Abstract
Previous studies have documented the cardiometabolic health benefits of plant-based diets; however, these studies were conducted in selected study populations that had narrow generalizability. Methods and Results—We used data from a community-based cohort of middle-aged adults (n=12 168) in the ARIC (Atherosclerosis Risk in Communities) study who were followed up from 1987 through 2016. Participants’ diet was classified using 4 diet indexes. In the overall plant-based diet index and provegetarian diet index, higher intakes of all or selected plant foods received higher scores; in the healthy plant-based diet index, higher intakes of only the healthy plant foods received higher scores; in the less healthy plant-based diet index, higher intakes of only the less healthy plant foods received higher scores. In all indexes, higher intakes of animal foods received lower scores. Results from Cox proportional hazards models showed that participants in the highest versus lowest quintile for adherence to overall plant-based diet index or provegetarian diet had a 16%, 31% to 32%, and 18% to 25% lower risk of cardiovascular disease, cardiovascular disease mortality, and all-cause mortality, respectively, after adjusting for important confounders (all P<0.05 for trend). Higher adherence to a healthy plant-based diet index was associated with a 19% and 11% lower risk of cardiovascular disease mortality and all-cause mortality, respectively, but not incident cardiovascular disease (P<0.05 for trend). No associations were observed between the less healthy plant-based diet index and the outcomes. Conclusions—Diets higher in plant foods and lower in animal foods were associated with a lower risk of cardiovascular morbidity and mortality in a general population. (J Am Heart Assoc. 2019;8:e012865. DOI: 10.1161/JAHA.119.012865.)
Generated Summary
This research investigates the association between plant-based diets and the risk of cardiovascular disease, cardiovascular disease mortality, and all-cause mortality in a general population of middle-aged adults. The study utilized data from the ARIC (Atherosclerosis Risk in Communities) study, a community-based cohort. Participants’ diets were classified using four diet indexes: overall plant-based diet index, provegetarian diet index, healthy plant-based diet index, and less healthy plant-based diet index. The study used Cox proportional hazards models to assess the relationships between diet index adherence and health outcomes. The research aims to determine whether plant-based diets are associated with a lower risk of cardiovascular disease, cardiovascular disease mortality, and all-cause mortality. The study also evaluated if the association differed based on the healthfulness of the plant-based diets.
Key Findings & Statistics
- The study included data from a community-based cohort of middle-aged adults (n=12 168) in the ARIC (Atherosclerosis Risk in Communities) study, with follow-up from 1987 through 2016.
- In the overall plant-based diet index and provegetarian diet index, higher intakes of all or selected plant foods received higher scores.
- In the healthy plant-based diet index, higher intakes of only the healthy plant foods received higher scores.
- In the less healthy plant-based diet index, higher intakes of only the less healthy plant foods received higher scores.
- In all indexes, higher intakes of animal foods received lower scores.
- Participants in the highest versus lowest quintile for adherence to overall plant-based diet index or provegetarian diet had a 16%, 31% to 32%, and 18% to 25% lower risk of cardiovascular disease, cardiovascular disease mortality, and all-cause mortality, respectively (all P<0.05 for trend).
- Higher adherence to a healthy plant-based diet index was associated with a 19% and 11% lower risk of cardiovascular disease mortality and all-cause mortality, respectively, but not incident cardiovascular disease (P<0.05 for trend).
- Incidence rates for cardiovascular disease events, cardiovascular disease mortality, and all-cause mortality were lower at higher quintiles of PDI, hPDI, and provegetarian diet index (Table S3).
- During a median follow-up of 25 years, 4381 incident cardiovascular disease events, 1565 deaths caused by cardiovascular disease, and 5436 deaths attributable to all causes occurred.
- For PDI, the P value for trend was <0.001 for incident cardiovascular disease, cardiovascular disease mortality, and all-cause mortality.
- For hPDI, the P value for trend was 0.11 for incident cardiovascular disease, 0.01 for cardiovascular disease mortality, and 0.01 for all-cause mortality.
- For uPDI, the P value for trend was 0.98 for incident cardiovascular disease, 0.13 for cardiovascular disease mortality, and 0.10 for all-cause mortality.
- For provegetarian diet index, the P value for trend was <0.001 for incident cardiovascular disease, cardiovascular disease mortality, and all-cause mortality.
- When score components of PDI were modeled, those in the highest quintile of animal food consumption had a higher risk of incident cardiovascular disease (HR, 1.14; 95% CI, 1.04-1.27; P<0.001 for trend), cardiovascular disease mortality (HR, 1.30; 95% CI, 1.10-1.54; P<0.001 for trend), and all-cause mortality (HR, 1.12; 95% CI, 1.02-1.23; P=0.001 for trend).
- When components of the provegetarian diet index were modeled, similar associations with animal foods were observed for all 3 outcomes (all P<0.01 for trend).
- For incident cardiovascular disease, we found evidence of statistical interaction by diabetes mellitus status with hPDI (P=0.01 for interaction) and provegetarian diet (P=0.03 for interaction).
- The PDI ranged from 28 to 74, the hPDI ranged from 29 to 77, the uPDI ranged from 27 to 76, and the provegetarian diet index ranged from 15 to 54.
- Participants in the highest quintiles of PDI, hPDI, and provegetarian diet index consumed an average of 4.1 to 4.8 servings of fruit and vegetables per day.
- Those in the highest quintiles of PDI, hPDI, and provegetarian diet had higher intake of carbohydrates and plant protein as a percentage of energy, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, and folate, and lower intake of saturated fat and cholesterol.
- During the study, the incident rate of cardiovascular disease was: 4.5 per 100,000 PY in the first quintile of PDI, to 3.3 per 100,000 PY in the 5th quintile of PDI.
- During the study, the incidence rate of cardiovascular disease mortality was: 6.5 per 100,000 PY in the first quintile of PDI, to 4.1 per 100,000 PY in the 5th quintile of PDI.
- During the study, the incidence rate of all-cause mortality was: 4.8 per 100,000 PY in the first quintile of PDI, to 0.65 per 100,000 PY in the 5th quintile of PDI.
Other Important Findings
- No associations were observed between the less healthy plant-based diet index and the outcomes.
- The strongest and most consistent associations were observed for PDI and provegetarian diet index, with all 3 outcomes in all 3 models.
- After adjusting for sociodemographic characteristics, dietary factors, and health behaviors, those in the highest versus lowest quintiles of PDI and provegetarian diet index had a 16% and 16% lower risk of incident cardiovascular disease, a 32% and 31% lower risk of cardiovascular mortality, and a 25% and 18% lower risk of all-cause mortality, respectively.
- For hPDI, after adjusting for sociodemographic characteristics, dietary factors, and health behaviors, those in the highest versus lowest quintile had a 19% lower risk of cardiovascular disease mortality and an 11% lower risk of all-cause mortality.
- In the continuous analysis, there was an approximately linear inverse relationship between PDI and provegetarian diet index scores and risk of incident cardiovascular disease.
- Higher intakes of eggs and red and processed meat were associated with a higher risk of all 3 outcomes when modeling individual food groups.
Limitations Noted in the Document
- Dietary intakes were self-reported, which is subject to measurement error.
- The study used a sample-based scoring method to assess the degree of adherence to plant-based diets, and the authors were unable to infer if there is an absolute level of plant food or animal food intake that is associated with health outcomes.
- Dietary intakes were measured several decades ago in the ARIC study, and the data may not reflect the modern food supply.
- The possibility of residual confounding remains because of unmeasured or incorrectly measured variables.
Conclusion
The study found that higher adherence to plant-based diets, especially those emphasizing plant foods and limiting animal foods, was associated with a lower risk of cardiovascular disease, cardiovascular disease mortality, and all-cause mortality in a general population. The overall plant-based diet index and provegetarian diet index showed the strongest and most consistent associations across different health outcomes. The study highlights the importance of the overall dietary pattern, suggesting that a comprehensive approach to diet characterization is crucial. The authors suggest that the quality of plant foods, specifically whether they are healthy or less healthy, within the framework of plant-based diets, needs further investigation to understand its effects on cardiovascular disease and all-cause mortality. The findings reinforce the benefits of diets high in plant foods, such as fruits, vegetables, whole grains, and plant proteins, while limiting animal foods like red and processed meats, for cardiovascular health. The study results suggest the need for future studies to consider the impact of specific food groups, such as potatoes, in relation to various health outcomes and disease risk. Overall, the research emphasizes the benefits of a plant-based diet for cardiovascular health and supports the need for further studies to explore various aspects of the dietary approach.
IFFS Team Summary
- 12168 subjects from Atherosclerotic Risk in Communities study (hence a small to moderate study compared to others)
- median follow‐up of 25 years
- 4381 incident cardiovascular disease events (CVD)
- 1565 deaths caused by CVD
- 5436 all cause mortality
- 4381 incident cardiovascular disease events (CVD)
- 1565 deaths caused by CVD
- 5436 all cause mortality
- People were scored on various plant based eating indices
- Scores were higher if a person ate more plant based foods, lower if consuming animal based foods
- Each scored with some differing criteria
- Scores were higher if a person ate more plant based foods, lower if consuming animal based foods
- Each scored with some differing criteria
- “Overall Plant based index” and “ Provegetarian Index” were scored in quintiles
- Comparing first to fifth quintiles found that: 16% lower risk of cardiovascular disease 31-32% lower risk of cardiovascular mortality 18-25% lower risk of all cause mortality
- Comparing first to fifth quintiles found that:
- 16% lower risk of cardiovascular disease
- 31-32% lower risk of cardiovascular mortality
- 18-25% lower risk of all cause mortality
- 16% lower risk of cardiovascular disease
- 31-32% lower risk of cardiovascular mortality
- 18-25% lower risk of all cause mortality
- Higher adherence according to “Healthy Plant Based Index”
- 19% lower cardiovascular disease mortality
- 11% decrease in all cause mortality
- 19% lower cardiovascular disease mortality
- 11% decrease in all cause mortality
- “Unhealthy Plant Based Eating Index” showed no benefit over a standard diet
- Demonstrating that unhealthy plant based foods are of little benefit
- Demonstrating that unhealthy plant based foods are of little benefit