Vitamin D was first studied to improve bone health and eradicate rickets. Almost every doctor is aware that vitamin D is important for skeletal health. There are thousands of studies that back up this point. But what have we found through our D*action data? Any differences? 

Your Data

When signing up for D*action we ask our participants if they have fallen in the last six months and if so how many times. The next question asks if they have broken a bone in the last 6 months and if so, how many times, which bone and the reason for the break. While these two questions are not linked, we are able to glean if the broken bone was from the fall by the free responses given. 

Your Answers

The analysis presented here is limited to participants aged 65 years and older (17% of all participants) since that age group is most likely to experience the effects of bone health. Within this group, 11% experienced a fall and 2% experienced a broken bone in the 6 months prior to their first test. Of those who broke a bone, the average number of breaks was one and the most common bones were in the feet and hands. The most common reasons were falling, tripping and running into furniture/wall.

  

Falls 

Our data did not show a difference in falls based on serum levels. There was no difference in serum levels between those who fell in the prior 6 months and those who didn't. The median serum level was 44 ng/ml for both those who fell and those who didn't. 

But does vitamin D help prevent breaks? We plotted the percentage of participants age 65+ who broke a bone vs. their vitamin D blood levels. Here are the results: 

Those who broke a bone were more likely to have a serum level <40 ng/ml than ≥40 ng/ml.

Those with serum levels <20 ng/ml had 3 times the risk of breaking a bone compared to those ≥40 ng/ml.

What about the normal population?

A quick Google search finds that approximately 33% of adults age 65+ will fall within a year (Medicine.net). For D*action, 22% of our participants aged 65+ fell within the last 12 months.This is 33% fewer falls than in the general population. Our average serum level is 44 ng/ml, the average in NHANES (the National Health and Nutrition Examination Survey) which is a representation (probably a little high) of the general population is about 28 ng/ml.    

According to a study by Janssen et al., Vitamin D deficiency, muscle function, and falls in elderly people, vitamin D deficiency is responsible for muscle weakness which can then lead to falls, and then the likelihood of a break. Since our average vitamin D level is 44 ng/ml, this would not be considered deficient (our measure is a minimum of 40 ng/ml). This would account for the much lower break ratio in our population. Janssen et al. found "Vitamin D supplementation in vitamin D-deficient, elderly people improved muscle strength, walking distance, and functional ability and resulted in a reduction in falls and nonvertebral fractures." They also noted an improvement in bone density after supplementation.

We did not notice a difference in number of falls with respect to vitamin D level, very likely because we don't have enough of the low values of vitamin D found in the general population. (Our lows are 20-30 ng/ml whereas the general population would have lows in the 5-20 ng/ml range.)