Bill Sickert

QUESTION: My Chiropractor discusses my diet and a concept called acidosis as it related to my medical diagnosis of calcium and bone loss. Has there been any research or documentation by the medical community in support of what my chiropractor said? Karen B. Birch Bay, Washington.
Karen the clinical aptitude of your chiropractor is a testament to the profession and please share the more technical answer and clinical references with the chiropractor on your next visit. The advice is both accurate and well supported in the medical literature.
Calcium in the form of phosphates and carbonates represents a large reservoir of base in our body. In response to an acid load such as the modern diet these salts are released into the systemic circulation to bring about pH homeostasis. It has been estimated that the quantity of calcium lost in the urine with the modern diet over time could be as high as almost 480 gm over 20 years or almost half the skeletal mass of calcium [1]. However, urinary losses of calcium are not a direct measure of osteoporosis. There are many regulatory factors that may compensate for the urinary calcium loss. When the arterial pH is in the normal range, a mild reduction of plasma bicarbonate results in a negative calcium balance which could benefit from supplementing bicarbonate in the form of potassium bicarbonate [2]. It has been found that bicarbonate, which increases the alkali content of a diet, but not potassium may attenuate bone loss in healthy older adults [3]. The bone minerals that are wasted in the urine may not have complete compensation through intestinal absorption, which is thought to result in osteoporosis. However, adequate vitamin D with a 25(OH)D level of >80 nmol/L may allow for appropriate intestinal absorption of calcium and magnesium and phosphate when needed [4]. Sadly, most populations are generally deficient in vitamin D especially in northern climates [5]. In chronic renal failure, correction of metabolic acidosis with bicarbonate significantly improves parathyroid levels and levels of the active form of vitamin D 1,25(OH)2D3 [6]. Recently, a study has shown the importance of phosphate in Remer’s PRAL formula. According to the formula it would be expected that an increase in phosphate should result in an increase in urinary calcium loss and a negative calcium balance in bone [7]. It should be noted that supplementation with phosphate in patients with bed rest reduced urinary calcium excretion but did not prevent bone loss [8]. The most recent systematic review and meta-analysis has shown that calcium balance is maintained and improved with phosphate which is quite contrary to the acid-ash hypothesis [9]. As well a recent study looking at soda intake (which has a significant amount of phosphate) and osteoporosis in postmenopausal American first nations women did not find a correlation [10]. It is quite possible that the high acid content according to Remer’s classification needs to be looked at again in light of compensatory phosphate intake. There is online information promoting an alkaline diet for bone health as well as a number of books. However, a recent systematic review of the literature looking for evidence supporting the alkaline diet for bone health found no protective role of dietary acid load in osteoporosis [11].
Another element of the modern diet is the excess of sodium in the diet. There is evidence that in healthy humans the increased sodium in the diet can predict the degree of hyperchloremic metabolic acidosis when consuming a net acid producing diet [12]. As well, there is evidence that there are adverse effects of sodium chloride in the aging population. A high sodium diet will exacerbate disuse-induced bone and muscle loss during immobilization by increasing bone resorption and protein wasting [13]. Excess dietary sodium has been shown to result in hypertension and osteoporosis in women [14, 15]. As well, dietary potassium which is lacking in the modern diet would modulate pressor and hypercalciuric effects of excess of sodium chloride [16].
Excess dietary protein with high acid renal load may decrease bone density if not buffered by ingestion of supplements or foods that are alkali rich [17]. However, adequate protein is necessary for prevention of osteoporosis and sarcopenia; therefore, increasing the amount of fruit and vegetables may be necessary rather than reducing protein (18).
REFERENCES
1. Fenton TR, Eliasziw M, Lyon AW, Tough SC, Hanley DA. Meta-analysis of the quantity of calcium excretion associated with the net acid excretion of the modern diet under the acid-ash diet hypothesis. American Journal of Clinical Nutrition. 2008;88(4):1159–1166. [PubMed]
2. Sebastian A, Morris RC., Jr. Improved mineral balance and skeletal metabolism in postmenopausal women treated with potassium bicarbonate. New England Journal of Medicine. 1994;331(4):p. 279. [PubMed]
3. Dawson-Hughes B, Harris SS, Palermo NJ, Castaneda-Sceppa C, Rasmussen HM, Dallal GE. Treatment with potassium bicarbonate lowers calcium excretion and bone resorption in older men and women. Journal of Clinical Endocrinology and Metabolism. 2009;94(1):96–102. [PubMed]
4. Heaney RP, Dowell MS, Hale CA, Bendich A. Calcium absorption varies within the reference range for serum 25-hydroxyvitamin D. Journal of the American College of Nutrition. 2003;22(2):142–146. [PubMed]
5. Schwalfenberg GK, Genuis SJ, Hiltz MN. Addressing vitamin D deficiency in Canada: a public health innovation whose time has come. Public Health. 2010;124(6):350–359. [PubMed]
6. Lu KC, Lin SH, Yu FC, Chyr SH, Shieh SD. Influence of metabolic acidosis on serum 1,25(OH)2D3 levels in chronic renal failure. Mineral and Electrolyte Metabolism. 1995;21(6):398–402. [PubMed]
7. Fenton TR, Lyon AW, Eliasziw M, Tough SC, Hanley DA. Phosphate decreases urine calcium and increases calcium balance: a meta-analysis of the osteoporosis acid-ash diet hypothesis. Nutrition Journal. 2009;8, article 41 [PubMed]
8. Hulley SB, Vogel JM, Donaldson CL, Bayers JH, Friedman RJ, Rosen SN. The effect of supplemental oral phosphate on the bone mineral changes during prolonged bed rest. Journal of Clinical Investigation. 1971;50(12):2506–2518. [PubMed]
9. Fenton TR, Lyon AW, Eliasziw M, Tough SC, Hanley DA. Meta-analysis of the effect of the acid-ash hypothesis of osteoporosis on calcium balance. Journal of Bone and Mineral Research. 2009;24(11):1835–1840. [PubMed]
10. Supplee JD, Duncan GE, Bruemmer B, Goldberg J, Wen Y, Henderson JA. Soda intake and osteoporosis risk in postmenopausal American-Indian women. Public Health Nutrition. 2011:1–7. [PubMed]
11. Fenton TR, Tough SC, Lyon AW, Eliasziw M, Hanley DA. Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill’s epidemiologic criteria for causality. Nutrition Journal. 2011;10(1, article 41) [PMC free article] [PubMed]
12. Frassetto LA, Morris RC, Jr., Sebastian A. Dietary sodium chloride intake independently predicts the degree of hyperchloremic metabolic acidosis in healthy humans consuming a net acid-producing diet. American Journal of Physiology—Renal Physiology. 2007;293(2):F521–F525. [PubMed]
13. Frings-Meuthen P, Buehlmeier J, Baecker N, et al. High sodium chloride intake exacerbates immobilization-induced bone resorption and protein losses. Journal of Applied Physiology. 2011;111(2):537–542. [PubMed]
14. Cappuccio FP, Meilahn E, Zmuda JM, Cauley JA. High blood pressure and bone-mineral loss in elderly white women: a prospective study. Lancet. 1999;354(9183):971–975. [PubMed]
15. Devine A, Criddle RA, Dick IM, Kerr DA, Prince RL. A longitudinal study of the effect of sodium and calcium intakes on regional bone density in postmenopausal women. American Journal of Clinical Nutrition. 1995;62(4):740–745. [PubMed]
16. Morris RC, Jr., Schmidlin O, Frassetto LA, Sebastian A. Relationship and interaction between sodium and potassium. Journal of the American College of Nutrition. 2006;25(3):262S–270S. [PubMed]
17. Barzel US, Massey LK. Excess dietary protein may can adversely affect bone. Journal of Nutrition. 1998;128(6):1051–1053. [PubMed]
18. Heaney RP, Layman DK. Amount and type of protein influences bone health. American Journal of Clinical Nutrition. 2008;87(5):156S–157S. [PubMed]