Is low-fat milk and dairy the healthy choice?

The health impact and weight control benefits of different dairy foods represent a major unanswered question of modern nutrition science and there is still substantial controversy and uncertainty with regards to the effects of whole-fat versus low-fat milk consumption.

While there is broader concordance about higher fat intake not being harmful, most dietary guidelines still group different types of dairy fat together, categorise these by fat content, and then recommend selection of lower-fat products.

Such recommendations are largely based on calorie content and theoretical considerations about nutrient intakes (total fat, saturated fat) rather than empirical evidence on health effects of the actual foods and implications for weight management.

What does the research say?

Health effects of dairy fat, milk intake, whole vs low-fat

Longitudinal studies, which involve repeated observations of a variable – here the consumption of whole-fat versus low-fat milk and dairy products – over long periods of time suggest several things:

Consuming whole-fat milk does not appear to raise the risk of obesity, type 2 diabetes or cardiovascular disease (CVD) in adults.
Total milk intake is generally not associated with a higher incidence of type 2 diabetes and dairy fat may even have potential benefits for type 2 diabetes.
People switching to low-fat dairy products tend to compensate elsewhere in their diet by increasing consumption of carbohydrates.

In cohorts using objective blood biomarkers, greater overall dairy fat consumption is associated with a lower incidence of type 2 diabetes and CHD, and with mixed findings for stroke.

A meta-analysis of 16 studies, though mostly observational in nature, found that full-fat dairy was either inversely associated with obesity and metabolic disease, or not associated with them at all. In other words, people who ate the most high-fat dairy foods had the lowest risk for obesity, type 2 diabetes, and CVD.

One study showed that people who ate the most full-fat dairy had a 69% lower risk of cardiovascular death than those who ate the least, for example.

While dairy fat itself may promote cardiometabolic health, it remains unclear whether this relate to health benefits of specific dairy fatty acids (eg, branched-chain fatty acids, medium-chain saturated fats), other lipid-soluble factors in dairy fat, or something else entirely.

Among potentially healthful components found in dairy fat, trans-palmitoleic acid has received a lot of attentio, for higher circulating levels have been associated with healthier levels of blood cholesterol, inflammatory markers, insulin levels, and insulin sensitivity.

Weight management, dairy intake and whole fat milk

Overall, research suggest that intakes of low-fat and whole-fat milk appear relatively neutral, suggesting they do not interfere with long-term weight control.

In short-term randomised trials, adding milk or dairy to energy-restricted diets increases lean mass and reduces body fat, whereas no significant effects related to body composition are seen when adding dairy to ad-libitum diets.

Although modern evidence provide little inference on the specific effects of lowering dairy fat among children, long-term weight gain in children seems to vary by the type of dairy.

For instance, children who habitually drink low-fat milk gain more weight, and those who drink whole-fat milk gain less weight, over time. Paradoxically, many school lunch programs have banned whole milk, but allow sugar-sweetened chocolate skim milk.

In longitudinal studies conducted among adults, neither low-fat nor whole-fat milk are appreciably related to chronic weight gain. However, as previously mentioned, when adults consume more low-fat dairy, they have a tendency to compensate in the long run by increasing carbs – which can drive many pathways leading to obesity.

Whole vs low-fat: Which should we be consuming?

Overall, there is little evidence supporting the opposing hypothesis, i.e, the superiority of low-fat milk and dairy products for health, including for the risk of obesity.

No long-term studies support harms, and emerging evidence suggests some potential benefits, of dairy fat or high-fat dairy products.

Together the above findings provide little support for the prevailing recommendations for dairy intake that emphasise low-fat dairy based on theorised influences on obesity and CHD.

New evidence also calls for further investigation of cardiometabolic effects of dairy foods, including relevant compounds and molecular mechanisms.

References

The relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease by Kratz M. Eur J Nutr.

The amount and type of dairy product intake and incident type 2 diabetes: results from the EPIC-InterAct Study by Sluijs I. Am J Clin Nutr.

Food sources of saturated fat and the association with mortality: a meta-analysis by O’Sullivan TA. Am J Public Health.

Effects of low-fat or full-fat fermented and non-fermented dairy foods on selected cardiovascular biomarkers in overweight adults by Nestel PJ. Br J Nutr.

Dairy consumption and patterns of mortality of Australian adults by Bonthuis M. Eur J Clin Nutr.

Biomarkers of dairy fatty acids and risk of cardiovascular disease in the Multi-ethnic Study of Atherosclerosis by de Oliveira Otto MC. J Am Heart Assoc.

Circulating biomarkers of dairy fat and risk of incident stroke in U.S. men and women in 2 large prospective cohorts by Yakoob MY. Am J Clin Nutr.

Natural trans fat, dairy fat, partially hydrogenated oils, and cardiometabolic health: the Ludwigshafen Risk and Cardiovascular Health Study by Mozaffarian D. Eur Heart J.

Plasma phospholipid fatty acid concentration and incident coronary heart disease in men and women: the EPIC-Norfolk prospective study by Khaw KT. PLoS Med.

Changes in diet and lifestyle and long-term weight gain in women and menby Mozaffarian D. N Engl J Med.