Dolomite (Calcium/Magnesium).

The active form of vitamin D drives expression of the intestinal calcium transport proteins, so how much of the calcium in dolomite crosses the gut depends on vitamin D status. Without adequate D3 a large part of a carbonate calcium dose passes through unabsorbed.

Osteocalcin and matrix Gla protein only bind calcium after vitamin K dependent carboxylation, which is how absorbed calcium is directed into bone matrix rather than soft tissue. K2 is the standard companion to any calcium dose for that reason.

Calcium interferes with iron uptake at the enterocyte when both are taken in the same dose, and the effect is large enough that the two are normally separated by a few hours. This is a spacing rule, not a reason to avoid either mineral.

High single doses of calcium reduce zinc absorption, an effect made worse when the meal also carries phytate. Taking dolomite and zinc at different times of day keeps both minerals available.

Fermentable inulin lowers colonic pH and keeps calcium and magnesium in solution for absorption further down the gut. It raises uptake of exactly the two minerals dolomite supplies.

Vitamin K2 is the cofactor that carboxylates osteocalcin and matrix Gla protein so absorbed calcium is directed into bone matrix. It governs where dolomite calcium ends up.

Dolomite is a calcium magnesium carbonate, so its calcium behaves like carbonate calcium and needs the same gastric acid to dissolve. Stacking the two adds carbonate load and total calcium toward the upper intake range.

Dolomite already carries magnesium in roughly a one to two ratio with calcium, so a separate magnesium dose adds to what is already there. Counting only the standalone product understates the total.

Boron reduces urinary loss of calcium and magnesium and influences how they are held in bone matrix. It acts on retention rather than on intake.

Silicon contributes to the collagen scaffold that bone mineral crystallises onto, while dolomite supplies the mineral. Scaffold and mineral are separate requirements.

Lysine raises intestinal calcium uptake and lowers its urinary excretion, and it is also cross-linked into the collagen matrix. Both effects point the same way as a calcium dose.

Phytate from grains and legumes binds calcium and magnesium in the gut lumen, and phytase hydrolyses it. Removing the binder raises how much of a dolomite dose is available.

Carbonate salts need free gastric acid to release their mineral, unlike citrate or glycinate forms. Added acid supports dissolution when stomach acid output is low.

Strontium and calcium are absorbed by the same intestinal pathways and compete for the same bone crystal sites. Taken together each reduces uptake of the other, which is why they are dosed at different times of day.

High intakes of calcium and other divalent minerals lower copper uptake by competing for shared transport and by raising luminal pH. Long-term high-dose mineral use is where this shows.

Manganese is a divalent cation absorbed partly by the same routes as calcium, magnesium and iron, so a large dolomite dose reduces its uptake. Manganese is also needed as a matrix enzyme cofactor, so the competition matters.

Carbonate raises gastric pH, and gastric acid plus pepsin are what free dietary B12 from its protein carrier. A large carbonate load taken with meals works against that release.

Viscous soluble fibre traps divalent cations and slows their diffusion to the absorptive surface. Calcium and magnesium doses are lower in yield when taken inside a psyllium gel.

Calcitriol induces the intestinal transport proteins that carry calcium across the enterocyte, so vitamin D status sets how much calcium from any carbonate source is taken up. Magnesium sits on the other side of the same axis as a cofactor for the enzymes that hydroxylate vitamin D. The two minerals in dolomite therefore meet vitamin D from both directions.

Potassium intake influences urinary calcium excretion, and potassium salts of organic acids also carry an alkali load once metabolised. A calcium and magnesium carbonate source arrives into that same acid-base setting. The interaction is about retention rather than about absorption in the gut.

Sodium and calcium are reabsorbed together in the renal tubule, so raising the sodium load raises urinary calcium loss. Nothing about the dolomite source changes that. It is a background dietary factor to note alongside any calcium supplement.

Caffeine causes a small short-lived rise in urinary calcium and a slight drop in absorption efficiency around the time it is taken. The magnitude is modest set against normal daily calcium turnover. Worth naming so a formulator can space the two, not worth alarm.

Calcium and phosphate form poorly soluble calcium phosphate in the intestinal lumen, which removes both from solution. A high phosphate load taken at the same time as a carbonate calcium source lowers what stays available. Separating the two is the usual formulation answer.

Fructooligosaccharides are fermented to short-chain fatty acids that acidify the colonic contents, keeping calcium and magnesium ionised where carbonate would otherwise precipitate. That opens an absorption window past the small intestine. What has been measured in this line of work is fractional mineral absorption, a marker rather than a bone outcome.

Resistant starch passes the small intestine intact and ferments in the colon, generating the acids that hold divalent minerals in solution. It works on a slower timescale than the short-chain fructans. The endpoint measured is absorption, not skeletal change.

Carbonate minerals need an acidic environment to dissolve, and an organic acid taken alongside lowers the local pH and helps that dissolution start. The same acid also reacts with carbonate to release carbon dioxide, which is where the fizz and some of the burping come from. Taking a carbonate source with a meal achieves the same acid boost more comfortably.

Tannins bind calcium, magnesium, iron and zinc and pull them out of solution in the gut lumen. Tea and other tannin-rich drinks taken with a mineral supplement reduce what stays available from that dose. An hour or two of separation is the ordinary way round it.

Vitamin B6 is routinely formulated with magnesium, on the basis of laboratory work suggesting an influence on magnesium movement into cells. The pairing is long-standing in the market and mechanistically plausible rather than settled. Present it as a convention with a mechanism attached, not as a demonstrated benefit.

Both carbonate minerals and bicarbonate neutralise stomach acid, so taking them together raises gastric pH more than either alone. Higher gastric pH then works against dissolution of the carbonate mineral itself. The two effects pull in opposite directions and are worth spacing.