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A longitudinal study of toddlers initially between 12 and 18 months of age found that higher levels of skin carotenoids at the start of the study predicted trending improvements in cognitive development in the period up to 30 months of age. These toddlers also showed stronger fine motor skills improvements across the entire 12-month period, and increased gains in their ability to understand spoken words in the latter part of this period. The research was published in the Journal of Cognitive Enhancement.
Skin carotenoids are naturally occurring pigments that accumulate in human skin after being consumed in the diet. They mainly come from fruits and vegetables that are rich in carotenoids, such as carrots, sweet potatoes, spinach, and tomatoes. Carotenoids include compounds like beta-carotene, lycopene, and lutein, which are known for their antioxidant properties.
When these compounds are absorbed into the bloodstream, some of them are deposited in the skin where they can be detected and measured. Skin carotenoid levels are considered a noninvasive biomarker of fruit and vegetable intake. Researchers sometimes use specialized optical devices, such as reflection spectroscopy scanners, to estimate carotenoid levels in the skin. Higher skin carotenoid levels are generally associated with healthier dietary patterns and greater consumption of plant-based foods.
Study authors Laura M. Rosok and her colleagues wanted to study the changes in sensory memory, vision, cognition, language, and motor abilities in toddlers over a 12-month period starting in their second year of life. They also wanted to examine whether skin carotenoid levels predict developmental changes in this period of life. Study authors hypothesized that toddlers with higher levels of carotenoids in the skin would experience stronger developmental changes during the study period.
Study participants were toddlers recruited from East Central Illinois. They were 12-18 months old at the start of the study and 24-30 months old at the time of the final assessment. 51 toddlers started the study, 46 provided their data at the study mid-point, and 41 of them participated in the final assessments.
Toddlers’ skin carotenoid concentrations were measured using the Veggie Meter™, a device that relies on reflection spectroscopy to identify pigments in the skin within the carotenoid light spectrum. At the start of the study, 6 months after the start, and 12 months after the start of the study, parents or guardians of participating toddlers provided three 24-hour recalls of their toddlers’ food intake. They reported what their toddlers ate and drank on three separate days during a 2-week period.
Toddlers completed a set of behavioral assessments using the Bayley Scale of Infant and Toddler Development IV Screening Test, which measures cognition, receptive and expressive communication, and fine and gross motor skills. They also completed two electroencephalography (EEG) assessments of their brain activity—mismatch negativity and visual evoked potentials.
The mismatch negativity measurement detects the brain’s automatic detection of deviations in a sequence of auditory stimuli. Visual evoked potentials are used to assess visual sensory pathways by recording electroencephalographic activity while a toddler is viewing a specific picture (a reversing checkerboard pattern).
The results showed that toddlers with higher skin carotenoid levels at the start of the study experienced increased gains in fine motor skills across both the first six months and the full 12-month study period. They also experienced increased gains in their ability to understand spoken words (receptive communication) in the latter half of the study.
Interestingly, the researchers found no significant changes in the toddlers’ sensory memory or visual processing (the EEG measurements) over the 12 months, nor were these brain wave outcomes predicted by baseline skin carotenoid levels.
While the data hinted at a possible link between carotenoid levels and overall cognitive improvements, this specific finding was not statistically significant, meaning the researchers could not conclusively prove that relationship.
“These findings suggest that skin carotenoids may be linked to cognitive, language, and motor development in toddlers,” the study authors concluded.
The study contributes to the scientific knowledge about biochemical indicators of cognitive development. However, it should be noted that the design of this study does not allow any causal inferences to be derived from the results. Additionally, the authors noted that the sample was predominantly white and from high-income households, which limits the generalizability of the findings to a broader, more diverse population.
The paper, “Associations between Skin Carotenoids, Sensory Processing, and Developmental Milestones in Midwestern Toddlers across 12 Months,” was authored by Laura M. Rosok, Lexi M. Fifield, Rhea Sarma, Shelby A. Keye, Anne M. Walk, Kara D. Federmeier, and Naiman A. Khan.
