Abstract
Introduction: Animal protein sources, especially red and processed meat, have been associated with adverse health outcomes. Epidemiological evidence on the isocaloric substitution of plant for animal protein on mortality risk remains limited. Hypothesis: We hypothesized that substituting plant protein for carbohydrates and animal protein would be associated with lower mortality. Method: We included a nationally representative sample of 37 233 US adults ≥20 years with 24-h dietary recall data from eight National Health and Nutrition Examination Survey (NHANES) cycles (1999-2014). Mortality from all causes, heart disease, and cancer were identified through National Death Index linkage (until December 31, 2015). We used Cox proportional hazards regression to estimate the association between plant and animal protein intake and mortality after adjustment for potential confounding factors. Results: During 297 768 person-years of follow-up, 4 866 total deaths occurred, including 849 deaths from heart disease and 1 068 deaths from cancer. After multivariable adjustment, higher intake of total animal protein was not associated with total mortality. Plant protein was associated with lower total mortality; when comparing the lowest with highest quintiles of plant protein intake, the multivariable adjusted HR (95% Cls) of total mortality was 0.73 (0.61, 0.88); P for trend <0.001. The HRs (95% Cls) comparing extreme quintiles were 0.71 (0.48, 1.05) for heart disease mortality, and 0.74 (0.53, 1.04) for cancer mortality. When isocalorically replacing 5% of energy from total animal protein with plant protein, the multivariable HRs were 0.49 (0.32, 0.74) for total mortality, 0.51 (0.28, 0.95) for heart disease mortality, and 0.53 (0.28, 1.00) for cancer mortality. For different food sources of animal protein, isocaloric substitution of 2% of energy from plant protein for protein in unprocessed red meat (0.74, 95% CI: 0.63, 0.87), processed meat (0.68, 95% CI: 0.53, 0.89), total dairy (0.74, 95% CI: 0.58, 0.94), and 1% of energy from plant protein for seafood (0.86, 95% CI: 0.79, 0.93) was each associated with a lower risk of total mortality. Conclusions: Higher plant protein intake was associated with lower total mortality. Isocalorically replacing animal protein with plant protein was associated with lower total mortality.
Generated Summary
This study investigated the association between animal and plant protein intake and mortality among US adults, utilizing a prospective cohort study design. The research examined data from the National Health and Nutrition Examination Survey (NHANES) cycles conducted between 1999 and 2014. The study’s primary objective was to determine the impact of substituting plant protein for animal protein on mortality risk. The methodology involved analyzing a nationally representative sample of 37,233 adults aged 20 years or older, with 24-hour dietary recall data. Cox proportional hazards regression was employed to estimate the association between plant and animal protein intake and mortality, controlling for potential confounding factors. The research aimed to explore how different dietary protein sources influence overall mortality, heart disease mortality, and cancer mortality. The study’s design allowed for an examination of the isocaloric substitution of plant protein for animal protein and its effect on mortality rates. This approach provided insights into the potential health benefits of dietary modifications.
Key Findings & Statistics
- The study included a sample of 37,233 US adults aged 20 years or older.
- The study used data from eight National Health and Nutrition Examination Survey (NHANES) cycles (1999-2014).
- During 297,768 person-years of follow-up, 4,866 total deaths occurred.
- Out of the total deaths, 849 were due to heart disease and 1,068 were due to cancer.
- Higher intake of total animal protein was not associated with total mortality after multivariable adjustment.
- Plant protein intake was associated with lower total mortality; the multivariable adjusted HR (95% Cls) of total mortality was 0.73 (0.61, 0.88); P for trend <0.001 when comparing the lowest with highest quintiles of plant protein intake.
- The HRs (95% Cls) comparing extreme quintiles were 0.71 (0.48, 1.05) for heart disease mortality, and 0.74 (0.53, 1.04) for cancer mortality.
- When isocalorically replacing 5% of energy from total animal protein with plant protein, the multivariable HRs were 0.49 (0.32, 0.74) for total mortality, 0.51 (0.28, 0.95) for heart disease mortality, and 0.53 (0.28, 1.00) for cancer mortality.
- For unprocessed red meat, the HR (95% CI) was 0.74 (0.63, 0.87).
- For processed meat, the HR (95% CI) was 0.68 (0.53, 0.89).
- For total dairy, the HR (95% CI) was 0.74 (0.58, 0.94).
- Isocaloric substitution of 1% of energy from plant protein for seafood was associated with a lower risk of total mortality, HR (95% CI): 0.86 (0.79, 0.93).
Other Important Findings
- The study found that plant protein intake was associated with lower total mortality.
- Isocalorically replacing animal protein with plant protein was associated with lower total mortality.
- Higher intake of animal protein was not associated with total mortality after multivariable adjustment.
Limitations Noted in the Document
- The study relies on dietary recall data, which is subject to recall bias and may not accurately reflect long-term dietary habits.
- The observational nature of the study design limits the ability to establish causality between plant protein intake and reduced mortality risk.
- Potential confounding factors were adjusted for, but residual confounding may still exist.
- Generalizability may be limited to the US adult population included in the NHANES cycles.
- The study does not account for potential variations in the quality of plant protein sources.
Conclusion
In conclusion, this study provides significant insights into the relationship between dietary protein sources and mortality risk in a large cohort of US adults. The findings underscore the importance of plant protein in promoting longevity. The data strongly suggest that increasing plant protein intake is associated with lower total mortality. Notably, the substitution of plant protein for animal protein, particularly from sources like red and processed meats, showed a marked impact on mortality rates. The multivariable HRs for total mortality, heart disease, and cancer mortality all favored the plant protein substitution. This highlights the potential health benefits of shifting dietary patterns towards more plant-based sources. The study supports the growing body of evidence linking diet to health outcomes, specifically emphasizing the role of protein sources. This is a key message for those focused on reducing mortality. The study’s findings reinforce the importance of public health initiatives that promote plant-based diets. This has significant implications for dietary guidelines and public health strategies aimed at improving population health and longevity.