Vitamin D – Vitamin D Deficiency Symptoms and Risk Factors

What is Vitamin D?

Vitamin D is unique among vitamins in that it can be provided to your body through food- or from exposure to the sun or tanning bed that allows the body to synthesize it (from cholesterol) . UV rays from sunlight triggers vitamin D synthesis in the skin. Vitamin D functions as an important hormone by sending a message to your intestines to increase the absorption of calcium by as much as 80%. Vitamin D is well known for maintaining normal calcium levels,1 but it is involved in so much more! Please read on.

You Are Probably Vitamin D Deficient!

In March 2006, Mayo Clinic Proceedings printed a shocking article about the high prevalence of vitamin D deficiency.2 The highly respected author, Michael Holick of the Boston University School of Medicine says “Vitamin D inadequacy has been reported in approximately 36% of otherwise healthy young adults and up to 57% of general medicine inpatients in the United States and even higher percentages in Europe! Low sunlight exposure, age related decreases in vitamin D synthesis in your skin, and diets low in vitamin D contribute to the high prevalence of vitamin D inadequacy.

Supplemental doses of vitamin D (taken together with calcium and magnesium) and sensible sun exposure could prevent deficiency in most of the general population” according to Holick. A few comments on choosing the best vitamin d supplement are noted toward the bottom of this web page.

Vitamin D Sources

Sunlight is the best source of vitamin D. It can provide you with your entire vitamin D requirement. Children and young adults who spend a short time outside two or three times a week will generally synthesize all the vitamin D they need. If you are older, you have diminished capacity to synthesize vitamin D from sunlight exposure and possibly use sunscreen or protective clothing in order to prevent skin cancer and sun damage, so you should consider getting your vitamin D from food and supplements.

The application of sunscreen with an SPF factor of 8 reduces production of vitamin D by 95%. In latitudes around 40 degrees north or 40 degrees south (Boston is 42 degrees north), there is insufficient UVB radiation available for vitamin D synthesis from November to early March. Ten degrees farther north (Edmonton, Canada) this “vitamin D winter” extends from mid October to mid March. According to Dr. Michael Holick, as little as 5-10 minutes of sun exposure on arms and legs or face and arms three times weekly between 11:00 am and 2:00 pm during the spring, summer, and fall at 42 degrees latitude should provide a light-skinned individual with adequate vitamin D and allow for storage of any excess for use during the winter with minimal risk of skin damage.35

Vitamin D Deficiency


Extreme vitamin D deficiency in infants and children does not allow bone to mineralize. This condition, called rickets, is most pronounced in youth when bones are growing fastest. When there is not adequate mineralization, weight-bearing limbs become bowed because the growth plates of bones continue to enlarge.
Vitamin D deficiency is a problem that many think is behind us due to fortified foods. However, the global evidence is that rickets have not been eradicated.18, 19


Even when our bones stop growing in the adult years, they still are turning over. As with hair, we gain and lose bone throughout our lives. However, with extreme vitamin D deficiency, bone mineral is lost even quicker, although the collagen bone matrix is maintained. The result is pain in the bones and ‘soft’ bones, called osteomalacia …more on Osteomalacia

Vitamin D Deficiency Symptoms

Pain and Muscle Weakness

Inadequate amounts of vitamin D has been proven to cause pain and muscle weakness in children and adults. 150 patients were part of a Minnesota cross sectional study to evaluate persistent, muscle and bone pain. The findings were that 93% had vitamin D deficiency!21

In a study of Arab and Danish Muslim women living in Denmark, muscle pain and weakness was a prominent symptom of vitamin D deficiency. 20

In another study, elderly women increased muscle strength and decreased the risk of falling by almost 50% by taking 800 IU/day of vitamin D and 1,200 mg/day of calcium for three months- compared to supplementation with calcium alone.22

Risk Factors for Vitamin D Deficiency

If you find yourself in any of the categories below, you would be well advised to get a blood test to determine your vitamin D levels.


In women who cover their skin, for religious, cultural or health reasons, osteomalacia has been reported.26, 27 As well vitamin D production is reduced by 95% by sunscreen with an SPF factor of as little as 8, which leads to the same bone health problem as covered skin. 1

Dark Skin

Those with dark skin tend to have lower vitamin D levels than those with light skin, as dark skinned people synthesize less vitamin D on exposure to sunlight.1 And the farther that dark skin people live from the equator means a greater likelihood of vitamin D deficiency.

Breast Fed Infants

Exclusively breast fed infants are also likely to have vitamin D inadequacy, because human milk generally provides 25 IU of vitamin D per liter, which is not enough for an infant if it is the sole source of vitamin D. This is compounded for dark skinned infants and ones that receive little sun exposure.19 Older children exclusively fed foods that are not vitamin D fortified are also at risk of vitamin D deficiency.18

The American Academy of Pediatrics recommends that all infants that are not consuming at least 500 ml (16 ounces) of vitamin D fortified formula or milk be given a vitamin D supplement of 400 IU/day.19


The elderly are especially at risk of vitamin D deficiency as they are are more likely than younger people to stay indoors or use sunscreen. On top of that, the elderly cannot synthesize vitamin D in the skin when exposed to the sun as well as when younger. These factors put the institutionalized elderly at a very high risk of low vitamin D levels- unless supplements are taken.24, 25

Inflammatory Bowel Disease

If you suffer from inflammatory bowel disease like Crohn’s disease you may be at increased risk of vitamin D deficiency, especially if you have had small bowel surgery.29

Fat Malabsorption Syndromes

Absorption of vitamin D is impaired by cholestatic liver disease and cystic fibrosis.29


If you have large stores of body fat you are at greater risk of vitamin D deficiency.30 Because once vitamin D is synthesized or ingested it is stored in body fat stores. However, it is less bio available in large stores of body fat.

Vitamin D Supplement?

There are many health benefits of vitamin D, but it is not always practical to get your vitamin D from sunshine, and quite difficult to get adequate amounts from your diet so for many people, a vitamin D supplement is a practical way to ensure adequate levels of this important protector are always available in your bloodstream.

Since a large body of science shows vitamin D works closely with calcium and magnesium, it is best to take your vitamin D in combination with calcium and magnesium to maintain a proper balance. Recent literature also shows most calcium supplements have too little vitamin D to be effective. And some of them use synthetic vitamin D2. A much better form is natural vitamin D3 which stays in your system longer and with more effect.

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