Dairy products such as butter, cheese, milk, and yogurt have long been demonized because of their saturated fat content. But despite decades of research, there is still no credible evidence that these foods are harmful to cardiovascular health.
As Soedamah-Muthu and Guo noted in a 2020 publication (1):
Total dairy, full-fat dairy, low-fat dairy, milk, cheese, and yoghurt consumption have no association with the risk of CHD [coronary heart disease].
More recently, Chen and colleagues published a paper called "Dairy Product Consumption and Cardiovascular Health: a Systematic Review and MetaAnalysis of Prospective Cohort Studies" (2). Although limited, this review has the largest analysis to date on high-fat products.
What did they find?
As with other reviews, the researchers found no association between high-fat dairy and coronary heart events. In fact, their analysis found that high-fat dairy was associated with a reduced risk of stroke:
Total high-fat dairy consumption was not associated with the risk of HTN [hypertension] and CHD, but showed a modest inverse association with stroke risk.
Also, there are likely unpublished studies with neutral or favorable results for high-fat dairy (publication bias).
For example, an abstract from Framingham found that butter intake "had no effect on CVD risk" (3), and another found that butter was "seemingly protective for both CAC [coronary artery calcium] and ASCVD [cardiovascular events]" (4).
Thus, the epidemiological evidence for full-fat dairy does not allow hypotheses of harm. And this is readily apparent in the vast majority of individual cohorts published in the past couple years.
Dairy in 2020 and 2021
A large French cohort published in 2020 showed that high-fat dairy was not associated with cardiovascular events and that fermented dairy was associated with a reduced risk of stroke (5). As the authors stated:
The consumption of at least 160 g/d of fermented dairy (e.g. cheese and yogurts) was associated with a reduced risk of cerebrovascular diseases compared to intakes below 57 g/d . . . Despite being a major dietary source of saturated fats, dairy consumption was not associated with CVD or CHD risks in this study.
Also in 2020, the HUSK cohort found that saturated fat, which came "primarily from dairy products," was associated with a reduced risk of CHD:
(Image: Taken from reference 6)
Moreover, in 2021, four publications from Sweden found no association or beneficial associations between dairy and cardiovascular events.
First, Acosta et al. noted that increased saturated fat intake (in a population where dairy is an important source of fat) was associated with a reduced incidence of cardiovascular events (7):
SFA was associated with reduced risk of ACVD, which has previously been shown for coronary events in women in the MDCS cohort.
Second, Olsson and colleagues found that moderate milk consumption was related to a lower risk of stroke (8):
Milk consumption (1–2 glasses/d) seem to have a protective effect on total stroke, compared to zero intake. Consumption of fermented milk was not associated with total stroke.
Third, a meta-analysis by Trieu et al. showed a beneficial relation between dairy fat biomarkers and cardiovascular risk (9):
The findings from our study using fatty acid biomarkers suggest that higher intake of dairy fat were associated with lower CVD risk in diverse populations including Sweden (a country with high dairy intake) . . .
And fourth, Sonestedt and colleagues observed a decreased risk of death for fermented milk and cheese, a decreased risk of death in men for cream intake, and no association between butter and death (10):
Fermented milk and cheese intake were inversely associated with mortality. Cream showed a protective association only among men. . . . Butter, which is a high-fat dairy product (~80% fat), was not associated with mortality in the present study.
On top of these, a case‐cohort study across nine European countries found that yogurt and cheese were associated with a reduced risk of heart events whereas milk had no association. Although butter was related to events, the finding was statistically weak (11).
Furthermore, the Alpha Omega Cohort from the Netherlands found no association between cardiovascular mortality and butter, fermented dairy, high-fat milk, and hard cheeses. But yogurt showed a protective association regardless of fat content (12).
Thus, the vast majority of cohorts published in the past two years have found no associations or beneficial associations between high-fat dairy products and cardiovascular outcomes.
Dairy and Risk Markers
High-fat dairy is often demonized for its relation with higher LDL cholesterol (especially butter). However, LDL is actually a very poor predictor of cardiovascular events/mortality. Therefore, as Dehghan and colleagues rightly stated (13):
Predicting the net clinical effect based on considering only the effects of nutrient intake on LDL cholesterol is not reliable in projecting the effects of diet on cardiovascular disease events or on total mortality.
In line with this, two cohorts found that milk intake tends to associate with increased LDL levels; yet, milk was still associated with a lower risk of cardiovascular death and a lower risk of coronary artery calcification progression (14,15).
Indeed, an Editorial in 2021 not only noted the potential benefits of the short- and medium-chain fatty acids, the protein, and other nutrients contained in dairy, but also the insufficiency of using saturated fat as a marker of risk (16):
The sole intake of saturated fatty acids may not be a sufficient risk factor for increasing LDL-cholesterol nor to establish the whole atherosclerotic process.
When tested in short-term trials, dairy intake — regardless of the fat content — has no "adverse" effects on a wide variety of risk markers (17). And this includes no adverse effects on inflammatory markers (16,18,19):
The substantial body of clinical research discussed in this review indicates that dairy foods do not increase concentrations of biomarkers of chronic systemic inflammation.
If anything, some dairy fatty acids are associated with a reduction in diabetes (9,20-22).
A 2021 study in Australian women found a relation between increased saturated fat intake and a reduced risk of diabetes, though the food sources of saturated fat were not stated (23).
Lastly, the Framingham Offspring Cohort found that myristic acid — a saturated fatty acid — may be related to better survival. Since dairy is a source of myristic acid, and that "dairy intake is associated with lower risk for type 2 diabetes mellitus and possibly CVD," the authors speculated that dairy foods might be responsible for the beneficial relation (24).
Trials on Hard Endpoints?
Some epidemiological studies attempt to model the substitution of different dairy products. For example, a 2020 cohort found that low-fat milk in place of high-fat milk and low-fat yogurt in place of high-fat yogurt had no beneficial association with heart attacks (25). Also, replacing butter with cheese was not associated with a benefit.
But these "substitution" models are hypothetical: No one actually substitutes anything. And they rely on the same poor-quality data that plagues nutritional epidemiology (26).
Chen and colleagues (2021) correctly acknowledged the lack of high-quality epidemiological evidence for dairy, stating in their analysis (2):
It is important to stress that nearly all of the inverse relationships between dairy intake, either total intakes or intakes of dairy sub-types, and risk of HTN, CHD or stroke were of modest effect-size (i.e., <10% difference in risk). In the NutriGrade scoring system, the effect size criteria accounts for 20% of the quality of evidence assessment (2/10 points) and NutriGrade considers any difference in risk estimates <20% between highest and lowest category of intake (RR: 0.80-1.20) as non-meaningful. Therefore, it is unlikely that the body of evidence on the relationship between dairy consumption and cardiovascular health will ever be considered of high quality despite the publication of additional studies in the future.
Therefore, what we really require are high-quality randomized trials on hard endpoints, which unfortunately do not exist.
For existing trials, a cluster randomized trial (no individual randomization) published in September of 2021 found a reduced risk of falls and fractures from increased dairy intake (27). Importantly, total mortality was not adversely affected despite a probable increase in saturated fat intake (1.01, 0.43 to 3.08; P=0.91).
Older dietary trials also suggest the same lack of harm on mortality outcomes, but other changes were made in these trials besides dairy fat.
For instance, the intervention group of Ball (1965) involved not only restriction of butter, cheese, and whole milk, but also meat, eggs, biscuits, and cakes. As a result, serum cholesterol levels decreased and the participants lost weight. These "favorable" changes, however, did not translate into a cardiovascular or mortality benefit, leading the investigators to conclude (28):
A low-fat diet has no place in the treatment of myocardial infarction.
Conclusion
Recent dietary guidelines continue to recommend "low-fat or fat-free dairy products instead of full-fat dairy products" (29). But as demonstrated in this post, these recommendations cannot be justified, even by low scientific standards. If anything, there is growing evidence that full-fat dairy products are not only harmless but potentially beneficial.
References
1) Soedamah-Muthu, S. S., & Guo, J. (2020). Dairy consumption and cardiometabolic diseases: Evidence from prospective studies. In Milk and Dairy Foods (pp. 1-28). Academic Press.
2) Chen, Z., Ahmed, M., Ha, V., Jefferson, K., Malik, V., Ribeiro, P. A., ... & Drouin-Chartier, J. P. (2021). Dairy Product Consumption and Cardiovascular Health: a Systematic Review and Meta-Analysis of Prospective Cohort Studies. Advances in Nutrition.
3) Yuan, M., Pickering, R. T., Singer, M., & Moore, L. L. (2020). Differential Effects of Dietary Fats on Serum Lipids and Risks of Cardiovascular Disease and Diabetes in the Prospective Framingham Offspring Study. Current Developments in Nutrition, 4(Supplement_2), 1508-1508.
4) Van Horn, L., Ning, H., Steffen, L., Jacobs, D., Shikany, J., Miedema, M., ... & Liu, K. (2017, March). Dietary Factors Associated with Cardiovascular Outcomes: 25 Year Findings from the Coronary Artery Risk Development in Young Adults (CARDIA) Study. In Circulation (Vol. 135). TWO COMMERCE SQ, 2001 MARKET ST, PHILADELPHIA, PA 19103 USA: LIPPINCOTT WILLIAMS & WILKINS.
5) Sellem, L., Srour, B., Jackson, K. G., Hercberg, S., Galan, P., Kesse-Guyot, E., ... & Touvier, M. (2020). Consumption of dairy products and CVD risk: results from the French prospective cohort NutriNet-Santé. British Journal of Nutrition, 1-11.
6) Haugsgjerd, T. R., Egeland, G. M., Nygård, O. K., Igland, J., Sulo, G., Lysne, V., ... & Tell, G. S. (2020). Intake of carbohydrates and SFA and risk of CHD in middle-age adults: the Hordaland Health Study (HUSK). Public Health Nutrition, 1-15.
7) Acosta, S., Johansson, A., & Drake, I. (2021). Diet and lifestyle factors and risk of atherosclerotic cardiovascular disease—a prospective cohort study. Nutrients, 13(11), 3822.
8) Olsson, E., Höijer, J., Larsson, S. C., Kilander, L., & Byberg, L. (2021). Milk and Fermented Milk Consumption and Risk of Total Stroke: A Population Based Cohort of Swedish Women and Men. Current Developments in Nutrition, 5(Supplement_2), 1073-1073.
9) Trieu, K., Bhat, S., Dai, Z., Leander, K., Gigante, B., Qian, F., ... & Marklund, M. (2021). Biomarkers of dairy fat intake, incident cardiovascular disease, and all-cause mortality: A cohort study, systematic review, and meta-analysis. PLoS medicine, 18(9), e1003763.
10) Sonestedt, E., Borné, Y., Wirfält, E., & Ericson, U. Dairy consumption, lactase persistence, and mortality risk in a cohort from southern Sweden. Frontiers in Nutrition, 999.
11) Steur, M., Johnson, L., Sharp, S. J., Imamura, F., Sluijs, I., Key, T. J., ... & Forouhi, N. G. (2021). Dietary Fatty Acids, Macronutrient Substitutions, Food Sources and Incidence of Coronary Heart Disease: Findings From the EPIC‐CVD Case‐Cohort Study Across Nine European Countries. Journal of the American Heart Association, e019814.
12) Cruijsen, E., Jacobo Cejudo, M. G., Küpers, L. K., Busstra, M. C., & Geleijnse, J. M. (2021). Dairy consumption and mortality after myocardial infarction: a prospective analysis in the Alpha Omega Cohort. The American Journal of Clinical Nutrition.
13) Dehghan, M., Mente, A., Zhang, X., Swaminathan, S., Li, W., Mohan, V., ... & Amma, L. I. (2017). Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study. The Lancet, 390(10107), 2050-2062.
14) Wang, X. Y., Liu, F. C., Yang, X. L., Li, J. X., Cao, J., Lu, X. F., ... & Shen, C. (2020). Association of cardiovascular diseases with milk intake among general Chinese adults. Chinese Medical Journal, 133(10), 1144-1154.
15) Ghosh, S., He, W., Gao, J., Luo, D., Wang, J., Chen, J., & Huang, H. (2021). Whole milk consumption is associated with lower risk of coronary artery calcification progression: Evidences from the Multi-Ethnic Study of Atherosclerosis. European Journal of Nutrition, 60(2), 1049-1058.
16) Grosso, G. (2021). Are there any concerns about dairy food consumption and cardiovascular health?.
17) Hirahatake, K. M., Astrup, A., Hill, J. O., Slavin, J. L., Allison, D. B., & Maki, K. C. (2020). Potential cardiometabolic health benefits of full-fat dairy: the evidence base. Advances in Nutrition, 11(3), 533-547.
18) Nicholl, A., Deering, K. E., Evelegh, K., Lyons-Wall, P., Lawrence, D., Mori, T. A., ... & O'Sullivan, T. A. (2021). Whole-fat dairy products do not adversely affect adiposity or cardiometabolic risk factors in children in the Milky Way Study: a double-blind randomized controlled pilot study. The American Journal of Clinical Nutrition, 114(6), 2025-2042.
19) Hess, J. M., Stephensen, C. B., Kratz, M., & Bolling, B. W. (2021). Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies. Advances in Nutrition, 12(Supplement_1), 1S-13S.
20) Pimpin, L., Wu, J. H., Haskelberg, H., Del Gobbo, L., & Mozaffarian, D. (2016). Is butter back? A systematic review and meta-analysis of butter consumption and risk of cardiovascular disease, diabetes, and total mortality. PloS one, 11(6), e0158118.
21) Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential?. Scientific reports, 10(1), 1-14.
22) Slurink, I. A., den Braver, N. R., Rutters, F., Kupper, N., Smeets, T., Elders, P. J., ... & Soedamah-Muthu, S. S. (2021). Dairy product consumption and incident prediabetes in Dutch middle-aged adults: the Hoorn Studies prospective cohort. European Journal of Nutrition, 1-14.
23) Gribbin, S., Enticott, J., Hodge, A. M., Moran, L., Thong, E., Joham, A., & Zaman, S. (2021). Association of carbohydrate and saturated fat intake with cardiovascular disease and mortality in Australian women. Heart.
24) McBurney, M. I., Tintle, N. L., Vasan, R. S., Sala-Vila, A., & Harris, W. S. (2021). Using an erythrocyte fatty acid fingerprint to predict risk of all-cause mortality: the Framingham Offspring Cohort. The American Journal of Clinical Nutrition.
25) Kvist, K., Laursen, A. S. D., Overvad, K., & Jakobsen, M. U. (2020). Substitution of milk with whole-fat yogurt products or cheese is associated with a lower risk of myocardial infarction: the Danish Diet, Cancer and Health cohort. The Journal of nutrition, 150(5), 1252-1258.
26) Zeraatkar, D., Kohut, A., Bhasin, A., Morassut, R. E., Churchill, I., Gupta, A., ... & de Souza, R. J. (2021). Assessments of risk of bias in systematic reviews of observational nutritional epidemiologic studies are often not appropriate or comprehensive: a methodological study. BMJ Nutrition, Prevention & Health, e000248.
27) Iuliano, S., Poon, S., Robbins, J., Bui, M., Wang, X., De Groot, L., ... & Seeman, E. (2021). Effect of dietary sources of calcium and protein on hip fractures and falls in older adults in residential care: cluster randomised controlled trial. bmj, 375.
28) Ball, K. P. (1965). Low-fat diet in myocardial infarction. A controlled trial. Lancet, 2, 501-504.
29) Lichtenstein, A. H., Appel, L. J., Vadiveloo, M., Hu, F. B., Kris-Etherton, P. M., Rebholz, C. M., ... & American Heart Association Council on Lifestyle and Cardiometabolic Health; Council on Arteriosclerosis, Thrombosis and Vascular Biology; Council on Cardiovascular Radiology and Intervention; Council on Clinical Cardiology; and Stroke Council. (2021). 2021 Dietary Guidance to Improve Cardiovascular Health: A Scientific Statement From the American Heart Association. Circulation, CIR-0000000000001031.