Yes, you read that correctly—taking more calcium than recommended amounts can weaken your bones and cause fractures.
If you consider the underlying science, that should not be surprising. But first, what is an excess calcium intake?
Calcium Recommended Dietary Allowance and Intake
Various countries have guidelines on how much calcium one should consume daily. This number—Recommended Dietary Allowance or RDA—also depends on the age and the life stage (e.g., pregnancy).
Roughly speaking, adults should look at consuming between 1,000 mg to 1,200 mg of calcium a day.
In contrast, no country in the world has its population consuming adequate calcium. Read on this Website some shocking data: Are you consuming enough calcium?
On average, people are found to be deficient in calcium intake by 500 mg a day.
Calcium is essential for many body functions, such as muscle movement, blood clotting, and hormone function, which are more vital than stronger bones. So when the blood calcium levels go down, your body pulls calcium out of the bones and gets the critical tasks done.
Thus, regular shortfall in calcium intake weakens bones making them susceptible to fractures—a condition called Osteoporosis or fragile bones.
To compensate for this, experts advise consuming more calcium-rich foods such as dairy products and green leafy vegetables.
If you cannot predictably increase food intake, they recommend taking 500 mg of supplemental calcium tablets.
Increasing calcium intake in either of these manners has been shown to improve bone strength and reduce fracture risk. You knew this part, didn’t you?
Excess Calcium Intake
If something is good, can more of it be better? Can you take more than 1,200 mg of calcium a day and get stronger bones?
The upper limit recommended for calcium intake is 2,000 mg a day. So how about 1,500 mg or 1,800 mg a day?
It turns out that taking calcium above 1,200 mg increases the risk of kidney stones as well as heart attacks. Experts attribute this to the deposition of excess calcium in kidneys and heart arteries, respectively, though the exact science is still under study.
What is surprising and counterintuitive is taking more than 1,200 mg of calcium a day has also been found to increase the risk of fractures. That means the bones become weaker with excess calcium. How can that be? Perhaps, the answer lies in the bone structure.
Most people think that bones are slabs of calcium compound the way chalk pieces are. But that would make them fragile, too.
Though chalk is rigid, it is easily breakable because if a small crack develops in it on impact, it propagates across the chalk length and the whole piece breaks or shatters.
To stop that fissure from progressing further, the material inside needs to change so that the crack comes up to that point and stops. Bones—nature’s engineering marvel—have exactly that property, which in technical terms is called a two-phase material.
How Bones Stop Fractures
Half of the bone is organic matter called collagen protein. The other half is calcium (in reality, it is a mix of calcium and phosphorous but we can refer to them together as calcium).
Collagen and calcium don’t form a homogenous blend—calcium sticks in small blobs in a collagen grid. That way, a breach in the calcium part traverses the blob but stops at the collagen part and does not cut across the entire bone. This is how bones stop a crack in its track!
Do you know any other natural material which is similarly hard but pliable? Well, bamboo.
And any manmade material that has such two-phase properties? Answer: Fibreglass.
Why Excess Calcium Increases Fractures
The inorganic calcium makes the bones more rigid but less pliable. The organic part renders the bones more flexible but less hard. Their balance makes the bones extremely strong.
If you increase your calcium intake beyond a point, your bones will be more calcium-like: more rigid but less pliable. The calcium blobs may increase in size and number in the bone’s collagen structure. It is easier for a crack to propagate through these bigger blobs developing into a fracture.
Thus, consuming too much calcium makes your bones chalk-like: one hit and they can shatter.
Medicine has also found the same: there is a specialized class of medicines, called Bisphosphonates, which are used for increasing bone mineral density. But long-term bisphosphonate use decreases fracture–resistance mechanisms in bones. No wonder!
Do not exceed 1,200 mg a day or whatever RDA of calcium is advised in your country for your age, gender, and life stage.
To Read More
- On this Website: Everything you want to know about strong bones
- UT Southwestern Medical Center: How much calcium is too much?
- Houston Methodist: Calcium Supplements: How Much Calcium Is Too Much?
First Published on: 8th June 2023
Image Credit: Engin Akyurt on Pixabay