Vitamin D supplementation is becoming ever popular, and companies are trying to find more novel and unique ways to get vitamin D into you. Most vitamin D supplements will are oral (tablets), but recently there has been interest in the transdermal (through skin) absorption of vitamin D. So the question is – is transdermal vitamin D better than oral?


Oral vitamin D absorption

Oral vitamin D absorption has been pretty well researched, and you can see the results from 4 different studies investigating 9 different types of tablets/ capsules in the table below. The studies all used different dosages, and were done over different amounts of time which can make comparisons difficult. So, to make comparisons easier, you can create a standardised unit by taking the total change in mean serum 25(OH)D, and dividing it by the mean dose of vitamin D administered per day multiplied by 100 IU. This figure is circled in red below, and the higher the value shows a better absoprtion1.


comparison of oral vitaminD absorption
You can see from the table that there is quite a range in the absorption of the different types of oral vitamin D supplementation, but you can see that fish oils provide the best vitamin D absorption with a standardised unit of 9nmol/L/100IU/day.


Transdermal vitamin D absorption

There has been less research on transdermal vitamin D absorption, simply because it is quite a new way to get vitamin D in you. However, there is one study on 50 medical students that showed after the 3 month of using a vitamin D spray, vitamin D levels increased by 25.9 nmol/L2. Now, before you can compare this value to oral vitaminD, the nmol/L needs to be converted to the same units as the above studies, which give a change of 64.8 nmol/l.

If we convert these figures to the same standardised units used in the oral trails, we get 47.14nmol/L/100IU/day. This shows that transdermal vitamin D absorption is just over 5 times more absorbable than oral vitamin D from fish oils.

I’ve put the figures into a graph to make it easier to compare – you can see that transdermal vitamin D trumps all oral vitamin D supplements.


Graph showing transdermal vitamin D is absorbed much better than oral vitamin D


How conclusive is this?

More research can always be done, and I would like to see another transdermal vitamin D study to confirm the findings of the one above just to make sure the results are consistent, but the current evidence is pretty clear cut. Absorbing vitamin D through your skin looks to be the most effective way to get it in your body.


So, what is the best vitamin D supplement?


If you are solely looking to raise your vitamin D levels, then transdermal vitamin D looks to be the best bet. However, there are very few transdermal vitamin D supplements out there, so your options are limited. There is Primal-D, which has recently been released, which is a vitamin D spray. Primal-D doesn’t use aloe vera as the carrier like the study does though, instead it used DMSO, which is well known for its ability to transport various chemicals through the skin. Although there is not aloe gel, I am sure that this will have a very similar, if not better, affect on your vitamin D levels than the above study.

Alternatively, there is a topical vitamin D cream from AnuMed which uses an aloe vera gel base and contains other ingredients which can help moisturise your skin. Both I’m sure will be effective at increasing your vitamin D levels.

These are the best way to get your vitamin D levels up, but, transdermal sprays can sometimes feel oily on your skin, and aren’t as convenient as a simple capsule.

Vitamin D capsules

Fish oils, particularly cod liver oils have been shown to have a very positive effect on vitamin D levels, and also have the all important omega-3 fatty acids – giving you a nutritional double-whammy. You won’t get the same amount of vitamin D from fish oils as you would with with transdermal vitamin D, but you may not need all that much vitamin D to be healthy anyway. If you live a nice healthy lifestyle then you may not need the high dosage from a transdermal cream/ spray, rather, you can just use fish oils as a convenient vitamin D/ omega-3 top up (maybe only for the winter months).

Finally, if you feel you are getting enough omega-3 from your diet, but want a convenient way of getting vitamin D in you, vitamin D in coconut oil has been shown to be almost as good as fish oils when it comes to upping your vitamin D levels.



A vitamin D cream/ spray is the best way to increase your vitamin D levels, so if you feel your vitamin D levels are very low and you just want to improve them, then this is your best bet. However, I don’t think everyone needs such a big vitamin D boost, certainly not throughout the year if you pay attention to your health. I would much prefer to simply take a fish oil capsules for my vitamin D and get some omega-3’s at the same time.




1. Ruth E. Grossmann. (2010). Evaluation of vehicle substances on vitamin D bioavailability: A systematic review. Mol Nutr Food Res. 54 (8), 1055-1061.

2. Mir Sadat-Ali. (2014). Topical Delivery of Vitamin D3: A Randomized Controlled Pilot Study. Int J Biomed Sci. 10 (1), 21-24.

Image courtesy of Mikal Danielle.

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