Abstract
Background—Red meat consumption has been associated with an increased risk of chronic diseases. However, its relationship with mortality remains uncertain. Methods—We prospectively followed 37698 men from the Health Professionals Follow-up Study (1986-2008) and 83644 women from the Nurses’ Health Study (1980-2008), who were free of cardiovascular disease (CVD) and cancer at baseline. Diet was assessed by validated food-frequency questionnaires and updated every four years. Results—We documented 23926 deaths (including 5910 CVD and 9464 cancer deaths) during 2.96 million person-years of follow-up. After multivariate adjustment for major lifestyle and dietary risk factors, the pooled hazard ratio (HR) and 95% confidence interval of total mortality was 1.13 (1.07-1.20) for 1-serving per day increase of unprocessed red meat, 1.20 (1.15-1.24) for processed red meat. The corresponding HRs were 1.18 (1.13-1.23) and 1.21 (1.13-1.31) for CVD mortality, 1.10 (1.06-1.14) and 1.16 (1.09-1.23) for cancer mortality. We estimated that substitutions of 1-serving per day of other foods (including fish, poultry, nuts, legumes, low-fat dairy, and whole grains) for 1-serving per day of red meat were associated with a 7%-19% lower mortality risk. We also estimated that 9.3% of deaths in men and 7.6% in women in our cohorts could be prevented at the end of follow-up if all individuals consumed <0.5 serving/d (≈42 g/d) of red meat.
Generated Summary
This study, published in the Archives of Internal Medicine, presents findings from two large prospective cohort studies: the Health Professionals Follow-up Study (HPFS) and the Nurses’ Health Study (NHS). The primary aim was to investigate the relationship between red meat consumption and mortality, including total, cardiovascular disease (CVD), and cancer-specific mortality. The research assessed the dietary habits of 37,698 men (HPFS, 1986-2008) and 83,644 women (NHS, 1980-2008) who were initially free of CVD and cancer. Dietary information was gathered using validated food-frequency questionnaires that were updated every four years. The study employed Cox proportional hazards models to evaluate the associations, with adjustments made for a variety of lifestyle and dietary risk factors. Furthermore, the study examined the potential mortality benefits of substituting red meat with other protein sources. The research also estimated the preventable proportion of deaths if all participants consumed a lower amount of red meat. The study’s scope is broad, encompassing long-term follow-up periods and repeated dietary assessments to comprehensively analyze the impact of red meat consumption on mortality risks.
Key Findings & Statistics
- The study documented 23,926 deaths, including 5,910 CVD deaths and 9,464 cancer deaths, across 2.96 million person-years of follow-up.
- For each 1-serving/day increase in unprocessed red meat consumption, the pooled hazard ratio (HR) for total mortality was 1.13 (95% CI: 1.07-1.20).
- For processed red meat, the HR for total mortality was 1.20 (95% CI: 1.15-1.24).
- The corresponding HRs for CVD mortality were 1.18 (1.13-1.23) and 1.21 (1.13-1.31) for unprocessed and processed red meat, respectively.
- For cancer mortality, the HRs were 1.10 (1.06-1.14) and 1.16 (1.09-1.23) for unprocessed and processed red meat, respectively.
- Substituting 1 serving per day of other foods for red meat was associated with lower mortality: fish (7%-19% lower mortality risk), poultry (14%), nuts (19%), legumes (10%), low-fat dairy (10%), and whole grains (14%).
- The study estimated that 9.3% of deaths in men and 7.6% in women could be prevented if all individuals consumed less than 0.5 serving/d of red meat (approximately 42 g/d).
- During the follow-up period, the mean intake of unprocessed red meat decreased from 0.75 to 0.63 serving/d in men (1986-2006) and from 1.10 to 0.55 serving/d in women (1980-2006).
- In the pooled analysis, the elevated risk of total mortality was 12% (HR, 1.12; 95% CI, 1.09-1.15) for a 1-serving/d increase of total red meat.
- For unprocessed red meat, the HR was 13% (HR, 1.13; 95% CI, 1.07-1.20).
- For processed red meat, the HR was 20% (HR, 1.20; 95% CI, 1.15-1.24).
- The HRs (95% CIs) for CVD mortality: Total red meat: 1.16 (1.12-1.20)
- For unprocessed red meat: 1.18 (1.13-1.23)
- For processed red meat: 1.21 (1.13-1.31)
- The HRs (95% CIs) for cancer mortality: Total red meat: 1.10 (1.07-1.13)
- For unprocessed red meat: 1.10 (1.06-1.14)
- For processed red meat: 1.16 (1.09-1.23)
Other Important Findings
- The study found a linear relationship between red meat intake and the risk of total mortality.
- No significant interaction was detected between red meat intake and BMI or physical activity.
- Adjusting for other dietary variables such as fish, poultry, nuts, legumes, and dairy products did not substantially alter the results.
- The associations became even stronger in the sensitivity analysis that accounted for measurement error in diet.
- Replacing 1-serving/d of total red meat with 1-serving/d of fish, poultry, nuts, legumes, low-fat dairy products, or whole grains was associated with a lower risk of total mortality.
- The study found that bacon and hot dogs were associated with a higher risk of mortality than other processed meat items.
Limitations Noted in the Document
- The study acknowledges potential measurement errors inherent in dietary assessments, including misclassification of certain food items and inaccuracies in assessing red meat content in mixed dishes.
- The prospective nature of the study means that measurement errors of meat intake are independent of outcome ascertainment, which could lead to an attenuation of associations towards the null.
- The generalizability of the observed associations may be limited, as the participants were predominantly non-Hispanic white health professionals.
- Analyses using only baseline dietary data yielded weaker associations.
- The study did not assess whether lean meat has the same health risks as meat with higher fat content.
- The study relied on self-reported data, which are subject to recall bias.
Conclusion
The study’s findings suggest a clear association between red meat consumption and increased mortality risk. Both unprocessed and processed red meat intakes were linked to a higher risk of total, CVD, and cancer mortality. The study underscores the importance of distinguishing between different types of red meat, as processed varieties were associated with a slightly greater risk. The observed link between red meat and increased mortality may be attributed to factors such as saturated fat, cholesterol, heme iron, and sodium content in processed meats. The study results also highlight the benefits of dietary substitutions. Substituting red meat with other healthy protein sources such as fish, poultry, nuts, legumes, low-fat dairy products, or whole grains was linked to a lower risk of mortality. The authors suggest that a diet emphasizing these alternative components could lead to a significant reduction in mortality risk. The research reinforces the existing evidence that links red meat consumption with health risks and advocates for dietary choices that could mitigate these risks. The study findings support the recommendation to moderate red meat intake and incorporate a variety of other healthy components into the diet.