Misconceptions about Vitamin D

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The main points:

  1. Vitamin D deficiency can cause many kinds of health aggravations and conditions beyond bone density, muscle, and development problems. Inadequate dosing during pregnancy or for the breastfeeding infant can be particularly damaging.
  2. Vitamin D levels are not assessed often enough as part of a diagnostic tool.
  3. The values from test results are often misinterpreted because the range is too wide; it does not reflect optimal levels for healthy individuals.
  4. Many people are either not taking enough, or taking too much vitamin D.
  5. Many people supplement it at the wrong time.

In my naturopathic practice, I see women who are pregnant and/or breastfeeding, who want to know how to best support the healthy development of their child(ren), prevent development of allergies and promote normal growth. And adults who are concerned about wellness and preventing cancer. I also see a lot of patients with symptoms ranging from fatigue, concerns about mood and/or sleep, muscle weakness, chronic pain, fibromyalgia, and concerns about infections and immune function. Every patient with concerns, of course, benefits from a thorough interview, and as needed an exam and complete work up to help figure out their specific risk factors, aggravating factors and diagnoses. However, one frequently overlooked factor by most health care providers, which can help cause or aggravate any of the previously mentioned concerns, is vitamin D deficiency.

Why is it overlooked? Sadly, education about nutrition and the role of nutrients is not given much time or consideration in conventional medical training. Medical advice dedicated to this nutrient usually only involves preventing osteoporosis in the elderly (a recent study from China disputed this generally accepted line of evidence), and rickets in children. While important, this doesn’t cover the whole story about why vitamin D is so important to functions of many of the body’s systems, throughout the life cycle.

Vitamin D’s origin story: UVB light from the sun reacts with a compound called 7-dehydrocholesterol in the epidermis of the skin to stimulate the first step in the production and metabolism of a vitamin D, which is biologically inactive until it undergoes 2 hydroxylation reactions to become active. It is hydroxylated first in the liver to form 25-hydroxyvitamin D, or (25[OH]D), and then by the kidneys to form 1,25-dihydroxyvitamin D, the biologically active form which functions as a hormone in the body, and there are receptors for the hormone in many body tissues. This is the primary route, though small, naturally occurring amounts can also be naturally consumed from foods such as cheese, egg yolks, cold water, fatty fish, and liver. It can also be produced by fungi as a response to irradiation, in the form of D2, and is often added to commercial foods such as dairy products, infant formula and multivitamins.

In New England, our high latitude creates a situation where we are especially challenged to get enough of this vitamin throughout the year. So while vitamin D deficiency is common throughout the U.S. (and world), it is especially common here.

So what are the misconceptions?

#1 Misconception: Testing: Most doctors are not trained about its biological importance, and most insurance carriers do not cover testing for it, unless there is a diagnosis of osteoporosis or a previous diagnosis of low vitamin D. So most people who are deficient have no idea they are deficient. When someone has problems with bone density, and/or any of the concerns I first listed, this can be an important avenue to investigate, and I find that it is not explored enough through primary care.

If your doctor won’t order it, and/or your insurance won’t cover it (and these tests can often range from between $120-$200 if insurance denies the claim), what can you do? If you don’t have a typically covered reason for testing through your doctor, you can opt to use a service such as LifeExtension, who partners with Labcorp for self directed tests. This one costs around $47. There are also panels that include it as part of a wellness screen. (I don’t have any relationships with, or receive any financial perks from LifeExtension, but I have found them helpful for patients wishing to pay cash for reasonably priced testing services for wellness, when insurance is not an option.)

#2 Misconception: The more the better! On the opposing side, there are practitioners that get very excited about vitamin D and recommend excessive doses. It cures everything! No, it is not a cure-all. It IS a fat soluble hormone that accumulates in the fat cells, so caution is warranted. Another confusing part are the testing standards; controversy exists about which vitamin D form is better to measure, and what the results mean. For example, a typical “normal range” of 25-Hydroxyvitamin D (25OHD) is 20-100ng/mL by lab standards. My experience is that patients with levels under 30 are often symptomatic for deficiency,  and serum levels over 55-60 are just not necessary, and might even be harmful. A study shows that Hawaiian surfers spending at least 15 hours per week in the sun have ranges including the 50’s to around 70 at the highest ends. And this is where it gets interesting: UVB exposure stimulates vitamin D production only up to certain point, and then it begins to degrade vitamin D in the skin. So the body’s levels are balanced when vitamin D is gained from sun exposure. But oral vitamin D is different, you don’t get that natural correction from supplementing too much. Research shows that taking vitamin D in bolus form (or intermittent, higher dosages) actually causes more falls and fractures in the elderly. From serum vitamin D levels from supplementation, the line between preventing fractures, and causing fractures, may be a slim window and located closer to the lower end of the “normal” testing ranges.

Add to this that the 25(OH)D level achieved by oral dose of vitamin D supplementation varies widely by individual. It is likely affected by calcium intake, race, age, body fat, and individual genetic factors. Genetic variation from polymorphisms of certain genes in the vitamin D metabolic pathway can also cause wide individual differences.

When I review a patient’s nutritional supplements I often find extra vitamin D added into many different sources: shakes, multivitamins, energy supplements, etc. It is important to look at all ingredient labels and to be aware of how much you are getting. Toxicity from vitamin D causes too much calcium to be released into the blood (hypercalcemia), which can cause bone demineralization, reduced appetite, nausea and vomiting, weakness, cardiac arrhythmias, increased urination and kidney problems.

Misconception #3- Take it Anytime! Since vitamin D is a fat soluble hormone, it should be taken with a food/meal that contains some fat, for best absorption. It is also stored in the fat, which might reflect why many people who are overweight can have sufficient stores of vitamin D, but low circulating levels. Alternatively, if an overweight person is on a weight loss plan, their levels may may rise significantly as vitamin D is released, especially from rapid or significant weight loss –  so extra caution is needed here, especially if there are issues of cardiac arrhythmia.

So how much is enough, without going overboard? I often recommend 400-600 IU’s daily for young children, 600-800 IU’s daily for older children, and 1,000 IU-2,000 IU’s for teens and adults as a general guideline – but I may adjust up or down depending on specific needs or risk factors, and individual responses according to testing and symptom resolution. People with malabsorption issues, or those taking medications like certain corticosteroids, heartburn medications, or anti-epileptic drugs, may experience higher likelihood and levels of deficiency. I usually recommend taking a break from vitamin D supplements from late spring through the summer months.

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Cora Rivard is a licensed naturopathic doctor and owner of Seasons Natural Healthcare, LLC in southern NH. She has been a healthcare practitioner, business owner, writer and advocate for family health and wellness since 2006. She loves leading her daughter’s Destination Imagination team, cooking, hiking with her family, playing beach volleyball and cross country skiing. Website: Seasons Natural Healthcare, LLC. She is currently accepting new patients.