Calcium Citrate
Tri-calcium citrate (Ca₃(C₆H₅O₇)₂·xH₂O)
Evidence: Strong
Calcium does more than build bone. It is a direct contributor to digestion: calcium contributes to the normal function of digestive enzymes, a role formally recognised by European authorities. We chose calcium citrate, one of the most bioavailable forms, because it dissolves readily even when stomach acid is low and is gentle on the stomach, with less of the gas or constipation sometimes associated with other calcium salts.
That gentleness matters in a product designed for daily digestive comfort. Citrate gives us reliable absorption without the trade-offs, which is why it is our preferred calcium source.
PubMed indexes over 700,000 peer-reviewed papers on calcium.
Selected study
Sakhaee K, Bhuket T, Adams-Huet B, Rao DS. Meta-analysis of calcium bioavailability: A comparison of calcium citrate with calcium carbonate. American Journal of Therapeutics. 1999;6(6):313-321. doi:10.1097/00045391-199911000-00005
Study summary
Study type: Meta-analysis pooling 15 human absorption trials involving 184 adults.
Observed benefits:
- Calcium absorption from calcium citrate was about 20 percent higher than from calcium carbonate overall.
- The advantage was 27 percent higher when taken fasting and 22 percent higher with meals.
Mechanisms: Citrate dissolves readily at neutral pH, so its calcium stays available even when stomach acid is low, including in people taking acid-reducing medicines.
Safety: Both salts were well tolerated at the doses studied.
Evidence strength: A meta-analysis of human trials with objective absorption endpoints, supporting calcium citrate as a highly bioavailable form.