Sodium, acid-base balance, and bone health

 

Salt shakerWe’ve known for years that excessive sodium intake contributes to hypertension, and a new meta-analysis of 13 studies has confirmed that high sodium intake is associated with increased risk of stroke and overall cardiovascular disease.1 Salt consumption is also associated with kidney disease, and a new study suggests that reduced sodium intake could benefit bone health.

Women 45-75 years old with prehyptertension or stage 1 hypertension were assigned to one of two diets.  Both diets supplied the same amount (800 mg) of calcium.  One diet was a high-carbohydrate, low-fat diet.  The other diet was a low-sodium diet (1500 mg), which included red meat but was designed to have a low acid load.2 

Western diets, generally high in animal protein, produce acid in the body, forcing the body to buffer this acid in part by the release of alkalizing salts from bone (e.g. calcium citrate and calcium carbonate) – this is associated with urinary calcium loss and is thought to contribute to osteoporosis. Fruits, vegetables, and legumes have favorable effects on acid-base balance, since the acid-forming effect of their protein content, which is lower than that of animal products anyway, are balanced by their mineral content.3-4

After 14 weeks, the women on both diets increased markers of bone formation and reduced their calcium excretion – those on the low sodium diet had a greater reduction in calcium loss. The authors concluded that this diet was protecting the mineral reserves in bone, and that this could have long-term implications for bone health. Future studies will likely measure bone mineral density and fracture incidence in response to these diets.2

The average daily consumption of sodium for Americans is around 4000mg, almost double the U.S. recommended maximum of 2300mg. The low sodium diet in this study provided a maximum of 1500mg of sodium per day, but included up to six servings of red meat per week, limited the consumption of nutrient-rich legumes to 4-5 per week, and was based on high-calorie, nutrient-poor grain products - 7-8 servings per day.5 The high-carbohydrate low-fat diet was likely based on grain products as well.

Although both of these diets had favorable effects when implemented in place of a standard western diet, they both have room for improvement. By minimizing the high-protein, high-saturated fat animal products, and replacing grain products with mineral- and phytochemical-rich vegetables, fruits, and legumes as the base of the diet, both acid load and sodium would be further reduced, presumably leading to further benefits on bone health.

 

References:

1. Strazzullo P et al. Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies. BMJ 2009;339:b4567

2. Nowson CA et al. The effects of a low-sodium base-producing diet including red meat compared with a high-carbohydrate, low-fat diet on bone turnover markers in women aged 45-75 years. Br J Nutr. 2009 Oct;102(8):1161-70. Epub 2009 May 18.

3. Welch AA et al. Urine pH is an indicator of dietary acid-base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and

Nutrition (EPIC)-Norfolk population study. Br J Nutr. 2008 Jun;99(6):1335-43. Epub 2007 Nov 28.

4. Massey LK. J Nutr. Dietary animal and plant protein and human bone health: a whole foods approach. 2003 Mar;133(3):862S-865S.

5. http://dashdiet.org/

 

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Comments (3) Read through and enter the discussion with the form at the end
Laura - December 8, 2009 4:00 PM

What kind of salt was used in this study? Is there not a difference between conventional table salt and sea salt?

Deana Ferreri - December 8, 2009 5:43 PM

It is a myth that sea salt is healthier than table salt - their sodium contents are the same - and that sodium is no less dangerous in sea salt than it is in table salt. Sea salt does contain slight amounts of trace minerals, but these amounts are insignificant compared to the amounts that can be obtained from plant foods.

Greg Kaler - December 9, 2009 7:02 AM

Great info as usual Dr. Fuhrman. Thank-you! I'm going to work harder than ever at eliminating salt from my diet.

Although there are a small % of exceptions, most people who are now "healthy" will not turn to eating and drinking healthy until they get a diet related disease. Even then most sick people will trust their uneducated doctors and fork out money/take their pills for their afflictions, unaware that pills don't heal. Taking pills for a diet related disease is like putting a band-aid on a cut that never heals. (I think that came from one of your books Dr. Fuhrman).

I'm afraid I have a VERY BLEAK OUTLOOK for the future health of Americans. I see ZILLIONS of unhealthy signs of this all over the country as my job brings me all across the U.S.-to 47 states. In my view the problem is unfixable.
It is so depressing to hear that the main reason our economy is doing as well as it is points to all the money spent on health care!
People who eat and drink unhealthy are like drug addicts, who even if informed, will fail to give up their meat, sugar, etc addictions, and eventually develop a diet related disease/die early.

The great majority of people will never know the wonderful tastes of real food until they give up their unhealthy dietary habits. I have been vegan and 99% processed sugar free since last April. I can tell my tastebuds are very healthy now. Foods have never tasted SO GOOD! The tastes are now incredible! :)

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