Dietary Carotenoids and Cognitive Decline: A Longitudinal Study Among Chinese Middle-Aged and Older Adults.

BACKGROUND: This study examined the association between dietary intakes of total and specific carotenoids and cognitive decline among Chinese middle-aged and older adults. METHODS: We included 4043 participants aged 55 years and older from the China Health and Nutrition Survey (1997-2006). Average daily dietary intakes of total carotenoids, α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein + zeaxanthin were calculated from 3-day 24-h dietary recalls. Cognitive function was measured repeatedly using the Telephone Interview for Cognitive Status-Modified. Linear mixed-effects models were utilized to estimate beta coefficients (β) and the 95% confidence intervals (CIs) for the association of energy-adjusted carotenoid intake with changes in cognitive z-scores. RESULTS: Higher intake of total dietary carotenoids was associated with slower cognitive decline. Comparing the top to bottom quintiles (median intake: 37.0 vs. 3.1 mg/day) of total carotenoids, the adjusted difference in annual decline rates (95% CI) was 0.018 (0.001-0.035, p-trend = 0.037). The strongest association was observed for moderate intake at the fourth quintile (median intake: 23.5 mg/day, β = 0.028, 95% CI: 0.011-0.046, p-quadratic = 0.030). Protective associations were also found for specific carotenoids, including α-carotene (β Q5 vs. Q1 = 0.037, 95% CI: 0.020-0.055), β-cryptoxanthin (β = 0.032, 95% CI: 0.014-0.049), lutein + zeaxanthin (β = 0.020, 95% CI: 0.002-0.037), lycopene (β = 0.018, 95% CI: 0.001-0.035) and β-carotene (β = 0.019, 95% CI: 0.001-0.036). CONCLUSIONS: A potential nonlinear association between dietary carotenoids and cognitive decline was observed in Chinese middle-aged and older adults. Further research is warranted to confirm optimal intake level for dietary carotenoids and to investigate the underlying biological mechanisms.