Can Vitamin D levels cause fatigue and increased pain?

Before the Coronavirus Covid-19 pandemic, Australian pharmacies and supermarkets shelves were heavily stocked with various vitamin supplements. I notice that they still seem to have more than enough despite this being the beginning of the third month of the pandemic in Australia.

What is Australia’s Annual Consumption of Vitamin D?

Many of the patients I see regularly take vitamin supplements, often consuming every day a number of multivitamin pills and/or various supplements. In 2018 over 8.3 million Australians bought vitamins, minerals and/or supplements.[1] During the same year they spent 2.77 billion dollars (AUD 277,000,000,000 dollars) on vitamins and minerals alone, representing a doubling of the amount spent in one year compared to 10 years earlier.[2] Based on a population of 25.17 million in 2018, then this amount of money is equivalent to about $11,000 per person. Based on the above popularity of taking vitamins, perhaps you are someone who is currently taking such pills? Are you sure that they are helping you?


Clients occasionally ask me whether they should be consuming various vitamins, minerals and supplements. In order to help them, I have put together the following information on just one vitamin, namely vitamin D. Future blog posts will look at others compounds. My articles will focus on the relationship between these tablets and symptoms of pain, fatigue and musculoskeletal issues such as fractures and weakness.

[1], accessed 24/03/2020

[2] Complimentary Medicines Australia, Australia’s Complementary Industry Snapshot 2018, t, accessed 24/03/2020

How Much Vitamin D is Enough?

A person’s vitamin D levels are often measured using a blood sample which is then allowed to clot. The portion of the sample of blood in the test-tube that has not clotted is called serum, and this is the part that is used to measure the concentration of vitamin D.

But how much vitamin D should be present in our serum? What is too little and what is optimal? According to the clinical guideline produced by the Endocrine Society[1] we need to have 30 ng/mL if we are to have a sufficient amount of vitamin D.[2] In other words our serum should have a vitamin D concentration of 30 nanograms (nanogrammes) per millilitre, which equals only 30 thousand millionths of a gram per millilitre! Please refer to the table at the end of this article to see the different units of measurement used in the scientific literature. The actual chemical being referred to is 25-hydroxyvitamin D [25(OH)D].

[1] The Endocrine Society ( produces the Journal of Clinical Endocrinology and Metabolism.

[2]  MF Holick et al, Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline, The Journal of Clinical Endocrinology & Metabolism, Volume 96, Issue 7, 1 July 2011, Pages 1911–1930,

Does anyone not have enough?

 As vitamin D can be made by sunlight on our skin, then it is understandable that cold countries with low levels of sunlight due to high latitudes have a high proportion of their people with low levels of vitamin D. Being in a cold country also likely means that they cover up more of their skin with clothing. Similarly warm countries with abundant levels of sunlight can be expected to have a relatively small proportion of people with low levels of vitamin D. One group of researchers found that in the North-West region of Russia, in a study of 1,226 participants, that about 83% of the people had inadequate 25(OH)D levels, which was defined as having less than 75 nMol/L (i.e less than about 29 ng/mL). Even more startling was that over 45% of all the people in the study had such low levels of vitamin D that they were classified as having vitamin D deficiency.[1]


By contrast approximately only 31% of adults in Australia have inadequate levels of vitamin D; inadequate was defined as < 50 nmol/L (i.e about < 20ng/mL).[2]

[1] T Karanova et al, Prevalence of Vitamin D deficiency in the North-West region of Russia: A cross-sectional study, J Steroid Biochem Mol Biol Nov;164:230-234. doi: 10.1016/j.jsbmb.2016.03.026.

[2] CA Nowson et al Vitamin D and health in adults in Australia and New Zealand: a position statement, Med J Aust 2012; 196 (11): 686-687. doi: 10.5694/mja11.10301,

What Happens if You Don’t Have Enough?

The problems we may experience due to a lack of vitamin D are numerous, and include:

depression, fatigue, headache, musculoskeletal pain, weakness and a decrease in cognitive performance.[1] So if you have one or more of these signs and symptoms then you may not have enough vitamin D, which is referred to as hypovitaminosis D. Of course there are many other reasons why you could be experiencing one or more of these signs and symptoms, and you may have more than one cause of poor health.


Here is a very brief look at some of the evidence that pain and fatigue can be linked to a lack of vitamin D.


  1. Pain related to your bones, muscles and joints (i.e. musculoskeletal pain)


One study looked at 150 consecutive patients over a two year period who were diagnosed with persistent, nonspecific musculoskeletal pain. This diagnosis means that the doctors could not find reasons that could explain why these people had pain. This inner city research was  based in Minneapolis, and it discovered that 140 of the clients (93%) had deficient levels of vitamin D (≤ 20 ng/mL).[2] The number of patients that were severely deficient (that is having levels ≤ 8 ng/mL) was 28%. This doesn’t doesn’t prove that all 140  people had pain only because of a lack of vitamin D, but it is circumstantial evidence that vitamin D is important.


One randomised, placebo-controlled study helped not only strengthen the relationship between musculoskeletal pain and inadequate levels of vitamin D, but it also provided insight as to how this worked at a molecular level. It involved examining the response of 80 people in pain to either a daily dose of 4,000 IU of vitamin D given in the form of capsules or a placebo tablet. Their response to the tablets was measured using: a visual scale of how much pain they were experiencing; a record of how much pain-killing (analgesic) medication they were taking; and measurements of various molecules in their blood. After 6 weeks of being on such a dose, and again at 12 weeks, it was found that those taking vitamin D had significantly less pain and were taking less analgesics than those taking the placebo. Even more startling is that in the group taking vitamin D the blood levels of the molecule called tumour necrosis factor alpha (TNFα, and also known as cachexin and cachectin) was reduced by 54% whereas the placebo group showed an increase of 16%. This molecule helps cause inflammation, which sometimes seems to lead to people experiencing unnecessary pain.[3]



  1. Fatigue

A well designed study of 120 healthy people who suffered fatigue and who were deficient in vitamin D. The otherwise healthy patients presented at a hospital in Zurich.[4]  The patients were considered to have deficient levels of vitamin D because they were found to have less than 20 μg/L of 25(OH)D.


Nearly half (58) of the clients were given a daily dose of 100,000 IU of vitamin D (taken as two tablets of 50,000 IU) and the other 62 were given two placebo tablets. The researchers ensured that the placebo and the vitamin D tablets had the same smell, appearance and taste. Response to the tablets were measured using: two questionnaires that the people completed asking them about the nature and severity of their fatigue, including physical and mental fatigue. These questionnaires were given at the beginning of the trial and at the end four weeks later. The researchers found that the group taking vitamin D had more people reporting that their fatigue had lessened. In fact examination of one of the questionnaires revealed improvement in 28 (48%) of the people taking vitamin D compared to only  23 (37%) of those taking the placebo. Also the average rating of fatigue was significantly decreased in those taking vitamin D compared to those receiving the placebo. The 25-OH vitamin D levels had increased on average by about 14  μg/L in those who had taken the vitamin D tablets.

[1] A Nowak et al, Effect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial, Medicine (Baltimore) 2016 95(52): e5353. Published online 2016 Dec 30. doi: 10.1097/MD.0000000000005353,

[2] GA Plotnikoff & JM Quigley, Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific musculoskeletal pain, Mayo Clinic Proc 2003, 78(12):1463-70.

[3] O Gendelman et al, A randomized double-blind placebo-controlled study adding high dose vitamin D to analgesic regimens in patients with musculoskeletal pain, Lupus 2015 Apr;24(4-5):483-9. doi: 10.1177/0961203314558676,

[4] A Nowak et al, Effect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial, Medicine (Baltimore) 2016 95(52): e5353. Published online 2016 Dec 30. doi: 10.1097/MD.0000000000005353,


From the above research, it is reasonable to consider having your doctor check your blood levels of vitamin D to see if this is a possible reason for you experiencing unexplained pain and fatigue. Compared to other forms of medical treatment,  vitamin D tablets are not expensive. It is possible that an optimal level of vitamin D in your blood is at least 50 µg/mL.

Definitions of low vitamin D levels
Status   Serum concentration level
nmol/Lµg/L = ng/mL
Severely deficient< 12< 4.8
Deficient< 50< 20
Insufficient52.5–72.521 – 29


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