Calcium Chloride Hexahydrate.

The active vitamin D metabolite drives the intestinal calcium transporters that move an oral dose into circulation. Absorption efficiency follows vitamin D status closely.

K2 carboxylates osteocalcin and matrix Gla protein so absorbed calcium is bound into bone matrix. Mineral plus addressing is the classic pairing.

Magnesium is the cofactor for vitamin D activation and for normal parathyroid signalling, both of which set calcium handling. The two minerals sit side by side in bone mineral.

Potassium lowers urinary calcium excretion, so a larger fraction of an absorbed dose is retained. This works downstream of absorption, at the kidney.

Sodium and calcium reabsorption are coupled in the renal tubule, so high sodium intake raises calcium loss in urine. An anti-synergy that belongs on every calcium label.

Calcium taken alongside an iron salt lowers non-heme iron uptake at the intestinal cell. The pair is normally split across separate doses.

Supplemental calcium reduces zinc absorption from the same meal via overlapping divalent uptake pathways. The size of the effect scales with the calcium dose.

Strontium rides the same intestinal transport as calcium and occupies the same bone sites, so together each lowers uptake of the other. Separate them in the dosing schedule.

Caffeine raises urinary calcium output modestly, lowering net retention from a given dose. Worth stating where an electrolyte or energy product carries both.

Bone mineral is calcium phosphate in a hydroxyapatite arrangement, so normal bone maintenance needs both ions in supply. Parathyroid hormone and fibroblast growth factor 23 regulate the two in opposite directions at the kidney. At high concentrations in the gut lumen calcium and phosphate also bind each other and precipitate, which lowers absorption of both when a large dose of each arrives at once.

Both ions move partly through the same paracellular tight junction pathway in the intestine and share segments of the renal tubule. A large single calcium dose reduces magnesium uptake in that window and the same is true in the other direction. Splitting the two across the day is the ordinary way formulators handle it. Magnesium is also required for parathyroid hormone secretion and action, so status in one affects handling of the other.

Calcium interferes with non-heme iron uptake at the enterocyte, an effect seen with single doses in the same meal. Chelated iron forms such as bisglycinate are less affected because they are absorbed by a partly different route, though the competition is not abolished. Standard practice is to separate a calcium dose from an iron dose by a couple of hours.

Divalent cations compete for shared intestinal transporters and for binding sites in the gut lumen. Large calcium doses lower the fraction of copper absorbed from the same meal. This matters most for people taking calcium at the higher end of intake alongside a low copper diet.

Manganese uptake is mediated in part by transporters that also carry other divalent metals, so a large calcium load in the same meal reduces the fraction taken up. Manganese needs are small and ordinary diets cover them, so the practical significance is modest. Separating doses removes the question.

Inositol hexaphosphate carries six phosphate groups that chelate divalent cations including calcium, holding them in an insoluble complex that passes through unabsorbed. Phytase cleaves those phosphate groups and releases the bound mineral. This is why phytase is standard in animal feed and why soaking and fermenting grains raises mineral availability.

Bacterial fermentation of inulin produces short-chain fatty acids that acidify the colonic lumen, keeping calcium in its soluble ionised form for longer. That raises the share absorbed by the paracellular route in the large bowel, a site that matters more when intakes are high. The effect has been measured with isotope methods in humans.

Fructooligosaccharides ferment more rapidly and more proximally than long-chain inulin, so the acidification occurs earlier in the large bowel. The mechanism for calcium is the same: a lower luminal pH keeps more of the mineral soluble. Faster fermentation also means more gas early on for some people.

Like other prebiotic oligosaccharides, GOS lowers colonic pH through fermentation, which keeps calcium ionised and available for paracellular movement. The evidence base here is smaller than for inulin-type fructans. It is an absorption-side effect and says nothing about what happens to the mineral afterwards.

Chloride salts lower the dietary cation-anion difference and push acid-base balance in the acid direction, which is precisely why chloride salts are used to acidify. Bicarbonate does the opposite. Taking the two together cancels the acid-base effect of the chloride while leaving the calcium delivery intact, which may be wanted or not depending on why the chloride form was chosen.

In a hydration mix the chloride contributes to the anion side alongside sodium and potassium, and the calcium contributes on the cation side. Highly soluble salts are chosen for these products because they dissolve fully and quickly in cold water. The trade-off is a sharp and bitter taste that has to be masked.

Boron has been associated with reduced urinary calcium and magnesium excretion in balance studies. The mechanism is not fully characterised and the data set is small. It appears in bone formulas on that basis rather than on a settled requirement.

Lysine forms soluble complexes with calcium and has been associated with greater calcium uptake in small human and laboratory studies. It is also a substrate for the hydroxylysine crosslinks of collagen, which is the protein scaffold that bone mineral deposits on. The absorption evidence is limited in size.

Type I collagen provides the fibrillar template into which hydroxyapatite crystals are deposited. Supplying peptides alongside the mineral addresses both phases of the tissue rather than one. Whether oral peptides change deposition is a separate question from the settled fact that the matrix is collagen.

Prolyl 4-hydroxylase and lysyl hydroxylase both require ascorbate to keep their iron centre reduced, and without it the collagen helix does not form stable crosslinks. Since bone mineral deposits onto a collagen scaffold, the cofactor requirement sits upstream of mineral handling. Ascorbate also keeps calcium in a more soluble state in the acidic gut lumen.

Orthosilicic acid has been associated in observational work with bone mineral density measures, and silicon is found at sites of active mineralisation. The observational nature of most of this data means an association, not a demonstrated cause. It is formulated with calcium on that basis.

Higher protein intake raises urinary calcium excretion and also raises intestinal calcium absorption, so the net effect depends on calcium supply being adequate. Protein supplies the amino acids for the collagen matrix. Whey concentrates and isolates also carry calcium themselves, which counts toward the total on the label.