The DASH diet and sodium reduction improve markers of bone turnover and calcium metabolism in adults.
Dietary strategies to prevent and treat osteoporosis focus on increased intake of calcium and vitamin D. Modification of whole dietary patterns and sodium reduction may also be effective. We examined the effects of two dietary patterns and three sodium levels on bone and calcium metabolism in a randomized feeding study. A total of 186 adults, aged 23-76 y, participated. After a 2-wk run-in period, participants were assigned randomly to diets containing three levels of sodium (50, 100 and 150 mmol/d) to be consumed for 30 d in random order. Serum osteocalcin (OC), C-terminal telopeptide of type I collagen (CTX), fasting serum parathyroid hormone (PTH), urinary sodium, potassium, calcium and cAMP were measured at baseline and at the end of each sodium period. The Dietary Approaches to Stop Hypertension (DASH) diet reduced serum OC by 8-11% and CTX by 16-18% (both P < 0.001). Urinary calcium excretion did not differ between subjects that consumed the DASH and control diets. Reducing sodium from the high to the low level significantly decreased serum OC 0.6 microg/L in subjects that consumed the DASH diet, fasting serum PTH 2.66 ng/L in control subjects and urinary calcium 0.5 mmol/24 h in both groups. There were no consistent effects of the diets or sodium levels on urinary cAMP. In conclusion, the DASH diet significantly reduced bone turnover, which if sustained may improve bone mineral status. A reduced sodium intake reduced calcium excretion in both diet groups and serum OC in the DASH group. The DASH diet and reduced sodium intake may have complementary, beneficial effects on bone health.
Lin PH, Ginty F, Appel LJ, Aickin M…
J. Nutr. Oct 2003
PMID: 14519796 | Free Full Text
Negative balance of calcium and magnesium under relatively low sodium intake in humans.
The balance of minerals (sodium [Na], potassium [K], calcium [Ca], and magnesium [Mg]) was measured in six female students for 10 d while under a relatively low Na intake (100 mmol/d or 2.2 g/d) with receiving adequate Ca (20 mmol/d or 800 mg/d) and Mg (12 mmol/d or 280 mg/d). Both the plasma renin activity (PRA) and aldosterone level were above the reference ranges throughout the experiment, which implied that the subjects were Na deficient. However, the urine Na excretion was about the same as that ingested, while there was no substantial reduction of sweat Na concentration observed during moderate physical exercise (13.2+/-2.6 mmol/L) (mean+/-SD). On the other hand, the urine Ca and Mg levels were high, but the apparent absorption of Ca and Mg was moderate (21 +/- 5%, 34 +/- 4%, respectively), which resulted in a negative balance of these two elements. It seems that the stored Na in the bone is eluted so as to compensate for the low dietary Na intake, while any excess Ca and Mg also inevitably flows into the blood stream with Na, which inhibited the intestinal absorption of both Ca and Mg and accelerates their excretion in urine.
Kodama N, Nishimuta M, Suzuki K
J. Nutr. Sci. Vitaminol. Jun 2003
Dietary sodium and bone mineral density: results of a 16-year follow-up study.
It has been proposed that high dietary sodium intake, resulting in a sodium-mediated increase in renal calcium excretion, is a risk factor for osteoporosis. To evaluate the relationship between dietary sodium intake and bone mineral density (BMD), a prospective study of the Rancho Bernardo cohort was performed. A 24-hour diet recall was done for the period 1973 through 1975; follow-up bone mineral density of the ultradistal radius, midradius, total hip, and spine was measured between 1988 and 1991. Covariates were ascertained by self-report and examination at baseline. Multivariable analysis of the sodium-BMD association was performed using gender and menopause-specific linear regressions.
All subjects were white. At the bone evaluation, there were 258 women (average age 73.3 years) and 169 men (average age 72.4 years). In both men and women, higher levels of sodium intake were strongly associated with higher levels of calcium intake and total calories. Body mass index increased with sodium quartile in women, while a modest negative association was seen in men. In women, after age adjustment, positive associations between dietary sodium and bone density were found at the ultradistal radius (beta = 0.01, P = 0.03) and the total hip (beta = 0.019, P = 0.02). BMD increased by 0.01 to 0.02 g/cm2 per gram increase in sodium ingested. After adjustment for estrogen use, body mass, dietary calcium, alcohol, and total calories, these effects were no longer significant. Similar patterns were seen in pre- and postmenopausal women. In men, age and multivariate-adjusted BMD increased with higher sodium intake at the ultradistal radius only (beta = 0.013, P = 0.05). Stratification by gender-specific median calcium level did not significantly effect the results.
After control for confounders, a small, statistically significant protective effect of sodium was found at the ultradistal radius in men only. At other sites in women and men, no effect of sodium on BMD was apparent in the multivariable models. These results do not support a detrimental effect of dietary sodium on bone mineral density. Rather, the findings suggest that sodium intake, in the range measured, is not a major osteoporosis risk factor.
Greendale GA, Barrett-Connor E, Edelstein S, Ingles S…
J Am Geriatr Soc Oct 1994