Effect of macular pigment carotenoids on cognitive functions: A systematic review.

2022-10
Physiology & behavior 254
- Marta-C García-Romera
- María-Carmen Silva-Viguera
- Inmaculada López-Izquierdo
- Alfredo López-Muñoz
- Raúl Capote-Puente
- Beatriz Gargallo-Martínez

PubMed: 35752349
DOI: 10.1016/j.physbeh.2022.113891

Study Design

Type: Systematic Review
Population: healthy people (no age, sex, or race limitations)
Methods: Systematic review of 19 studies (7 RCTs, 11 observational) examining association between carotenoids (lutein, meso-zeaxanthin, zeaxanthin) and cognitive function; databases scoured, PROSPERO registration CRD42021254833

Lutein and zeaxanthin-xanthophyll carotenoids with antioxidant and anti-inflammatory characteristics-are present in the retina and the brain. High concentrations of these carotenoids have been positively related to cognitive performance. Therefore, this systematic review analyses the relationship between macular pigment density and cognitive functions. Most relevant databases were scoured for studies on healthy people relating cognitive functions to macular pigment optical density (MPOD). There were no age, sex, or race limitations. PROSPERO registration: CRD42021254833. Nineteen studies were included, seven randomized controlled trials (RCT) and eleven observational studies. The general aim of the studies was to examine the association between carotenoids (lutein, meso‑zeaxanthin and zeaxanthin) and cognitive function. Most observational studies correlates MPOD levels with cognitive function or brain activity. Besides, RCTs compared the cognitive function and/or brain activity after increasing lutein and zeaxanthin intake though dietary supplementation or avocado consumption. Dietary lutein and zeaxanthin intake increased MPOD in six of the seven clinical trials and significantly improved most of the cognitive functions studied. A wide variety of test and methodologies for measuring cognitive functions were observed. Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults. Brain activity also was related to MPOD, but the results were inconsistent. Only four of the eleven observational studies were based on young people and all studies showed a significant relationship between MPOD and cognitive functions. This systematic review showed a direct relationship among cognitive functions, macular pigment and the intake of lutein and zeaxanthin.

Research Insights

Blood Orange→Changed Brain Activity
Brain activity also was related to MPOD, but the results were inconsistent.
Effect
Neutral
Effect size
Small
Blood Orange→Improved Attention Span
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Blood Orange→Improved Cognitive Function
The general aim of the studies was to examine the association between carotenoids (lutein, meso‑zeaxanthin and zeaxanthin) and cognitive function. ... dietary lutein and zeaxanthin intake increased MPOD ... and significantly improved most of the cognitive functions studied.
Effect
Beneficial
Effect size
Moderate
Blood Orange→Improved Memory Function
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Blood Orange→Improved Processing Speed
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Blood Orange→Improved Reasoning
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Blood Orange→Increased Macular Pigment Optical Density
Dietary lutein and zeaxanthin intake increased MPOD in six of the seven clinical trials
Effect
Beneficial
Effect size
Moderate
Lutein→Changed Brain Activity
Brain activity also was related to MPOD, but the results were inconsistent.
Effect
Neutral
Effect size
Small
Lutein→Improved Attention Span
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Lutein→Improved Cognitive Function
The general aim of the studies was to examine the association between carotenoids (lutein, meso‑zeaxanthin and zeaxanthin) and cognitive function. ... dietary lutein and zeaxanthin intake increased MPOD ... and significantly improved most of the cognitive functions studied.
Effect
Beneficial
Effect size
Moderate
Lutein→Improved Memory Function
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Lutein→Improved Processing Speed
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Lutein→Improved Reasoning
Memory, processing speed, attention and reasoning were the cognitive function significantly related to MPOD levels in adults.
Effect
Beneficial
Effect size
Moderate
Lutein→Increased Macular Pigment Optical Density
Dietary lutein and zeaxanthin intake increased MPOD in six of the seven clinical trials
Effect
Beneficial
Effect size
Moderate