• Women Over 50
• Osteoporosis

Should You Take Calcium Supplements For Osteoporosis Prevention?

For many years now, doctors have prescribed calcium supplements to prevent and treat osteoporosis, a condition that weakens bones. However, there is limited evidence to support its effectiveness for this condition, but there is evidence that high levels of calcium can cause harm. Should you take calcium for osteoporosis prevention? Read this article and decide for yourself.

Understanding the Role of Calcium in Bone Health

For many years now, experts have suggested using calcium supplements to prevent and treat osteoporosis, a condition that weakens bones. Back in the 1960s and 1970s, we didn't have the osteoporosis medications we have today, so calcium supplements were more emphasized, but even today, many doctors recommend their patients take calcium supplements.

Calcium is a major part of our bones. But it's important to remember that bones aren't just made of calcium. They're actually a type of connective tissue, which means they have a protein framework, mainly made of something called type I collagen. This framework is built and maintained by special cells: osteoblasts create it, and osteoclasts reshape or remove it.

As adults, our bones are constantly being remodeled. This means small sections of bone are regularly removed and replaced. After osteoblasts lay down new collagen, calcium and phosphate, another mineral, settle in between the collagen fibers. This is what gives bones their strength.

The overall health of our bones, or how dense they are, depends on the balance between these bone-building cells (osteoblasts) and bone-removing cells (osteoclasts). Simply adding more calcium and phosphate to our diet won't automatically make our bones stronger or denser. That's because the amount of new bone we make depends on how many osteoblasts we have and how active they are.

While it's important to have enough calcium and phosphate so that the new bone is strong and healthy, having too much of these minerals doesn't really help. In other words, just taking lots of calcium won't necessarily make your bones better if the body's bone-building process isn't working properly.

Calcium intake and bone

It is often assumed that eating more calcium leads to stronger bones and fewer fractures, but there's not much evidence to back this up. Interestingly, when doctors calculate someone's risk of breaking a bone using tools like FRAX or Garvan, they don't even consider how much calcium the person eats. Large studies, like the National Health and Nutrition Examination Survey, have shown that there's no clear link between how much calcium someone consumes and their bone density or their risk of fractures¹.

There have been many clinical trials to see if calcium supplements can make bones denser and reduce the chance of fractures. These studies generally find that calcium supplements can slow down bone loss in postmenopausal women by about 20%². For example, one study³ found that giving calcium and vitamin D to older women in care homes helped reduce their risk of hip fractures. However, this positive effect isn't seen in people living in the community. From 2005 to 2010, six big studies looked at whether calcium supplements (with or without vitamin D) could prevent fractures in people living at home, and none of these studies found a significant benefit.

Recent reviews of many studies (meta-analyses) confirm that calcium supplements, with or without vitamin D, don't really prevent fractures in the spine, other bones, or hips for people living at home. So, the usefulness of calcium supplements for managing osteoporosis is being questioned, especially when you consider the possible side effects of taking these supplements.

Cardiovascular effects of calcium supplements

Several studies have looked into whether eating more calcium can affect heart health. Most of these studies didn't find a clear link. However, some experiments with calcium supplements showed they might help lower cholesterol levels and slightly reduce blood pressure. Based on these findings, researchers thought calcium supplements might lower the risk of heart problems. This idea was tested in a study called the Auckland Calcium Study. Surprisingly, the study found that calcium supplements actually increased the risk of heart attacks and possibly strokes.

To understand this better, researchers gathered data from other major studies on calcium supplements in older adults. Their analysis confirmed that these supplements increased the risk of heart attacks and suggested a possible increase in stroke risk, although this wasn't definitive.

The Women's Health Initiative (WHI) also explored this issue in a large study using calcium and vitamin D⁵. They noticed some concerning trends in heart health, especially in women who weren't overweight. However, they concluded that the supplements didn't have a significant overall effect. The WHI study was different because it included vitamin D with calcium, the participants were younger, and many were already taking calcium supplements when the study began. Researchers thought that the widespread use of calcium supplements might have made it harder to see any negative effects on heart health in the study.

They proposed a new analysis, focusing on women who weren't already taking calcium when the study started. This analysis showed that women who started taking calcium and vitamin D during the study had an increased risk of heart attacks. This wasn't the case for women who were already taking calcium supplements. The increase in heart attack risk was significant and matched the results of previous studies on calcium supplements alone. Both sets of data showed that the risk of heart attacks increased within the first year of taking supplements, while the impact on stroke risk took longer to appear.

When combining data from women new to calcium in the WHI study with other trials, researchers found a significant increase in the risk of heart attacks and strokes. These findings, along with the lack of evidence that high calcium diets harm heart health, have led to recommendations that we should get our calcium from food rather than supplements.

Despite this evidence, there's still debate about the heart risks of calcium supplements. At a 2013 meeting, another analysis confirmed the risks associated with calcium supplements alone. However, when including data from women already taking calcium in the WHI study and another study with low participation, the increased risk of heart attacks wasn't statistically significant anymore. But it still hinted at a possible risk, which might outweigh any benefits in preventing fractures. So, this analysis didn't provide a clear argument for the benefits of calcium supplements.

Other adverse effects of calcium

The Women's Health Initiative (WHI) conducted a study that found that taking calcium and vitamin D supplements increased the risk of kidney stones by 17%.

For a long time, people have known that calcium supplements can cause stomach problems. They are often linked to constipation and other digestive issues. A recent study showed that people taking calcium supplements were twice as likely to be hospitalized with severe digestive problems.

This negative effect is so significant that it cancels out any benefits these supplements might have in preventing bone fractures.

Conclusion

Calcium supplements became popular when there were no other good ways to prevent osteoporosis. It was thought that taking more calcium would help build stronger bones. However, our current understanding of how bones work suggests that this isn't really the case. Calcium might help a bit by slowing down bone loss after menopause, but it doesn't seem to do this by building new bone. Instead, it works by lowering the levels of a hormone called parathyroid hormone.

Despite this, recent studies have shown that calcium supplements don't really prevent bone fractures. In fact, they might even increase the risk of hip fractures. On top of this, taking calcium supplements seems to raise the risk of heart problems, kidney stones, and severe digestive issues, including hospitalization for these problems.

Because of these risks, most experts now recommend getting calcium from food rather than supplements. Food sources of calcium don't have the same risks as supplements. This is probably because the calcium in food is less concentrated and is absorbed more slowly, especially when eaten with protein and fat, which slows down digestion.

It's also important to know that there are now much better treatments for preventing bone fractures than calcium supplements. These new treatments are more effective and safer for long-term use. So, when it comes to preventing osteoporosis, the focus should be on assessing someone's risk of fractures and using the best treatments for those at higher risk. Given all this, calcium supplements don't have much of a role in modern osteoporosis treatment.

References

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