Table 1.

Characteristics of cohort at baseline by quintiles of serum folate concentration, Third National Health and Nutrition Examination Survey Linked Mortality File 1988-2000

Total populationQuintiles of serum folate concentration (ng/mL)*
P for trend
<3.03.0-<4.34.3-<6.16.1-<9.4≥9.4
Serum folate geometric mean in ng/mL (SE)5.4 (0.12)2.2 (0.02)3.6 (0.01)5.1 (0.01)7.5 (0.02)14.2 (0.17)<0.001
Number of cancer deaths4036299858671
Person-years of follow-up125,17925,24030,60226,02322,96720,346
Mean age in y (SE)44.2 (0.47)38.9 (0.37)40.9 (0.43)43.7 (0.58)45.8 (0.65)51.3 (0.76)<0.001
% male (95% CI)48.4 (47.4-49.3)54.7 (50.5-56.8)52.1 (49.5-54.7)50.3 (47.6-52.9)46.7 (44.0-49.5)39.4 (36.5-42.3)<0.001
Race or ethnicity, % (95% CI)
    Non-Hispanic white76.6 (74.0-79.0)71.7 (68.5-74.7)71.4 (67.5-75.0)73.8 (70.3-77.0)79.2 (75.3-82.7)86.3 (83.5-88.7)
    Non-Hispanic black or African American10.5 (9.4-11.8)15.6 (13.6-17.9)12.8 (11.1-14.7)10.9 (9.6-12.4)8.4 (7.1-9.9)5.4 (4.5-6.4)
    Hispanic American5.2 (4.4-6.2)6.2 (5.2-7.5)6.8 (5.7-8.1)5.9 (4.9-7.0)4.5 (3.6-5.6)2.7 (2.0-3.7)
    Others7.7 (6.2-9.5)6.5 (5.0-8.4)9.0 (6.7-12.0)9.4 (7.1-12.5)7.9 (5.8-10.8)5.6 (4.0-7.9)<0.001
Years of education, % (95% CI)
    <1224.2 (22.2-26.3)28.4 (25.3-31.8)26.6 (24.0-29.3)24.3 (21.0-27.9)22.7 (19.9-25.8)19.4 (16.7-22.3)
    12-1554.6 (52.9-56.2)56.4 (53.9-59.0)56.9 (53.8-59.8)55.5 (51.9-59.0)52.3 (49.2-55.4)52.0 (48.5-55.5)
    >1521.2 (19.5-23.1)15.2 (12.6-18.3)16.7 (14.3-19.3)20.2 (17.7-23.1)25.0 (21.9-28.3)28.6 (25.2-32.4)<0.001
Smoking status, % (95% CI)
    Never46.2 (44.6-47.8)38.3 (35.3-41.3)41.7 (38.6-45.0)47.1 (43.5-50.7)49.5 (46.1-52.8)53.9 (51.0-56.7)
    Former25.2 (23.9-26.6)17.1 (14.9-19.6)22.1 (19.2-25.3)26.6 (23.8-29.5)27.6 (25.3-30.0)32.2 (29.7-34.8)
    Current28.6 (26.8-30.4)44.6 (41.5-47.8)36.1 (32.5-39.9)26.4 (23.7-29.2)22.9 (20.6-25.4)13.9 (11.8-16.3)<0.001
Alcohol intake in drinks/wk, % (95% CI)
    None46.5 (43.6-49.3)45.5 (41.7-49.0)42.9 (39.8-46.1)45.8 (42.3-49.2)45.6 (41.2-50.0)52.5 (48.0-56.9)
    <326.6 (25.0-28.2)27.1 (24.5-29.8)26.3 (23.4-29.5)26.3 (23.5-29.2)27.9 (24.6-31.5)25.5 (21.9-29.5)
    ≥3-<712.2 (11.0-13.5)12.9 (10.3-16.1)13.1 (11.0-15.6)12.4 (10.7-14.2)11.6 (9.7-13.8)10.9 (8.6-13.5)
    ≥714.7 (13.4-16.2)14.2 (12.4-16.3)17.7 (14.9-20.7)15.5 (13.5-17.8)14.9 (12.5-17.7)11.2 (9.2-13.5)0.001
NSAID use, % (95% CI)
    None42.6 (41.3-43.8)44.4 (41.8-47.0)43.9 (41.2-46.5)42.9 (39.7-46.2)41.9 (38.4-45.5)39.9 (36.8-43.1)
    Irregular (<15 times in last mo)38.0 (36.4-39.7)38.3 (35.2-41.4)40.4 (37.6-43.2)38.7 (34.9-42.7)38.7 (35.5-42.1)34.0 (30.6-37.6)
    Regular (≥15 times in last mo)19.4 (18.1-20.8)17.4 (15.2-19.7)15.8 (13.7-18.1)18.4 (16.4-20.7)19.4 (17.0-21.9)26.1 (23.2-29.2)0.001
Mean BMI in kg/m2 (SE)26.6 (0.12)27.5 (0.25)26.7 (0.15)26.7 (0.18)26.2 (0.23)25.7 (0.18)0.02
Physical activity in times/wk, % (95% CI)
    None21.6 (19.7-23.6)26.6 (23.8-29.5)23.0 (20.2-26.0)21.6 (19.0-24.5)19.7 (17.0-22.8)17.5 (15.0-20.4)
    <5/wk35.3 (33.9-36.8)36.0 (32.9-39.3)39.3 (36.3-42.5)35.2 (32.4-38.1)34.6 (31.3-38.0)31.6 (29.0-34.3)
    ≥5/wk43.1 (40.9-45.3)37.5 (34.1-41.0)37.7 (34.3-41.2)43.1 (40.3-46.1)45.7 (41.9-49.6)50.9 (47.7-54.1)<0.001
Total energy intake geometric mean in kcal/d (SE)1,971 (17.1)2,058 (26.8)2,050 (28.8)1,975 (28.1)1,923 (31.7)1,863 (32.7)<0.001
Food folate intake geometric mean in μ/d (SE)230 (2.3)175 (3.1)204 (4.1)228 (4.2)256 (5.6)298 (6.0)<0.001
Folic acid supplement users (%)29.3 (27.7-30.9)10.6 (8.8-12.7)14.3 (12.0-17.0)18.3 (16.2-20.6)33.9 (30.5-37.5)67.7 (65.0-70.2)<0.001
Healthy Eating Index (SE)§63.6 (0.29)58.5 (0.38)60.7 (0.34)63.4 (0.37)65.8 (0.34)69.6 (0.43)<0.001
  • * Mean and SE for continuous variables, and % and 95% CI for categorical variables presented by quintiles of serum folate concentration.

  • P value for difference across quintiles of serum folate concentrations based on ANOVA for continuous variables and χ2 test for categorical variables; all tests two-tailed.

  • Regular users (≥15 times in last mo) included all users of prescription NSAIDs.

  • § HEI is a score that ranges from 0 to 100 and contains information on the consumption of 10 subcomponents of the diet: grains, fruits, vegetables, dairy, meats, fats, saturated fat, cholesterol, sodium, and dietary variety. A higher score is indicative of a healthier eating pattern.