Would you rather have a $50 pay rise or a $100 tax cut? I know which one I’d prefer. The same goes for calcium. It’s not how much calcium you get, it’s how much you get to keep that matters. What matters most is not your calcium intake (the amount you consume) but your calcium balance (the amount of calcium you consume minus what you excrete in the urine).
While we take in calcium into our diet we also can lose it by excreting it into the urine. After all, most kidney stones contain calcium in addition to other chemicals. Similarly some people eat a lot of calcium but still get osteoporosis as they pass most of it in the urine. Other people eat small amounts of calcium but pass very little into the urine and don’t get osteoporosis. And most of us fall between these extremes.
The main thing that determines how much calcium gets passed into the urine is the ACID LOAD of the diet. Dietary acid must be neutralised to keep our blood and cells pH neutral so that our enzymes can function properly. One of the quickest ways to neutralise acid is to dissolve a little bone. The skeleton has many metabolic roles and one of them is to be the major acid base buffer. Dissolving a little bone releases the alkali and calcium at the same time.
The more dietary acid load, the more bone is dissolved and the more calcium goes into the urine.
Westerners eat a lot of dairy products and so take in a lot of calcium. But the cost of dairy products is that they are very acidic, so much of the calcium gets lost.
Other foods that have a high acid load include:
– soft drink (phosphoric acid or citric acid are used as they hold more hydrogen and thus promote more fizz).
– salt. Through the magic of chloride and how it is metabolised by the kidneys. (ask a builder how good chloride is at causing concrete cancer, via salt spray or magnesite (magnesium chloride)).
Conversely, foods with a high alkali (base) load promote the retention of calcium.
– strong mineral waters i.e. most European mineral waters such as Evian. But not Australian mineral waters which curiously have their minerals removed.
Asians and Africans traditionally eat low amounts of dairy products. There are no Paleolithic osteoporotic fractures other than some in Inuit who eat 95% animal calories. The dairy industry would have us believe they should all have problems.Marketing 101= if you repeat it often enough it becomes the truth.
If salt and soft drink were banned, the incidence of osteoporotic fractures would be 50 to 90% less. A 3% increase in bone density= a 20% drop in fracture rate.
And yes, acidic foods promote kidney stones! Acidic foods give us acidic urine which promotes stone formation and it is high in calcium which also promotes kidney stones. In contrast alkaline calcium supplements such as calcium carbonate tablets provide carbonate which is alkaline and helps the calcium to be retained. Also, carbonate is a component of bone which is helpful. I prefer calcium carbonate to calcium citrate as citrate is not a component of bone.
Also look at http://www.ncbi.nlm.nih.gov/pubmed/12450898?ordinalpos=7&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
Softdrink and osteoporosis
Garcia-Contreras, F. et al., Arch Med Res 2000; 31: 360-365
This is interesting as the rats didn’t get demineralised bones on water plus half rations (thus half calcium magnesium), whereas they did on cola plus half rations (all that they would eat on top of the cola).
You’ll be pleased to know that last week I went to an educational meeting on osteoporosis and had my bone density tested and it was fine!
<SNIP> I found this summary of the 2002 ASBMR meeting by Susan New on Medscape. (medscape is a professional medical site- free and worthwhile) http://www.medscape.com/viewarticle/443217 Interesting that the mineral water paper quoted focuses on bicarbonate. Mineral water was mentioned the Lisbon conference but the focus was on calcium sulfate (sic). http://www.medscape.com/viewarticle/434330 .
http://www.medscape.com/viewarticle/420853 is an earlier article by New with a focus on acid base.
There is also info at www.betterbones.com under “Alkaline For Life”. This website focuses on the therapy of osteoporosis. Dr Susan Brown is a nutritionist with a PhD in bone nutrition.
Dietary alkali loading (within limits) is definitely anabolic and should improve muscle strength. There is data suggesting it may help the brain.
It is an interesting new field and most of the experts are renal physicians. eg Sebastian, Frassetto and Morris.