Vitamin D: the “normal” level found to be TOO LOW for muscle growth & regeneration

Over the past decade interest in Vitamin D has exploded. The reason for this increase in interest is partly due to the re-emergence of the bone disease rickets, but also due to a better understanding of the many biological roles of this vitamin…well, it’s actually not a vitamin. It is a “pre-hormone.” A growing body of evidence shows that vitamin D plays a crucial role in disease prevention and maintaining optimal health. There are about 30,000 genes in your body, and vitamin D affects nearly 3,000 of them, as well as vitamin D receptors located throughout your body.

Areas that have Vitamin D Receptors Include:

  • Islet cells of the pancreas
  • B-Cells (immune system)
  • T-Cells (immune system)
  • Neurons
  • Prostate cells
  • Ovarian cells
  • Pituitary cells (in the brain)
  • Aortic endothelial cells (in the heart)

It is now known that many tissues in the human body have vitamin D receptors, suggesting that Vitamin D plays a much more important role than what had been initially thought! It is now clear that both innate and acquired immune function, cardiovascular health and even muscle growth and repair are regulated by vitamin D. Muscle growth and repair are particularly important for athletes and body builders.

Currently the US Institute of Medicine state that a daily dose of 600 IUs & serum level of >20 ng/mL is adequate enough for bone health and over health, although many leading researchers seriously question this as being too conservative. Detrimental effects on muscle function are significant when concentrations of vitamin D are inadequate. The EFSA have recently stated that 4000 IUs of vitamin D has been shown to be an effective dose in correcting deficiencies. 


Below are conditions that have been associated with vitamin D levels – (According to the Institute for Functional Medicine):

< 10        Severely deficient

<15         Risk of rickets

<20         75% greater risk of colon cancer

<30         Deficient

  • Increased risk of osteoporosis, poor wound healing, increased muscle pain, increased joint and back pain, greater risk of depression, increased diabetes, increased schizophrenia, increased migraines, increased autoimmune disease (lupus & scleroderma), increased allergies, increased preeclampsia, increased inflammation.

30 – 50  Suboptimal levels

<34         Twice the risk of heart attack

<36         Increased incidence of high blood pressure

<40         3X risk of multiple sclerosis

50-80     Optimal levels

>50         50% reduction in breast cancer, decreased risk of all solid cancers

80-100   Slowing of cancer growth in patients with cancer

>100      Toxicity can occur



Athletes: Sub-optimal levels of vitamin D Can Impair Muscle Regeneration

This emerging knowledge, combined with many studies that have indicated that many athletes are vitamin D deficient, largely due to inadequate sun exposure and poor dietary sources of vitamin D, even those living in sunny climates has resulted in vitamin D being one of the most widely supplemented vitamins in sports nutrition.

More recently, studies have demonstrated that vitamin D deficiencies may impair muscle regeneration and perhaps more importantly this effect may occur even when vitamin D concentrations are around 20 (which is within the “adequate” lab range). Functional Medicine ranges for vitamin D tend to near 70-80 and in those with auto-immune conditions, upper levels closer to 100 are more beneficial.

It is clear that much research is required on vitamin D and athletic performance with future studies; but it is important to make sure your vitamin D levels are between 70-80 for optimal health!


Other Influences of Vitamin D:


  • Vitamin D modulates neurotransmitter and neurological function, as shown by its anti-depressant and anti-convulsant benefits: Epilepsy, Seasonal Affective Disorder
  • Reduces inflammation & inflammatory markers such as CRP
  • Suppresses and/or prevents certain auto-immune diseases: Graves Disease, ankylosing spondylitis, lupus, Rheumatoid Arthritis. Multiple Sclerosis, Type 1 Diabetes
  • Reduces the risk of all cancers
  • Reduce the severity and frequency of infectious disease such as pneumonia in children.
  • Supplementation of Vitamin D normalized menstrual irregularities and fertility issues in women with PCOS
  • Heart attack risk is twice as high for those with vitamin D levels less than 34.


I recommend D3 5000 from the company Xymogen – small soft gel emulsified in sunflower oil (avoid those who emulsify in soybean or corn oil)




Vasquez, A., Manso, G., & Cannell, J. (2004). The Clinical Importance Of Vitamin D: A Paradigm Shift With Implications For All Healthcare Providers. Alternative Therapies, 10(5), 28-36.

Close, G. L., Hamilton, D. L., Phillip, A., Burke, L. M., & Morton, J. P. (2016). New Strategies in sports nutrition to increase exercise performance. Free Radical Biology and Medicine98(2016), 144-158.;jsessionid=A5C97B9111EFBB2E38D34B839F15A0FD.f04t01


Author: Melissa Mullin

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