Aviva A Musicus, Dong D Wang, Marie Janiszewski, Gidon Eshel, Stacy A Blondin, Walter Willett, Meir J Stampfer. Health and environmental impacts of plant-rich dietary patterns: a US prospective cohort study. The Lancet Planetary Health. Volume 6, Issue 11. 2022. Pages e892-e900. ISSN 2542-5196. https://doi.org/10.1016/S2542-5196(22)00243-1
- Background – Diets that are rich in animal-based foods threaten planetary and human health, but plant-rich diets have varied health and environmental effects. We aimed to characterise a healthy dietary index and three plant-based indices by their environmental impacts and associations with risk of cardiovascular disease.
- Methods – In this prospective cohort study, we used data from a food-frequency questionnaire in the US-based Nurses’ Health Study II. Participants were categorised by quintiles of four dietary indices, including the alternative healthy eating index-2010 (AHEI), plant-based diet index (PDI), unhealthy PDI, and healthy PDI. We calculated environmental impacts (greenhouse gas emissions and irrigation water, nitrogenous fertiliser, and high-quality cropland needs), and relative risks (RRs) of cardiovascular disease from 1991–2017, comparing quintiles.
- Findings – We included 90 884 participants in the health-impact analysis and 65 625 participants in the environmental-impact analysis. Comparing the top and bottom quintiles, higher AHEI scores were associated with a decreased cardiovascular disease risk (relative risk 0·77 [95% CI 0·66–0·89]); 30% lower greenhouse gas emissions (Q5 2·6 kg CO2 equivalent vs Q1 3·7 kg CO2 equivalent); and lower fertiliser, cropland, and water needs (all ptrends<0·0001). Similarly, the highest healthy PDI and PDI quintiles were associated with a decreased cardiovascular disease risk (healthy PDI 0·71 [0·60–0·83] and PDI 0·74 [0·63–0·85]) and lower environmental impacts (PDI water needs ptrend=0·0014; all other ptrends<0·0001). Conversely, the highest unhealthy PDI quintile had a higher cardiovascular disease risk compared with the lowest unhealthy PDI quintile (1·15 [1·00–1·33]; ptrend=0·023) and required more cropland (ptrend<0·0001) and fertiliser (ptrend=0·0008).
- Interpretation – Dietary patterns that are associated with better health had lower greenhouse gas emissions and nitrogenous fertiliser, cropland, and irrigation water needs. Not all plant-based diets conferred the same health and environmental benefits. US dietary guidelines should include nuanced consideration of environmental sustainability.
Funding – US National Institutes of Health.
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