The association is established; acting on it is not advised
Genetics has run the experiment nobody could run deliberately — lifelong high milk intake, assigned at conception. It did not reduce hip fractures.
Solid lines are connections this site curates. Dashed lines mean the two ends share a research paper — worth knowing, and not a claim that one explains the other.
The worry is straightforward. People who cannot digest lactose drink less milk, milk is a major source of dietary calcium, and calcium builds bone. So do lactase non-persistent people end up with weaker bones?
This question has an unusually good answer, because the variant controlling lactase persistence — rs4988235 — is assigned at conception and does not shift with income, diet fashion or anything else. It works as a natural experiment.
A study of 97,811 Danish adults did exactly that. Each copy of the persistence allele was worth 0.58 more glasses of milk per week (95% CI 0.49–0.68) — so the genotype does change behaviour, measurably, across a lifetime. The hazard ratio for hip fracture per allele was 1.01 (0.94–1.09). Nothing. Pooled with other Northern European studies, the odds ratio for any fracture was 0.86 (0.61–1.21) — an interval wide enough to hold a benefit, a harm and no effect at all.
Femoral neck bone density was very slightly higher in persistent homozygotes (0.10 g/cm², 0.02–0.18). Lumbar spine and total hip showed no difference. A small density difference at one site, and no difference in the thing that actually breaks.
None of this means calcium does not matter, and none of it is advice for someone already diagnosed with osteoporosis. It means that if you avoid dairy because of lactose, the fracture argument for a calcium supplement is weaker than it sounds. See also lactose intolerance.
Calcium is a mineral essential for bone strength, muscle function and nerve signaling, obtained mainly from dairy and fortified foods. Genetics affects how much of it the body actually absorbs from milk.
A study of 97,811 Danish adults found no meaningful effect: the hazard ratio for hip fracture per persistence allele was 1.01, despite the genotype genuinely changing milk intake across a lifetime.
The fracture-based argument is weaker than it sounds. This page does not recommend for or against a supplement either way.
No — this is about the general population's fracture risk, not advice for someone with an existing diagnosis.
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Calcium. MyGeneLog™. https://www.mygenelog.com/supplements/calcium
Nothing on this page recommends taking anything. If a result here matters to you, take it to a doctor or a pharmacist rather than to a shop.