A new meta-analysis found that, in many cases, switching from an animal product to a plant-based alternative is associated with lower risk of cardiovascular, diabetes and all-cause mortality (1).
Replace with a plant?
The question of whether an entirely or predominantly plant-based diet is good for your health has been the subject of heated debate. On the one hand, studies have consistently placed plant-based diets among the healthiest food options available (2). On the other hand, completely excluding animal foods may not be ideal, especially for younger and older people (3). Becoming vegan can make it more difficult to maintain a balanced diet because certain nutrients are rare or even nonexistent in plants.
Apparently, more nuanced analysis is needed on what happens when people replace specific animal products with plant-based alternatives. This is the subject of a new review published in BMC. After sifting through hundreds of articles, the authors included 37 in their analysis. They then studied the associations between switching from animal products to plant-based alternatives and cardiovascular health, the onset of type 2 diabetes, and all-cause mortality.
All studies presented in this review were prospective cohort studies and no randomized controlled trials were included. This is understandable, because detecting the occurrence of cardiovascular disease or diabetes, or even death, requires a long follow-up period: in this review, the average follow-up duration was 19 years.
Switching to plants reduces risks
The researchers calculated shared risk ratios (SHR): the difference in prevalence of an outcome between two groups. For example, replacing 28-50 grams of nuts with 50 grams of processed meat per day resulted in an SHR of 0.73, that is, it reduced the risks of contracting any type of cardiovascular disease ( MCV) by 27%. Substitution with 50 grams of legumes gave an SHR of 0.77. Whole grains performed best, with an SHR of 0.64: a total decrease of 36% in the incidence of cardiovascular disease. This is consistent with previous research that has called processed meat very unhealthy. The World Health Organization considers processed meat carcinogenic, but its harmful effects are likely much broader.
Replacing one egg per day with nuts resulted in a 17% reduction in the incidence of cardiovascular disease. Interestingly, replacing butter with olive oil only resulted in a slight decrease in risk of 4%. Researchers also found that replacing red meat with nuts, unprocessed red meat with nuts or legumes, poultry with nuts, and eggs with legumes was associated with a lower risk of disease. cardiovascular, but for these associations the certainty of the evidence was low.
Butter, however, did not fare well in the analysis of type 2 diabetes incidence. Researchers calculated that replacing butter with olive oil was associated with a slight decrease of risk. Interestingly, red meat also appears to be more strongly associated with diabetes than cardiovascular disease: replacing nuts with red meat is associated with an 8% decreased risk. The same parameter for replacing processed meat with nuts was 22%, replacing poultry with whole grains was 13%, and replacing eggs with nuts or whole grains was 8%.
Finally, replacing processed meat with nuts or whole grains was associated with a 21% decreased risk of all-cause mortality, with moderate certainty of the evidence. Replacing eggs with nuts or legumes represented a 15% decrease, replacing red meat with nuts or whole grains represented a 7% decrease, and replacing butter with olive oil represented a decrease of 6%.
Importantly, switching to a plant-based alternative has never been associated with an increase in risk, with the exception of the slight increase in cardiovascular disease risk when replacing butter with margarine. However, the certainty of the evidence for this particular association was very low.
Plant-based eaters tend to lead healthier lives overall
Demographic studies can only indicate an association, but not causation. Their results should therefore be taken with a grain of salt. Although meta-analyses generally improve the quality of evidence, they are still subject to the same problems as the individual studies within them.
According to the authors, the included studies all adjusted for major lifestyle confounding factors, such as total energy intake, physical activity, alcohol consumption and smoking. However, it is impossible to completely eliminate confusion. One of the alternative explanations proposed by the authors for the observed associations is that people following a plant-based diet tend to adopt a healthier lifestyle in general.
Our results suggest that a dietary shift from high consumption of animal-based foods, particularly red and processed meat, to plant-based foods (e.g., nuts, legumes, and whole grains) is associated with a lower risk of all-cause disease. mortality, cardiovascular diseases and T2DM. Thus, a change in dietary habits toward an increase in plant-based products appears to be important for cardiometabolic health. However, further research is needed to strengthen existing evidence and investigate new associations, particularly with a focus on meat and dairy alternatives.
Literature
(1) Neuenschwander, M., Stadelmaier, J., Eble, J. et al. (2023). Substitution of animal-based foods with plant-based foods on cardiometabolic health and all-cause mortality: a systematic review and meta-analysis of prospective studies. BMC Med 21, 404.
(2) Hodge, AM, O’Dea, K., English, DR, Giles, GG and Flicker, L. (2014). Dietary patterns as predictors of successful aging. The Journal of Nutrition, Health and Aging, 18(3), 221-227.
(3) Domic, J., Grootswagers, P., van Loon, LJ and de Groot, LC (2022). Perspective: Vegan Diets for Older People? A perspective on the potential impact on muscle mass and strength. Advances in Nutrition, 13(3), 712-725.
