Vitamin D looks like one of the greatest acne remedies in existence, but there’s still some dark clouds of uncertainty hanging over it.
It’s one thing to say that vitamin D lowers this or that inflammatory chemical, it’s another to have direct studies wiping pimples of the face of the Earth. The thing is, The Sunshine Vitamin’s benefits are particularly those that could be lost in translation.
Vitamin D’s claim to fame is calming obscure inflammatory cytokines like interleukin-8 and neutrophils. The immune system is so complex that while clear skin would be a smart guess, it’s hard to predict precisely how this whirlwind might manifest.
There are so many interacting and competing inflammatory players. It’s the opposite to say, the oily skin remedy green tea, which simply binds to sebaceous glands without much competition.
That’s why today, we won’t cover inflammation, we won’t cover insulin, and we won’t cover antioxidants. Nor we will we cover rats from New York’s sewer system.
Instead, we will analyse every direct study to date on whether vitamin D causes acne in humans.
The shining trio of positive studies
Right now, there are dozens of promising natural acne remedies with nary a single study to their name. Raw honey, magnesium, and MSM have all been totally neglected despite glowing testimonials from the clear skin community.
Sometimes, it really does feel like scientists are locked in an isolated underground bunker in the desert. Scientists often get focused on one obscure remedy above all else, like the Thai fruit mangosteen, with about 5 studies on acne.
Luckily, vitamin D’s overwhelming popularity has reached scientists ears for once. In fact, the studies are gathering pace into a raging torrent, and of the 10 we’re analysing today, 8 have been released since early 2015 (and one came out before World War 2).
ONE: the best might be this Korean study unleashed upon the world in 2016. Firstly, in 80 healthy Koreans, 22.5% were vitamin D deficient. In the acne group? The figure was more than double, at 48.8%. The correlation was strongest for inflammatory acne.
Part two involved supplementing 39 patients with vitamin D3, which led to a significant improvement. The study was probably the most reliable here. 160 is a strong sample size, and the vitamin D deficiency rates in the healthy group matched the overall Korean population, proving that it was properly representative; taking samples from the sunniest beach in Korea would ruin the test. They were tested for 2 months, which is important, because vitamin D takes several weeks to accumulate in the bloodstream.
The only serious flaw was that their diets weren’t accounted for, including vitamin D-containing foods like eggs, dairy and salmon. Fortunately, those foods only contain small amounts anyway, which separately, is why I always recommend focusing on sunshine and supplements. Weirdly, the scientists worried that their dosage of 1000IU was too low, but that’s a good thing, because it proves that lower dosages work too. My unofficial reliability rating: 8/10.
TWO: secondly, we teleport halfway across the world to the land of pyramids and Pharaohs (study). There were four neat and tidy groups: 30 healthy, 20 with mild acne, 20 moderate, and 20 severe. The age range was 18-30, missing high schoolers, but young enough so that it isn’t only useful for adult acne. Inflammatory and comedogenic acne were both tested, as were the back, chest and face.
There was strict exclusion criteria to prevent distorted results: liver disease, pregnancy, medications, post-menopausal women, and kidney disease. The flaws were having only 90 patients (which isn’t terrible), and that all patients were gathered from Egyptian dermatology clinics, increasing their chances of the poor nutrition behind other skin diseases.
The experiment was a simple blood test, and the acne patients had significantly lower circulating vitamin D3, “suggesting a possible role for vitamin D supplementation in acne treatment.” The numbers of sufficient people were nearly identical; most young Egyptian adults lacked it despite the scorching desert sun. However, 14/20 severe acne patients were downright deficient, compared to 9/20 moderate and 4/20 mild. Between healthy and acne overall, 10/30 (33.3%) sufficient vs 8/60 (13.3%). 7/30 (23.3%) were deficient vs 27/60 (45.0%). The middle category was “insufficient”. My reliability rating: 7/10.
THREE: next, we have a freshly baked study released in January 2020. 100 acne patients and 100 clear-skinned people were given vitamin D for 3 months, and at the beginning, the acne patients’ vitamin D levels were “significantly lower“, inversely correlated to severity. As a bonus, the pro-inflammatory cytokines IL-6 and TNF-a plummeted, adding yet more evidence that vitamin D calms inflammation. The sample size was strong and the 3 month time period was decent. The flaws were that diet wasn’t mentioned, nor the season they gathered the blood data in, which affects the sunlight. My reliability rating: 6/10.
These three studies are the best proof around that vitamin D is the secret solution to acne.
The less trustworthy positive studies
However, a series of weaker studies also exists, the second tier of proof.
These experiments have serious methodological flaws, but combined, they’re still a great indicator that simple vitamin D can cure acne. An advantage we have is experiments testing both vitamin D supplements and bloodstream levels:
FOUR: firstly, we hop into a time machine back to 1933 Chicago, two years after Al Capone was locked up for tax evasion (study). Like teenagers today, a couple of scientists were jolted by a brainwave when they noticed sunlight transforming people’s skin.
They swallowed some vitamin D drops, the predominant supplement in 1933, and were astonished when 75-80% of their pustules vanished.
In part 2, they gathered 35 men and women aged 17-30 from the University of Chicago (all this taking place in grainy black and white). Like before, they started with 10 drops daily and finished with 20. The result: 70-80% percent improvement in 90% of participants. The other ten percent improved by 40-50%.
For a control, they discontinued the vitamin D in ten random people, and nodded their heads eagerly as their pimples dutifully reformed. They concluded that “those who continued the treatment noticed a sustained improvement“, but nothing was heard of them again.
Chicago is not the sunniest city, so it’s an excellent place to test. Seasons aren’t a factor, because they were all supplemented at the same time. However, 35 patients isn’t many. If anything, their improvements were too huge; we need more detail than a simple letter. Reliability rating: 5/10.
FIVE: over in Turkey, 43 nodulocystic acne patients were compared to 46 clear-skinned controls (study). Little needs to be said: vitamin D deficiencies affected 95.3% of the acne group, compared to 56.5% of the controls. The acne group contained 16 men and 27 women.
The problem? The sample size was far too small at 43. Meanwhile, diet was ignored, and the study only tested severe acne. Nodulocystic acne is the most aggressive, red and inflamed form in existence. More positively, the mean age for the acne patients was fairly young at 23.31, and the exclusion criteria was strict, forbidding numerous medications, and calcium supplements.
A less important problem the scientists confessed to was sampling the vitamin D in autumn and winter. If the 95.3% deficiency rate was presented in isolation, then it would be totally misleading, but as long as we have a comparison, it’s trustworthy. Meanwhile, the groups didn’t differ in their BMI or calcium levels. Reliability rating: 5/10.
SIX: another Egyptian study (2018), gathering 60 lucky acne patients and 90 clear-skinned people. Their focus was partially on isotretinoin (AKA accutane), but the acne patients averaged at 17.34ng/mL in their bloodstream while the clear skinned achieved 44.83ng/mL. They concluded that “vitamin D may play a potential role in pathogenesis of acne vulgaris”, but also that acne may lower vitamin D; they weren’t definite on the order.
The flaws included having just 15 men versus 45 women. More ominously, the differences seem so gigantic as to be unbelievable. The moderate acne group averaged at 18.54, the severe at 14.56 and the very severe at 11.32. Even this is an insane difference. The very severe group had only 6 members vs 66 for moderate acne; such a small sample size could easily be distorted. However, the overall sample size was strong. The exclusion criteria was tight; anyone taking medications, lactating or even with hormonal disorders was sent packing.
Again, we have a juicy little bonus; the BMIs, liver enzymes, and cholesterol were no different. The obesity and acne question is as old as the universe itself, so this study adds to the evidence pile (see this article). Reliability rating: 6/10.
SEVEN: a unique study because it mainly trawled through old medical records. Australian patients were followed intimately for 10 years, allowing scientists to compile nutritional data on 453 acne patients.
Quickly, a deficiency in vitamin D materialised, with “significant associations” with acne compared to controls. The average age was 22.8 years, and the vitamin D was recorded within one month of the acne levels.
One self-confessed flaw was using questionnaires rather than face to face professional analysis. The seasons weren’t mentioned, and that’s particularly important with this style of study, because the cases are distributed across time. The acne patients could have all been tested in winter (gloomy) and the controls all in summer (sunshine everywhere). Using data from only one season would have been perfect.
Meanwhile, BMI didn’t affect acne, but non-vegans were twice as likely to have pimples as their plant-munching brethren. The scientists blamed dairy. Reliability rating: 4/10.
The contradictory studies
Now for the annoying part. The first happy fact is that these negative studies are severely outnumbered, with no armoured troops on horseback riding to the rescue.
There’s 7 positive studies, two negative, and 1 neutral. I will admit to being biased and hoping that they fail, but the stone cold reality is that the negative studies are just as methodologically flawed.
That said, we can’t simply brush them aside either.
EIGHT: actually a positive study, but a bit feeble. 39 acne patients and 40 controls faced off, with steroid abusers forbidden. There was “no statistical significant difference“, but a closer look reveals a difference of 20%, a bloodstream content of 8.4 ng/mL in the acne group vs 10.4 ng/mL in the healthy. Both groups had 4 “sufficient” members, but 24 acne patients were “severely deficient” vs 20 for controls, a small difference.
The sample size was weak, diet was forgotten and the seasons weren’t mentioned. However, questionnaires were only used for sun exposure; for pimples, the technical Global Acne Grading Score (GAGS) was rolled out. Vitamin D supplements were banned and so was alcohol, which could theoretically deplete levels. Reliability rating: 5/10.
NINE: the best evidence the anti-vitamin D crusaders have to offer. This 2018 Kuwaiti study is the largest experiment here, with 714 participants randomly selected from public schools, 479 of whom had acne. Using acne data from questionnaires, vitamin D was significantly lower in the acne group, at 27.15nmol/L versus 33.00 nmol/L.
But using the scientific method, which is far more reliable, the difference shrank to minuscule levels of 30.0 versus 32.5. This led them to the gut wrenching conclusion that “our data do not support vitamin D supplementation either to treat or to prevent AV (acne vulgaris)”.
Unlike other studies, the scientists took massive care with their statistical analysis, adjusting for diet, age, BMI, and education. Yet the mean age of 12.1 was strangely young, with a range of 11-16. At that age, it’s possible hormones haven’t fully kicked in yet, it’s possible that vitamin D synthesis has some quirks. These theories aren’t proven, but the point is that 12.1 years is not representative of most acne patients.
More seriously, only 31 of 714 participants had normal levels of vitamin D, with everybody else deficient. Taking a supplement would restore your levels to the optimal, but this study doesn’t test that. Most cases were mild and moderate as well, and severe acne might have greater potential to improve. Reliability rating: 6/10.
TEN: if you take this study at face value, then the case for vitamin D starts to look as shaky as a bowl of jelly. A tidy 80 acne patients and 80 controls had their bloodstream vitamin D analysed between October 2015 and April 2017. The sample size was solid, with an age range of 15-45, meaning plenty of teenagers.
In their words: “no significant relationship between AV disease and vitamin D… was observed“. The acne patients had significant higher circulating 25-Hydroxyvitamin D3. From mild to severe acne, bloodstream levels were 18.5 nmol/L versus 18. Vitamin D’s career as an acne-clearer is over… or is it? It isn’t, because firstly, the study skipped three out of the 6 skin types.
Most fatally, this study had absolutely no control over the seasons. Some vitamin D samples were collected in dark winter, others in sunny spring. It’s perfectly possible that 70% of acne patients were analysed in warm sunshine, totally distorting the results.
Surely that would be a coincidence? But as it turns out, that’s what happened; 58 (72.5%) of acne patients were tested in spring versus 22 (27.5%) in winter. Meanwhile, 34 (42.5%) of the controls were tested in spring versus 46 (57.5%) in the winter months. As they stated: “The primary limitation of our study was not being able to eliminate the role of seasonal differences“.
So great news: the worst looking study for vitamin D and acne is also the worst conducted on the list. Reliability rating: 1/10.
Analysis – where does the evidence point?
Normally, this would be where we dissect the reliability piece by piece and arrive at a conclusion. If it was an even split between positive and negative, it would be necessary, but today, the numbers speak for themselves. 7 out 10 studies showed that vitamin D causes acne to evaporate.
Now, this wouldn’t be important, if the two negative studies were the most professional ever, conducted by world-renowned scientists determined to show amateur acne enthusiasts the error of their ways. However, if anything, the balance of reliability tilts towards the positive studies. All 7 offer at least some evidence. Number five, the nodulocystic study only tested severe acne, but that’s a redeeming feature too, because it’s hyper focused on one level of severity. Maybe you’re a severe acne patient reading this.
The Chicago study has gathered dust over the decades of mystery (although the exact methods are probably written in a logbook stashed in his grandson’s cupboard somewhere), but the only truly crippled study was number ten, the negative Turkish one. Not testing vitamin D in the same seasons is an unbelievable mistake. The scientists specifically found that vitamin D was higher in spring, proving that levels had time to increase. It’s so flawed that our tally is effectively one versus seven now.
None of our studies are perfect, a shining hero of reliability that stands tall above the rest. They all have flaws, whether it’s the sample size or ignoring diet.
But it’s interesting how nearly every “untrustworthy” experiment leans towards vitamin D being beneficial. It could be a coincidence, but eventually, 10 or 20 flawed studies can add up to just as strong evidence as two worthy of Einstein himself.
There’s still flaws; the Kuwaiti study is biggest reason not to secretly dump vitamin D in the water supply (apart from ethics, I guess). It’s also impossible to judge its effectiveness. The sample sizes are the killer; they’re enough to observe beneficial results overall, but our vision is too clouded to see the magnitude when broken down. Vitamin D could only work for monstrously red acne, rather than the last few stubborn pimples that cling on for dear life.
However, there are positives here too; 66/90 patients in the 2018 Egyptian study (number six) had moderate acne, versus only 6 for very severe. This is a focused study for moderate acne patients just like the nodulocystic study was for severe.
On the face of it, there’s a huge flaw that most studies were conducted in sunny countries like Turkey, rather than the cold dampness of New York or Britain. Unlike vitamin C, you can’t take higher and higher vitamin D doses and continue to reap rewards. Fixing vitamin D deficiencies is the path for acne; it’s like magnesium, with few benefits beyond a certain point. In fact, when full up, your skin will stop manufacturing it in response to sunlight.
Therefore, testing sunny countries might be useless, but luckily, this would only be a flaw for the negative studies. If people improved despite the sunny weather, that’s absolutely fine.
Furthermore, many of the patients specifically lacked vitamin D, so this rules the sunshine factor out. In the 2019 Egyptian study, there was somehow no relationship between sun exposure and vitamin D, suggesting that acne patients are less efficient at activating vitamin D in the liver using the 25 hydroxylase enzyme (a topic for another time).
Verdict – the state of vitamin D today
We’ve reached our conclusion – the direct studies on vitamin D and acne are not 100% definitive, but strongly points towards benefits.
So what’s your revised vitamin D strategy as of 2020, to become so clear that you forget acne’s existence? The updated strategy is that there are no updates. Our old opinion here is that vitamin D is slightly less revolutionary than zinc, as the testimonials are slightly less shocking and sometimes lean more towards enriched glow, but still a gamechanging supplement. That opinion hasn’t changed. In certain circumstances, vitamin D could clear your acne completely.
If vitamin D didn’t boast a shred of scientific evidence then I would still recommend it, thanks to 1) the great testimonials, and 2) the logic based on its proven anti-inflammatory properties. Now though, the case for supplementation (or sunlight) is conquering all in its path.
I still recommend fixing your vitamin D levels if you’re an office worker, a citizen of northern latitude countries, or rarely exercise outside. Everyone should mull over their sunlight exposure.
With so many experiments in the last 5 years, it’s almost guaranteed that more are coming; a bespectacled scientist might be counting a guy’s pimples with a magnifying glass at this very second. I wrote the original vitamin D article back in 2015, and it’s great to see how the evidence is now flooding in; it’s exactly what we were hoping for.
Step by exhausted step, vitamin D has almost climbed the mountain of undeniably proven acne remedies. It hasn’t caught up with zinc’s war chest of studies yet, but vitamin D has officially charged past vitamin E, which is strangely unresearched, but so logically important that we barely need studies anyway.
Thanks for reading!