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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #218093
Title: Net Endogenous Acid Production (NEAP) and Bone Mineral Density in Men and Women: The Framingham Offspring Study

Author
item MCLEAN, ROBERT - HEBREW SENIOR LIFE, MA
item MCLENNAN, CHRISTINE - HEBREW SENIOR LIFE, MA
item QIAO, NING - JM USDA HNRCA @ TUFTS
item BROE, KERRY - HEBREW SENIOR LIFE, MA
item Tucker, Katherine
item CUPPLES, L - BOSTON UNIVERSITY
item HANNAN, MARIAN - HEBREW SENIOR LIFE, MA

Submitted to: American Society for Bone and Mineral Research
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2007
Publication Date: 9/16/2007
Citation: Mclean, R.R., Mclennan, C.E., Qiao, N., Broe, K.B., Tucker, K., Cupples, L.A., Hannan, M.T. 2007. Net Endogenous Acid Production (NEAP) and Bone Mineral Density in Men and Women: The Framingham Offspring Study. In: American Society for Bone and Mineral Research Annual Meeting, Sept. 16-19, 2007, Honolulu, HI. T309, p S307.

Interpretive Summary:

Technical Abstract: In the short term, bone may buffer excess acid by releasing calcium. It has been proposed that diets high in protein, which have high potential renal acid load, may contribute to low BMD. In contrast, some evidence indicates higher protein intake may be beneficial for bone health, possibly by enhancing calcium absorption. NEAP is the daily amount of net acid produced by the metabolic system and can be estimated using the ratio of average dietary intakes of protein to potassium. We hypothesized that NEAP is directly associated with BMD, but only among individuals with dietary calcium intakes <800 mg/day. We examined the cross-sectional relation between NEAP and BMD among 1287 men and 1581 women (mean age 61 yrs, range 29-86) of the Framingham Offspring Study who completed the Willett food frequency questionnaire between 1996-2001. We also determined whether the association between NEAP and BMD differed by dietary calcium intake. Estimated NEAP (mEq/day) was calculated as [62.1 x protein / potassium (mEq)]-17.9, standardized to 10.46 MJ and adjusted for energy using the residual method. BMDs (g/cm2) of the proximal femur (neck, trochanter) and lumbar spine (L2-L4) were measured using a Lunar DPX-L. Multivariable linear regression was used to calculate the association between NEAP and BMD for men and women separately and within dietary calcium intake groups (<800 mg/day: y/n). Analyses were adjusted for age (yrs), height (in), weight (lbs), smoking (c/f/n), physical activity, daily intakes of alcohol (g), caffeine (mg), dietary vitamin D (IU), dietary calcium (<800 mg: y/n) and total calories (MJ), vitamin D supplement use (y/n), calcium supplement use (y/n), and in women, estrogen use (c/f/n) and menopause status (y/n). Mean NEAP (+/-SD) was 47.4 (14.9) for men and 45.2 (14.5) for women. For both men and women, NEAP was not associated with BMD at the femoral neck (p>/=0.7), trochanter (p>/=0.4) or lumbar spine (p>/=0.1). 65% of men and 61% of women had dietary calcium intake <800 mg/day. NEAP was not associated with BMD at any site among men with calcium intake >/=800 mg/day (p>/=0.5). Among men with calcium intake <800 mg/day, higher NEAP tended to be associated with increased lumbar spine BMD (p=0.06), but not with femoral neck or trochanter BMD (p>/=0.3). NEAP was not associated with BMD among women regardless of dietary calcium intake. Although these cross-sectional results suggest diets with high potential acid load, such as those high in protein, may not contribute to low BMD in community-dwelling men and women, further studies of longitudinal bone loss are needed.