Picking Your Calcum Supplement
Our bodies needs calcium for everything from maintaining strong bones and teeth, to regulating heart rhythm and nerve impulses. Muscle function is very dependent on adequate calcium and magnesium.
We store about 99% of our calcium in our bones and teeth and thus only a small amount is present in blood. The brain will remove calcium from bony stores to maintain blood calcium within a narrow range. For this reason you can not really know your bone calcium stores by measuring a blood calcium level. With the exception of dairy products and canned salmon, there really is not a lot of well absorbed calcium present in our diets. With the move away from dairy use, we must all consider taking daily calcium supplements. Here is some information to help you choose the best calcium source in supplements.
Calcium absorbs best in the stomach in an acidic environment. There are two types of calcium supplements, ones that are alkaline like calcium carbonate and ones that are acidic like calcium citrate, calcium lactate, and calcium gluconate. The cheapest and most available calcium supplements are based on calcium carbonate, which is also the basis for oyster shell calcium, and coral calcium. Calcium carbonate would not be a good choice for anyone using acid blockers like ranitidine, Aciphex©, Pepcid©, Prilosec©, Nexium©, Protonix© or Prevacid©. Calcium carbonate must be taken with food to enhance absorption. And remember caffeine increases calcium loss through the kidneys, as do carbonated drinks. OsCal©, a common form of calcium carbonate, typically contains 500 mg of calcium per tablet.
Calcium citrate will often be better absorbed because it is an acidic form of calcium compared to the alkaline calcium carbonate. However it takes more pills of calcium citrate to get the same amount of elemental calcium compared to taking calcium carbonate. CitracCl©, one of the better known brands of calcium citrate contains 200 or 250 mg calcium per tablet depending on which product you buy. It can be taken on any empty stomach and is absorbed even by people taking any of the many acid-blocking drugs mentioned above.
Calcium lactate and gluconate contain smaller amount of elemental calcium by capsule and so more capsules will be required. However, both absorb well. Calcium lactate typically contains 115 mg of calcium per capsule. Calcium gluconate contains only about 10% elemental calcium per mg of the gluconate salt and is not a good choice as your only calcium source.
The calcium in Coral Calcium is nothing but calcium carbonate and not any better absorbed than any other calcium carbonate product.
Suggested adult dosing of calcium is between 1000 and 1500 mg daily of elemental calcium from all sources. Dairy products such as milk or yogurt will readily supply 300 mg of elemental calcium per 8 ounce serving. These recommendations were made alongside an RDA recommendation of only 400 units of Vitamin D.
Has anyone looked at the effect of Vitamin D levels on calcium absorption? In April 2003 the Journal of the American College of Nutrition published a study comparing absorption of calcium carbonate with calcium citrate in postmenopausal women. Both supplements were given with breakfast, so that avoided the problem of adequate stomach acid. It seems that none of the women were on acid-blockers. In this situation, the calcium absorption was equal. This is not exactly a real-life situation for many. Most importantly this study looked at the impact of adequate Vitamin D supplementation and found that both calciums were best absorbed if the 25-OH Vitamin D blood levels were above 80 nmol/L. I have never seen this high a level in any postmenopausal woman, and frequently find their Vitamin D levels below 30. With three weeks of Vitamin D3 pre-treatment to get a blood level over 80 nmol/L the calcium absorption of either form of calcium was 65% better than without the Vitamin D. The RDA recommendation of 400 units of Vitamin D per day will not produce a blood level of anywhere near 80 nmol/ in any adult that I have ever tested.
This study was supported by Glaxo-Smith-Kline, maker of OsCa©l and thus they found the results favorable to their product. I would support this study result, as long as everyone realizes they need adequate Vitamin D3 for best calcium absorption. I regularly test blood levels of Vitamin D3 now in many adults. I recently found a patient in their 20's with a vitamin D3 level below even the so-called lower limit of lab test normal which is 25.
It's important to not get too high a blood calcium level with excess use of calcium supplements. Too high a level can lead to kidney stones and heart rhythm problems. If you have a history of calcium kidney stones, then you need medical advice about your calcium supplementation.
I think magnesium should also be taken daily by most adults alongside your calcium. Some products contain both. In a later installment, I'll discuss how to pick the best magnesium product.
drBob