Vitamin D Guide

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What is Vitamin D | Vitamin D Deficiency | How Much Vitamin D Do You Need? | How to Test Your Vitamin D | Vitamin D Risk Factors | Vitamin D Sources | Vitamin and Bone Health | Organic Vitamin D Supplement

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 May Have Vitamin D Deficiency

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 Deficiency

  • Rickets: 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
  • Osteomalacia: 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! 21In a study of Arab and Danish Muslim women living in Denmark, muscle pain and weakness was a prominent symptom of vitamin D deficiency. 20In 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
  • Low vitamin D levels are linked to chronic pain, fatigue, depression, osteoporosis and more. We work inside, we live inside, if we go outside, we’re taught to wear sunscreen because we want to lower the risk of skin cancer, which makes sense, but a sunscreen of SPF 15 or greater blocks 99 percent of the synthesis of vitamin D. It is recommended that every person in get their vitamin D checked, because so many people are low and the ramifications of having low vitamin D are so severe. Many health groups now recommend adults take 1,000 to 2,000 units of vitamin D daily; that’s five to ten times the old recommendation.

Watch the videos below for more on vitamin D deficiency:

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Women with Vitamin D Deficiencies

Dr. Heaney shares if women with vitamin D deficiencies have increased fracture risk and are more likely to fall and break bones.

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Vitamin D-deficient women are much more like to fall and break a bone. A marvelous randomized trial conducted by Heiki Bischoff about 5 or six 6 ago showed that elderly South German women randomized to receive either calcium alone or calcium plus Vitamin D had a 50% reduction in fall risk in the Vitamin D-treated arm, relative to just the calcium-treated arm, which is not to suggest that calcium isn’t important, but it’s not important for falls, whereas Vitamin D is. We don’t know for sure how Vitamin D is working there, but the effect is very evident. That may well be one of the most important reasons why it reduces fracture risk. If you don’t fall, you’re less likely to break something.

How to Combat Vitamin D Deficiency

An estimated 65-95% of Americans are vitamin D deficient.

Low levels of vitamin D have been linked to osteoporosis, type I diabetes, multiple sclerosis, fibromyalgia, rheumatoid arthritis, autoimmune disorders, various types of cancer, cardiovascular disease, poor muscle strength and depression.

Safe sun exposure is the fastest way to replenish your vitamin D on a regular basis. In order to get enough vitamin D from exposure to the sun, you need to be out in the sun for an estimated 15-30 minutes without sunscreen three times per week. If your skin is darker toned, this estimate may need to be increased, check with your dermatologist to determine safe exposure times.

During the winter months, or seasons when the sun isn’t available, you may want to consider taking a vitamin D supplement. Check with your health care provider or nutritionist to determine how much is right for you.

How Much Vitamin D Do You Need?

Vitamin D is essential to overall health. The requirements for vitamin D are set by the Institute of Medicine’s Food and Nutrition Board based on the strength and quality of current scientific evidence.

BUT everyone is different and will need different amounts depending on their ability to utilize and absorb calcium. To know for sure how much YOU need, get tested.

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For instance, the amount of Vitamin D needed in your diet can actually change depending on how much UV light you get from the sun. The less your skin makes Vitamin D, the more Vitamin D you’re going to need from your food or from supplements. The question might be asking is ‘What things affect how much Vitamin D my skin can make?’ There’s a few things, but basically, comes down to anything that protects your skin from the sun is going to block your skin’s ability to make Vitamin D.

If you have dark skin, the melanin in your skin’s going to prevent Vitamin D production. If you cover your arms and legs with clothes, or if you use sunscreens appropriately, you won’t make Vitamin D in your skin. In fact, even the glass that’s in your windows at home and in your car will prevent the rays from the sun that help you make Vitamin D from affecting your skin and making Vitamin D. A few other things can affect how much Vitamin D can be made in your skin.

Unfortunately as you get older, your skin changes and it’s no longer able to make Vitamin D as well as it used to when you were young. Another thing that can happen is Vitamin D is affected by the season of the year. In the summer when the UV rays of the sun are very strong, you can make a lot of Vitamin D, but in the winter, you really can’t make much at all, especially up in places more North. That’s another thing that’s important; it depends where you are in the country as to how much this seasonal effect influences your ability to make Vitamin D in the skin. If you’re in the north, there’s a big seasonal effect. When you’re in the south, this effect is still there but it’s not quite as strong.

Let me give you an example: In places like Indiana (and farther North), you just can’t make any Vitamin D of any substantial amount in your skin from October through March. The UV rays from the sun just can’t reach you and can’t allow your skin to make Vitamin D. There’s a few people in particular, few groups of people, that have to worry about making Vitamin D and getting enough Vitamin D in particular. Elderly people tend to stay out of the sun because of worries about skin cancer, people who are institutionalize, often the elderly in nursing homes are documented to have low Vitamin D status.

Again, if you have very dark skin, or if for religious reasons or other reasons you cover up, you’re not going to make Vitamin D from the sun. Exclusively breastfed infants should probably also be taking a Vitamin D supplement.

If you’re in any one of those groups, without question, you should have your Vitamin D status tested. This way you’ll know if you need a Vitamin D supplement or if you need to increase the amount of Vitamin D in your diet.

How to Test Your Vitamin D Levels

Your vitamin D levels are measured by your blood levels of 25(OH)D (the form in which vitamin D circulates in the bloodstream).  The Vitamin D Council will now send you a test kit in the mail. It’s easy and very accurate– a tiny finger prick is all that’s needed to get a drop of blood for this test – and then you just pop it back in the mail. 

Once you get your results back and know what your blood levels of vitamin D are, you can then determine if you are taking enough vitamin D3 to keep your levels optimal. The optimal range is from 50-80 ng/mL. If your levels are not in this range, you will want to increase your intake of vitamin D. The Vitamin D Council recommends increasing your intake to 5,000 iu/day for 3 months and then retesting.

But, there are a couple things you need to take into consideration:

  • Your blood levels of vitamin D tend to be higher in the spring and summer than fall and winter. This is (of course) because of the lack of sun during the winter months. You may need to supplement with more vitamin D3 during this time.
  • Sunblock will literally ‘block’ the sun and not allow you to create vitamin D. Try to get at least 15-20 minutes of sunshine on your bare skin each day.

How often should you test?

Twice a year, in the winter and in the summer. As discussed above, your vitamin D levels tend to change during different seasons.

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.

Autoimmune Diseases – Diabetes, Multiple Sclerosis and Rheumatoid Arthritis

Diabetes mellitus, multiple sclerosis, and rheumatoid arthritis, are each examples of autoimmune disease. Autoimmune diseases occur when the body launches an immune response to its own tissue, rather than a foreign pathogen. Treatment with vitamin D has beneficial effects in animal models of all of the above mentioned diseases. Studies have found that the prevalence of diabetes, multiple sclerosis, and rheumatoid arthritis increases as latitude increases, suggesting that lower exposure to sun light and associated decreases in vitamin D synthesis may play a role in the development of these diseases.

The results of several studies also suggest that adequate vitamin D intake may decrease the risk of autoimmune diseases. Evidence from animal models and human studies suggests that maintaining sufficient vitamin D levels may help decrease the risk of several autoimmune diseases, but more studies are needed to draw any solid conclusions.

Vitamin D and Hypertension (High Blood Pressure)

The results of epidemiological and clinical studies suggest an inverse relationship between serum vitamin D levels and blood pressure. Data from epidemiological studies suggest that conditions that decrease vitamin D synthesis in the skin, such as having dark skin and living in temperate latitudes, are associated with increased prevalence of hypertension.71 In randomized controlled trials of vitamin D supplementation, a combination of 1,600 IU/day of vitamin D and 800 mg/day of calcium for eight weeks significantly decreased systolic blood pressure in elderly women by 9% compared to calcium alone,73 but supplementation with 400 IU/day or a single dose of 100,000 IU of vitamin D did not significantly lower blood pressure in elderly men and women over the next two months.74, 75 At present, data from controlled clinical trials are too limited to determine whether vitamin D supplementation will be effective in lowering blood pressure or preventing hypertension.

Tolerable Upper Intake Level (UL) for Vitamin D

  • Infants 0-12 months- : 1000 IU
  • Children 1-18 years : 2000 IU
  • Adults 19 years and older : 2000 IU

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

For More Information : Vitamin D Sources

Vitamin D, A Bone Building Co-factor

When it comes to building strong bones – calcium tends to take center stage.  But vitamin D plays a vital supporting role in the bone-building process.

Co-Factors & Absorption

In order for any nutrient to work, it must be properly absorbed. One reason a nutrient might not be properly absorbed is if it is missing key co-factors. Co-factors are key helper molecules that assist in the body’s biochemical processes, such as building bones. Calcitriol, the active form of vitamin D, needs to be present to signal the bones to absorb calcium, making vitamin D one of the key co-factors for bone building. So even if you are consuming calcium, without the appropriate levels of vitamin D (and other co-factors), the bones will not get the signal to absorb all the calcium. So what happens to the calcium that is not absorbed?  It can end up in places it is not wanted, like the arteries of the heart, or kidney stones.  According to a study published in the May 2010 issues of the BMJ, high dose calcium administered without vitamin D is associated with an increased risk of myocardial infarction.

How do we get our vitamin D?  The best source by far is the sun, which is why vitamin D is called the “Sunshine Vitamin.” For years we have been told by doctors and dermatologists to avoid the sun’s rays.  But without being told to obtain our vitamin D elsewhere, many Americans are now deficient in vitamin D, some with severely low levels.  A study published in 2009 in the Archives of Internal Medicine, found that 70% – 97% of Americans have insufficient blood levels of Vitamin D.

Vitamin D is key to many bodily functions beyond bone health.  Low vitamin D levels are associated with increased susceptibility to a wide range of health issues, ranging from the common cold to cancers. According to Dr. Cedric F. Garland of the Moores Cancer Center and UCSD School of Medicine, “75% of breast cancers could be prevented with higher vitamin D serum levels.”  So it is of paramount importance to know your serum blood levels of vitamin D to protect our bones and many other key biological functions.  Your healthcare practitioner can order a vitamin D screen.

Organic 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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