Acute effect of poly-gamma-glutamic acid on calcium absorption in post-menopausal women.
OBJECTIVE
Poly-gamma-glutamic acid (PGA) increases calcium (Ca) solubility in vitro and in vivo, and is associated with reduced bone loss in post-menopausal Japanese women. This study is the first to examine the effect of PGA on Ca absorption in humans.


METHODS
A single-blind, randomized, crossover study with a 3-4 week wash-out was performed to determine the effect of PGA (80.6% glutamic acids) on Ca absorption measured by the double stable isotope method. Twenty-four healthy, non-smoking, postmenopausal women (mean age: 56.4 +/- SE 0.9) were given 200 g of orange juice containing 200 mg Ca as Ca-44 enriched CaCO(3), with or without 60 mg of PGA, after an overnight fast. The two tests were separated by 3-4 weeks. An intravenous injection of Ca-42 (CaCl(2) solution) was given 30 min after consuming the drink and a complete urine collection carried out from 24-48 h post-dosing. Ca absorption was calculated from the Ca isotope ratios measured by thermal ionization quadrupole mass spectrometry (TIQMS).


RESULTS
Mean Ca absorption with PGA was significantly higher (P < 0.01) than without PGA, 39.1 (SE 1.6) % and 34.6 (SE 1.9) %, respectively. The effect of PGA on increasing Ca absorption was more marked in a sub-group of subjects whose baseline Ca absorption (without PGA) was lower than the population mean value.


CONCLUSIONS
Postmenopausal women who received a single dose of PGA increased their intestinal Ca absorption particularly those individuals with lower basal absorptive capacity.
Tanimoto
Hiroyuki
H
Institute of Food Research, Norwich Research Park, Colney, UK. hiroyuki_tanimoto@ajinomoto.com
Fox
Tom
T
Eagles
John
J
Satoh
Hitoshi
H
Nozawa
Hiroko
H
Okiyama
Atsushi
A
Morinaga
Yasushi
Y
Fairweather-Tait
Susan J
SJ
D002118:Calcium / Q000493:pharmacokinetics*; D002127:Calcium Isotopes; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007408:Intestinal Absorption / Q000187:drug effects*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000517:prevention & control; D011099:Polyglutamic Acid / Q000494:pharmacology*; D017698:Postmenopause
D002127:Calcium Isotopes; D011099:Polyglutamic Acid; D002118:Calcium