Neutralization of Western diet inhibits bone resorption independently of K intake and reduces cortisol secretion in humans

• Published in: American journal of physiology. Renal physiology 2003, Vol.53 (1), p.F32-F40
• Main Authors: MAURER, Marc, RIESEN, Walter, MUSER, Juergen, HULTER, Henry N, KRAPF, Reto
• Format: Article
• Language: English
• Subjects: Acids; Biological and medical sciences; Bones; Diet; Diseases of the osteoarticular system; Fundamental and applied biological sciences. Psychology; Medical sciences; Metabolism; Metabolisms and neurohumoral controls; Osteoporosis; Osteoporosis. Osteomalacia. Paget disease; Potassium; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Water and mineral metabolism. Osmoregulation. Acidobasic balance
• ISSN: 1931-857X; 1522-1466

A Western-type diet is associated with osteoporosis and calcium nephrolithiasis. On the basis of observations that calcium retention and inhibition of bone resorption result from alkali administration, it is assumed that the acid load inherent in this diet is responsible for increased bone resorption and calcium loss from bone. However, it is not known whether the dietary acid load acts directly or indirectly (i.e., via endocrine changes) on bone metabolism. It is also unclear whether alkali administration affects bone resorption/calcium balance directly or whether alkali-induced calcium retention is dependent on the cation (i.e., potassium) supplied with administered base. The effects of neutralization of dietary acid load (equimolar amounts of NaHCO3 and KHCO3 substituted for NaCl and KCl) in nine healthy subjects (6 men, 3 women) under metabolic balance conditions on calcium balance, bone markers, and endocrine systems relevant to bone [glucocorticoid secretion, IGF-1, parathyroid hormone (PTH)/1,25(OH)2 vitamin D and thyroid hormones] were studied. Neutralization for 7 days induced a significant cumulative calcium retention (10.7 plus or minus 0.4 mmol) and significantly reduced the urinary excretion of deoxypyridinoline, pyridinoline, and n-telopeptide. Mean daily plasma cortisol decreased from 264 plus or minus 45 to 232 plus or minus 43 nmol/l (P = 0.032), and urinary excretion of tetrahydrocortisol (THF) decreased from 2,410 plus or minus 210 to 2,098 plus or minus 190 mug/24 h (P = 0.027). No significant effect was found on free IGF-1, PTH/1,25(OH)2 vitamin D, or thyroid hormones. An acidogenic Western diet results in mild metabolic acidosis in association with a state of cortisol excess, altered divalent ion metabolism, and increased bone resorptive indices. Acidosis-induced increases in cortisol secretion and plasma concentration may play a role in mild acidosis-induced alterations in bone metabolism and possibly in osteoporosis associated with an acidogenic Western diet.