In the old days, when people thought of healthy bones, they thought of calcium. Later vitamin D, vitamin K and possibly magnesium joined the list. But not many people would think that selenium is also an important contributor: a new study has looked at the link between this little-known trace mineral and the health of our bones.

Why might selenium be important for our bones?

Previous studies have suggested that selenium also plays a role in bone health, but exactly why it is important is still somewhat hazy.

Its effect probably stems from its essential role in protecting cells from oxidative damage. Oxidative stress is also thought to have a destructive effect on bones, so it makes sense that selenium - an important part of our body's antioxidant system - is protective against osteoporosis and helps maintain bone density.

What does the new study look at?

This research is a so-called meta-analysis, which means that it includes pooled results from different relevant studies, not just one single outlier. These have looked at bone density, osteoporosis incidence and risk of fractures based on dietary selenium intake and serum selenium levels.

A total of 18 observational studies and 1 randomized trial were included in the analysis, analyzing data from nearly 70,000 people. Similar meta-analyses use strict criteria to select and exclude irrelevant and low-quality studies in order to make the results more reliable.

Dietary selenium intake and bone density

Four studies have examined the relationship between dietary selenium intake and bone density, and it is clear that the two are related: those who consumed more selenium had proportionally higher bone density. The results were not significant, however, as selenium is only a tiny component of healthy bones - but it is worth paying attention to.

Two studies analyzed the relationship between dietary selenium intake and the risk of osteoporosis, and the results were much more striking: higher selenium intake more than halved the incidence of osteoporosis.

A positive change was also observed in the number of hip fractures, but the overall effect on the risk of fractures was not considered significant, as there was a wide variation between studies.

The connection between serum selenium levels and bone health

Selenium is one of the trace elements whose intake is difficult to accurately assess. The most commonly used tests are plasma and serum selenium concentrations. Here, research has looked at the relationship between serum selenium levels, and arrived at the following conclusions:

• Data from 4 studies and 3370 participants showed that higher serum selenium levels were positively associated with bone density, so those with better selenium levels had better bone density.
• With the exception of 1 observational study, the association between serum selenium levels and osteoporosis was significant: people who had osteoporosis also had low selenium levels.
• There was no significant association between serum selenium levels and the risk of bone fractures.

The only randomized trial that looked at the effects of selenium supplementation found no association between selenium supplementation and bone density, but this study used less bioavailable selenium salts and subjects had a good selenium intake.

It is worth remembering that low bone density is only one of the important risk factors for fractures. The fact that bone density does not improve may still change the structure of the bones. Vitamin K1, for example, halved fracture risk in one study, while not increasing bone density. (2)

Summary

Although the results are somewhat mixed, it is clear that bone health can be compromised by too low an intake of selenium, as both higher dietary intakes and higher selenium levels have been shown to be beneficial for bone density, osteoporosis and fracture risk.

The amount of selenium in food is mainly determined by the amount of selenium in the soil, so inadequate intakes are very common in some areas. In such cases, supplementation can be particularly important as avoiding deficiency can help prevent many problems.

In addition to selenium, vitamin D, vitamin K, vitamin A, calcium and magnesium are also very important for healthy bones; we recommend these articles on the subject!

On the main page, click on selenium and you will find several excellent sources of selenium, along with recipes.