Saturated fat from dairy sources and cardiometabolic health: Findings from the Framingham Offspring Study

A study using prospective data from 2,391 adults (30 years+) from the Framingham Offspring Study evaluated the associations between saturated fat intake from dairy and non-dairy sources and markers of cardiometabolic health (such as body fat, inflammatory biomarkers, lipid concentrations and particle size) over an 8-year follow-up period. Dietary intake was measured using two sets of 3-day dietary records and diet quality was evaluated using the 2015 Healthy Eating Index (HEI-2015). Analyses also accounted for confounding factors, such as level of education, smoking, alcohol consumption, physical activity levels, and other potential dietary confounders (such as diet quality score and fruit and vegetable intake). 

After a 4-year period, women in the highest quintile of saturated fat from dairy (13.7–40.4 g/d of saturated fat from dairy) had a lower BMI (26.6 kg/m²), while those in the lowest quintile (0.0 to <4.5 g/d) had a mean BMI of 27.8 kg/m². In both sexes, no further association was detected between saturated fat (dairy or non-dairy sources) and other anthropometric measurements, such as between body fat percentage and waist-to-height ratio. 

Beneficial associations were detected between cardiometabolic biomarkers and saturated fat intake, but effects differed between men and women.

In men:

• Compared to men who consumed the least dairy-derived saturated fats (0.0 to <4.5 g/d), those who consumed the most (13.7–40.4 g/d) had less atherogenic risk profiles, including higher levels of HDL, greater HDL and triglyceride particle size, and lower levels of triglycerides;
• Dairy-derived saturated fat intake was also linked to lower C-reactive protein and fibrinogen, two indicators of inflammation;
• Consuming more saturated fat from dairy was linked to a more favourable triglyceride-to-HDL ratio, a strong predictor of both cardiometabolic health and reduced all-cause mortality. 

In women:

• Higher saturated fat intake from non-dairy sources was associated with greater HDL particle size, while greater saturated fat intake from dairy source was linked to greater LDL particle size, which decreases its ability to penetrate the arterial wall;
• Higher intake of saturated fats from non-dairy sources led to a more favourable triglyceride-to-HDL ratio.  

For all other outcomes, no association was detected between saturated fat intake, regardless of the source, and indicators of cardiometabolic health. In fact, the authors note no adverse effect of saturated fat, regardless of the source, on any cardiometabolic parameter.

The authors highlight dairy’s unique nutritional profile and food matrix as a potential contributor to the beneficial results that were observed. Suggested mechanisms include the high protein content of dairy, which may encourage the preservation of lean muscle mass, and its mineral content (such as calcium, potassium, magnesium, and phosphorus). Regarding dairy fats specifically, the authors note the unique fat profile of dairy, which includes a complex and diverse fatty acid profile of short-, medium-, long-, odd-, and branched-chain fatty acids that may modulate its effect on health outcomes.