in omega-3 metabolism), the impact of several dairy-specific fatty acids (such as trans-vaccenic acid and trans-palmitoleic acid) on insulin sensitivity, hypotensive effects of dairy biopeptides and anti-inflammatory effects of dairy fats. Some dairy SFAs consist of short- and medium-chain fatty acids that are readily β-oxidized and have been associated with various potentially beneficial effects on lipid metabolism. The consumption of milk polar lipids and milk fat globule membrane have been shown to reduce LDL cholesterol, apolipoprotein B, and triacylglycerol concentrations, to reduce intestinal cholesterol absorption (human/randomized controlled trial) and cholesterol liver storage, increase lipid β-oxidation, and reduce lipid accumulation in tissues (preclinical) [22]. Milk polar lipids may also reduce circulating concentrations of atherogenic sphingolipids (such as ceramide Cer24:1) [65]. Specific milk fatty acids may also reduce lipid accumulation in the liver and adipose tissue. Other potentially beneficial effects of dairy components on digestion and postprandial lipid metabolism have been documented. For example, the structure and texture of the dairy matrix may modulate digestion, gastric emptying rate, and postprandial lipemia [66]. Consumption of yogurt and cheese has been shown to favorably influence satiety, notably via glucagon-like peptide 1 mediated signaling. The calcium and polar lipid content of the dairy matrix, and its rigid texture, may reduce intestinal absorption of some fatty acids, cholesterol, and/or polar lipids. Finally, dairy components may influence gut signaling and homeostasis, including favorable modulation of the gut microbiome and the production of beneficial postbiotics such as short-chain fatty acids.

FIGURE 3

Effects of food substitution on the proportion of Canadians in 2015 with saturated fatty acid intake <10% of total energy. Modeling of the proportion of the Canadian population (aged 2 y or more) with usual total SFA intakes <10% of total energy before and after the substitution of foods high in SFA with the corresponding foods that are low in SFA/high in UFA. Reproduced with permission from Harrison et al. [73]. 10%E, 10% of total energy intake; UFA, unsaturated fatty acid.