Carotenoids and Retinoids (CARIG)
Overweight and obesity affect over two-thirds of the US population. This is concerning, as excess adiposity increases risk for dementia in later life. Thus, it is important to elucidate dietary approaches that benefit cognition. Lutein is a xanthophyll carotenoid thought to impact cognitive function. Daily consumption of avocado has been shown to improve cognitive function and lutein status but it is not clear whether these benefits extend to populations with overweight and obesity. Thus, we evaluated the influence of daily avocado consumption on cognitive function, serum lutein concentrations, and retinal xanthophyll status among adults with overweight and obesity using a randomized-controlled study.
Methods : Adults (N=72, 25-45 years, 31 males) with overweight or obesity (BMI 25 kg/m2) were randomized to an intervention group (N=38) that received a daily meal with one avocado or a control group (N=34) that received an isocaloric meal without avocado for 12 weeks. Fasting serum lutein concentrations were evaluated through high-performance liquid chromatography. Macular pigment optical density (MPOD) was assessed through heterochromatic flicker photometry. Selective attention was assessed by a modified Flanker task.
Results : Group by time interactions were seen for serum lutein concentrations (p=0.002) and flanker accuracy (p=0.006) whereby the intervention group exhibited a more substantial increase in serum lutein concentrations (0.04ug/ml; 95% CI, 0.02 to 0.06) and overall task accuracy (2.4%; 95% CI, 0.4 to 4.5). However, there was no relationship between task performance and changes in serum lutein concentration (p=0.23), nor changes in MPOD.
Conclusions : Daily consumption of a meal containing avocado improved selective attention and serum lutein concentrations among adults with overweight and obesity. The cognitive benefits of avocado consumption were apparent even prior to changes in retinal lutein status. Given that avocados are comprised of a variety of nutrients, additional work is necessary to determine non-carotenoid dependent mechanisms by which avocados may impact cognitive function.
Funding Sources : This work was supported by funds from the Hass Avocado Board, the Department of Kinesiology and Community Health at the University of Illinois, and the USDA National Institute of Food and Agriculture, Hatch project 1009249.