Diet and cognitive decline at middle age: the role of antioxidants.

Population-based Doetinchem Cohort Study; prospective cohort; 2613 participants (1288 men, 1325 women) aged 43–70 at baseline; cognitive testing at baseline (1995–2002) and follow-up after ~5 years; 77 stroke cases excluded; habitual antioxidant intake assessed by validated FFQ at two time points; regression analyses relating quintiles of intake to change in cognitive-domain scores; adjustments for age, sex, education, energy intake, smoking, physical activity, waist circumference, mental quality of life, and baseline cognitive function; no dosing intervention.

Higher lignan intake was associated with slower cognitive decline in global function, memory, and processing speed, with about twofold less decline in the highest vs. lowest quintile. Baseline differences partly explained some magnitudes (lowest lignan quintile showed ~3.5× greater global decline, 6× greater memory decline, and 2× greater processing-speed decline than highest quintile). No associations for vitamin C or beta-carotene; memory decline was ~2× greater in the lowest vitamin E quintile; higher flavonoid intake linked to greater decline in cognitive flexibility; highest lutein intake showed greater global decline. Overall, within habitual dietary ranges, lignans consistently correlate with less cognitive decline; other antioxidants show no consistent protection. The authors suggest increasing habitual lignan-rich foods could potentially reduce midlife cognitive decline, but this is observational and requires confirmatory studies.

Observational design with potential residual confounding; baseline cognitive differences across lignan quintiles; ~80% follow-up may bias toward healthier participants; FFQ-based dietary assessment has measurement error; findings may not generalize to older or diseased populations; flavonoid finding may be due to chance; follow-up duration may be insufficient to detect some associations.