Vitamin D Phototherapy Frequently Asked Questions  (FAQ)

How do humans get Vitamin-D ?
Who is at greatest risk of Vitamin-D deficiency ?
How much Vitamin-D does a person need ?
How is Vitamin-D status measured ?
How effective is UVB light for Vitamin-D production ?
Who should consider using artificial UVB light sources for Vitamin-D ?
If using an UVB phototherapy device for Vitamin-D, how is dosing controlled ?
What is the best fluorescent UV lamp type for Vitamin-D production ?
Are Solarc devices approved by the government for Vitamin-D deficiency ?
What is the recommended treatment method for Vitamin-D phototherapy ?
Is there a risk of getting too much Vitamin-D ? (Vitamin-D toxicity
How is Vitamin-D linked to psoriasis ?
Can human evolution explain today's widespread occurrence of Vitamin-D deficiency among people living at high latitudes ?
How do furry animals get their Vitamin-D ?
References and Links

"Vitamin-D" has received tremendous media attention lately, and for good reason. Vitamin-D is essential to human health for its role as a catalyst for calcium absorption, yet many people are deficient, especially those that live at higher latitudes, far away from the earth's equator. There is increasing evidence that Vitamin-D protects against the development of many chronic diseases, including: cancer (breast, colorectal, prostate), cardiovascular disease, multiple sclerosis, osteomalacia, osteoporosis, type 1 diabetes mellitus, rheumatoid arthritis, hypertension, and depression. There have also been positive reports associating Vitamin-D with influenza and dental health. A central problem is that Vitamin-D deficiency does not cause immediate obvious degradation in the patient's health. Rather, the effects are more long term, such as the gradual loss of bone density in the case of osteoporosis.

Please appreciate that the information provided here is only a collection of commonly available material, and not a substitute for the advice of your physician. As with natural sunlight, long term use of a UVB phototherapy device can cause premature aging of the skin and skin cancer.

How do humans get Vitamin-D ?
Vitamin-D can be obtained by humans five ways:
1. By exposing bare skin to UVB radiation in natural sunlight, if available.
2. By exposing bare skin to UVB radiation created by artificial light sources. (UVB phototherapy)
3. By consuming food that naturally contains Vitamin-D: eggs, chicken livers, salmon, sardines, herring, mackerel, swordfish and fish oils such as halibut and cod liver oils. (Note that there are now recommendations to NOT use cod liver oil because it contains very high amounts of vitamin A.)
4. By consuming food fortified with Vitamin-D: milk (100 IUs per 250 ml glass in Canada), margarine
5. By taking oral Vitamin-D supplements: Vitamin-D tablets

There is a very good Wikipedia article on Vitamin-D

Who is at greatest risk of Vitamin-D deficiency ?
Mortality maps for diseases related to Vitamin-D show a strong correlation with the amount of environmental ultraviolet B (UVB) available from natural sunlight. Those living at higher latitudes receive less natural UVB and therefore have greater risk. During the winter months, regions such as Canada and Northern Europe receive practically zero UVB. This is because the sun's rays strike the earth at a more shallow angle, geometrically causing the rays to travel a longer path through the earth's atmosphere, and ozone filtering out nearly all of the UVB. Consequently, most people living far away from the equator have the lowest amount of Vitamin-D at the end of the winter, after months of depletion. The risk of Vitamin-D deficiency is compounded for those with dark skin, such as African Americans, because their skin pigment acts like a filter, reducing the amount of UVB deliverable to the biologically active skin beneath. Black skin can require five to ten times longer UVB exposure to create the same amount of cutaneous (in the skin) Vitamin-D as a white person.
Other groups with greater risk of Vitamin-D deficiency include:
- all people over the age of 50 (Vitamin-D absorption decreases with age)
- people in religious groups that are fully clothed for all outdoor activities
- obese people, because their excess fat holds on to the Vitamin-D.

How much Vitamin-D does a person need ?
A human can use 1000 (Holick) to 3600 (Heaney 2003) International Units (IU) of Vitamin-D per day, so there is a need for constant intake to maintain the target concentration. (keeping the tank full) If UVB is not available, the only option is to get Vitamin-D orally. Food provides a limited amount of the daily requirement. (In Canada, milk has only 100 IUs per 250 ml glass) Oral Vitamin-D dosing suggestions are seasonal and range from; 400 IU/day for those over 50 years of age per Canada's Food Guide , 1000 IU/day year-round per the Canadian Cancer Society (subject to physician guidance), and up to 2000 and 4000 IU/day depending on risk factors per other organizations.
How is Vitamin-D status measured ?
The only method to determine Vitamin-D status is by a blood test for precursor Vitamin-D known as any of: "25-hydroxy-Vitamin-D" "25(OH)D" "25D" or "Calcidiol". (Important: This is NOT to be confused with a similarly named test for activated Vitamin-D known as any of: "1,25-dihydroxyVitamin-D" "1,25(OH)2D3" "1,25D3" or "Calcitriol".)

25-hydroxy-Vitamin-D tests are available in Canada at LifeLabs, but a physician's requisition is required, and full or partial payment by the patient. The ideal concentration of calcidiol has not been established. Various sources suggest 3570 nanograms per millilitre of blood (ng/mL), and ideally more than 50. Periodic Vitamin-D blood tests are needed to determine current status, the effectiveness of previous actions taken, and your action plan for the future. Other methods to quantify efficacy might be to perform an ultrasonic bone density test. This can be done on the heel of the foot, using a device such as the McCue C.U.B.A. This test may be particularly informative for those in risk of osteoporosis and osteomalacia, such as post-menopausal women.

How effective is UVB light for Vitamin-D production ?
If a 100% of a person's skin area can be exposed to UVB light, one single dose of sub-erythema UVB (1 MED) can make the equivalent of 10,000 to 25,000 IU of Vitamin-D orally. (Holick) Note that it would NOT be advisable to take 1 MED because that dose is too close to burning, and such a large dose is not necessary if regular exposures are taken; but this does show that getting Vitamin-D using UVB light is much more effective than getting Vitamin-D through diet or supplements. "Sub-erythema" UVB is the dose just slightly less than the dose needed to cause mild skin burning. Erythema is undesirable because it causes patient discomfort, is a major risk factor for skin cancer, and reaching that state does not produce any additional Vitamin-D. By irradiating a larger area of skin, a lower dose per unit area can be taken to create the same amount of Vitamin-D, thus maximizing Vitamin-D production and minimizing the risk of adverse effects. Or, in other words, the cumulative risk is minimized by spreading it over a larger area. Alternatively, if a small phototherapy device is used, treatments can be taken on different parts of the body on alternate days. If the device used includes significant quantities of UVA light (such as a commercial tanning machine), skin tanning usually occurs, which acts as a UVB filter and results in longer treatment times to acheive the same Vitamin-D production, while needlessly exposing the patient to UVA light. If some areas of the body have received significant amounts of cumulative UVB during a patient's lifetime; such as the face/head, lower arms, chest and shoulders/upper back, etc.; it is sensible to NOT further irradiate these areas of the body for Vitamin-D production. Conversely, using areas that have received very little cumulative UVB during a patient's lifetime are the best sites to use, such as the buttocks. All assuming again, that burns are strictly avoided.
Who should consider using artificial UVB light sources for Vitamin-D ?
Depending on geographic latitude, most people should be able to maintain proper Vitamin-D levels by judicious use of natural sunlight (short exposures without sunscreen), food and supplements; adjusted for the seasonality of naturally occurring UVB in sunlight.

The greatest single warning when using natural sunlight is MODERATION ! DON'T GET BURNED ! Sunburn is a major risk factor for skin cancer. It is much better to take 10 minutes per day for a week than 70 minutes in one session. There is some excellent guidance for using natural sunlight for Vitamin-D in Dr. Holick's book: "The UV Advantage" Chapter Seven

Some people; however, are not capable of absorbing the necessary amount of Vitamin-D orally. Malabsorption problems are likely to occur in people with crohn's disease, kidney/liver disease, gastric bypass surgery, cystic fibrosis and cholestatic liver disease. These patients might consider use of a UVB phototherapy device. Solarc Systems has supplied several UVB devices for this application. Artificial UVB light sources have the advantage that the UVB dose can be closely controlled, always available and repeatable. Natural UVB from sunlight, on the other hand, is subject to many variables including: distance from the equator, time of year, time of day, and cloud cover; thus making it more difficult to optimize Vitamin-D production, and exposing the patient to increased risk of sunburn, should they ever underestimate the sun's skin burning potential. Natural light contains UVB and UVA, but it only the UVB wavelengths (up to ~315nm) that contribute to Vitamin-D production. UVA serves primarily to induce tanning, with a minor contribution to erythema (burning). Sunscreen lotions are formulated to block both UVA and UVB.

If using an UVB phototherapy device for Vitamin-D, how is dosing controlled ?
The objective with UVB phototherapy for Vitamin-D production is generally the same at that for psoriasis: to take only enough UVB to first correct the underlying problem, then to minimize dose and frequency to maintain that healthy state in balance. For example, at the start of UVB phototherapy for psoriasis, the treatment dose is increased progressively, and given at a frequency of 3 to 7 times per week, all while strictly avoiding erythema (sunburning). Then, once significant clearing is achieved, dose and frequency can usually be reduced and maintained in balance, using UVB doses much less than one Minimum Erythemal Dose (1 MED). (Haykal & DesGroseilliers 2006, Walters 1999) It is reasonable to expect the same result for restoration of Vitamin-D levels, assuming regular Vitamin-D blood tests are used to quantify efficacy. Solarc UVB devices are provided with a Users Manual that contains detailed exposure guidelines based on skin type (dark skin or light skin), device power, and waveband type. As with natural sunlight, long term use of a UVB phototherapy device can cause premature aging of the skin and skin cancer.
What is the best fluorescent UV lamp type for Vitamin-D production ?
UVB light is required for Vitamin-D production in human skin. There are three main candidate fluorescent ultraviolet lamp types, they are:
  • UVA Cosmetic Tanning Lamps, as found in tanning salons worldwide. These lamps contain a small percentage of UVB.
  • UVB Broadband Lamps. In use for at least 50 years for the medical treatment of psoriasis, but now being used less often in favor of UVB Narrowband lamps.
  • UVB Narrowband Lamps. A relatively new development, used very successful for the medical treatment of psoriasis.
All of these lamps will produce Vitamin-D, but the optimal lamp type has NOT been medically established. For a detailed study of this subject, please visit our Lamps for Vitamin-D webpage.

Are Solarc devices approved by the government for Vitamin-D deficiency ?
In Canada, all Solarc Systems' UVB devices (UVB-Narrowband and UVB-Broadband) received Health Canada approval to add "Vitamin-D Deficiency" to the "Indications of Use" on July 21, 2008 per Health Canada Device Licence #12783. This includes the E-Series, 1000-Series, 500-Series and 100-Series.

In the USA, using the FDA's 510(k) process, Solarc failed in its attempt to get "Vitamin-D Deficiency" added to the "Indications for Use", because no comparable "predicate" (pre-existing) device existed, and to obtain approval would instead have required a severely cost prohibitive Premarket Approval "PMA" application. In the USA, Solarc is therefore NOT permitted to promote the devices for "Vitamin-D Deficiency"; and instead only for the approved "Indications for Use" of psoriasis, vitiligo and eczema. In this context, "Vitamin-D Deficiency" is considered to be an "off-label" use, but regardless a physician can still request information regarding the off-label use, and the physician is legally permitted to write a prescription for the patient to obtain the product. This concept is known as the "practice of medicine", which means that a physician can prescribe or administer any legally marketed product for any off-label use that they deem to be in the best interest of the patient.

What is the recommended treatment method for Vitamin-D phototherapy ?
For recommendations on using a Solarc UVB device to treat Vitamin-D deficency, see our
Vitamin-D Users Manual Supplement (pdf).

Is there a risk of getting too much Vitamin-D ? (Vitamin-D toxicity)
Vitamin-D toxicity (hypervitaminosis D) is possible when [25(OH)D] levels reach approximately up to about ~200 ng/ml. Vitamin-D toxicity has not been observed to result from exposure to natural sunlight. The skin maximizes Vitamin-D production before erythema (sunburning) occurs. Further exposure does not create more Vitamin-D, thereby automatically preventing Vitamin-D toxicity.

However, Vitamin-D toxicity is possible by taking chronic daily excessive amounts of Vitamin-D orally, in the order of 40,000 IU/day or more; or theoretically in lesser amounts if combined with significant UVB skin exposure.

Vitamin-D toxicity has also been observed in a few patients using UVB-Broadband and UVB-Narrowband devices. This emphasizes the need for regular Vitamin-D tests, and especially for those taking high UVB doses and/or supplements over a long period of time.

How is Vitamin-D linked to psoriasis ?
There are several ways that Vitamin-D is linked to psoriasis:
- The action spectrum for psoriasis corresponds to the best wavelengths for Vitamin-D production.
- Patients beginning UVB phototherapy for psoriasis are typically Vitamin-D deficient.
- The popular topical psoriasis drug Calcipotriol (trade name: Dovonex®) is a Vitamin-D derivative.
This suggests that psoriasis patients especially should be following suggestions for Vitamin-D supplementation. One wonders how many psoriasis patients were simply Vitamin-D deficient before getting the disease?

To learn more, there are many medical abstracts on this subject at: PubMed

Can human evolution explain today's widespread occurrence of Vitamin-D deficiency among people living at high latitudes ?
Considering/assuming that primates have been evolving for some 85 million years, (and humans for a couple of million years), in an environment awash with natural ultraviolet light from the sun, it is reasonable that we have developed ways to use UV beneficially (Vitamin-D production), and a means to prevent overexposure (tanning). As some humans migrated away from the equatorial regions of Africa, the skin lightened to compensate for less UVB. With reduced pigment filtering, more Vitamin-D could be produced for a given amount of UVB, which could be very limited for regions such as Scandinavia. Then in recent history, at about the time of the industrial revolution, people begun to spend more time indoors, and were more fully clothed when going outdoors. Nowadays, we are even more protected from the sun, with many working in buildings all day, dire warnings from some to avoid any UV exposure whatsoever, and now even many cosmetics for daily use including a sun block; the overriding concern being increased risk of melanoma skin cancer. It has been suggested by many that the virtual elimination of UVB exposure for a large number of people, especially in regions far away from the equator, has created a health crisis in the form of Vitamin-D deficiency and its associated diseases. This has occurred in a relatively infinitesimal amount of time in a evolutionary sense, leaving no time for an evolutionary correction.
How do furry animals get their Vitamin-D ?
If humans need Vitamin-D, then it is logical to think that animals with fur also need Vitamin-D. They do, but how can they do this if their fur blocks light? The answer is that they make Vitamin-D in their fur (or feathers in the case of birds) and in the action of grooming themselves, they lick the nutrient from their fur and ingest it orally. It is interesting to note that Vitamin-D tablets are made from defatted lamb's wool that is exposed to UVB and then purified.

For detailed product and ordering information, please visit our primary website at

References & Links:

Action Spectrum for the Production of PreVitamin-D3 in Human Skin
CIE 174:2006

Erythema reference action spectrum and standard erythema dose
ISO-17166:1999(E) | CIE S 007/E-1998

Canada's Food Guide An official publication of Health Canada.

The Canadian Cancer Society Search: "Vitamin-D".

2006 North American Conference on UV, Vitamin-D and Health. Key messages endorsed by the Canadian Cancer Society, Canadian Dermatology Association, Osteoporosis Canada, and many other organizations. (pdf)

Vitamin-D Council A nonprofit group of concerned citizens that believe many humans are needlessly suffering and dying from Vitamin-D Deficiency.

Sunarc Sunlight, Nutrition And Health Research Center
An organization devoted to research, and education relating to the prevention of chronic disease through changes in diet and lifestyle.

Book: The UV Advantage by Michael R. Holick, PH.D., MD and Mark Jenkins
1st Edition 2003, ISBN 0-7434-8647-1,

Wikipedia entry for Vitamin-D

PARRISH JA, JAENICKE KF (1981) Action Spectrum for phototherapy of psoriasis. J Invest Dermatol. 76 359

WALTERS I, (1999) Suberythematogenic narrow-band UVB is markedly more effective than conventional UVB in treatment of psoriasis vulgaris. J Am Acad Dermatol 1999;40:893-900

Are Narrow-band Ultraviolet B Home Units a Viable Option for Continuous or Maintenance Therapy of Photoresponsive Skin Diseases?
Journal of Cutaneous Medicine & Surgery, Volume 10, Issue 5 : 234-240

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This website is not intended for use by residents of the USA.
Vitamin-D Deficiency is not an US-FDA approved Indication for Use.
For more information, see our Regulatory webpage.

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