Abstract
Not all plant-based and animal foods exert the same health effects due to their various nutrient compositions. We aimed to assess the quality of plant-based v. animal foods in relation to mortality in a prospective cohort study. Using data collected from a nationally representative sample of 36 825 adults in the National Health and Nutrition Examination Survey 1999-2014, we developed a de novo Comprehensive Diet Quality Index (cDQI) that assesses the quality of seventeen foods based on the healthfulness and separately scored the quality of eleven plant-based foods in a plant-based Diet Quality Index (pDQI) and six animal foods in an animal-based Diet Quality Index (aDQI). Mortality from all causes, heart disease and cancer were obtained from linkage to the National Death Index up to 31 December 2015. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% CI after multivariable adjustments. During a median follow-up of 8-3 years, 4669 all-cause deaths occurred, including 798 deaths due to heart disease and 1021 due to cancer. Compared with individuals in the lowest quartile, those in the highest quartile of cDQI had a lower risk of all-cause mortality (HR 0.75, 95% CI 0.65, 0.86; Ptrend < 0.001), which largely reflected the inverse relationship between quality of plant-based foods (pDQI) and all-cause mortality (HR 0.66, 95% CI 0.58, 0.74; Ptrend < 0.001). No independent association was found for the quality of animal foods (aDQI) and mortality. Our results suggest that consuming healthy plant-based foods is associated with lower all-cause mortality among US adults.
Generated Summary
This cohort study investigated the association between the quality of plant-based and animal-based diets and mortality in US adults. The study utilized data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014, involving a sample of 36,825 adults. A de novo Comprehensive Diet Quality Index (cDQI) was developed to assess the quality of seventeen foods, with separate Plant-based Diet Quality Index (pDQI) and Animal-based Diet Quality Index (aDQI) scores. The study aimed to determine how these diet quality indices relate to all-cause, heart disease, and cancer mortality. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) after adjusting for multiple variables. The findings explore the relationship between diet quality and mortality, providing insights into the impact of plant-based and animal-based foods on health outcomes within a large, nationally representative sample.
Key Findings & Statistics
- During a median follow-up of 8.3 years, there were 4,669 all-cause deaths, including 798 from heart disease and 1,021 from cancer.
- Compared with individuals in the lowest quartile, those in the highest quartile of cDQI had a lower risk of all-cause mortality (HR 0.75, 95% CI 0.65, 0.86; Ptrend < 0.001).
- Individuals in the highest quartile of pDQI had a lower all-cause mortality (HR 0.66, 95% CI 0.58, 0.74; Ptrend < 0.001).
- No independent association was found for the quality of animal foods (aDQI) and mortality.
- The mean total score of the cDQI among US adults was 43.8 (out of maximum score 85).
- The mean score for plant-based components was 27.6 (out of maximum score 55).
- The mean score for animal-based components was 16.2 (out of maximum score 30).
- Among the seventeen food components, three plant-based food components had mean scores below 50% of the maximum score: whole grains (25.4%), sugar-sweetened beverages (26.8%), and vegetables.
- Compared with individuals in the lowest quartile of cDQI, those in the highest quartile had a 25% lower all-cause mortality (Q4 v. Q1: HR 0.75, 95% CI 0.65, 0.86; Ptrend <0.001).
- After controlling for aDQI, individuals in the highest quartile of pDQI had a 34% lower all-cause mortality (Q4 v. Q1: HR 0.66, 95% CI 0.58, 0.74; Ptrend <0.001).
- The aDQI was not associated with any of the mortality outcomes after controlling for pDQI.
- When each component of cDQI was evaluated individually, lower all-cause mortality was associated with higher intake of vegetables (excluding white potatoes) (HR 0.75, 95% CI 0.64, 0.88), whole fruits (HR 0.72, 95% CI 0.57, 0.91), nuts/seeds/legumes (HR 0.77, 95% CI 0.67, 0.89), vegetable oils (HR 0.82, 95% CI 0.71, 0.94), and coffee/tea (HR 0.81, 95% CI 0.70, 0.94).
- Among individuals with co-morbidity conditions at baseline, those in the highest quartile of CDQI (HR 0.72, 95% CI 0.64, 0.82; Ptrend < 0.001) or pDQI (HR 0.66, 95% CI 0.58, 0.75; Ptrend <0.001) had a lower risk of all-cause mortality.
- The inverse association between pDQI and all-cause mortality was slightly stronger among individuals who were overweight (Q4 v. Q1: HR 0.59, 95% CI 0.48, 0.73; Ptrend <0.001) compared to those with a healthy weight (HR 0.69, 95% CI 0.52, 0.91; Ptrend = 0.007) or obese individuals (HR 0.68, 95% CI 0.51, 0.89; Ptrend = 0.02).
- The inverse association between cDQI and all-cause mortality was slightly stronger among individuals who were physically active (HR 0.62, 95% CI 0.42, 0.93; Ptrend = 0.008) compared with those physically inactive (HR 0.80, 95% CI 0.68, 0.94; Ptrend = 0.003).
- Although no association was found for aDQI and all-cause mortality among older individuals, younger individuals (20-44 years old) in the highest quartile of aDQI had a lower risk of all-cause mortality compared with those in the lowest quartile (Q4 v. Q1: HR 0.65, 95% CI 0.43, 0.97; Ptrend = 0.09).
- The association between pDQI and all-cause mortality was only found among older individuals (45–59 years old: HR 0.67, 95% CI 0.47, 0.96; Ptrend = 0.05; 60+ years old: HR 0.73, 95% CI 0.61, 0.88; Ptrend <0.001) but not younger ones.
Other Important Findings
- The study found that eating a diet with both high-quality plant-based and animal foods (i.e., scoring high in both the pDQI and the aDQI) was associated with a lower risk of all-cause mortality.
- The association largely reflected the inverse relationship between quality of plant-based foods and all-cause mortality.
- No independent associations were found for the quality of animal foods with mortality.
- The study supports the dietary recommendations that promote high-quality plant-based diets for improving health.
- The inverse association between high-quality plant-based foods and all-cause mortality was observed among individuals with co-morbidity conditions at baseline.
Limitations Noted in the Document
- Distribution of diet was estimated based on self-reported dietary intake subject to measurement error.
- The NHANES used 1 or 2 d of 24-h diet recalls as the primary source to measure dietary intake, which does not well capture usual intake.
- Some components included in cDQI were scored based on quintiles of consumption, which may affect the comparability of study findings.
- Diet quality is correlated with participants’ socio-economic status and lifestyle factors.
- Mortality was determined through probabilistic matching with the National Death Index, which is subject to misclassification.
- The sample size was limited to evaluate cause-specific mortality.
- Repeated assessment on dietary intake for the same individual was not available.
Conclusion
In conclusion, the study highlights the significant role of diet quality in relation to mortality among US adults. The findings emphasize the benefits of consuming high-quality plant-based foods, as evidenced by the inverse association between pDQI and all-cause mortality. These results support current dietary recommendations that promote plant-based diets for improved health outcomes. The study’s findings also suggest that the quality of animal foods, as assessed by aDQI, does not independently contribute to mortality risk. However, the nuances in the relationship between diet quality and mortality, particularly among different age groups and health conditions, warrant further investigation. The study also acknowledges limitations such as reliance on self-reported dietary intake and the challenges in capturing usual dietary patterns. Future research should focus on refining dietary assessment methods and exploring how different dietary patterns, including the balance of plant-based and animal-based foods, influence chronic disease prevention and overall longevity. The study underscores the importance of promoting diets rich in whole, unprocessed plant foods to improve public health, emphasizing that dietary choices can significantly impact health outcomes. The study’s findings emphasize the importance of focusing on improving the intake of high-quality plant-based foods to enhance public health. This research provides valuable insights into the complex relationship between diet, health, and longevity, offering a basis for targeted dietary interventions and public health strategies.