Table 1.

Age-adjusted variables by quintiles of caffeine intake in the NHS and HPFS

Caffeine intake per day in NHS (quintile median)Caffeine intake per day in HPFS (quintile median)
Q1Q2Q3Q4Q5Q1Q2Q3Q4Q5
Characteristics31 mg (N = 14,586)122 mg (N = 14,589)232 mg (N = 14,597)372 mg (N = 14,566)604 mg (N = 14,583)8 mg (N = 8,146)59 mg (N = 7,895)154 mg (N = 7,951)321 mg (N = 8,010)584 mg (N = 7,974)
Age (1986), ya52.7 (7.4)52.7 (7.3)52.6 (7.2)52.6 (7.0)51.9 (6.9)54.5 (10.0)53.5 (9.9)54.1 (9.9)53.3 (9.6)52.4 (8.9)
BMI (1986), kg/m225.8 (5.2)25.5 (4.9)25.3 (4.8)25.1 (4.5)24.9 (4.5)25.1 (3.3)25.6 (3.4)25.6 (3.4)25.7 (3.5)25.8 (3.3)
Physical activity (1986), met-h/wkb15.1 (19.4)14.4 (20.0)14.1 (19.2)13.6 (20.0)12.5 (20.2)22.6 (29.1)21.9 (33.1)20.7 (27.4)19.7 (25.5)18.4 (30.0)
Current smoker (1986), %11151822385681117
Family history of melanoma, %3333333333
Number of sun burns 6+, %50515252513335343536
Number of moles on the left arm 6+, %5555455555
Tanning ability, %30313130312121202123
Red or blonde hair, %15161516161413121414
College/high school sun exposure 11+ h, %13141414155051485149
Age 25–35 sun exposure 11+ h, %12131314143132313332
Age 36–59 sun exposure 11+ h, %9101010102626272928
Age 60+ sun exposure 11+ h, %787882527252927
At Birth UV index ≥7, %1191010112325252728
Age 15 UV index ≥7, %1191010112426262829
Age 30 UV index ≥7, %15131415152731303333

NOTE: Values are means (SD) or percentages and are standardized to the age distribution of the study population.

  • aValue is not age adjusted.

  • bMetabolic equivalents from recreational and leisure-time activities.