Abstract
IMPORTANCE Plant-based diets have gained popularity for both environmental and health reasons, but a comprehensive assessment of their quality in relation to risk of mortality and major chronic diseases is lacking. OBJECTIVE To examine whether healthful vs unhealthful plant-based dietary patterns are associated with mortality and major chronic diseases among UK adults. DESIGN, SETTING, AND PARTICIPANTS This prospective cohort study used data from adults in the UK Biobank, a large-scale population-based study. Participants were recruited between 2006 and 2010 and followed up using record linkage data until 2021; follow-up for different outcomes ranged between 10.6 and 12.2 years. Data analysis was conducted from November 2021 to October 2022. EXPOSURES Adherence to a healthful vs unhealthful plant-based diet index (hPDI vs uPDI) derived from 24-hour dietary assessments. MAIN OUTCOMES AND MEASURES The main outcomes were hazard ratios (HRs) and 95% Cls of mortality (overall and cause specific), cardiovascular disease (CVD [total, myocardial infarction, ischemic stroke, and hemorrhagic stroke]), cancer (total, breast, prostate, and colorectal), and fracture (total, vertebrae, and hip) across quartiles of hPDI and uPDI adherence. RESULTS This study included 126 394 UK Biobank participants. They had a mean (SD) age of 56.1 (7.8) years; 70 618 (55.9%) were women. The majority of participants (115 371 [91.3%]) were White. Greater adherence to the hPDI was associated with lower risks of total mortality, cancer, and CVD, with HRs (95% Cls) of 0.84 (0.78-0.91), 0.93 (0.88-0.99), and 0.92 (0.86-0.99), respectively, for participants in the highest hPDI quartile compared with the lowest. The hPDI was also associated with lower risks of myocardial infarction and ischemic stroke, with HRs (95% Cls) of 0.86 (0.78-0.95) and 0.84 (0.71-0.99), respectively. By contrast, higher uPDI scores were associated with higher risks of mortality, CVD, and cancer. The associations observed did not show heterogeneity across strata of sex, smoking status, body mass index, or socioeconomic status or with polygenic risk scores (specifically with regard to CVD end points). CONCLUSIONS AND RELEVANCE The findings of this cohort study of middle-aged UK adults suggest that a diet characterized by high-quality plant-based foods and lower intakes of animal products may be beneficial for health, irrespective of established chronic disease risk factors and genetic predisposition.
Generated Summary
This prospective cohort study, based on data from the UK Biobank, investigated the association between adherence to a healthful plant-based diet (hPDI) and unhealthful plant-based diet (uPDI) and the risk of mortality and major chronic diseases among UK adults. Participants were recruited between 2006 and 2010 and followed up until 2021. The study utilized 24-hour dietary assessments to derive hPDI and uPDI scores. The main outcomes included hazard ratios (HRs) and 95% CIs for mortality (overall and cause-specific), cardiovascular disease (CVD), cancer, and fracture across quartiles of hPDI and uPDI adherence. Data analysis was conducted from November 2021 to October 2022.
Key Findings & Statistics
- The study included 126,394 UK Biobank participants, with a mean age of 56.1 (7.8) years; 70,618 (55.9%) were women, and the majority (91.3%) were White.
- Participants in the highest hPDI quartile had a 16% lower risk of all-cause mortality (HR, 0.84 [95% CI, 0.78-0.91]; corrected P = .004).
- Participants with higher uPDI scores had a 23% higher risk of all-cause mortality (HR, 1.23 [95% CI, 1.14-1.32]; corrected P = .004).
- Greater hPDI adherence was associated with a 7% lower risk of any cancer (HR, 0.93 [95% CI, 0.88-0.99]; corrected P = .03).
- Participants with higher uPDI scores had a 10% higher risk of any cancer (HR, 1.10 [95% CI, 1.03-1.17]; corrected P = .004).
- Higher hPDI scores were associated with lower risks of total CVD, ischemic stroke, and myocardial infarction, with HRs (95% CIs) of 0.92 (0.86-0.99; corrected P = .007), 0.84 (0.71-0.99; corrected P = .08), and 0.86 (0.78-0.95; corrected P = .004) in multivariable models.
- Higher uPDI scores were associated with higher risks of total CVD, ischemic stroke, and myocardial infarction, with HRs (95% CIs) of 1.21 (1.05-1.20; corrected P = .004), 1.23 (0.95-1.33; corrected P = .02), and 1.17 (1.06-1.29; corrected P = .004).
- The ICCs (ranges) for reproducibility of the PDI scores over time were 0.58 (34-83) for hPDI and 0.55 (29-77) for uPDI (eTable 6 in Supplement 1).
Other Important Findings
- The study found no associations between hPDI or uPDI and risk of hemorrhagic stroke.
- Subgroup analyses showed no differential associations between hPDI and end points across key covariates, including polygenic risk scores, with a few exceptions.
- An inverse association between hPDI and CVD mortality was observed among ever smokers (HR, 0.77 [95% CI, 0.65-0.91]; P = .002 for trend) but not among nonsmokers (HR, 1.02, [95% CI, 0.84-1.24]; P = .85 for trend).
- An inverse association between hPDI and ischemic stroke risk was observed among participants with a high education level (HR, 0.87 [95% CI, 0.75-1.00]; P = .06 for trend), but not among those with a low education level (HR, 0.98, [95% CI, 0.83-1.15]; P = .77 for trend).
Limitations Noted in the Document
- The study’s reliance on two 24-hour dietary assessments to quantify habitual diet composition may have led to an underestimation of associations between PDIs and end points due to regression dilution.
- The UK Biobank population is not fully representative of the general UK population, which may limit the generalizability of the findings.
- Subgroup analyses of non-European ancestry participants were based on smaller sample sizes.
Conclusion
The findings from this cohort study of middle-aged UK adults suggest that a healthful PBD, characterized by a higher intake of plant-based foods and a lower intake of animal products, may be beneficial for health, regardless of established chronic disease risk factors and genetic predisposition. The study demonstrated that greater adherence to a healthful PBD was associated with a lower risk of total mortality, cancer, and CVD, highlighting the potential benefits of a diet rich in plant-based foods. Conversely, the study found that greater adherence to an unhealthful PBD was associated with higher risks of mortality, CVD, and cancer. These results support a shift toward food intake that emphasizes healthy plant foods to improve health and provide data to support a healthful PBD for CVD prevention irrespective of genetic disease risk. The study’s findings also suggest that the associations between hPDI and CVD end points (total CVD, myocardial infarction, and stroke) were independent of genetic disease risk, which has particular public health relevance. Future studies among more racially, ethnically, and culturally diverse populations are needed to assess the risk of major chronic disease in relation to PBDs.