Most Absorbable Calcium
Most absorbable calcium claims abound. Unfortunately, there is no way to definitively measure calcium uptake by the body. Existing absorption models all have limitations. Perhaps that is why so many brands can boast about being the most absorbable calcium. It‘s largely improvable.
In the Journal of Nutrition, 2001; 131:1344S-1348S, Heaney reviewed models that have been used to test for the most absorbable calcium.
“The balance method: It refers in this case not to total body balance, but to intestinal balance, i.e., the difference between what goes in at the mouth and what comes out in the feces. In this conceptually simple form, the method is cumbersome, imprecise, time consuming and expensive.….
Serum concentration: This approach is an analog of the classical pharmacokinetic measure used for drugs, i.e., it yields an area under the curve (AUC),3… It also tends to have a very low signal-to-noise ratio, particularly for minerals. This is because, in contrast to drugs, the test substance is normally present in the serum, and its level often tightly regulated….Hence, this method exhibits limited sensitivity.
Tracer method: The method has very high sensitivity because the normal background for the tracer (particularly if radioactive) is usually very low; hence, the signal-to-noise ratio is usually very favorable... [However,][e]xtrinsic labeling of a source using a small synthetic labeled sample of the same nutrient and assuming that the labeled and unlabeled moieties will mix in the stomach cannot be relied upon unless the two methods have been shown to yield identical results for the nutrient concerned ..
Urine increment: It is a much less expensive method than the classical serum AUC method, but it is also much less precise, because it adds another layer of biological variability (variable renal clearance). Hence, it is even less sensitive than the serum method.
Target system effects: The effect of the nutrient on target systems is intuitively attractive, because methods with such endpoints get directly at the reason for taking the supplement in the first place. Their weaknesses lie in the fact that they are not easily calibrated and are often ill-suited for the testing of nutrients…”
Your most absorbable calcium may depend on age and health factors. Recker showed in the New England Journal of Medicine that older adults who do not produce stomach acid, cannot absorb calcium carbonate, unless taken with food. The most absorbable calcium for some may be impaired in your body because of lactose intolerance, celiac or crohn’s disease, other supplements/drugs taken or life stage changes.
Finding the most absorbable calcium may be a quixotic journey. You don’t take calcium to be absorbed. Most take it to build bone density. In a recently published meta analysis, study participants taking AdvaCAL had impressive bone density gains among 32 different calcium studies, involving seven different types of calcium. Identifying the best bone building calcium is probably more useful than uncovering the most absorbable calcium, if even provable.