High vitamin C intake is associated with lower 4-year bone loss in elderly men

Abstract

Vitamin C is essential for collagen formation and normal bone development. We evaluated associations of total, supplemental, and dietary vitamin C intake with bone mineral density (BMD) at the hip [femoral neck, trochanter], spine, and radial shaft and 4-y BMD change in elderly participants from the Framingham Osteoporosis Study. Energy-adjusted vitamin C intakes were estimated from the Willett FFQ in 1988-89. Mean BMD and 4-y BMD change was estimated, for men and women, by tertile/category of vitamin C intake, adjusting for covariates. We tested for interaction with smoking, calcium, and vitamin E intake. Among 334 men and 540 women, the mean age was 75 y and mean vitamin D intake was 8.25 mug/d (women) and 8.05 mug/d (men). We observed negative associations between total and supplemental vitamin C intake and trochanter-BMD among current male smokers (P-trend = 0.01). Among male nonsmokers, total vitamin C intake was positively associated with femoral neck BMD (P-trend = 0.04). Higher total vitamin C intake was associated with less femoral neck and trochanter-BMD loss in men with low calcium (all P-trend </= 0.03) or vitamin E intakes (all P-trend = 0.03). Higher dietary vitamin C intake tended to be associated with lower femoral neck-BMD loss (P-trend = 0.09). These associations were attenuated but retained borderline significance (P-trend < 0.1) after adjusting for potassium intake (a marker of fruit and vegetable intake), suggesting that vitamin C effects may not be separated from other protective factors in fruit and vegetables. Null associations were observed among women. These results suggest a possible protective role of vitamin C for bone health in older men.

FIGURE 1

Flowchart showing total number of subjects enrolled in the Framingham Heart Study and the final number of subjects included in the analyses. 1, Framingham Heart Study; 2, FFQ.

FIGURE 2

Adjusted mean 4-y changes in femoral neck (A), trochanter BMD (B) by tertiles of total vitamin C intake among men stratified by total calcium intake. Low calcium group: total calcium intake < median intake (661 mg/d); high calcium group: total calcium intake > median intake. Models were adjusted for age at exam 20 (y), BMI (kg/m²), height at exam 1 (m), total energy intake (MJ/d), physical activity index at exam 20, alcohol intake (none/moderate: <26.4 g/d of alcohol; high: ≥26.4 g/d of alcohol), smoking (never/former/current smokers), and intake of total vitamin D (µg/d), caffeine (mg/d), and multivitamin use (yes/no). Values are means ± SE, n = 201 (femoral neck) or 193 (trochanter). Analysis was based on a general linear model with Dunnett’s adjustment for multiple comparisons. *Different from T1, P < 0.05.

FIGURE 3

Adjusted mean 4-y changes in femoral neck (A) and trochanter BMD (B) by tertiles of total vitamin C intake among men stratified by total vitamin E intake. Low vitamin E group: total vitamin E intake < median intake (7.7 mg TE/d); high vitamin E group: total vitamin E intake > median intake. Models were adjusted for age at exam 20 (y), BMI (kg/m²), height at exam 1 (m), total energy intake (MJ/d), physical activity index at exam 20, alcohol intake (none/moderate: <26.4 g/d of alcohol; high: ≥26.4 g/d of alcohol), smoking (never/former/current smokers), and intake of total calcium and vitamin D (µg/d), caffeine (mg/d), and multivitamin use (yes/no). Values are means ± SE, n = 201 (femoral neck) or 193 (trochanter). Analysis was based on a general linear model with Dunnett’s adjustment for multiple comparisons.

FIGURE 4

Adjusted mean 4-y changes in femoral neck (A) and trochanter BMD (B) and lumbar spine (C) by tertiles of dietary vitamin C intake among men. Models adjusted for intake of vitamin C from supplements (category 1 = nonsupplement users; category 2 = supplemental vitamin C intake > 0 mg/d but <90 mg/d; category 3 = intake ≥90 mg/d), multivitamin use (yes/no), age at exam 20 (y), BMI (kg/m²), height at exam 1 (m), total energy intake (MJ/d), physical activity index at exam 20, alcohol intake (none/moderate: <26.4 g/d of alcohol; high: ≥26.4 g/d of alcohol), smoking (never/former/current smokers), and intake of total calcium (mg/d), vitamin D (µg/d), and caffeine (mg/d). Values are means ± SE, n = 201 (femoral neck), 193 (trochanter), and 158 (lumbar spine). Analysis was based on a general linear model with Dunnett’s adjustment for multiple comparisons.