Cardiovascular disease

Low-fat, calcium-rich dairy products are generally considered to lower blood pressure. This was supported by a meta-analysis of six observational studies, whereas no association was found with intake of high-fat dairy products (23). High-fat dairy products are known to increase high density lipoprotein (HDL)- and low density lipoprotein (LDL)-cholesterol concentrations. The latter normally predicts risk of cardiovascular disease (24), but this may depend on the size of the LDL-cholesterol particles. Small, dense LDL particles are more atherogenic than their larger counterparts (25–28) due to their lower affinity for the LDL-receptor and higher susceptibility to oxidation (29). In agreement, some of the fatty acids typically found in milk and dairy products have been associated with less small, dense LDL particles (4:0–10:0 and 14:0 in the diet, and 15:0 and 17:0 in serum phospholipids) (30). In addition, the minerals in milk and dairy products have been shown to attenuate the LDL-response to high-fat dairy intake (31, 32).

Among high-fat dairy products, cheese in particular does not seem to increase LDL-cholesterol to the extent expected, based on the high content of saturated fat (33). When compared to habitual diet with a lower total and saturated fat content (33), or compared to diets with lower total fat content but higher content of high-GI carbohydrates (34, 35), a high intake of cheese was found not to increase LDL-cholesterol. A meta-analysis of randomised controlled trials studying the effect of cheese consumption compared with other foods on blood lipids and lipoproteins showed that cheese caused lower total cholesterol, LDL-cholesterol, and HDL-cholesterol concentrations compared with butter (36). Compared with milk, however, there was no statistically significant difference in blood lipids (32, 37). Several meta-analyses have been conducted on the relationship between intake of milk and dairy products and risk of developing cardiovascular disease. There was no consistent association between milk or dairy intake and cardiovascular disease, coronary heart disease or stroke in a meta-analysis by Soedamah-Muthu et al. (38). In a recent update, including a higher number of prospective cohort studies, there was a significant inverse association between milk intake and stroke, with a 7% lower risk of stroke per 200 ml milk/day, but considerable heterogeneity. Further, stratification for Asian and Western countries showed a more marked reduction in risk in Asian than in Western countries. This is consistent with a previous meta-analysis by Hu et al. (39) showing a non-linear dose–response relationship between milk intake and risk of stroke, with the highest risk reduction of 7–8% with a milk intake of 200–300 ml/day. Also, the meta-analyses by Hu et al. (39) and de Goede et al. (40) both showed an inverse association between cheese intake and stroke, however only borderline significant in the latter. Accordingly, another meta-analysis on dairy and cardiovascular disease found that intake of cheese and milk as well as yoghurt was inversely associated with cardiovascular disease risk (41). A later meta-analysis by Qin et al. (42) found that dairy intake was associated with a 12% lower risk of cardiovascular disease, and 13% lower risk of stroke as compared to individuals with no or a low dairy consumption (42). Likewise, a recent and comprehensive meta-analysis, including 31 cohort studies, suggested that a high dairy intake was associated with a 9% lower risk of stroke, whereas no association was found with total cardiovascular disease or coronary heart disease (43). Moreover, a high intake of cheese was associated with an 8% lower risk of coronary heart disease and a 13% lower risk of stroke. In addition, high plasma levels of the saturated fatty acid C 17:0, which primarily originates from dairy, were found to be associated with a reduced risk of coronary heart disease (44). Finally, a meta-analysis by O’Sullivan et al. (45) found no indication of total dairy intake or any specific dairy product being associated with an increased cardiovascular mortality. Studies are emerging showing that dairy products, particularly the low-fat types, cluster within a healthy dietary pattern (46), and therefore, the risk of residual confounding in the observational studies cannot be ruled out.

In accordance with the latest meta-analyses presented above, the latest Nordic Nutrition Recommendations have concluded that high consumption of low-fat milk products is associated with reduced risk of hypertension and stroke (47).

Conclusion on cardiovascular disease

The overall evidence indicates that a high intake of milk and dairy products, that is, 200–300 ml/day, does not increase the risk of cardiovascular disease. Specifically, there is an inverse association with risk of hypertension and stroke.

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