Table 2

 Relative risks (95% confidence intervals) of incident AD by quintile of intake of niacin, tryptophan, and niacin equivalents among 815 participants initially free of AD and followed a median 3.8 years, Chicago Health and Aging Project, 1993–2000

MeasurementTotal niacin including supplementsNiacin from foodsTryptophanNiacin equivalents
Quintile of intakepQuintile of intakepQuintile of intakepQuintile of intakep
12345123451234512345
*Weighted for the stratified random sampling design
†Basic adjusted model includes terms for age (years), sex, race, education (years), ApoE e4, interaction between ApoE e4 and race, time between disease free determination and clinical evaluation for incident disease. All models were weighted by the inverse of the sampling probability.
‡Multiple adjusted model includes terms from the basic adjusted model plus vitamin E intake from foods (ln(IU/day)), total vitamin C intake (ln(mg/day)), total beta-carotene (ln(IU/day)), and an indicator variable for multiple vitamin use.
AD, Alzheimer’s disease; RR, relative risk; CI, confidence interval.
Median intake, mg/day14.117.019.428.945.012.615.216.918.922.40.560.680.750.820.9424.029.233.242.358.5
% AD*20.58.45.610.76.721.68.210.17.05.917.39.514.57.75.721.97.77.58.97.1
RR (95% CI)
    Basic adjusted†1.00.3 (0.1 to 0.6)0.3 (0.1 to 0.7)0.6 (0.3 to 1.3)0.3 (0.1 to 0.7)0.121.00.3 (0.1 to 0.8)0.3 (0.1 to 0.9)0.3 (0.1 to 0.6)0.2 (0.1 to 0.6)0.0021.00.5 (0.2 to 1.3)0.7 (0.3 to 1.7)0.4 (0.1 to 0.9)0.3 (0.1 to 0.8)0.031.00.3 (0.1 to 0.7)0.3 (0.1 to 0.7)0.5 (0.2 to 1.1)0.3 (0.1 to 0.8)0.07
    Multiple adjusted‡1.00.3 (0.1 to 0.6)0.3 (0.1 to 0.7)0.5 (0.2 to 1.3)0.2 (0.01 to 0.7)0.041.00.4 (0.2 to 0.9)0.4 (0.1 to 1.0)0.3 (0.1 to 0.7)0.3 (0.1 to 0.7)0.0061.00.5 (0.2 to 1.3)0.7 (0.3 to 1.8)0.4 (0.1 to 0.9)0.4 (0.1 to 0.8)0.031.00.3 (0.1 to 0.7)0.3 (0.1 to 0.7)0.4 (0.1 to 0.9)0.2 (0.1 to 0.8)0.01