3 Reasons Most Vitamin D Lamps Will Not Work

Vitamin D is a steroid hormone essential to human health—research suggests that sufficient levels can help lower the chances of a range of illnesses from the common cold to certain cancers. But there is a pandemic of vitamin D insufficiency, particularly in the winter months and among those living at higher latitudes. For many, vitamin D lamps could be a viable solution.

As awareness of the health benefits of vitamin D has spread, so has the use of oral supplements but there are lesser-known vitamin D lamps available to purchase for those more serious about achieving therapeutic vitamin D levels. Studies have indicated that light therapy from lamps can be significantly more effective than oral supplements1)..Bogh, M.K.B. et al(2012), Narrowband ultraviolet B three times per week is more effective in treating vitamin D deficiency than 1600 IU oral vitamin D3 per day: a randomized clinical trial. British Journal of Dermatology, 167: 625–630.2)..Ala-Houhala, M.J. et al,(2012), Comparison of narrowband ultraviolet B exposure and oral vitamin D substitution on serum 25-hydroxyvitamin D concentration. British Journal of Dermatology, 167: 160–164., vitamin D produced in the skin may last at least twice as long in the blood compared with ingested vitamin D3)..Haddad JG, et al Human plasma transport of vitamin D after its endogenous synthesis. Journal of Clinical Investigation. 1993;91(6):2552-2555.

, and if used for long enough, lamps should be more economical for the user. In certain latitudes, light therapy may even be a better way to increase vitamin D than the sun.4)..Cicarma E et al. Influence of narrowband UVB phototherapy on vitamin D and folate status. Experimental Dermatology 2010; 19: e67–e72

If you’re in the market for a vitamin D lamp, there are some prerequisites you should be aware of—very few light devices available are capable of triggering vitamin D synthesis, so look out for the following:

Lamps need to emit the correct wavelengths of light

Vitamin D can only be synthesised from a specific waveband; the UVB range of the light spectrum. At a minimum, a lamp needs to emit a significant intensity of light from within this waveband, which ranges from 280nm to 315nm.

Only specific, purpose built bulbs emit sufficient levels of UVB radiation and are more costly than general use bulbs. It’s essential to verify the waveband of light emitted by the lamp or you may be buying a cheap imitation.

What has been proven to work and is commonly used in vitamin D lamps is narrowband UVB, or nUVB. Narrowband UVB is a specific wavelength of light, peaking at 311nm, which was initially developed, and been shown to be effective at treating skin disorders such as psoriasis, while minimising the erythema (reddening of the skin) side effect5)..Fischer, T et al. (1984), Ultraviolet-action Spectrum and Evaluation of Ultraviolet Lamps for Psoriasis Healing. International Journal of Dermatology, 23: 633–637.. Studies on nUVB have measured vitamin D levels in the patients before treatment, then again after treatment and in addition to clearing the psoriasis in patients, vitamin D levels rose significantly, even with low doses of light therapy.

The graph above shows how vitamin D levels changed for 19 patients undergoing nUVB therapy, t0 being before the study, t1 during and t2 after treatment.6)..Cicarma E et al. Influence of narrowband UVB phototherapy on vitamin D and folate status. Experimental Dermatology 2010; 19: e67–e72

‘Broadband UVB’, or bUVB has also shown to be effective and one study even showed it to be more efficient than nUVB. The study split participants into two groups, Vitamin D3 levels increased by 58.71% in the bUVB group, 45.5% in the nUVB group.7)..Osmancevic, A., et al (2009), Vitamin D production in psoriasis patients increases less with narrowband than with broadband ultraviolet B phototherapy. Photodermatology, Photoimmunology & Photomedicine, 25: 119–123. doi:10.1111/j.1600-0781.2009.00418.x

Cheap imitations include lizard lamps and ordinary fluorescent bulbs – these do not emit enough UVB to be effective and no clinical trials have been done using these lamps. Tanning beds emit roughly 97% UVA light and less than 3% UVB, which while is enough to increase levels in sun bed users, is less than ideal. Do not buy lamps with these bulbs because they will not be effective.

As well as ensuring there are adequate levels of UVB emitted by a vitamin D lamp, it’s also important to note that certain wavelengths ideally should be avoided.

UVA has been shown to inhibit vitamin D production8)..Godar, Dianne E. et al Increased UVA exposures and decreased cutaneous Vitamin D3 levels may be responsible for the increasing incidence of melanoma Medical Hypotheses , Volume 72 , Issue 4 , 434 – 443 and is therefore best kept to a minimum during treatment, there’s also evidence to suggest that some wavelengths of blue light are damaging to health9)..Godley BF1 et al. Blue light induces mitochondrial DNA damage and free radical production in epithelial cells. 2005 Jun 3;280(22):21061-6., and should avoided.

Glass and plastics will block most beneficial UVB light

Most lamps will have a glass or plastic between the user and the bulbs. If a lamp has a layer of ordinary glass over the bulbs, most, if not all of the shorter wavelength ultraviolet, the UVC and the necessary UVB light will be blocked but the UVA is more likely to pass through due to its longer wavelength.

% of vitamin D synthesis through different materials

The above graph shows that no vitamin D was synthesised with glass, plexiglass or plastic shielding the light from the patient.10)…McCollum Award Lecture, 1994: vitamin D–new horizons for the 21st century.
Holick MF1. 1994 Oct;60(4):619-30.

Not all glass is made the same or necessarily uses the same materials, some glass such as fused quartz will transmit the shorter UV wavelengths and is used to make lenses for UV cameras. As a general rule acrylic will block all UVB, but some brands of purpose made acrylics designed for use in sunbeds, psoriasis lamps and vitamin D lamps boast UV transmission rates of over 90%, which is ideal.

Manufacturers may cut corners in an effort to save money, so be sure it’s a suitable material before you purchase anything.

A vitamin D lamp needs to be powerful

Studies showing success with light therapy have used either narrowband or broadband UVB fluorescent bulbs, but there are now LED based products being marketed as being capable of cutaneous vitamin D synthesis. The issue with LED bulbs is they are only capable of emitting UVB at more than a fraction of a watt and so do not have the intensity we see in lamps used in clinical trials.

A light source needs to be intense enough to be able to cover large area of skin. One study used a combination of UVA and UVB bulbs to simulate summer sunlight and proposed 35% of skin area needed to be exposed to avoid deficiency.11)…Farrar MD et al. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: implications for targeted guidance on sun exposure. Am J Clin Nutr. 2013 Jun; 97(6): 1210–1216


Another, more in depth study used 28 broadband UVB bulbs on three groups of people, one group exposed their hands and faces to the light, another group their upper body and the third group exposed their whole body. The study confirmed that large areas of skin needed to be exposed in order for optimal vitamin D production and that increasing exposure time to smaller areas of skin was not only less effective but also increased risks of UV over exposure.12)…Osmancevic A et al. Size of the exposed body surface area, skin erythema and body mass index predict skin production of vitamin D. 2015 Aug;149:224-9.


For most, oral supplements are all that’s necessary to raise vitamin D levels, a lamp is not required. But for those whom the benefits may out weigh the costs, a good lamp is hard to come by, lights made for any other purpose will not be effective—and even those made for the purpose and marketed as vitamin D lamps may still be less than ideal.

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