The claimEvidence D · marketing folklore
Bone broth is a good calcium source
The evidence
Measured broth has ~26-80 mg calcium/L — a bowl is <5% of daily need vs ~300 mg in a cup of milk (7-30x more); what renders out is mostly fat.
The mechanism, in brief
The two most widespread pregnancy food beliefs fall apart once you check them against the absorption gate.
Sources (3)
- Hsu, D., Lee, C., Tsai, W., & Chien, Y. (2017). Essential and toxic metals in animal bone broths. Food & Nutrition Research, 61(1), 1347478. Ca and Mg per serving did not exceed low tens of mg (<5% of daily recommended); Pb/Cd intake risk judged minimal.
- Chen, J., & Tsim, K. W. K. (2020). A review of edible jujube, the Ziziphus jujuba fruit: a health food supplement for anemia prevalence. Frontiers in Pharmacology, 11, 593655.
- Hurrell, R., & Egli, I. (2010). Iron bioavailability and dietary reference values. The American Journal of Clinical Nutrition, 91(5), 1461S-1467S. Abstract only (the AJCN supplement full text could not be retrieved): iron bioavailability is estimated at 14-18% for mixed diets and 5-12% for vegetarian diets in subjects with no iron stores, the values used to set dietary reference values. Phytate, polyphenols, calcium, ascorbic acid and muscle tissue shift absorption strongly in single-meal isotope studies but only modestly in multimeal studies with a varied diet; the nature of the meat factor is unresolved; iron status generally has a greater effect than diet composition. The abstract gives no separate heme vs non-heme absorption percentages (abstract, PMID 20200263).