Abstract
Background: Protein-rich foods are major parts of the human diet and are highly heterogeneous in nutrient composition and health effects. Designing healthy diets for disease prevention requires careful consideration of substituting unhealthier protein foods with healthier protein foods. Methods: This was a pooled analysis of six prospective cohort studies of 29 682 US participants. Data were collected in 1985–2016. Adjusted hazard ratios (HRs) and 30-year absolute risk differences (ARDS) were calculated for the associations between simultaneous substitution of one or more animal protein foods with other animal or plant protein foods at various amounts, and incident cardiovascular disease (CVD) and all-cause mortality. Results: Substituting eggs, processed meat, unprocessed red meat or poultry with nuts, whole grains, legumes or fish was associated with lower risks of incident CVD and all-cause mortality. According to different substitution amounts (varying from one serving per week to one serving per day) and different numbers of protein foods being simultaneously substituted (varying from one to four), estimates ranged between 1%: HR, 0.99 [95% confidence interval (CI), 0.98–1.00], and 54%: HR, 0.46 (0.35–0.60), lower risks on the relative scale and between 0.3%: ARD, -0.29% (-0.48% to -0.05%), and 14.0%: ARD, -13.96% (-17.29% to -9.96%) lower risks on the absolute scale. Conclusions: Nuts, whole grains, legumes and fish appeared to be healthier protein sources than eggs, processed meat, unprocessed red meat and poultry for preventing incident CVD and premature death. The magnitude of lower risk for incident CVD and all-cause mortality was driven by amount and number of animal protein foods substituted.
Generated Summary
This study, published in the *International Journal of Epidemiology*, employed a pooled analysis of six prospective cohort studies involving 29,682 US participants. The primary objective was to determine relative and absolute risks, up to three decades of follow-up, for incident cardiovascular disease (CVD) and all-cause mortality associated with simultaneous substitution of one or more animal protein foods with other animal or plant protein foods at various amounts. Data were collected between 1985 and 2016. Adjusted hazard ratios (HRs) and 30-year absolute risk differences (ARDs) were calculated to analyze the associations between substituting animal protein foods with other animal or plant protein foods and incident CVD and all-cause mortality. The study sought to understand how different substitution amounts and combinations of protein foods influenced these health outcomes, providing insights into the relationship between dietary choices and disease prevention.
Key Findings & Statistics
- The study included 29,682 participants with a mean age of 53.7 years at baseline; 55.6% were women, and 30.7% were non-White.
- During the follow-up period, there were 6,963 incident CVD cases and 8,875 deaths.
- Substituting eggs with fish, nuts, legumes, or whole grains was associated with a 2-3% lower relative risk and 0.4-0.7% lower absolute risk for incident CVD when the substitution amount was one serving per week.
- Substituting eggs with unprocessed red meat, poultry, fish, nuts, or whole grains was associated with a 2-3% lower relative risk and 0.5-1.0% lower absolute risks for all-cause mortality when the substitution amount was one serving per week.
- Substituting processed meat with fish, nuts, legumes, or whole grains was associated with 4-5% lower relative risks and 0.9-1.2% lower absolute risks for incident CVD when the substitution amount was one serving per week.
- Substituting processed meat with poultry, fish, nuts, or whole grains was associated with 2% lower relative risks and 0.5-0.7% lower absolute risks for all-cause mortality when the substitution amount was one serving per week.
- Substituting unprocessed red meat with nuts or whole grains was associated with a 1-2% lower relative risks and 0.3-0.4% lower absolute risks for incident CVD when the substitution amount was one serving per week.
- Substituting unprocessed red meat with fish or nuts was associated with 1-2% lower relative risks and 0.4-0.5% lower absolute risks for all-cause mortality when the substitution amount was one serving per week.
- Substituting poultry with nuts or whole grains was associated with a 1-2% lower relative risks and 0.5-0.6% lower absolute risks for incident CVD when the substitution amount was one serving per week.
- Substituting eggs, processed meat, and unprocessed red meat with nuts, legumes, and whole grains: 5-8% lower relative risks and 1.4-2.0% lower absolute risks for incident CVD and all-cause mortality when the substitution amount was one serving per week.
- Substituting eggs, processed meat, unprocessed red meat, and poultry with fish, nuts, legumes, and whole grains: 28-50% lower relative risks and 8.9-13.3% lower absolute risks when the substitution amount was one serving per day.
Other Important Findings
- Substituting eggs with fish, nuts, legumes or whole grains was associated with 15-21% lower relative risks and 3.0-4.8% lower absolute risks for incident CVD when the substitution amount was one serving per day.
- Substituting eggs with unprocessed red meat, poultry, fish, nuts or whole grains was associated with 11-22% lower relative risks and 3.5-6.8% lower absolute risks for all-cause mortality when the substitution amount was one serving per day.
- Substituting processed meat with fish, nuts, legumes or whole grains was associated with 28-34% lower relative risks and 7.5-9.0% lower absolute risks for incident CVD when the substitution amount was one serving per day.
- Substituting processed meat with poultry, fish, nuts or whole grains was associated with 10-15% lower relative risks and 3.1-4.6% lower absolute risks when the substitution amount was one serving per day.
- Substituting unprocessed red meat with nuts or whole grains was associated with 9-13% lower relative risks and 2.0-2.8% lower absolute risks when the substitution amount was one serving per day.
- Substituting unprocessed red meat with fish or nuts was associated with 10-11% lower relative risks and 2.9-3.5% lower absolute risks when the substitution amount was one serving per day.
- Substituting poultry with nuts or whole grains was associated with 10-14% lower relative risks and 3.1-3.8% lower absolute risks for incident CVD when the substitution amount was one serving per day.
- Substituting eggs, processed meat, and unprocessed red meat with nuts, legumes and whole grains: 28-50% lower relative risks and 8.9-13.3% lower absolute risks when the substitution amount was one serving per day.
Limitations Noted in the Document
- The study acknowledges potential for misclassification bias due to self-reported dietary intake and the use of baseline data.
- Confounding may be amplified in substitution analysis due to potential differences in the relationship between a single dietary factor and an outcome versus multiple factors.
- Causal relationships cannot be directly inferred due to the observational nature of the study.
- The study did not consider food preparation methods, which could affect health outcomes.
- Generalizing the results to other countries requires caution due to variations in background diets, nutrition, and health statuses.
Conclusion
The study’s findings suggest that the choice of dietary protein sources is crucial in preventing incident CVD and premature death. The research indicates that nuts, whole grains, legumes, and fish are healthier protein sources compared to eggs, processed meat, unprocessed red meat, and poultry. The study emphasizes that the magnitude of risk reduction is dependent on both the amount and number of animal protein foods being substituted. The study states, “According to different substitution amounts (varying from one serving per week to one serving per day) and different numbers of protein foods being simultaneously substituted (varying from one to four), estimates ranged between 1%: HR, 0.99 [95% confidence interval (CI), 0.98–1.00], and 54%: HR, 0.46 (0.35-0.60), lower risks on the relative scale and between 0.3%: ARD, -0.29% (-0.48% to -0.05%), and 14.0%: ARD, -13.96% (-17.29% to -9.96%) lower risks on the absolute scale.” The research highlights that substituting two or more protein foods, even in small amounts, can lead to appreciable benefits in reducing the risks of CVD and premature death. It also notes that the effect sizes from making informed protein source choices are comparable to those associated with other lifestyle factors like alcohol intake, exercise, and smoking. The researchers state that the “magnitude of lower risk for incident CVD and all-cause mortality was driven by amount and number of animal protein foods substituted.”