Dairy intake and risk of major cardiovascular events: a prospective cohort study of 0.5 million Chinese adults
Authors: Du H , Kakkoura M , Tim K , Chen Z ,   the China Kadoorie Biobank study
Published: October 2021

Abstract

Background
Evidence on the association between dairy consumption and risk of cardiovascular disease has been highly inconsistent, with findings suggesting either harmful, neutral or beneficial effects. In addition, a very large majority of the previous studies on this topic were conducted among populations in Europe and North America who usually consume a higher amount of dairy products and very few data, particularly prospective data, come from China where the dairy consumption level is low.

Purpose
We therefore investigated the associations between intake of dairy products and incidence of several major types of cardiovascular diseases in Chinese adults.

Methods
During 2004–2008, the prospective China Kadoorie Biobank Study recruited slightly over 0.5 million adults from ten diverse regions (five urban and five rural) across China. Information on the consumption frequency of dairy products was collected at baseline and periodic resurveys, using a validated interviewer-administered laptop-based questionnaire. Over a mean follow-up of 10.9 years, there were 47,128 incident ischaemic heart disease events, 43,481 ischaemic strokes and 9749 intracerebral haemorrhages among 489,595 study participants, who did not report a prior history of cardiovascular disease at baseline. Cox regression analyses were performed to estimate multivariable-adjusted hazard ratios (HRs) for incident events associated with dairy intake.

Results
Overall, 69.3% of participants reported never or rare consumption (i.e. non-consumers) and 11.3% of them reported regular consumption (i.e. ≥4 days/week) of dairy products, with milk accounting for the largest proportion of total dairy intake (∼77%). Male and female regular dairy consumers had 2.1/1.5 and 1.7/1.1 mmHg lower systolic/diastolic blood pressure, respectively compared to non-consumers. In a subset (∼18,000) of participants with blood lipid levels measured, regular dairy consumers had ∼0.1 mmol/L higher LDL levels than non-consumers. After adjusting for a range of potential confounders, including sociodemographic and lifestyle factors, BMI and other dietary factors, dairy consumption was positively and significantly associated with risk of ischaemic heart disease, with the adjusted HR per 50 g/day increase in usual dairy consumption being 1.11 (95% confidence interval [CI] 1.09–1.14). Dairy consumption was not significantly associated with risk of ischemic stroke but was inversely associated with risk of intracerebral haemorrhage, with each 50 g/day increase in usual dairy consumption being associated with 17% lower risk (HR 0.83, 0.78–0.88). These associations remained significant after additional adjustment for systolic blood pressure.

Conclusion
In this large study of Chinese adults, higher intake of dairy products was associated with a higher risk of ischaemic heart disease but a lower risk of intracerebral haemorrhage. The exact mechanisms underlying such associations require further investigation.

Funding Acknowledgement
Type of funding sources: Public Institution(s). Main funding source(s): The CKB baseline survey and the first re-survey were supported by the Kadoorie Charitable Foundation in Hong Kong. The long-term follow-up has been supported by Wellcome grants to Oxford University (212946/Z/18/Z, 202922/Z/16/Z, 104085/Z/14/Z, 088158/Z/09/Z) and grants from the National Key Research and Development Program of China (2016YFC0900500, 2016YFC0900501, 2016YFC0900504, 2016YFC1303904) and from the National Natural Science Foundation of China (91843302). The UK Medical Research Council (MC_UU_00017/1,MC_UU_12026/2 MC_U137686851), Cancer Research UK (C16077/A29186; C500/A16896) and the British Heart Foundation (CH/1996001/9454), provide core funding to the Clinical Trial Service Unit and Epidemiological Studies Unit at Oxford University for the project.