In a recent study published in the journal Brain Sciences, scientists examine the role of β-carotene in maintaining cognitive performance and mental health, either alone or in combination with other dietary components.

Study: The Effect of Beta-Carotene on Cognitive Function: A Systematic Review. Image Credit: Danijela Maksimovic / Shutterstock.com

About the study

All relevant studies were obtained from multiple databases, including Scopus, PubMed, and Web of Science. The MySLR digital platform was used to select and evaluate the quality of articles obtained from different sources. MySLR is a digital tool equipped with the Latent Dirichlet Allocation (LDA) algorithm to analyze large datasets using text mining. 

The current study included all adult participants without mental disorders. Several types of studies were considered for the analysis, including randomized clinical trials, prospective or cross-sectional studies, and longitudinal studies.

A total of 168 studies were identified after the initial search. However, after considering the eligibility criteria and removing the duplicates, 16 studies were included in the final review.

Importance of optimal cognitive function to maintain daily life

Cognitive behavior is vital to an individual's overall health and well-being. Cognitive functions include learning, language, memory, attention, perceptual-motor function, and social cognition, as well as receiving, processing, and interpreting information. The lack of equilibrium within the brain structure and disorientation at the molecular/cellular level, neural interactions, and protein–protein interaction networks lead to cognitive dysfunction.

Importantly, cognitive function is not stable, as it continually evolves throughout life. Aging is associated with cognitive impairment, with one recent study estimating that 19% of individuals under 75 years of age suffer from variable degrees of cognitive dysfunction compared to about 29% among people above 85 years of age.

About 30% of the global population above 65 years of age have been diagnosed with Alzheimer's, a brain disorder that affects memory and thinking skills. Cancer patients treated with chemotherapy often develop cognitive impairment referred to as "chemobrain" after or during the treatment. The currently ongoing coronavirus disease 2019 (COVID-19) pandemic also caused brain fog, which is a type of temporary cognitive impairment.

Thus, developing effective strategies linked to dietary interventions is imperative to prevent cognitive decline.

Use of β-carotene to combat cognitive dysfunction in adults

Carotenoids are common antioxidants and anti-inflammatory agents that can effectively improve cognitive health. To date, there are no guidelines or recommendations regarding the optimal dose of carotenoid intake for favorable outcomes.

β-carotene is an essential natural carotenoid and dietary source of pro-vitamin A. Moreover, β-carotene possesses significant free radical scavenging and antioxidant properties due to the presence of abundant unsaturated bonds in its molecule. β-carotene is present in fruits, vegetables, soup/bouillon, and food coloring additives.

Vitamin A is essential for multiple functions pertaining to vision, immunity, and fertility. Few studies have explored the association between β-carotene and cognitive function. Some epidemiological studies have presented inconclusive results regarding how β-carotene influences cognitive function. 

One recent study indicated that β-carotene dietary intake was inversely associated with cognitive function decline. A linear dose-response relationship between dietary β-carotene intake and Consortium to Establish a Registry for Alzheimer's Disease word learning (CERAD WL) test, alpha-fetoprotein test, and Defense Subject Standardized Test (DSST) results were observed; however, these results varied based on sex.

A positive correlation between high β-carotene levels in the blood and improved semantic memory performance has been observed. Thus, β-carotene serum levels appear to be a significant predictor of semantic memory performance.

The Rotterdam study reported that a lower consumption of β-carotene causes decreased cognitive performance. Comparatively, long-term dietary β-carotene consumption at a higher concentration was linked with a lower possibility of poor cognitive function. 

Many randomized clinical trials have supported the protective role of β-carotene against cognitive impairment. For example, the Physicians' Health Study (PHS) recommended that 50 mg of β-carotene on every alternate day could improve verbal and cognitive memory in adults.

Greater episodic memory and semantic fluency have been reported when β-carotene was supplemented with vitamins C and E. Notably, cognitive improvement was more significant among non-smokers.

Mechanistically, β-carotene and vitamin E work synergistically to prevent lipid peroxidation. However, in some cases, high antioxidant intake can increase lipid peroxidation and DNA oxidative damage. Recent studies have indicated that β-carotene intake alleviates brain fog through the calcium/calmodulin-dependent protein kinase IV (CAMKIV) pathway.

Conclusions

The current study summarized the clinical evidence regarding the benefits of using β-carotene as a nutritional intervention for cognitive maintenance. Most epidemiological and randomized control studies support the beneficial role of β-carotene in improving cognitive function.

A combination of β-carotene with other nutrients with higher antioxidant properties, such as zinc, vitamin C, and vitamin E, has been shown to significantly impact cognitive function.

Journal reference:

• Abrego-Guandique, D. M., Bonet, M. L., Caroleo, M. C., et al. (2023) The Effect of Beta-Carotene on Cognitive Function: A Systematic Review. Brain Sciences 13(10); 1468. doi:10.3390/brainsci13101468