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The Deal with Vitamin D3

We have all heard of vitamin D3 and that it's important, right? If you're lucky, this is something your primary care provider checks regularly. Unfortunately, this is something I've had to specifically request for in past blood draws because for some reason, that wasn't something they routinely checked. I really hope that my experience was benign. Vitamin D3 is something we get from some foods and the sun. It is most notorious for playing a role in our immune system and bone metabolism but there is so much more! Vitamin D3 deficiencies have been observed in people that have autoimmune rheumatic diseases, several forms of cancer, bone loss, diabetes, and infections such as sepsis. (3,13) But what I was surprised to learn recently is that vitamin D3 has a role with our muscles and pain.

In a systematic literature review of randomized control trials in 2022, researchers found that vitamin D3 supplementation resulted in pain reduction for those with a diagnosis of fibromyalgia and chronic widespread musculoskeletal pain (CMP). In this study, they also mentioned that in the scientific literature, vitamin D3 deficiency has been correlated with an increased risk for fibromyalgia and CMP. This is because vitamin D3 plays a role in muscle tissue's structure and function, including making new cells, metabolism, and endothelial function (how well blood is delivered to/from the area). Therefore, with a vitamin D3 deficiency, researchers have observe muscle atrophy (muscle gets smaller), sarcopenia (muscle loss), as well as difficulties with coordination and balance as a result. (1)

Some other surprising results about vitamin D and muscles or pain in the research:

  • Vitamin D supplementation has been shown to improve symptoms (pain and emotions) of premenstrual syndrome (PMS) and dysmenorrhea. (2)

  • Vitamin D supplementation has decreased pain intensity for those diagnosed with chronic pain. (4)

  • Vitamin D deficiency has been associated with women that have pelvic organ prolapse post menopause. (5)

  • Women with low vitamin D levels have demonstrated more pelvic floor disorders, such as urinary incontinence (6). This is has been observed with older adults (male and female) as well. (7)

  • Vitamin D deficiency has been correlated with decreased physical performance due to a fatty degeneration of type 2 muscle fibers (the fast twitch kind that help us lift heavy things and sprint!) (14)

These results are surprising but now that we know how important they are for our muscle tissue, they actually make sense!

What should our levels be? The National Institutes of Health and Cleveland Clinic Journal of Medicine recommend levels should be above 50 nmol/L (8, 9). The Cleveland Clinic Journal of Medicine describes higher than 50 nmol/L is better for our immune function (9). This study from 2021 mentions that the research supports levels of 75-100 nmol/L as sufficient for body-wide function, whereas previous recommendations of 50 nmol/L were only considering bone health. (12) Needless to say, no one can agree about what the optimal level should be. Below 50 nmol/L seems to be understood across the board to be a low level in which intervention is absolutely necessary. I'm sure your primary care provider, nutritionist, or dietician have their own guidelines so pick their brain!

We have to get blood work done in order to know our vitamin D3 level. If it is low, that's where supplementation comes into play. How much? You don't really know until you get your blood drawn again after you've taken a supplement for a few weeks. This is something that may need some tinkering. The recommendations of how much to take are all over the place. The National Institutes of Health, Mayo Clinic, and Harvard recommend starting at 600 IU daily for adults and 800 IU for over 70 years of age (8,9,10). The Cleveland Clinic Journal of Medicine and the The Endocrine Society recommend a daily supplement with 2,000 IU (9). A 2021 paper called, "Vitamin D Dosing" recommends a similar dose of 1,000 IU-2,000 IU (12) whereas another 2020 paper recommends dosing anywhere from 800 IU to 2,000 IU daily. With this mixture of information, how do you know how much to take? Test and retest. Compare lab results pre and post supplementation for a few weeks and go from there. Please be aware that vitamin D3 toxicity from too much supplementation does exist but it is rare.

This is all just to say, no matter the physical symptom, it is wise to take a look at the foundation. Making sure we are getting the correct amount of vitamins and minerals for our bodies to function at their best is paramount. Substantial vitamin D3 levels are one of the many key players that have shown to correlate with good health. Don't just chase the symptoms. Think global first.

Here is a chart of some of the many systems vitamin D3 plays a role in:


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