January 2003

Vol. 2   No. 1

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The Right Diet Will Save Your Bones

Two recent publications clearly demonstrate the effects of diet on bone health (osteoporosis) and kidney stone formation.  On the destructive side, research from the University of Chicago looked at the effects of the high protein Atkins diet on calcium balance.1 Data was collected for 2 weeks of the Atkins induction diet and 4 weeks on the maintenance diet.  The induction diet contained 164 grams of protein a day and the maintenance 170 grams/day.  The Atkins diet produced an acid load, because animal proteins are high in sulfur-containing amino acids, which break down into very potent sulfuric acid.2 Dietary acids must be buffered to prevent an acidic build-up in the body.  The bones provide the alkaline materials to neutralize the acids.  The end result was a large increase in calcium loss into the urine caused by the breakdown of bone materials.  (The calcium balances decreased by 130 mg/day and 90 mg/day, respectively on the two phases of the diet).  Markers of bone resorption increased, suggesting loss of bone during this short 6 week trial.  Eventually, chronic calcium loss results in osteoporosis.  The large amount of calcium in the urine, along with other changes produced by a diet high in animal proteins, is a setup for calcium-based kidney stones.  Over 95% of kidney stones in Western societies are made primarily of calcium.

On the constructive side, a study from the University of Applied Sciences in Germany examined vegans (on an all vegetable-foods diet with no animal protein) and found them to be in positive calcium balance – more calcium entered the body than left.3  The balance was a positive 119 mg/day.  There were no changes in markers of bone resorption, suggesting the bones were not breaking down.  The vegans consumed an average of 843 mg of calcium a day from their foods and calcium-rich mineral water.

These effects of animal protein on bone health are not limited to only 2 weeks as has been claimed by some poorly informed people (such as Robert Atkins claiming that the calcium losing effects of his diet are limited to 2 weeks, on the January 6, 2002 Larry King Live CNN-TV Show), but continues as long as the person’s diet is high in protein.1,4  Therefore, to save your skeleton and prevent kidney stones, you need to follow a (vegan) diet based on starches, vegetables, and fruits; and limit rich foods to special events, such as turkey for Thanksgiving and fish for a special night out.  Bone loss is reversible,5 and there is every reason to believe that with a healthy starch-based diet and exercise the skeleton will become stronger and the possibility of fractures will be lowered.

References:

1)  Reddy ST. Effect of low-carbohydrate high-protein diets on acid-base balance, stone-forming propensity, and calcium metabolism.  Am J Kidney Dis. 2002 Aug;40(2):265-74.

2)  Barzel US.  Excess dietary protein can adversely affect bone.  J Nutr. 1998 Jun;128(6):1051-3. Review.

3)  Kohlenberg-Mueller K.  Calcium balance in young adults on a vegan and lactovegetarian diet.  J Bone Miner Metab. 2003;21(1):28-33.

4)  Hegsted M.  Long-term effects of level of protein intake on calcium metabolism in young adult women.  J Nutr. 1981 Feb;111(2):244-51.

5)  Doty SB.  Pathophysiology of immobilization osteoporosis.  Curr Opin Orthop. 1995 Oct;6(5):45-9.


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