📋 THE STUDY
🔬 WHAT THEY DID
Study design: Technical report and reveiw (a team of experts looked at global data)
Who was studied: People all over the world, comparing wealthy countries to lower-income countries, with a special focus on pregnant women, women after menopause, and teenagers.
How long: The expert team met in 2021 to review past and current evidence.
What they measured: How much calcium people eat versus how many health problems they have, such as broken bones, pregnancy complications, and high blood pressure.
Funding: The Children’s Investment Fund Foundation (CIFF)
📊 WHAT THEY FOUND
Main finding 1: You cannot diagnose calcium deficiency with a standard blood test.
Your body keeps blood calcium levels normal by "stealing" calcium from your bones if you don't eat enough, meaning a blood test will look fine even if your bones are starving.
Main finding 2: Calcium intake is tricky because it interacts with other foods.
High salt intake causes you to lose calcium in urine, while certain plant compounds (in grains and vegetables) can block calcium absorption. This means how much you absorb matters more than just how much you eat.
Main finding 3: The Calcium Paradox
About 3.5 billion people, mostly in Africa and Asia, don’t get enough calcium, yet these populations often have lower rates of hip fractures than people in wealthy Western countries who consume high amounts of dairy. (However, this may be a prime example of ecological fallacy at play.)
⚠️ LIMITATIONS
Rather than a new experiment with patients, a task force of experts reviewed existing evidence. This means that conclusions are only as good as the older studies they analyzed, and many of those studies use different methods that are hard to compare directly.
Estimates vs. Reality: In countries without diet surveys, researchers estimated calcium intake using national data on food availability. This method guesses how much people eat based on the national food supply, which ignores food waste and doesn’t account for how food is distributed between rich and poor or men and women.
Data gaps for non-Western countries: Data from low- and middle-income countries is sparse and often relies on estimates rather than direct measurement.
Hospital bias: In regions like South Asia, much of the data comes from hospital-based studies rather than the general healthy population. Patients in hospitals may be sicker or have different risks than the average woman, meaning these results might not apply to everyone.
Comparing “apples to oranges” in bone health: The study compares fracture rates and bone density across the world, but different regions use different measuring tools. This makes it difficult to scientifically compare bone health between regions.
Correlation is not causation: Trends seen at a country level does not necessarily apply to individuals. Most of the evidence linking calcium to bone health is observational and there is a lack of high-quality randomized controlled trials in populations experiencing the “calcium paradox.”
💡 BOTTOM LINE
Because standard blood tests cannot detect nutritional calcium deficiency, women should focus on dietary consistency and absorption (like vitamin D and limiting salt) rather than waiting for a test result to show a problem.
🔗 MORE TO EXPLORE
To be added
