Biomarkers of milk fat and the risk of myocardial infarction in men and women: a prospective, matched case-control study by Warensjo et al. (2010) provide great insights into biomarkers of milk fat and its correlation of the risk of MI.
The Research Approach
The objective of this prospective case-control study was to investigate the association between serum milk fat biomarkers (pentadecanoic acid 15:0, heptadecanoic acid 17:0, and their sum 15:0+17:0) and the risk of a first myocardial infarction (MI). The authors used a nested case-control design within a large Swedish population-based cohort study. Clinical data, anthropometric measurements, and blood samples were collected at baseline from participants who later became cases (had a first MI) or controls (matched to cases). The milk fat biomarker levels were measured, and dietary intake data was obtained from a food frequency questionnaire.
Methods and Results
The methods used to measure the milk fat biomarkers and other clinical parameters appear valid and well-described. However, some concerns arise regarding the dietary data, as it was not available for all participants, and food frequency questionnaires are prone to measurement errors.
The key finding was an inverse association between higher proportions of milk fat biomarkers and risk of MI, especially in women. Each standard deviation increase in the biomarker sum was associated with a 26% lower MI risk in women after adjusting for confounders. This contradicts the traditional view linking saturated fat intake to increased cardiovascular risk.
Interpretations and Implications
The authors interpret their findings as contradicting the diet-heart hypothesis and suggest that components in dairy products, apart from saturated fats, may have beneficial effects. They propose that the bioactive compounds in dairy could promote favorable metabolic changes, counteracting the negative impacts of saturated fats.
While this interpretation is plausible, it is important to consider some limitations. The authors acknowledge that the observational nature of the study cannot establish causality, and residual confounding from unmeasured or imprecisely measured factors cannot be ruled out. Additionally, the lack of a consistent dose-response relationship between biomarker levels and MI risk weakens the evidence for a causal link.
Research Significance
This study adds to the conflicting evidence regarding dairy product consumption and cardiovascular disease risk. It suggests that the role of dairy fats may be more complex than previously thought and that the food matrix, rather than individual nutrients, could be more relevant for health outcomes.
However, given the contradictory findings with previous studies and the inherent limitations of the case-control design, these results should be interpreted with caution. Further research, particularly well-designed prospective cohort studies and intervention trials, is needed to clarify the relationship between dairy fat intake and cardiovascular disease risk, as well as the potential mechanisms involved.
In summary, while this study presents an intriguing perspective on the role of milk fat biomarkers and dairy products in myocardial infarction risk, its observational nature and conflicting evidence from other studies warrant a cautious interpretation of the findings. The authors’ proposed explanations are plausible but require further investigation to establish the true significance and implications of this research.
