This topic came up in the current 10 day program, so I bumped this thread up so it easy for them to find and am adding in a few more comments.
From the following CPE course, written by my colleague, Jay Kenney, PhD, RD
http://www.foodandhealth.com/cpecourses ... orosis.phpDietary Salt Increases Bone Loss
One of the most important factors contributing to an increased loss of calcium in the urine and the development of osteoporosis has been widely ignored by most clinicians and the mass media. The scientific evidence is very consistent that excessive intake of dietary salt greatly increases the loss of calcium in the urine. Increased salt intake has also been associated with reduced peak bone mass and a more rapid loss of BMD in older people. It is hard to escape the conclusion that the amount of salt added to commercial foods and at home in all modern societies must play a major role in the development of ostepenia and eventually osteoporosis. It seems likely that dramatically reducing dietary salt would help prevent many broken bones in America every year. One must increase the intake of dietary calcium by approximately 1000 mg daily to prevent bone loss in postmenopausal women who are ingesting an extra 2000 mg of sodium as salt daily. Results of a longitudinal study suggested that reducing dietary sodium excretion by 50% (from 3450 to 1725 mg/d) would be as effective in slowing the loss of bone as increasing dietary calcium by 891 mg/d.
A study in New Zealand showed that there was a progressive increase in urinary calcium excretion as dietary salt intake increased from 70 to 220 mmol/d (or about 1600 to 5000 mg of sodium). Data from this study suggested that reducing dietary sodium from 5000 to 1600 mg daily would reduce the loss of calcium in the urine by 32% in men and 27% in women. Simply put, the more salt you eat, the more calcium you'll excrete.
However, it should be noted that the problem with increased urinary excretion of calcium with increased dietary salt is not caused by the sodium ion alone. Even 5500 mg of sodium when given as either sodium citrate or sodium bicarbonate did not increase urinary calcium excretion as sodium chloride does. Using low-sodium baking powder (which contains potassium bicarbonate) in place of regular baking powder (which contain sodium bicarbonate) will also help to reduce urinary calcium excretion and presumably also the loss of BMD.
It has been shown that both a lack of calcium and/or an excess of salt in the diet leads to a reduction in bone density in young females. In postmenopausal women, an increase in dietary salt has been shown to increase urinary calcium excretion and lead to an increased loss of bone minerals. While increased dietary phosphate can blunt the increased calcium excretion caused by a high protein intake, increased dietary phosphate has no impact on the increased excretion of calcium caused by adding more salt to the diet.
An excessive intake of dietary salt is the primary causal factor in the development of essential hypertension. High blood pressure is also associated with increased bone loss in elderly white women. While there is no prospective human data on the long-term impact of reducing dietary salt on BMD, the data showing a strong correlation between urinary sodium and both urinary calcium and urinary hydroxyproline (a marker for bone loss) certainly suggests that the unnaturally high intake of salt in all modern human populations plays a major role in the development of osteoporosis. Because older Americans will develop either high blood pressure, osteoporosis or both it is perplexing that the media and most health professionals do not more strongly encourage people to reduce their salt intake. A low salt intake combined with a diet higher in fruits, vegetables, whole grains and nonfat dairy products (DASH-style diet) should slow the loss of bone mineral density as people age by improving bone metabolism.
Low-Sodium DASH Diet Improves Bone Metabolism
Epidemiological studies have found that people who consume more fruits and vegetables tend to have stronger bones. [New SA, Robins SP, Campbell MK, et al. Dietary influences on bone mass and bone metabolism: further evidence of a positive link between fruit and vegetable consumption and bone health? Am J Clin Nutr 2000; 71:142-51]. In addition numerous studies have shown that increasing dietary salt intake leads to an increased loss of calcium in the urine and an increased serum parathyroid hormone level. [Massey L, Whiting S. Dietary salt, urinary calcium and bone loss. J Bone Miner Res 1996;11:731-6 ]. In theory, it seems likely that combining a DASH-style diet with a low sodium intake should improve bone metabolism and may help prevent the development of osteoporosis.
A recent studied examined the combined impact of either the DASH diet versus a more conventional American diet each fed with 3 different levels of dietary sodium intake. The DASH- Sodium trial enabled researchers to examine the impact of 3 different levels dietary salt (50, 100 & 150mmol of Sodium/day) with either a typical American diet or with the DASH diet. Compared to a typical Americican diet the DASH diet contains more whole grains, fruits, vegetables and low-fat dairy products and less meat and other foods high in saturated fat as well as less sugar and refined carbohydrates. This new study specifically examined the individual and combined impact of different levels sodium intake and consuming the DASH diet on bone metabolism. Switching from a typical American diet to the DASH diet resulted in about a 10% reduction in osteocalcin, a hormone associated with more rapid breakdown of bone. Another marker of bone breakdown called C-terminal telopeptide of type 1 collagen (CTX) was also about 16-18% lower on the DASH diet than the more typical American diet. However, urinary calcium loss was not significantly increased on the American diet compared to the DASH diet. Increasing dietary sodium (as salt) was associated with a greater loss of calcium in the urine on both the DASH diet and the more typical American diet. Urinary calcium excretion was increased somewhat more on the typical American diet than on the DASH diet. Calcium excretion was also increased significantly more with increasing dietary salt in subjects with high blood pressure compared to those who were normotensive. The authors of this study conclude, “…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 osteocalcin in the DASH group. The DASH diet and reduced sodium intake may have complementary, beneficial effects on bone health.” [Pao-HWA L, Ginty F, Appel LJ, et al. The DASH diet and sodium reduction improve markers of bone turnover and calcium metabolism in adults. J Nutr 2003;133:3130-6]. Given the fact that most older Americans have or will soon develop hypertension and that most are also at risk of developing osteoporosis it seems prudent to encourage all older Americans to adopt a low-sodium DASH-style diet.
Massey LK, Whiting SJ. Dietary salt, urinary calcium, and bone loss. J Bone Miner Res 1996;11:731-6
Devine A, Criddle RA, Dick IM, et al. A longitudinal study of the effect of sodium and calcium intakes on regional bone density in postmenopausal women. Am J Clin Nutr 1995;62:740-5
Goulding A. Fasting urinary sodium/creatinine in relation to calcium/creatinine and hydroxyproline/creatinine in a general population of women NZ Med J 1981;93:294-7 and Goulding A. Osteoporosis: why consuming less sodium chloride helps conserve bone. NZ Med J 1990;103:120-2
Lemann J, Gray RW, Pleuss JA. Potassium bicarbonate, but not sodium bicarbonate, reduces urinary calcium excretion and improves calcium balance in healthy men. Kidney Int 1989;35:688-95
Kurtz TW, Al-Bander HA, Morris RC. Salt sensitive essential hypertension in men. Is the sodium ion alone important? N Engl J Med 1987;317:1043-8
Matkovic V, Illich JZ, Andon MB, et al. Urinary calcium, sodium, and bone mass in young females. Am J Clin Nutr 1995;62:417-25
Zarkadas M et al. Sodium Chloride supplementation and urinary calcium excretion in postmenopausal women. Am J Clin Nutr 1989;50:1088-94
Devine A, Criddle RA, Dick IM, et al. A longitudinal study of the effect of sodium and calcium intakes on regional bone density in postmenopausal women. Am J Clin Nutr 1995;62::740-5
Whiting SJ, Anderson DJ, Weeks SJ. Calciuric effects of protein and potassium bicarbonate but not sodium chloride or phosphate can be detected acutely in adult women and men. Am J Clin Nutr 1997;65:1465-72
Kenney JJ. Salt: Has it been given a fair shake? Or is it a serial killer?
http://www.foodandhealth.com/cpecourses/salt.htm Cappacino FP, Meilahn E, Zmuda JM, et al. High blood pressure and bone-mineral loss in elderly white women: A prospective study. Lancet 1999;354:971-5
Jones G, Beard T, Parameswaren V, et al. A population-based study of the relationship between salt intake, bone resorption and bone mass. Eur J Clin Nutr 1997;51:561-65
In addition, excess salt is about more then just blood pressure and bone health, it has been linked with;
- Stroke and cardiovascular disease.
- Left ventricular hypertrophy
- Duodenal ulcers and gastric ulcers
- GERD
- Heartburn
- Headaches
- Osteoporosis
- Gastric cancer
- Arteriosclerosis
- Angina
- immune dysfunction
- endothelial dysfunction
In Health
Jeff