SolRx UVB Home Phototherapy

for Vitamin D Deficiency


A naturally effective source of Vitamin D for general health,

and especially for those with problems absorbing Vitamin D

in the digestive system, caused by conditions such as:


Cystic Fibrosis • Kidney/Liver Disease • Bowel Resection

Crohn’s Disease • Gastric Bypass Surgery

Inflammatory Bowel Disease (IBD) • Lyme Disease

SolRx UVB Home Phototherapy

for Vitamin D Deficiency

A naturally effective source of Vitamin D for general health, and especially for those with problems absorbing Vitamin D in the digestive system, caused by conditions such as:
Cystic Fibrosis • Kidney/Liver Disease • Bowel Resection • Crohn’s Disease • Gastric Bypass Surgery • Inflammatory Bowel Disease (IBD) • Lyme Disease

It is important that you discuss with your physician / healthcare professional the best choices for you; their advice always takes priority over any guidance provided by Solarc.

Quick Facts About Vitamin D & UVB Light 

We All Need Vitamin D

Over millions of years of exposure to the sun, the human body has evolved the need for UVB and Vitamin D for general health. It is a biological certainty that UVB makes Vitamin D in human skin and nearly every cell in the human body has a Vitamin D receptor.

Skin Pigment Is Nature’s Sunscreen

The darker the skin, the more UV-blocking melanin it contains. Over thousands of years, the humans that migrated north from Africa into less-sunny Europe had their skin naturally lighten so more UVB could penetrate and make the Vitamin D they needed.

Vitamin D Tablets Don’t Work For Everyone

Modern lifestyles inside buildings and the use of sunscreens prevent most of us from getting adequate Vitamin D from the sun. Oral Vitamin D tablets can maintain levels for most of us, but not for those with absorption problems in the gut.

Solar UVB Is Inconsistent

The UVB content of natural sunlight is highly variable, making proper dosing difficult, along with greater risk of skin burning. UVB from the sun varies with latitude, time-of-day, time-of-year, altitude, cloud cover, and pollution.

UVB Is Not For Tanning

UVB does not typically cause skin tanning – the skin tanning wavelengths are in the UVA range. However, the more UVB a patient takes in one session, the more pink/red the skin will become. This reddening typically fades within a day.

UVB Provides Photoprotection

UVB creates new melanocytes in the skin which are ready to produce melanin and provide photoprotection when the skin receives natural sunlight. This is of particular value to those that occasionally travel to sunnier climates.

Too Far North?

The further north you are, the less UVB reaches the earth, especially in the winter. This is because the tilt of the earth makes the sun’s rays travel longer through the atmosphere, which filters out the shortest wavelengths first: UVB.

Tanning UVA Won't Do

Only UVB makes Vitamin D in the skin. Cosmetic tanning beds and some UV equipment specifically marketed for Vitamin D produce almost entirely UVA with only a small amount of beneficial UVB.

Sensible Exposure Means Excluding Some Skin Areas

The risk of premature skin aging and skin cancer increases with cumulative lifetime repeated exposure of UV to a specific skin area, so it makes sense to exclude any such skin areas from further UV exposure, such as the face and chest.

Why Use a SolRx Device for Vitamin D?

It Works!

Many Solarc customers have seen large increases in their Vitamin D blood levels within a few months of use. Once Vitamin D levels have been restored, treatment times and frequency can be reduced and levels maintained indefinitely.

Ready When You Are

Home phototherapy units are available when you are, in the privacy of your own home. It’s easy – have a shower, spend a few minutes with your lights, and then get dressed. It takes very little time.

Health Insurance Coverage

Purchase of a SolRx device is often covered by employer health insurance plans such as Manulife, or claim it as a Medical Expense Tax Credit (METC) on your Canadian income tax return.

Up To 25,000 IU per UVB Treatment

A single full body dose of UVB can make up to the equivalent of 25,000 IU of oral Vitamin D, but that requires the skin to get just under the state of skin burning. Instead, Solarc suggests taking more frequent smaller UVB doses, with every second day being ideal for many.

Only The Best Wavelengths

UVB light occurs naturally in sunlight but only in small quantities. SolRx devices make exactly the same UVB using fluorescent medical lamps, but concentrated in the most therapeutic wavelengths around 311 nm, known as “UVB-Narrowband”.

Low Maintenance

SolRx Home UV light therapy units are very low maintenance. The Philips UVB‑Narrowband bulbs typically last 5 to 10 years. An occasional cleaning is all that it needs.

Safe & Effective

Premature skin aging and skin cancer are known risks of UV light, but when only UVB is used and UVA excluded, decades of medical use for skin disorders has proven these risks to be of only a minor concern.

Dosing Is Important

UVB are the skin burning rays of the sun, but also the only wavelengths that make Vitamin D. Dosing is important, so to accurately limit exposure all SolRx devices have a built-in digital countdown timer.

Full Body Device Recommendation

Every square inch of skin area exposed to UVB contributes to making Vitamin D, so it is sensible to expose as much skin area as possible and use lower doses. A full-body SolRx device works best for this, with many patients using just one E‑Series MASTER device.

Vitamin D Deficiency FAQ

How do humans get Vitamin D?

Vitamin D can be obtained by humans in six ways:

  • By exposing bare skin to UVB radiation in natural sunlight, if and when available.
  • By exposing bare skin to UVB radiation created by artificial light sources (UVB phototherapy).
  • By consuming food that naturally contains Vitamin D, such as: 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).
  • By consuming food fortified with Vitamin D: milk (100 IUs per 250 ml glass in Canada), margarine.
  • By taking oral Vitamin D supplements: Vitamin D tablets. 
  • By taking Vitamin D injections by hypodermic needle. 
Who is at the 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 because their skin pigment acts like a filter, reducing the amount of UVB delivered 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 because Vitamin D absorption decreases with age, people in religious groups that keep fully clothed for all outdoor activities, and obese people because their excess fat retains their 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. If UVB is not available, the only other options are to get Vitamin D orally, or for the most severe cases, by needle. Food provides only a limited amount of the daily requirement, for example 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, 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 35–70 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 most of a person’s skin area is exposed to UVB light, and the skin receives enough UVB such that it gets just under the state of mild sunburn, known as “suberythema” or one Minimal Erythema Dose (1 MED), it can produce the equivalent of up to 25,000 IU of oral Vitamin D (Holick). However, it is not advisable to regularly take 1 MED because that dose is too close to burning (erythema), and such a large dose is not necessary if instead regular lower doses 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. Erythema is undesirable because it causes patient discomfort, is a risk factor for skin cancer, and dosing beyond erythema 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 while minimizing the risk of adverse effects. Or, in other words, the 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 and some UV products marketed for Vitamin D), skin tanning usually occurs, which acts as a UVB filter and results in longer treatment times to achieve 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 UV during a patient’s lifetime; such as the face/head, forearms, chest and shoulders/upper back, etc.; it is sensible to exclude these skin areas from further UV exposure. Conversely, using skin areas that have received very little cumulative UVB during a patient’s lifetime are the best sites to use, such as the buttocks. 

Who should consider using a UVB phototherapy device 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 mid-day exposures without sunscreen), as well as food and supplements; adjusted for the seasonality of naturally occurring UVB in sunlight. The greatest single warning when using natural sunlight is sunburns. Moderation – DON’T GET BURNED, because sunburns are painful and a 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 chapter 7 of Dr. Holick’s book: “The UV Advantage“. 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, bowel resection, cystic fibrosis and cholestatic liver disease. These patients might consider use of a UVB phototherapy device, which has 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 only the UVB wavelengths (up to ~315 nm) 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. Here is a recent talk Dr. Holick gave at the Boston University Medical Center.  


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 as that for skin disorders: 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, treatments are taken 3 to 5 times per week while the dose increased progressively to avoid sunburn. Then, once significant clearing is achieved, dose and frequency can usually be reduced and maintained in balance indefinitely, usually using UVB doses much less than the maximum (Haykal & DesGroseilliers 2006, Walters 1999). It is reasonable to expect the same result for restoration of Vitamin D levels, with regular Vitamin D blood tests used to confirm progress. Solarc’s UVB devices are provided with a User’s Manual that contains detailed exposure guidelines based on skin type (dark skin or light skin), device power, and waveband type. Please also request the SolRx “Vitamin D User’s Manual Supplement”.

What is the best fluorescent UV lamp type for Vitamin D production?

There are three main candidate fluorescent ultraviolet lamp waveband types for Vitamin D, but it is important to remember that only UVB produces Vitamin D in the skin:

  • UVA Cosmetic Tanning Lamps. As found in tanning salons worldwide. These lamps produce no more than about 5% UVB, with the remainder being potentially harmful UVA.
  • UVB Broadband Lamps. In use for at least 60 years for the medical treatment of psoriasis, but now being used far less often in favor of UVB-Narrowband lamps.
  • UVB Narrowband Lamps. The gold standard for medical treatment of skin disorders such as Psoriasis, Vitiligo and Eczema. Nearly all SolRx devices use UVB-Narrowband lamps (Philips /01 311 nm).

All of these lamps will produce Vitamin D, but as with the treatment of skin disorders, UVB-Narrowband is almost certainly the best choice. For a detailed study of this subject, please keep reading below.

Are Solarc devices approved by the government for Vitamin D deficiency?

In Canada, all of Solarc’s UVB devices (UVB-Narrowband and UVB-Broadband) have 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 SolRx 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 have required a severely cost prohibitive Premarket Approval “PMA” application. Solarc is therefore not permitted to promote SolRx devices for “Vitamin D Deficiency” in the USA; 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 a physician can still request information regarding that 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. The same holds true for the many other skin disorders that UVB is also used to treat.

How are Vitamin D phototherapy UVB treatments taken?

A Vitamin D phototherapy treatment typically begins with a shower or bath (which sheds dead skin that would otherwise block some of the UVB light, and removes any foreign material on the skin that might result in an adverse reaction), followed immediately by the UVB light treatment, and then, if necessary, the application of any moisturizers. During treatment, the patient must always wear the UV protective goggles supplied and unless affected, males should cover both their penis and scrotum using a sock. Treatments are typically 3 to 5 times per week, with every second day being ideal for many patients. A significant increase in Vitamin D can be expected in 4 to 12 weeks, after which treatment times and frequency can be reduced and Vitamin D blood levels maintained indefinitely, even for decades. For further information regarding the use of a Solarc UVB device to treat Vitamin D deficiency, please read our Vitamin D User’s 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 because the skin stops making Vitamin D once erythema (sunburn) is reached. 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 also typically Vitamin D deficient.
  • The popular psoriasis topical 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 occurrence of Vitamin D deficiency?

Considering that primates have been evolving for some 85 million years, and humans for a couple million years, all while living 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 exposure. 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 began 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; with the overriding concern being increased risk of skin cancer. It has been suggested 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 many associated diseases. This has occurred in a relatively infinitesimal amount of time, 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.

Lamps for Vitamin D Phototherapy

Comparison of UV Lamp Types: UVB-Narrowband, UVB-Broadband & UVA-Tanning

What is the best fluorescent UV lamp waveband type for Vitamin D production?

There are three main candidate fluorescent ultraviolet lamp waveband types for Vitamin D, but it is important to remember that only UVB produces Vitamin D in the skin:

  • UVA Cosmetic Tanning Lamps. As found in tanning salons worldwide. These lamps produce no more than about 5% UVB, with the remainder being potentially harmful UVA.
  • UVB Broadband Lamps. In use for at least 60 years for the medical treatment of Psoriasis, but now being used far less often in favor of UVB-Narrowband lamps.
  • UVB Narrowband Lamps. The gold standard for medical treatment of skin disorders such as Psoriasis, Vitiligo and Eczema. Nearly all SolRx devices use UVB-Narrowband lamps (Philips /01 311 nm).

All of these lamps will produce Vitamin D, but as with the treatment of skin disorders, UVB-Narrowband is almost certainly the best choice.

The study below evaluates the effectiveness of these three wavebands by mathematically comparing the lamps’ spectral distribution to the relevant action spectrums of Vitamin D, Erythema, and Non-Melanoma Skin Cancer.

Different wavelengths of “light” produce different effects on materials. Many important processes have been scientifically studied to determine the relative contribution of each wavelength to the studied process. Graphs known as “action spectrums” are used to describe these relationships. The greater the “action spectrum sensitivity”, the more responsive is the process to that wavelength.

The Vitamin D Action Spectrum has been thoroughly studied [Ref: CIE (International Commission on Illumination)] and shows that the most therapeutic wavelengths are in the UVB range as shown in Figure 1.

In the following sequence of pictures, additional action spectrums and UV lamp spectral curves will be added to explain the benefits and risks for each lamp type. Note that the relative size of the lamp curves are dependent on the power and number of lamps in the device, while the relative distribution of wavelengths does not change. To make the comparison fair, the spectral curve of each lamp curve has been mathematically “normalized” so the total energy of each lamp waveband type is the same; in other words, the area under each lamp curve has been made to be the same.

The action spectrum for “sunburning” of human skin, also known as “erythema”, has also been studied. Erythema is undesirable because it causes patient discomfort, it is a risk factor for skin cancer, and UV exposure beyond erythema does not produce any additional Vitamin D. The Erythema Action Spectrum (in red) shows similarities to the Vitamin D Action Spectrum, but an interesting opportunity appears in the region of 298 to 316 nm, where the Vitamin D sensitivity exceeds the erythema sensitivity, as shown in grey in Figure 2. In this region, the ratio of Vitamin D produced to erythema received is at its most favorable; a “sweet spot” with a peak at about 308 nm. It is not surprising that this region corresponds very nicely with the Psoriasis Action Spectrum shown in green (296 to 313 nm), and that 308 nm is the exact wavelength produced by excimer lasers, which are similarly successful for the treatment of the same skin disorders.

Common UVA cosmetic “tanning” lamps have been shown to produce Vitamin D. This is possible because, even though most of the lamp’s energy is in the UVA region, there is still a small amount of UVB produced, limited by regulatory bodies such as the US-FDA to not exceed about 5%. The small shaded area in Figure 3 (where the curves intersect) gives a pictorial representation of the Vitamin D producing potential of these UVA tanning lamps (in this example, “350BL” type is used, where 350=Wavelength Peak, and BL=Black Light). These lamps provide the vast majority of their energy in the UVA range, which does not provide any Vitamin D, increases treatment time, causes skin tanning (which acts as a filter to inhibit Vitamin D production) and subjects the patient to some UVA erythema (the erythema action spectrum extends all the way to 400 nm – each wavelength contributes). The UVA spectral curve does however most closely approximate the sun’s natural spectrum.

A logical option for making Vitamin D is to use “UVB-Broadband” lamps. These lamps do a good job of spanning the Vitamin D Action Spectrum as pictorially represented by the grey shaded area in Figure 4. The vast majority of energy produced is in the UVB range, which produces Vitamin D, but the light is spread broadly across UVB wavelengths (280 to 315 nm), including very significant amounts deep into the most potent regions of the Erythema Action Spectrum. This means that the user must take great care when dosing, so as to not exceed the Minimum Erythema Dose (MED), which is the dose where skin starts to sunburn. UVB treatment times are therefore quite short in duration. 

UVB-Broadband lamps typically provide little tanning effect because dosing is limited by erythema, long before the UVA content can cause tanning. In other words, the spectral profile is too heavily weighted in UVB to allow significant tanning effects. Although some people do report getting tanned, the more common outcome is slight pinkness, or little to no effect when dosing conservatively. UVB-Broadband lamps have been used to treat psoriasis for more than 60 years, but the possibility of burning has always been a concern. In the USA, UVB-Broadband lamps require a physician prescription per 21CFR801.109. Solarc’s UVB-Broadband models have only a “UVB” suffix, such as 1740UVB.

A more recent option for making Vitamin D is to use “UVB-Narrowband” lamps, such as the Philips TL100W/01-FS72 6-foot long, 100-watt T12 lamp, made popular for its superior effectiveness in the treatment of psoriasis, vitiligo and other skin disorders. This lamp has a very large amount of energy concentrated at 310-311 nm, and a minor peak at about 306 nm. The grey shaded area in Figure 5 shows only partially its Vitamin D making potential, because the peak of the UVB-NB curve is so high, its contribution cannot fully be represented pictorially.

These lamps produce Vitamin D, and they take advantage of the “sweet spot” between the action spectrum curves of Vitamin D and Erythema as explained using Figure 2 (the theoretical ratio of erythemogenic potential of UVB-Broadband to UVB-Narrowband is in the range of 4:1 to 5:1). This means that more Vitamin D can be produced before skin burning occurs, accurate dosing is less important, and the treatment is theoretically safer and easier to use, especially in the home environment. In psoriasis patients, UVB-Narrowband is capable of producing good therapeutic results without the patient ever reaching the erythemogenic threshold (Haykal & DesGroseilliers 2006, Walters 1999). For these reasons, UVB-Narrowband is now the phototherapy treatment of choice for many skin disorders, and is considered to be less aggressive than UVB-Broadband phototherapy. To wit, Solarc’s UVB-Narrowband sales exceed UVB-Broadband sales by more than 100:1, and several medical studies have shown the effectiveness of UVB-NB in producing Vitamin D.

As with UVB-Broadband, UVB-Narrowband lamps provide little tanning effect because dosing is limited by erythema, long before the UVA content can cause tanning. In other words, the UVB-NB spectral profile is too heavily weighted in UVB to allow significant tanning effects. In the USA, UVB-Narrowband lamps require a physician prescription per 21CFR801.109. Solarc’s UVB-Narrowband models have a “UVB-NB” or “UVBNB” suffix in the model number, such as 1780UVB‑NB.

Another way to evaluate lamp types is to study the action spectrum RATIO of Vitamin D to erythema, with the expectation that the best fitting lamp type will be the best for treatment purposes. In other words, what wavelength produces the most Vitamin D with the least erythema? For this we invented a new curve called the “Normalized Vitamin D to Erythema Ratio”, or “NVDER” for short, shown in Yellow in Figure 6. This NVDER curve is created by dividing the Vitamin D Action Spectrum by the Erythema Action Spectrum, and “normalizing” the result, so the maximum value is 1.0, just like an action spectrum.

This new curve is really just another way to show the “sweet spot” as discussed at Figure 2. It shows that the best ratio (peak) occurs at 308 nm. All three lamp types intersect the NVDER curve, but the UVB-Narrowband curve is likely the best fit, with its peak at 310 to 311 nm. Also note that, because the peak of the UVB-NB curve is so high, the UVB-Narrowband curve shows only partially its Vitamin D making potential, and that its contribution is not fully represented in this pictorial format. Note that the peak of the UVB-Narrowband curve is about ten times higher than the UVB-Broadband curve, thus the source of the name “Narrowband”.


In 2008, Health Canada evaluated and granted Solarc Systems Inc. permission to add “Vitamin D Deficiency” to the “Indications For Use” of our UVB and UVB-NB devices, per Medical Device Licence #12783. Indications For Use are health conditions for which Solarc can legally advertise. 

Note: The figures used in this document are simplified representations. The UVB-Broadband curve is derived from the SolRx 1740UVB and the UVB-Narrowband curve is derived from the SolRx 1760UVB‑NB.



“I am using it because I have a severe sensitivity to Vitamin D supplements. Have had a pre melanoma, so periods of time in the sun are not for me. My blood levels go up nicely at 8 minutes four times a week—4 minutes front, and 4 minutes in back.

Very satisfied. I feel so much better when I am using it regularly. Sometimes I go off for a few weeks, but pick back up.”

Margaret, VA, USA
Vitamin D deficiency patient

References & Links:

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

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)

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 35

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

HAYKAL K-A, DESGROSEILLIERS J-P (2006) Are Narrowband 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 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.


The information and material contained in this website is for general information purposes only.

While effort is made to ensure that the information provided in this website is current and accurate, the trustees, officers, directors and employees of Solarc Systems Inc., as well as the authors and website administrators of and will assume no responsibility for the accuracy and correctness of the information on this site or for any consequences of relying on it.

The information provided herein is not intended and does not represent medical advice to any person on any specific matter and should not be a substitute for the advice and/or treatment from a medical practitioner. You must consult your physician or a specialist dermatologist to obtain medical advice. Individuals or users who place reliance on the information contained in this site do so entirely at their own risk and no action or claim shall be brought against the authors, website administrators or any representatives of, or for, Solarc Systems Inc., for any consequences arising out of such reliance.

External links

Certain links on this site may take you to other websites that are neither owned nor controlled by Solarc Systems Inc.

Solarc Systems Inc. does not monitor or endorse any of the information found at these external sites. The links are provided merely as a convenience to users. Solarc Systems Inc. assumes no responsibility for the information of content available on any other website accessed by these links, nor does Solarc Systems Inc. endorse the material provided on such sites. The inclusion of links on this website does not necessarily imply any association with the organizations or administrators or authors responsible for those sites.