Dietary α-carotene and β-carotene Intake Inversely Associated with Cognitive Decline in Older Adults

by | Feb 9, 2023 | 2023, Aging, Antioxidants, Brain Health, Carotenoids, Cognitive Health

Written by Taylor Woosley, Staff Writer. Compared with the subjects in the lowest quartile of β-carotene dietary intake, those in the highest quartile had lower risk of both CERAD W-L decline (OR = 0.63, 95% CI: 0.44-0.90) and AFT decline (OR = 0.66, 95% CI: 0.47-0.94). 

fruit and vegetablesThe proportion of older people has increased rapidly in recent decades, with this proportion expected to be greater than one-fifth of the population by 20501. Thus, the prevalence of age-related diseases, such as neurodegenerative diseases like dementia, are continuously increasing each year2. Dementia is associated with impaired functionality and disability and by 2050 it is expected to affect 135.5 million people worldwide3. Alzheimer’s disease, the most common form of dementia, features a progressive decline in cognitive function and is characterized by neuroinflammation and oxidative stress, giving rise to synapse loss and neuronal death4.

Oxidative stress therapeutics such as antioxidants and carotenoids can reduce oxidation and prevent cognitive decline in neurodegenerative conditions5. Carotenoids are naturally occurring pigments in red, yellow, orange, and dark green fruits and vegetables with emerging evidence from epidemiological studies linking higher levels of carotenoids with a lower risk of cognitive decline6. Furthermore, β-carotene has potent free radical scavenging abilities to reduce the expression of inflammatory factors such as nuclear factor kappa-B and interleukins7.

Zhong et al. conducted a cross-sectional study to explore the association of dietary α-carotene and β-carotene intake with cognitive function in elderly people using data from the National Health and Nutrition Examination Survey (NHANES). Additionally, they investigated the dose-response relationships of dietary α-carotene and β-carotene consumption with cognitive function decline. Data on dietary α-carotene and β-carotene intake and cognitive function from two cycles of NHANES (2011-2012 and 2013-2014) were included in the study using a total of 2009 participants.

Dietary data collection was obtained using 24 h dietary recall interviews and nutrient intake profiles reported by subjects. Dietary α-carotene and β-carotene intake was categorized into quartiles: Q1: <25th percentile, Q2: ≥25th to 50th percentile, Q3: ≥50th to 75th percentile, and Q4: ≥75th percentile. Assessment of cognitive function contained three tests including the Consortium to Establish Registry for Alzheimer’s disease (CERAD W-L), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST). Covariates selected included age, gender, race/ethnicity, education, body mass index (BMI), smoking status, drinking status, and health factors such as diabetes.

Dietary α-carotene and β-carotene intake were modeled as both continuous (Ln-transformed) and categorical variables to analyze the associations with cognitive function by logistic regression. Student’s t-test and the chi-squared test were also utilized to examine the differences between the two groups. Furthermore, the restricted cubic spline (RCS) was included to explore the dose-response relationships of dietary α-carotene and β-carotene intake with cognitive function. Significant findings of the study are as follows:

  • Regarding CERAD W-L, the odds ratio (OR) values of cognitive function with β-carotene intake in Q2, Q3, Q4 were 0.72 (95% CI: 0.53, 0.98), 0.66 (95% CI: 0.50, 0.88) and 0.60 (95% CI: 0.37, 0.69), respectively, compared to those in Q1.
  • In the AFT, the OR values of cognitive function with β-carotene intake in the Q2, Q3, and Q4 groups were 0.65 (95% CI: 0.47, 0.88), 0.51 (95% CI: 0.38, 0.69), and 0.52 (95% CI: 0.38, 0.71), respectively, compared to those in the Q1 group.
  • In the DSST, the OR values of cognitive function with β-carotene intake in the Q2, Q3, and Q4 groups were 0.64 (95% CI: 0.47, 0.87), 0.45 (95% CI: 0.34, 0.60), and 0.42 (95% CI: 0.30, 0.57), respectively, compared to those in the Q1 group.

Results of the study using data from NHANES shows that higher dietary intake of α-carotene and β-carotene had a lower risk of cognitive decline based on cognitive function assessment scores. Further research should continue to explore the beneficial effects of carotenoid intake on cognition. Study limitations include the inability to confirm causality due to the cross-sectional nature of the study, lack of including all possible confounding factors, and the use of dietary recall to assess carotenoid levels rather than the measurement in a laboratory.

Source: Zhong, Qiya, Wen Sun, Yao Qin, and Huadong Xu. “Association of Dietary α-Carotene and β-Carotene Intake with Low Cognitive Performance in Older Adults: A Cross-Sectional Study from the National Health and Nutrition Examination Survey.” Nutrients 15, no. 1 (2023): 239.

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Posted February 9, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

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