That claim is partly based on real research but is misleading as written.
Eggshells contain calcium, but the research on joint health is primarily about the thin eggshell membrane, not eating ordinary crushed eggshell. The membrane contains collagen and other compounds, and several small randomized trials have found that standardized eggshell-membrane supplements may modestly reduce knee osteoarthritis pain or stiffness. A 2024 systematic review of seven randomized trials found improvements in pain and overall WOMAC scores, but the authors emphasized that more high-quality research is needed.
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Importantly, this does not mean eggshell membrane “rebuilds lost knee collagen” or restores damaged cartilage. The existing studies primarily measured symptoms such as pain, stiffness, and function, rather than demonstrating regeneration of worn cartilage.
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PubMed
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A more accurate headline
“Eggshell Membrane May Help Knee Pain and Stiffness—But It Doesn’t Rebuild Your Knee Cartilage.”
And I wouldn’t recommend simply grinding up household eggshells and eating them as a treatment. The clinical studies used processed, standardized eggshell-membrane products, not homemade eggshell powder.
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