Vegetarian and vegan diet may lower risk of CVD and CAD but not stroke: Study
Norway: People who consume vegetarian diets may be at a lower risk of ischemic heart disease (IHD) and cardiovascular disease (CVD) but not stroke, the researchers state in a meta-analysis published in the European Journal of Nutrition. The researchers further suggest considering these findings in dietary guidelines.
The study showed a 21% and 15% reduction in the relative risk of IHD and CVD respectively for vegetarians compared to nonvegetarians, but could not establish any clear association for total stroke or subtypes of stroke.
Previous studies have shown vegetarian diets to be associated with a reduced risk of ischemic heart disease. However, there was not much clarity on the results regarding cardiovascular disease overall and stroke. To clarify these associations, Jarle Sæby Dybvik, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway, and colleagues conducted a systematic review and meta-analysis of prospective cohort studies on CVD, IHD, and stroke risk in vegetarians or vegans versus nonvegetarians.
For this purpose, the researchers searched the online databases through August 12, 2021. It included prospective cohort studies reporting adjusted relative risk (RR) estimates for incidence or mortality from IHD, CVD, and stroke comparing vegetarians and vegans to nonvegetarians. ROBINS-I was used to assess the risk of bias (RoB) and World Cancer Research Fund (WCRF) criteria were used to assess the strength of evidence.
The study led to the following findings:
- Thirteen cohort studies (844,175 participants, 115,392 CVD, 30,377 IHD, and 14,419 stroke cases) were included.
- The summary RR for vegetarians vs. nonvegetarians was 0.85 (n = 8) for CVD, 0.79 (n = 8) for IHD, 0.90 (n = 12) for total stroke, and for vegans vs. nonvegetarians was 0.82 (n = 6) for IHD.
- RoB was moderate (n = 8) to serious (n = 5).
- The associations between vegetarian diets and CVD and IHD were considered probable causal using WCRF criteria.
"We observed a 15% reduction in the relative risk of CVD and a 21% reduction in the relative risk of IHD for vegetarians compared to nonvegetarians but did not observe any clear association for total stroke or stroke subtypes," the researchers wrote.
"Our findings are consistent with existing guidelines recommending plant-based dietary patterns for CVD prevention but suggest more emphasis may be put on vegetarian diets," they wrote in their conclusion. "Further studies are required for clarifying the association between vegetarian diets and stroke risk, and the association between vegan diets, and CVD, IHD, and stroke.
Reference:
Dybvik, J.S., Svendsen, M. & Aune, D. Vegetarian and vegan diets and the risk of cardiovascular disease, ischemic heart disease and stroke: a systematic review and meta-analysis of prospective cohort studies. Eur J Nutr (2022). https://doi.org/10.1007/s00394-022-02942-8
