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Exchangeable zinc pool mass (EZP) and fat free mass (FFM) in healthy elderly
Author(s) -
Chung Carolyn,
Montelius Lynn,
Nguyen Tuan,
Stookey Jodi,
Dare Doris,
Yamamoto Vera,
King Janet
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a721-a
Subject(s) - chemistry , urine , zinc , endocrinology , medicine , zoology , fat free mass , albumin , urinary system , body weight , fat mass , organic chemistry , biology
Zn intake and metabolism are altered in elderly individuals. The mass of combined pools of Zn that exchange with plasma within 2d are lower in late middle aged adults. This decline in EZP with age may reflect FFM loss. We determined the relationship between EZP, body weight (wt), FFM, and Zn status markers (serum albumin and alkaline phosphatase (AP), and urinary zinc) in 8 healthy elderly, 5 women and 3 men. All were fed a diet containing the Zn estimated average requirement (EAR) or the EAR + 40% for 2 wks. On d9, 1.6 mg of 67 Zn tracer was given IV. Urine collected d 3–5 after infusion was analyzed by ICPMS for 67:66 Zn ratios and by ICP for total Zn. EZP equaled the 67 Zn dose divided by the tracer/tracee value at the y intercept of the linear regression of a semi‐log plot of the urine tracer/tracee data. Body wt, FFM (DXA), albumin, and AP were measured on the day of infusion. EZP correlated significantly with body wt and FFM (r = 0.93 and 0.91), as expected as the skeletal muscle contains 60% of body Zn. Men had 32% and 35% greater EZP and FFM than women, respectively. When EZP was adjusted for kg body wt and kg FFM, there was no difference between sexes. As in younger adults, EZP mass is related to body wt and FFM in the elderly, and the amount of EZP/kg FFM is similar to that reported for younger adults. EZP per kg FFM is a valid measure of Zn status that corrects for differences in body composition. Supported by USDA NRI 2004‐01842 and NIH MO1‐RR00083‐43.