Association of Cardiovascular Diseases with Milk Intake Among General Chinese Adults

Association of Cardiovascular Diseases with Milk Intake Among General Chinese Adults

Cardiovascular diseases (CVDs) remain a leading cause of morbidity and mortality globally, with significant implications for public health. In China, the burden of CVDs is particularly pronounced due to rapid urbanization, aging populations, and lifestyle changes. Understanding modifiable risk factors, such as dietary habits, is crucial for developing effective prevention strategies. Milk, a widely consumed beverage rich in essential nutrients, has been a subject of debate regarding its association with CVDs. This study investigates the relationship between milk intake and CVD incidence, cause-specific mortality, and all-cause mortality among general Chinese adults, providing valuable insights for dietary recommendations and public health interventions.

Background and Rationale

CVDs account for a substantial proportion of disability-adjusted life years (DALYs) globally, with China contributing significantly to this burden. The incidence and mortality rates of CVDs are declining in developed countries but continue to rise in China and other developing nations. This trend underscores the importance of identifying modifiable risk factors and implementing evidence-based prevention strategies. Milk, a key source of protein, calcium, potassium, and other essential nutrients, is widely recommended in dietary guidelines worldwide. However, the association between milk consumption and CVDs remains controversial, with inconsistent findings across studies. While some studies suggest protective effects, others report null or even adverse associations. The evidence from Chinese populations is particularly limited and inconsistent, necessitating further investigation.

Study Design and Methods

This study is based on the China-PAR (Prediction for Atherosclerotic Cardiovascular Disease Risk in China) project, a large-scale collaborative study designed to investigate CVD epidemiology and risk factors in the general Chinese population. The study included 104,957 participants who underwent a questionnaire survey, physical examinations, and biochemical tests between 2007 and 2008. Data on demographic characteristics, lifestyle factors, and milk intake were collected using standardized questionnaires. Participants were categorized into four groups based on daily milk intake: none, 1–150 g/day, 151–299 g/day, and ≥300 g/day. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for CVD incidence, cause-specific mortality, and all-cause mortality. Restricted cubic splines (RCSs) were employed to examine dose-response relationships.

Study Population and Baseline Characteristics

The study population consisted of 91,757 participants after excluding those with a history of CVD, cancer, or other major chronic diseases, as well as those without milk intake information. The median follow-up period was 5.8 years, during which 3,877 CVD cases and 4,091 all-cause deaths were documented. The average daily milk intake among participants was 26.2 g/day, with 75.4% of participants reporting no milk consumption. Milk consumers were more likely to be male, urban residents, and from northern regions. They also had higher levels of education, healthier diets, and greater physical activity. Baseline characteristics, including blood pressure, fasting blood glucose, and lipid profiles, were comparable across milk intake categories, with slight variations.

Association Between Milk Intake and CVD Incidence

The study found a significant inverse relationship between milk intake and CVD incidence. Compared to participants who never consumed milk, those who consumed 1–150 g/day, 151–299 g/day, and ≥300 g/day had HRs of 0.94 (95% CI: 0.86–1.03), 0.77 (95% CI: 0.66–0.89), and 0.59 (95% CI: 0.40–0.89), respectively, after adjusting for demographic and lifestyle factors. Each 100 g/day increase in milk intake was associated with an 11% reduction in CVD risk (HR: 0.89; 95% CI: 0.85–0.94). Similar trends were observed for stroke incidence, with HRs of 1.02 (95% CI: 0.91–1.14), 0.78 (95% CI: 0.64–0.94), and 0.72 (95% CI: 0.44–1.17) for the respective milk intake categories. The dose-response analysis confirmed a linear relationship between milk intake and CVD incidence, as well as stroke incidence.

Association Between Milk Intake and Cause-Specific Mortality

Milk intake was also inversely associated with CVD mortality. Participants who consumed 1–150 g/day, 151–299 g/day, and ≥300 g/day had HRs of 1.00 (95% CI: 0.87–1.15), 0.81 (95% CI: 0.63–1.02), and 0.52 (95% CI: 0.26–1.04), respectively, compared to non-consumers. Each 100 g/day increase in milk intake was associated with an 11% reduction in CVD mortality risk (HR: 0.89; 95% CI: 0.82–0.97). The dose-response analysis indicated a significant linear relationship between milk intake and CVD mortality. However, no significant association was observed between milk intake and all-cause mortality.

Subgroup and Sensitivity Analyses

Subgroup analyses stratified by demographic characteristics, lifestyle factors, and cardiometabolic risk factors revealed consistent inverse associations between milk intake and CVD incidence, as well as cause-specific mortality. For example, the HRs associated with each 100 g/day increase in milk intake were 0.88 (95% CI: 0.81–0.95) for women and 0.90 (95% CI: 0.84–0.96) for men. Sensitivity analyses, excluding cases occurring within the first two years of follow-up, yielded similar results, confirming the robustness of the findings. Competing risk models also supported the observed associations.

Discussion and Implications

The findings of this study suggest that higher milk intake is associated with a lower risk of CVD incidence and mortality among general Chinese adults. The protective effects of milk may be attributed to its nutrient composition, including high-quality protein, calcium, and potassium, which help mitigate risk factors such as dyslipidemia, insulin resistance, and hypertension. The study also highlights the importance of considering dietary patterns and genetic backgrounds when interpreting the health effects of milk consumption. While the results are consistent with previous studies in East Asian populations, they contrast with findings from Western populations, where higher milk intake has been associated with increased CVD risk in some cases. This discrepancy may be due to differences in average intake levels, types of dairy products, and overall dietary patterns.

The study has several strengths, including its large sample size, prospective design, and comprehensive adjustment for potential confounders. However, limitations include the lack of information on fat content and fermentation types of milk, as well as the reliance on self-reported dietary data. Future studies should address these limitations and explore the long-term effects of milk intake on health outcomes.

Conclusion

This study provides strong evidence that daily milk intake is associated with a lower risk of CVD incidence and mortality in a linear inverse relationship among general Chinese adults. The findings support the inclusion of milk in dietary guidelines for CVD prevention in China and populations with similar dietary patterns. Further research is needed to validate these results and explore the mechanisms underlying the observed associations. Public health initiatives should promote moderate milk consumption as part of a balanced diet to reduce the burden of CVDs.

doi.org/10.1097/CM9.0000000000000786

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