Background/Purpose: Interest in niacin has increased in the setting of reports suggesting that niacin plays a role in diseases of aging, including Parkinson’s disease and nonmelanomatous skin cancers. Because niacin regulates NAD-dependent deacetylase Sirtuin 1 expression and decreases inflammation, it plausibly may improve skeletal health. However, experimental studies in chicks suggest that higher niacin intake may result in impaired bone strength. No study to date has examined the association of dietary niacin intake with multiple skeletal health parameters including bone mineral density (BMD), hip fractures, and body composition, and none have included both African-American and Caucasian men and women.

Methods: Participants included 5187 men and women ≥ 65 y from the Cardiovascular Health Study (CHS) who had complete dietary information by FFQ on niacin intake in 1989-1990 and had data collected on incident hip fractures (ascertained from hospital discharge ICD-9 codes 820.xx) from their 1989-90 study visit through June 30, 2013. A subset (n=1336) also underwent Dual Energy X-ray absorptiometry (DXA) measurements of the hip and total body and body composition assessments in 1994-1995. Risk of incident hip fracture per 10 mg increment of daily dietary niacin intake was estimated using Cox regression.

Results: Mean daily dietary niacin intake was 32.6 mg, with quartiles 1 through 4 defined as 3.6-21.8 mg/day, 21.9-30.2 mg/day, 30.3-40.9 mg/day and 41.0-102.4 mg/day, respectively. During a median follow-up of 13 years, 725 participants had an incident hip fracture. The overall incidence rate for hip fractures was 1.08 per 100 person-years (95% CI: 0.91, 1.3). In multivariable-adjusted models adjusted for age, gender, race, clinic site, BMI, cystatin C, diabetes, education, calcium and vitamin D intake, medications associated with osteoporosis, smoking, alcohol, frailty, total energy (kcal/day) and protein intake, higher niacin intake was significantly associated with hip fractures (hazard ratio (HR) 1.12 (95% CI: 1.01, 1.24). In multivariable-adjusted models both the lowest (HR, 1.31; 95% CI, 1.04-1.66) and highest (HR, 1.53; 95% CI, 1.20-1.95) quartiles of niacin intake were associated with an increased risk of incident hip fracture versus quartiles 2 and 3. In multivariable adjusted linear regression models, there was a trend for a significant inverse association of niacin intake with hip BMD (p=0.06). There was no significant association of niacin intake with total body BMD or any measures of body composition.

Conclusion: In this cohort of elderly, community-dwelling African American and Caucasian men and women, both high and low dietary niacin intakes were associated with a significantly increased risk of subsequent hip fracture, suggesting a possible U-shaped association. By comparison, dietary niacin may have an inverse linear association with hip BMD. There may be an optimum intake of dietary niacin (approximately 22-41 mg/day) which does not impair skeletal health.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-of-niacin-intake-with-osteoporosis-the-cardiovascular-health-study/