Table 2.

Specificity of Vitamin C in Modifying the Effect of Vitamin E Supplementation on the Mortality of Participants Aged 50–62 Years, Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, 1985–1993

Subgroup	No. of Participants	Vitamin E		No Vitamin E		Risk Ratioa	95% Confidence Interval	Test of Interaction (P Value)
		No. of Deaths	Rateb	No. of Deaths	Rateb
All	24,000	1,292	18.4	1,202	17.0	1.08	1.00, 1.17
Dietary vitamin Cc
<90 mg/day	10,965	614	19.2	616	19.1	1.00	0.90, 1.13	0.048d
≥90 mg/day	11,448	552	16.3	469	13.7	1.19	1.05, 1.35
Residual of fruit, vegetables, and berriese
<0 g/day	11,839	638	18.5	575	16.5	1.11	1.00, 1.25	0.5
≥0 g/day	10,574	528	16.9	510	16.1	1.05	0.93, 1.19
Dietary vitamin Ec
<10 mg/day	9,295	516	19.1	499	18.2	1.05	0.92, 1.19	0.5
≥10 mg/day	13,118	650	16.8	586	15.0	1.11	1.00, 1.25
β-Carotene
No	12,041	617	17.5	567	15.9	1.10	0.98, 1.23	0.7
Yes	11,959	675	19.3	635	18.1	1.06	0.95, 1.19

^aProportional hazards regression model comparing participants who received vitamin E with those who did not.

^bNumber of deaths per 1,000 person-years.

^cInformation on dietary vitamins C and E intake was missing for 1,587 participants, with 126 deaths of vitamin-E and 117 deaths of no-vitamin-E participants.

^dDietary vitamin C as a continuous variable: test for vitamin E interaction, P = 0.011.

^eDifference between an individual's intake and the mean intake with a given dietary vitamin C intake; refer to the Materials and Methods section of the text. Information on fruit, vegetables, and berries intake was missing for 1,587 participants, with 126 deaths of vitamin-E and 117 deaths of no-vitamin-E participants.