In the JournalsPerspective

Higher dairy intake may lower CVD, mortality risks

More than two servings of dairy per day was associated with a lower risk for CVD and death, according to new data published in The Lancet.

Among 136,384 participants in the PURE study, those who consumed more than two servings of dairy per day, compared with non, had decreased risk for the composite of major CV events or death (HR = 0.84; 95% CI, 0.75-0.94), total mortality (HR = 0.83; 95% CI, 0.72-0.96), non-CV mortality (HR = 0.86; 95% CI, 0.72-1.02), CV mortality (HR = 0.77; 95% CI, 0.58-1.01), major CVD (HR = 0.78; 95% CI, 0.67-0.9) and stroke (HR = 0.66; 95% CI, 0.53-0.82).

However, data did not denote a significant relationship between dairy intake and risk for MI (HR = 0.89; 95% CI, 0.71-1.11).

In addition, associations between higher daily dairy intake and these outcomes were more pronounced among those who consumed only whole-fat dairy. When compared with less than 0.5 servings of dairy per day, those who consumed more than two servings per day had lower risk for the composite outcome (HR = 0.71; 95% CI, 0.6-0.83), total mortality (HR = 0.75; 95% CI, 0.6-0.92) and major CVD (HR = 0.68; 95% CI, 0.56-0.84).

Differences with dairy products

The researchers also analyzed consumption of specific dairy products — milk, yogurt and cheese — to determine whether consumption of more than one serving of milk daily, as compared with none, was associated with lower risk for the composite outcome (HR = 0.9; 95% CI, 0.82-0.99) and major CVD (HR = 0.82; 95% CI, 0.72-0.93). Similarly, more than one serving of yogurt daily was associated with lower risk for the composite outcome (HR = 0.86; 95%, CI, 0.75-0.99), total mortality (HR = 0.83; 95% CI, 0.69-0.99) and major CVD (HR = 0.9; 95% CI, 0.75-1.07). Although the risks for the composite outcome, total mortality and major CVD were also lower with higher daily cheese intake, the associations were not significant, according to the researchers.

Conversely, higher butter consumption, as compared with none, was associated with a greater risk for the composite outcome (HR = 1.09; 95% CI, 0.9-1.33) and major CVD (HR = 1.19; 95% CI, 0.92-1.53), but the relationships were not significant.

No differences emerged after adjustment for alcohol intake and number of cigarettes per day.

Regional variation

The PURE study included data on 136,384 people aged 35 to 70 years from 21 countries in five continents. The researchers used validated country-specific food-frequency questionnaires to assess dietary intake of dairy products. One standard serving of dairy was equivalent to a glass of milk (244 g), a cup of yogurt (244 g), one slice of cheese (15 g) or a teaspoon of butter (5 g).

Across regions, at more than four servings daily, total dairy intake was highest in North America and Europe and, at less than one serving daily, was lowest in south Asia, China, Africa and southeast Asia.

Results demonstrating an association between total dairy intake and adverse outcomes were consistent across regions, although higher dairy intake was linked to a lower risk for the composite outcome with a larger protective effect in regions with higher dairy intake (P for trend = .01).

'Another piece of evidence

The researchers acknowledged inherent limitations of the study, including self reporting of diets and measurement only at baseline. However, they noted that dairy consumption may have benefits, in contrast to dietary guidelines that recommend decreased consumption of whole-fat dairy.

“Our findings support that consumption of dairy products might be beneficial for mortality and CVD, especially in low-income and middle-income countries where dairy consumption is much lower than in North America or Europe,” Mahshid Dehghan, PhD, investigator for the Nutrition Epidemiology program at the Population Health Research Institute, McMaster University, Canada, said in a press release.

Dehghan and colleagues also noted that more research into why dairy might be associated with lower levels of CVDs is needed.

Commenting on the findings of the new study, Jimmy Chun Yu Louie, BSc, MNutrDiet, PhD, APD, AN, from the School of Biological Sciences, Faculty of Science, University of Hong Kong, and Anna M. Rangan, PhD, from the School of Life and Environmental Sciences and Charles Perkins Center, Faculty of Science, University of Sydney, urged caution when interpreting the results.

“The results from the PURE study seem to suggest that dairy intake, especially whole­fat dairy, might be beneficial for preventing deaths and major cardiovascular diseases. However, as the authors themselves concluded, the results only suggest the ‘consumption of dairy products should not be discouraged and perhaps even be encouraged in low­income and middle-­income countries,’” they wrote. “It is not the ultimate seal of approval for recommending whole­-fat dairy over its low­-fat or skimmed counterparts. Readers should be cautious, and treat this study only as yet another piece of the evidence (albeit a large one) in the literature.” – by Melissa Foster

Disclosures: The authors report no relevant financial disclosures. Louie reports he receives funding for projects by Dairy Australia and was sponsored to present the findings of the projects at an Australian national conference. Rangan reports she receives funding for projects by Dairy Australia and funding from Meat and Livestock Australia for non-dairy-related projects.

More than two servings of dairy per day was associated with a lower risk for CVD and death, according to new data published in The Lancet.

Among 136,384 participants in the PURE study, those who consumed more than two servings of dairy per day, compared with non, had decreased risk for the composite of major CV events or death (HR = 0.84; 95% CI, 0.75-0.94), total mortality (HR = 0.83; 95% CI, 0.72-0.96), non-CV mortality (HR = 0.86; 95% CI, 0.72-1.02), CV mortality (HR = 0.77; 95% CI, 0.58-1.01), major CVD (HR = 0.78; 95% CI, 0.67-0.9) and stroke (HR = 0.66; 95% CI, 0.53-0.82).

However, data did not denote a significant relationship between dairy intake and risk for MI (HR = 0.89; 95% CI, 0.71-1.11).

In addition, associations between higher daily dairy intake and these outcomes were more pronounced among those who consumed only whole-fat dairy. When compared with less than 0.5 servings of dairy per day, those who consumed more than two servings per day had lower risk for the composite outcome (HR = 0.71; 95% CI, 0.6-0.83), total mortality (HR = 0.75; 95% CI, 0.6-0.92) and major CVD (HR = 0.68; 95% CI, 0.56-0.84).

Differences with dairy products

The researchers also analyzed consumption of specific dairy products — milk, yogurt and cheese — to determine whether consumption of more than one serving of milk daily, as compared with none, was associated with lower risk for the composite outcome (HR = 0.9; 95% CI, 0.82-0.99) and major CVD (HR = 0.82; 95% CI, 0.72-0.93). Similarly, more than one serving of yogurt daily was associated with lower risk for the composite outcome (HR = 0.86; 95%, CI, 0.75-0.99), total mortality (HR = 0.83; 95% CI, 0.69-0.99) and major CVD (HR = 0.9; 95% CI, 0.75-1.07). Although the risks for the composite outcome, total mortality and major CVD were also lower with higher daily cheese intake, the associations were not significant, according to the researchers.

Conversely, higher butter consumption, as compared with none, was associated with a greater risk for the composite outcome (HR = 1.09; 95% CI, 0.9-1.33) and major CVD (HR = 1.19; 95% CI, 0.92-1.53), but the relationships were not significant.

No differences emerged after adjustment for alcohol intake and number of cigarettes per day.

Regional variation

The PURE study included data on 136,384 people aged 35 to 70 years from 21 countries in five continents. The researchers used validated country-specific food-frequency questionnaires to assess dietary intake of dairy products. One standard serving of dairy was equivalent to a glass of milk (244 g), a cup of yogurt (244 g), one slice of cheese (15 g) or a teaspoon of butter (5 g).

Across regions, at more than four servings daily, total dairy intake was highest in North America and Europe and, at less than one serving daily, was lowest in south Asia, China, Africa and southeast Asia.

Results demonstrating an association between total dairy intake and adverse outcomes were consistent across regions, although higher dairy intake was linked to a lower risk for the composite outcome with a larger protective effect in regions with higher dairy intake (P for trend = .01).

'Another piece of evidence

The researchers acknowledged inherent limitations of the study, including self reporting of diets and measurement only at baseline. However, they noted that dairy consumption may have benefits, in contrast to dietary guidelines that recommend decreased consumption of whole-fat dairy.

“Our findings support that consumption of dairy products might be beneficial for mortality and CVD, especially in low-income and middle-income countries where dairy consumption is much lower than in North America or Europe,” Mahshid Dehghan, PhD, investigator for the Nutrition Epidemiology program at the Population Health Research Institute, McMaster University, Canada, said in a press release.

Dehghan and colleagues also noted that more research into why dairy might be associated with lower levels of CVDs is needed.

Commenting on the findings of the new study, Jimmy Chun Yu Louie, BSc, MNutrDiet, PhD, APD, AN, from the School of Biological Sciences, Faculty of Science, University of Hong Kong, and Anna M. Rangan, PhD, from the School of Life and Environmental Sciences and Charles Perkins Center, Faculty of Science, University of Sydney, urged caution when interpreting the results.

“The results from the PURE study seem to suggest that dairy intake, especially whole­fat dairy, might be beneficial for preventing deaths and major cardiovascular diseases. However, as the authors themselves concluded, the results only suggest the ‘consumption of dairy products should not be discouraged and perhaps even be encouraged in low­income and middle-­income countries,’” they wrote. “It is not the ultimate seal of approval for recommending whole­-fat dairy over its low­-fat or skimmed counterparts. Readers should be cautious, and treat this study only as yet another piece of the evidence (albeit a large one) in the literature.” – by Melissa Foster

Disclosures: The authors report no relevant financial disclosures. Louie reports he receives funding for projects by Dairy Australia and was sponsored to present the findings of the projects at an Australian national conference. Rangan reports she receives funding for projects by Dairy Australia and funding from Meat and Livestock Australia for non-dairy-related projects.

    Perspective
    Monica Aggarwal

    Monica Aggarwal

    The PURE data continues to provide insight on the impact of diet quality on a large cohort of patients without CVD worldwide from varying socioeconomic backgrounds. The observational survey data on food intake showed that higher dairy intake was associated with lower CVD, driven primarily by stroke. Multiple confounders including BMI were removed to isolate the impact of dairy alone with CVD.

    The benefits of dairy are potentially related to fermentation and role of the microbiome. Prospective data, however, is needed before we can make direct associations about the impact of dairy on cardiovascular disease/mortality. Dairy is a saturated fat and there is an abundance of data showing that saturated fat is associated with worse CV outcomes. While dairy has more medium-chain fatty acids, making its composition different, we still cannot make clear recommendations for people to drink and eat more dairy based on this observational data. Regardless of how you interpret this data, there is still enough of a database of potential harm in the medical literature that caution is needed when it comes to consuming dairy. We can only continue to note that while saturated fat intake is associated with increased CV mortality, refined carbohydrates are associated with worse mortality, and it is not that saturated fats are good and carbohydrates are bad but rather that saturated fats are bad for us and refined carbohydrates are worse. We have to focus on what we do know.

    I don’t think we can make any definite recommendations on the role of dairy in our diets, and we should still be cautious regarding intake based the medical literature in total and with the knowledge that dairy is comprised of a significant amount of saturated fat.

    The data are interesting, but prospective trials looking at associations with individual food lines are needed. In terms of counseling, we should focus on eliminating refined carbohydrates first and saturated fats second: Whether that is only meat or meat and dairy is unclear.

    • Monica Aggarwal, MD, FACC
    • Cardiology Today Next Gen Innovator
      Assistant Professor of Medicine
      Division of Cardiovascular Medicine
      University of Florida

    Disclosures: Aggarwal reports no relevant financial disclosures.