Abstract
Background There is growing evidence that substituting animal-based with plant-based foods is associated with a lower risk of cardiovascular diseases (CVD), type 2 diabetes (T2D), and all-cause mortality. Our aim was to summarize and evaluate the evidence for the substitution of any animal-based foods with plant-based foods on cardiometabolic health and all-cause mortality in a systematic review and meta-analysis. Methods We systematically searched MEDLINE, Embase, and Web of Science to March 2023 for prospective studies investigating the substitution of animal-based with plant-based foods on CVD, T2D, and all-cause mortality. We calculated summary hazard ratios (SHRs) and 95% confidence intervals (95% CI) using random-effects meta-analyses. We assessed the certainty of evidence (CoE) using the GRADE approach. Results In total, 37 publications based on 24 cohorts were included. There was moderate CoE for a lower risk of CVD when substituting processed meat with nuts [SHR (95% CI): 0.73 (0.59, 0.91), n = 8 cohorts], legumes [0.77 (0.68, 0.87), n=8], and whole grains [0.64 (0.54, 0.75), n = 7], as well as eggs with nuts [0.83 (0.78, 0.89), n=8] and butter with olive oil [0.96 (0.95, 0.98), n = 3]. Furthermore, we found moderate CoE for an inverse association with T2D incidence when substituting red meat with whole grains/cereals [0.90 (0.84, 0.96), n = 6] and red meat or processed meat with nuts [0.92 (0.90, 0.94), n=6 or 0.78 (0.69, 0.88), n = 6], as well as for replacing poultry with whole grains [0.87 (0.83, 0.90), n = 2] and eggs with nuts or whole grains [0.82 (0.79, 0.86), n = 2 or 0.79 (0.76, 0.83), n = 2]. Moreover, replacing red meat for nuts [0.93 (0.91, 0.95), n = 9] and whole grains [0.96 (0.95, 0.98), n = 3], processed meat with nuts [0.79 (0.71, 0.88), n = 9] and legumes [0.91 (0.85, 0.98), n = 9], dairy with nuts [0.94 (0.91, 0.97), n = 3], and eggs with nuts [0.85 (0.82, 0.89), n = 8] and legumes [0.90 (0.89, 0.91), n = 7] was associated with a reduced risk of all-cause mortality. Conclusions Our findings indicate that a shift from animal-based (e.g., red and processed meat, eggs, dairy, poultry, butter) to plant-based (e.g., nuts, legumes, whole grains, olive oil) foods is beneficially associated with cardiometabolic health and all-cause mortality.
Generated Summary
This meta-analysis and systematic review investigated the association between substituting animal-based foods with plant-based foods and cardiometabolic health and all-cause mortality. The study systematically searched MEDLINE, Embase, and Web of Science to March 2023 for prospective studies. Summary hazard ratios (SHRs) and 95% confidence intervals (95% CI) were calculated using random-effects meta-analyses. The certainty of evidence (CoE) was assessed using the GRADE approach. The research aimed to summarize and evaluate the evidence for the substitution of any animal-based foods with plant-based foods on CVD, T2D, and all-cause mortality in a systematic review and meta-analysis.
Key Findings & Statistics
- A total of 37 publications based on 24 cohorts were included.
- There was moderate CoE for a lower risk of CVD when substituting processed meat with nuts [SHR (95% CI): 0.73 (0.59, 0.91), n = 8 cohorts], legumes [0.77 (0.68, 0.87), n=8], and whole grains [0.64 (0.54, 0.75), n = 7], as well as eggs with nuts [0.83 (0.78, 0.89), n=8] and butter with olive oil [0.96 (0.95, 0.98), n = 3].
- Moderate CoE was found for an inverse association with T2D incidence when substituting red meat with whole grains/cereals [0.90 (0.84, 0.96), n = 6] and red meat or processed meat with nuts [0.92 (0.90, 0.94), n=6 or 0.78 (0.69, 0.88), n = 6], as well as for replacing poultry with whole grains [0.87 (0.83, 0.90), n = 2] and eggs with nuts or whole grains [0.82 (0.79, 0.86), n = 2 or 0.79 (0.76, 0.83), n = 2].
- Replacing red meat for nuts [0.93 (0.91, 0.95), n = 9] and whole grains [0.96 (0.95, 0.98), n = 3], processed meat with nuts [0.79 (0.71, 0.88), n = 9] and legumes [0.91 (0.85, 0.98), n = 9], dairy with nuts [0.94 (0.91, 0.97), n = 3], and eggs with nuts [0.85 (0.82, 0.89), n = 8] and legumes [0.90 (0.89, 0.91), n = 7] was associated with a reduced risk of all-cause mortality.
- In meta-analyses on total CVD, the study observed an association with a lower incidence of total CVD for the substitution of processed meat (50 g/day) with nuts (28-50 g/day) [SHR (95% CI): 0.73 (0.59, 0.91)], legumes [0.77 (0.68, 0.87)], or whole grains (30 g/day) [0.64 (0.54, 0.75)]; one egg/day with nuts (25-28 g/day) [0.83 (0.78, 0.89)]; and butter (5 g/day) with olive oil (5 g/day) [0.96 (0.95, 0.98)] with moderate certainty of evidence.
- Replacing red meat (50 g/day) with nuts (10-50 g/day) or whole grains (11-15 g/day) [SHR (95% CI): 0.93 (0.91, 0.95), or 0.96 (0.95, 0.98)], processed meat (50 g/day) with nuts (28-50 g/day) or legumes (50 g/day) [0.79 (0.71, 0.88), or 0.91 (0.85, 0.98)], and unprocessed red meat (50 g/day) with nuts (10–16 g/day) [0.93 (0.92, 0.94)], was associated with a lower risk of all-cause mortality.
- The meta-analyses regarding total T2D (incidence and mortality combined) and T2D incidence revealed moderate certainty of evidence for a lower risk of total T2D associated with replacing butter (5 g/day) with olive oil (5 g/day) [SHR (95% CI): 0.94 (0.91, 0.98)].
- There was moderate certainty of evidence for a lower risk of total T2D associated with replacing butter (5 g/day) with olive oil (5 g/day) [SHR (95% CI): 0.94 (0.91, 0.98)], as well as processed meat (50 g/day) with nuts (10-28 g/day) [SHR (95% CI): 0.78 (0.69, 0.88)], and poultry (50 g/day) with whole grains (30 g/day) [SHR (95% CI): 0.87 (0.84, 0.91)].
- Replacing red meat (50 g/day) with nuts (10-28 g/day) was associated with a lower T2D incidence with moderate certainty of evidence.
Other Important Findings
- Replacing processed meat, yogurt, cheese, eggs, and butter with avocado was associated with a lower incidence of CVD.
- Replacing poultry, fish, and eggs with peanuts and peanut butter or with whole grain was associated with a lower T2D incidence.
- The estimates on change over time were pooled from three cohorts and showed an inverse association with T2D when substituting red meat, as well as unprocessed and processed red meat with nuts and legumes.
- Replacing processed meat, unprocessed red meat, dairy, and eggs with whole grains was associated with a lower risk of all-cause mortality.
- The estimates on change over time showed an inverse association with T2D for the replacement of red meat with whole grains or refined grains.
- Replacing butter with margarine was associated with an increased incidence of CVD and CHD.
- An inverse association with T2D incidence was found for the substitution of milk with coffee or tea, as well as of sweetened milk-beverages with drinking water.
Limitations Noted in the Document
- Only few studies were available for some of the meta-analyses.
- Several substitution analyses were only investigated in one study.
- The portions of the replacement still varied, leading to the comparison of different amounts of the replacement.
- Due to the observational design, unknown confounding cannot be ruled out.
- No study is available regarding meat and dairy replacement products.
- Dairy products were mostly treated as one group.
Conclusion
The findings suggest that shifting from a diet high in animal-based foods, especially red and processed meat, to plant-based foods (e.g., nuts, legumes, and whole grains) is associated with a lower risk of all-cause mortality, CVD, and T2D. This underscores the importance of dietary habits that prioritize plant-based products for cardiometabolic health. Replacing red and processed meat with nuts, legumes, and whole grains reduced the risk of total CVD, CHD, and T2D, and all-cause mortality, with moderate certainty of evidence. The replacement of eggs with nuts was associated with a lower incidence of total CVD and all-cause mortality. Replacing butter with olive oil lowered the incidence of total CVD, CVD mortality, total diabetes, and all-cause mortality with moderate certainty of evidence. To strengthen existing evidence and investigate new associations, more research is needed. Future studies should focus on meat and dairy replacement products. There is a need for further studies to improve our confidence in the findings and increase the certainty of evidence with well-conducted prospective observational studies.