I would like to say that I am opening this topic because it is tiresome to interact with the online fear-mongering about SUNLIGHT. Even when it comes to gradually exposing yourself to sunlight, the push is to instead swallow vitamin D pills. It is mostly touted in cosmetology and dermatology, and the internet is chuck full of this content aimed especially at women. Whilst it is still a good idea to apply some basic skin care as an adult, in areas with high UV radiation and not only, and especially on the face, neck, and shoulders, I feel like it's gone too far. (As, for example, overall in Europe -which isn't the best statistic for an individual person but here we go - there are less people dying to skin cancer ~around 15k~ than due to car accidents ~around 20k~).

The data is pretty clear. Skin cancer (which includes basal cell carcinoma, squamous cell carcinoma, and melanoma) is largely caused by UV radiation, especially UVB, although other contributing or enabling factors should naturally not be ignored, should you be subject to these (such as a weakened skin barrier, like during an active episode of psoriasis).

Despite that, the countries in Europe with the higher UV indexes ->

-> such as Romania, Bulgaria, Greece, Cyprus, Malta, all get significantly lower skin cancer rates than their more northern brothers (Denmark, Ireland, Sweden, Netherlands), despite people's purchasing power being significantly lower.

https://www.euronews.com/health/2023/07/19/skin-cancer-which-eu-countries-have-the-highest-melanoma-incidence-and-mortality-rates

North America, New Zealand, Australia, all are chart records in terms of skins cancers https://www.sciencedirect.com/science/article/pii/S2949713224000582 , and something much less discussed is these countries is that they are populated with a type of people that did not evolve in those UV areas of the world, with frequent genealogy tracing back to Irish, German, British, etc. settlers, with not just low epidermal melanin, but also habitually less exposure to sunlight especially nowadays.

Arguably, people in countries like Spain, Greece, Romania, etc. have higher melanin and "capacity for tanning" even when starting off from the same "white-ish" baseline (for example, a long winter) as an environmental adaptation.

And that's what I wanted to point out. Gradual exposure to sun (don't burn yourself until the skin peels off) is more beneficial than hiding under umbrellas and 3 layers of sunscreen because you're milk-white in the middle of August! That kind of avoidance is more dangerous.

Agree?

There is a point I'd like to discuss, which is the following AI statement on Google:

- "Darker skin tones, with more melanin, have a natural SPF of around 13, while lighter skin tones have a much lower natural SPF, potentially as low as 2-3. However, these natural levels are still far below the recommended minimum SPF 30 for adequate sun protection."

Have you found the study indicating the measurements of 30 "SPF"?

Edited August 12Aug 12 by FreeStyle

1 hour ago, FreeStyle said:

And that's what I wanted to point out. Gradual exposure to sun (don't burn yourself until the skin peels off) is more beneficial than hiding under umbrellas and 3 layers of sunscreen because you're milk-white in the middle of August! That kind of avoidance is more dangerous.

Possibly, I don't know, anything to back that up?

Any Studies?

2 hours ago, FreeStyle said:

I would like to say that I am opening this topic because it is tiresome to interact with the online fear-mongering about SUNLIGHT. Even when it comes to gradually exposing yourself to sunlight, the push is to instead swallow vitamin D pills. It is mostly touted in cosmetology and dermatology, and the internet is chuck full of this content aimed especially at women. Whilst it is still a good idea to apply some basic skin care as an adult, in areas with high UV radiation and not only, and especially on the face, neck, and shoulders, I feel like it's gone too far. (As, for example, overall in Europe -which isn't the best statistic for an individual person but here we go - there are less people dying to skin cancer ~around 15k~ than due to car accidents ~around 20k~).

The data is pretty clear. Skin cancer (which includes basal cell carcinoma, squamous cell carcinoma, and melanoma) is largely caused by UV radiation, especially UVB, although other contributing or enabling factors should naturally not be ignored, should you be subject to these (such as a weakened skin barrier, like during an active episode of psoriasis).

Despite that, the countries in Europe with the higher UV indexes ->

-> such as Romania, Bulgaria, Greece, Cyprus, Malta, all get significantly lower skin cancer rates than their more northern brothers (Denmark, Ireland, Sweden, Netherlands), despite people's purchasing power being significantly lower.

https://www.euronews.com/health/2023/07/19/skin-cancer-which-eu-countries-have-the-highest-melanoma-incidence-and-mortality-rates

North America, New Zealand, Australia, all are chart records in terms of skins cancers https://www.sciencedirect.com/science/article/pii/S2949713224000582 , and something much less discussed is these countries is that they are populated with a type of people that did not evolve in those UV areas of the world, with frequent genealogy tracing back to Irish, German, British, etc. settlers, with not just low epidermal melanin, but also habitually less exposure to sunlight especially nowadays.

Arguably, people in countries like Spain, Greece, Romania, etc. have higher melanin and "capacity for tanning" even when starting off from the same "white-ish" baseline (for example, a long winter) as an environmental adaptation.

And that's what I wanted to point out. Gradual exposure to sun (don't burn yourself until the skin peels off) is more beneficial than hiding under umbrellas and 3 layers of sunscreen because you're milk-white in the middle of August! That kind of avoidance is more dangerous.

Agree?

There is a point I'd like to discuss, which is the following AI statement on Google:

- "Darker skin tones, with more melanin, have a natural SPF of around 13, while lighter skin tones have a much lower natural SPF, potentially as low as 2-3. However, these natural levels are still far below the recommended minimum SPF 30 for adequate sun protection."

Have you found the study indicating the measurements of 30 "SPF"?

Perhaps you have heard the expression,” Mad dogs and Englishmen go out in the mid day sun”?

To put it more scientifically, I think you need first to disentangle the effect of social behaviour from skin tone. In the Med, the locals generally don’t lie around on the beach getting burnt, like the tourists from N Europe. They stay inside in the heat of the day.

Another confounding factor may be genetic skin tone vs. acquired skin tone. My son, whose mother was French, can tolerate longer in the sun than me, a Brit with a tendency to freckles. Also he tans much faster than me. So he may have inherited a better natural resistance to skin damage from UV.

I think if you have naturally light skin it is dangerous for you to imagine that you can rely on progressive tanning as a substitute for sun cream. But I would agree that a little gentle exposure, to give you a light tan, without ever burning, may give you a bit more of a safety net than hiding away from the sun completely - which almost nobody does anyway. In fact I’ve a feeling I read a recommendation to that effect quite recently, but I can’t remember where.

Edited August 12Aug 12 by exchemist

50 minutes ago, exchemist said:

an hiding away from the sun completely - which almost nobody does anyway. In fact I’ve a feeling I read a recommendation to that effect quite recently, but I can’t remember where

The moderate exposure literature on line seems to be Vit D focused rather than reduced cancer risk.

Only a brief search so far though.

One interesting point is that SOC (skin of colour) does have reduced risk but can be harder to detect especially with Afro Caribbean.

So SOC more likely to present with stage 3 or 4 - ref open bmj - I'll forward some citations tomorrow.

Edited August 12Aug 12 by pinball1970
"more likely"

1 hour ago, pinball1970 said:

Possibly, I don't know, anything to back that up?

Any Studies?

I wrote it in the original post, lack of melanin in strong sun is extremely damaging to the skin, otherwise noticed to an extreme in albino and patients with vitiligo. Melanin is what protects it, but the only "safe" way to obtain more of it is through sun exposure, which is ideal when the sun is mild, to begin with.

1 hour ago, exchemist said:

I think if you have naturally light skin it is dangerous for you to imagine that you can rely on progressive tanning as a substitute for sun cream. But I would agree that a little gentle exposure, to give you a light tan, without ever burning, may give you a bit more of a safety net than hiding away from the sun completely - which almost nobody does anyway. In fact I’ve a feeling I read a recommendation to that effect quite recently, but I can’t remember where.

I think most of us on this forum do, but it has been quite an efficient tactic throughout the years for people from my circles, aka progressive tanning. It's the natural way. Overreliance on sun cream is intense right now, too exaggerated exactly because people don't go out anymore because they think "oh no, the sun is cancerous because it shoots ghost noises radiatioooon 🤯", and that's just pure fear-mongering. Sooo... maybe, how light do you mean? Pink? lol :P As a side note, China, Korea and Japan have disproportionately high numbers of sun avoidance exaggerations like that. I mostly see it driven by aesthetics. A commercial tactic for a BOOMING market and "fight against sagging skin, looking old is ugly!".

1 hour ago, exchemist said:

Perhaps you have heard the expression,” Mad dogs and Englishmen go out in the mid day sun”?

To put it more scientifically, I think you need first to disentangle the effect of social behaviour from skin tone. In the Med, the locals generally don’t lie around on the beach getting burnt, like the tourists from N Europe. They stay inside in the heat of the day.

I do not think that is true. The research I linked says it didn't manage to show any correlation between occasional sunbathing holidays and melanoma incidence. I'd also add that most of the population were farmers, and although they'd try to make their lives easier, they'd still have to stay out in the sun A LOT compared to us, because of the nature of their occupation and need to connect to people or reach out to them, though it may be that men got out more than women. Women, due to the Churchly beliefs and other social practices, were likely kept indoors more?

26 minutes ago, pinball1970 said:

point is that SOC (skin of colour) does have reduced risk but can be harder to detect especially with Afro Caribbean.

So SOC more likely to present with stage 3 or 4 - ref open bmj - I'll forward some citations tomorrow.

Yeah, there are a few different statistics on the lines of:

-detection rates

-who dies more from them

-who finds them more often but escapes alive

With low healthcare access seemingly still not even denting the big Nordic figures otherwise present

Edited August 12Aug 12 by FreeStyle

13 hours ago, FreeStyle said:

And that's what I wanted to point out. Gradual exposure to sun (don't burn yourself until the skin peels off) is more beneficial than hiding under umbrellas and 3 layers of sunscreen because you're milk-white in the middle of August! That kind of avoidance is more dangerous.

Agree?

Is there any credible scientific study to back this up

13 hours ago, FreeStyle said:

There is a point I'd like to discuss, which is the following AI statement on Google:

- "Darker skin tones, with more melanin, have a natural SPF of around 13, while lighter skin tones have a much lower natural SPF, potentially as low as 2-3. However, these natural levels are still far below the recommended minimum SPF 30 for adequate sun protection."

And not AI crap. Get the source if the information, not a possible fabrication

6 hours ago, swansont said:

And not AI crap. Get the source if the information, not a possible fabrication

My brother, you need to read it again because you did not understand it. I copied the AI paragraph to question it, not to provide it as a reference for my words, hence why I'm asking quite clearly at the end if anyone can help provide the original reference to it.

6 hours ago, swansont said:

Is there any credible scientific study to back this up

As I answered in my reply to pinball, melanin production is a result of skin exposure to the sun, and lack of melanin in strong sunlight is the number one reason for burning, as observed in patients with extreme lack of melanin such as albinism or vitiligo. However, I want to underline that the way I word these posts is to learn, not to push a reality, or come across as a jerk that imposes its theories on others because 3 studies say so. To start the conversation by drawing a circle in a territorial manner is to, essentially, end it prematurely.

Some things I write are obvious to me whilst some are not to you, but you may need to search the baseline yourself if you did not know or are completely unfamiliar with that, essentially. I hope I don't come across as accusing you of "ignorance", the only thing is I'd appreciate if you could contribute with some theory. If for some obscure reason you might be averse to all of that, then I assume you won't read a fully-fledged study, so, here I am providing something, just scroll to the conclusions: https://pmc.ncbi.nlm.nih.gov/articles/PMC2671032/ that is from 2009, when they were observing that "subjects with White skin are approximately 70 times more likely to develop skin cancer than subjects with Black skin" however, the European-level incidence of skin cancer suggest that we don't need to be of such drastically different origins to observe statistical differences... The study also shows microscope pictures of what melanin looks like and is. If you would like to help/contribute with a study that's younger than 6 years, please do. I believe salon bed tanning habits is probably not having a big influence on the overall numbers given the low number of users compared to the general population, although perhaps incidence of skin cancer is higher among sunbed tanners, as we'd think logically?

Otherwise, this is good at explaining what we think melanin does and how it protects the skin, not just as a barrier, but as a free radical scavenger, which studies that only measure SPF will miss: https://www.nature.com/articles/s41598-024-53941-0.

However, it also questions whether other independent factors might affect the degree of sun protection granted, other than melanin.

If skin cancer mapping clearly shows a preponderance of such disease in countries with the least sun exposure and skin melanin, but you've got in-vitro studies concluding everyone should use sunscreen and they didn't find skin melanin to be important, is it probably worth questioning those studies and their sponsors? and if cancer prevention is enabled by other factors than melanin? So far, according to most studies, it seems that melanin has the highest protective role, and there is not much to indicate otherwise.

"Skin pigmentation has been considered the main photoprotective factor against UVR, and ionizing radiation, with many epidemiological studies showing a lower skin cancer incidence (20- to 60-fold) in dark skin (skin type VI) compared to light skin (skin types: I–II). The risk has often been attributed to differences in the content and composition of melanin in the skin. Melanin, a complex biopolymer with condensed oxidized tyrosine as basis, is the most abundant skin chromophore, being presented as dark eumelanin and reddish pheomelanin. Melanocytes synthesize and package melanin in the form of melanosomes and transfer it to adjacent keratinocytes, where the pigments arrange perinuclearly to protect the skin against UV-induced cell damage. The distribution of melanin in a capsular structure over the keratinocyte nuclei is required to constitute a physical barrier that scatters, absorbs, and thus, reduces the penetration of UVR through the epidermis. It is well known that photoprotective properties of melanin derive from its broad absorption capacity in the UV–Vis range, together with its antioxidant and radical scavenging properties."

I would like to add that with a lifetime or years of consistent sun exposure, melanin will persist in the skin even in skins type "I and II" as used above, even throughout periods of no sun exposure when the skin would otherwise return to its lower melanin content, as I have personally observed in families with older individuals who were farmers or spent a lot of time outdoors vs siblings or other relatives who didn't.

Additionally, I posted those maps to ask users what they think of those trends and what could drive them, as my opinion/theory is, basically, due to melanin production through sun exposure, because people in those areas have normal white skin in winter, but the capacity for "tanning" (melanin production) is quite high in the general population, but only granted with sun exposure (otherwise, generally, people will still burn with sudden exposure to summer sun in Romania, Greece, Spain, etc.)

Edited August 13Aug 13 by FreeStyle

3 hours ago, FreeStyle said:

My brother, you need to read it again because you did not understand it. I copied the AI paragraph to question it, not to provide it as a reference for my words, hence why I'm asking quite clearly at the end if anyone can help provide the original reference to it.

Hmm. I did read it again. What you wrote was “There is a point I'd like to discuss, which is the following AI statement on Google:” and I’m pretty sure that no matter how many times I read it, it’s going to say discuss and not say anything about questioning the statement.

The original reference you asked for was only for 30 SPF, not the skin tone claims, and by asking for a reference it’s clear you were accepting the claim, not questioning it. My comment was a caution not to rely on AI as a source, which is against the board rules.

3 hours ago, FreeStyle said:

As I answered in my reply to pinball, melanin production is a result of skin exposure to the sun, and lack of melanin in strong sunlight is the number one reason for burning, as observed in patients with extreme lack of melanin such as albinism or vitiligo. However, I want to underline that the way I word these posts is to learn, not to push a reality, or come across as a jerk that imposes its theories on others because 3 studies say so. To start the conversation by drawing a circle in a territorial manner is to, essentially, end it prematurely.

Asking for a reference of a claim is not “drawing a circle” it’s heading off a potential waste of time of conversing about something that’s not established. This is a science discussion site. You should expect claims to be challenged. If you want to make a plausibility argument that’s fine, but you have to phrase it as such and not assert it as fact.

On 8/12/2025 at 10:16 AM, exchemist said:

I think if you have naturally light skin it is dangerous for you to imagine that you can rely on progressive tanning as a substitute for sun cream. But I would agree that a little gentle exposure, to give you a light tan, without ever burning, may give you a bit more of a safety net than hiding away from the sun completely - which almost nobody does anyway. In fact I’ve a feeling I read a recommendation to that effect quite recently, but I can’t remember where.

There's been recent research that a smallish exposure to sun is overall healthier because it stimulates the immune system to protect better from various forms of cancer and also some autoimmune diseases and depression. The risk mitigation of those outweighs the skin cancer risk, apparently. There was a SciAm article a couple months ago on this topic - or the autoimmune aspect, anyway. I link that, not fully recalling its conclusions.

(Always took the moderate approach myself, which my Millennial children are appalled by, though one has softened a bit in response to new data suggesting that a life slathered in sunblock may not be optimal for overall health)

Scientific American

Sunlight Might Hold the Key to Treating Autoimmune Diseases

Sunshine may hold healing rays for a variety of autoimmune diseases such as multiple sclerosis. Scientists are turning this surprising discovery into treatments

42 minutes ago, TheVat said:

suggesting that a life slathered in sunblock may not be optimal for overall health

Interestingly, there is some evidence that while sunblock is protective against skin cancer, it does not seem to affect other processes significantly. I am not entirely sure regarding the whole autoimmune angle, but in terms of easier measurable factors such as Vitamin D the impact of sunscreen seems to be fairly low (except on the very high end). The general recommendation I have seen in that regards is to sue SPF 30 with intensive UVB radiation (regardless of season) and daily SPF15 in temperate climates.

2 hours ago, CharonY said:

Interestingly, there is some evidence that while sunblock is protective against skin cancer, it does not seem to affect other processes significantly. I am not entirely sure regarding the whole autoimmune angle, but in terms of easier measurable factors such as Vitamin D the impact of sunscreen seems to be fairly low (except on the very high end). The general recommendation I have seen in that regards is to sue SPF 30 with intensive UVB radiation (regardless of season) and daily SPF15 in temperate climates.

Is this saying that applying sunscreen does not much inhibit synthesis of vitamin D by the body? If so, good to know.

(I'm interested in this as since the Covid pandemic I've been taking a daily vitamin D pill in the winter 6 months, on the advice of my doctor brother, to keep my immune system in good order. But I don't in the summer 6 months on the basis that I get enough sunshine to keep the level up.)

21 hours ago, exchemist said:

Is this saying that applying sunscreen does not much inhibit synthesis of vitamin D by the body? If so, good to know.

That's what B.A.D. (British Association of Dermatoogists) says;

https://www.bad.org.uk/sunscreen-application-does-not-prevent-vitamin-d-production-in-the-majority-of-people

Pretty interesting read. The gist is that even if there is an effect to reduce vitamin D production in some small number of cases, the benefits far outweigh the effect. (not sure if they have anything to say about very high spf 30+ sunscreens)

22 hours ago, exchemist said:

Is this saying that applying sunscreen does not much inhibit synthesis of vitamin D by the body? If so, good to know.

(I'm interested in this as since the Covid pandemic I've been taking a daily vitamin D pill in the winter 6 months, on the advice of my doctor brother, to keep my immune system in good order. But I don't in the summer 6 months on the basis that I get enough sunshine to keep the level up.)

As mentioned the effect seems to be small. Most studies I have seen were based on tracking folks who used high levels of SPF (e.g. because of some underlying conditions) and then track their Vitamin levels. There are also handful of controlled trials but usually at lowish SPF (see an example for Australia doi:10.1001/archderm.1995.01690160043006).

Obviously, there could also be other effects, but after sufficient such studies you should see an overall lower level among those whop regular use sunscreen, vs the control groups. So far, metastudies have not shown a strong effect. An example is here https://doi.org/10.1111/bjd.17980

However, also as mentioned, the data for very high levels of SPF are still sparse (I think I saw an abstract somewhere suggesting that very high SPF could increase risk of vitamin D deficiency but cannot recall it very clearly).

21 hours ago, swansont said:

Hmm. I did read it again. What you wrote was “There is a point I'd like to discuss, which is the following AI statement on Google:” and I’m pretty sure that no matter how many times I read it, it’s going to say discuss and not say anything about questioning the statement.

The original reference you asked for was only for 30 SPF, not the skin tone claims, and by asking for a reference it’s clear you were accepting the claim, not questioning it. My comment was a caution not to rely on AI as a source, which is against the board rules.

Long story short to avoid useless sophistry... The references for that AI statement exist in the online realm, I am just curious how they were measured: https://pmc.ncbi.nlm.nih.gov/articles/PMC8766623/

16 hours ago, CharonY said:

Interestingly, there is some evidence that while sunblock is protective against skin cancer, it does not seem to affect other processes significantly. I am not entirely sure regarding the whole autoimmune angle, but in terms of easier measurable factors such as Vitamin D the impact of sunscreen seems to be fairly low (except on the very high end). The general recommendation I have seen in that regards is to sue SPF 30 with intensive UVB radiation (regardless of season) and daily SPF15 in temperate climates.

Where did you see this recommendation? I keep seeing it on pages that need to make sales or are funded by such companies, which isn't always bad, except when it is.

What other processes are you thinking about that don't seem to be affected? Just Vitamin D synthesis?

There are a lot of sunscreen ingredients with potential for endocrine disruption: https://academic.oup.com/ieam/article-abstract/17/5/940/7727851

I personally for example use sun cream only if I know I will be in strong sun for more than 1 hour, but with an acquired tan I only really apply it on face neck and shoulders, and then on areas of the body with moles, and I won't do that each time, just because I think it wouldn't matter a lot, maybe I'm wrong. Overall, I prioritise vitamin D intake, which is low in countries such as the UK. Perhaps this is important to specify, because of my skin colour, which because of my genes can go from the standard inbetween type I-II to type IV (dark olive, or even darker) without much headache, which I can only do because I afford to relax in the sun even during the day because of my working arrangements as opposed to an office worker, and additionally, as I am not an average Caucasian in the Tenerife summer in my habits and observations. As a rule of thumb, I will not try to draw general conclusions of how much A Danish person burns or synthesizes vitamin D on a week in Sicily, if you understand what I mean. What you need to remember is that if your test group has Type I skin which does not seem to go olive with sun exposure but bright red, the sun may not only be too much, but they've either very nordic in genes or have genuinely not been exposed to the sun throughout their lives or past few years (scinency lingo? their melanocytes have not been stimulated).

13 hours ago, exchemist said:

Is this saying that applying sunscreen does not much inhibit synthesis of vitamin D by the body? If so, good to know.

(I'm interested in this as since the Covid pandemic I've been taking a daily vitamin D pill in the winter 6 months, on the advice of my doctor brother, to keep my immune system in good order. But I don't in the summer 6 months on the basis that I get enough sunshine to keep the level up.)

Depends on how much you were taking, I was told by a few doctors that 1000 IU and 2000 IU are recommended daily especially if coming from a sunny climate, which, of course, would have been hard for our ancestors to obtain over winter unless they had nice fat stores, as vitamin D is also stored in fat. Have you done a blood test to see how much plasma vitamin D you have during winter or summer?

My practical, or more personal, example: 50 year-old farmer lady, manager job. She goes in the sun almost every morning and evening with exposed face, arms, neck, and sometimes legs (but less so) (England). She also goes out because she trains for marathons and triathlons, and wears shorts throughout the year except winter. She also drinks coffee every morning. She was vitamin D deficient, in summer, with health side effects (bone mass loss, through this one happens over time). The caffeine from one-two cups a day significantly inhibited vitamin D synthesis, but I am unable to tell you how many coffee beans she'd extract it from in her cups at home. She was told to reduce caffeine or take D supplements, and her D levels improved. I can acknowledge there may be knowledge gaps in here, but it is a practical example of habit analysis - medical plasma analysis - almost daily exposure - still ends up with deficiency in summer.

https://www.health.harvard.edu/staying-healthy/the-science-of-sunscreen

"Q. Does everyone need to use sunscreen? I've heard some people say that they don't need to wear it because they have darker skin that tans well.

A. We recommend sunscreen for skin cancer prevention, including melanoma prevention, which has been demonstrated in cohort studies as well as prospective randomized trials. Given that darker-skinned patients have a very low risk of skin cancer, using sunscreen for skin cancer prevention is not necessary. However, people looking to ward off the aging effects from sun would still benefit from sun-protective habits, which include sunscreen, sun-protective clothing, and sun avoidance."

The loss of nuance is strong, yet it is clearly observed. The article does not specify, but quite obviously, "darker skinned patients" are not just the passively darker ones... this darker skin is also, very importantly, obtained through exposure. It is quite important to not be virtually transparent (it's a joke) when you step out in the summer sun, like so many people from northernmost countries do for absolutely no reason other than being silly and not caring, as is to not burn yourself (or chop your fingers off - some things are a logical given). It is rather detrimental to your pocket and health to always be lathered in cream, assuming you do what most people do by mistake due to sweat and other factors, such as getting it in your eyes, nose, groin, or eating it by mistake because you wiped your forehead before eating, because chemicals bioaccumulate, and they are everywhere around us. It is useless to analyse just one ingredient and say "swallowing this from this source is not going to harm you" because it simply means that item only, and you may still have everything else with dodgy ingredients in them.

15 hours ago, npts2020 said:

Is this saying that applying sunscreen does not much inhibit synthesis of vitamin D by the body? If so, good to know.

That's what B.A.D. (British Association of Dermatoogists) says;

https://www.bad.org.uk/sunscreen-application-does-not-prevent-vitamin-d-production-in-the-majority-of-people

Pretty interesting read. The gist is that even if there is an effect to reduce vitamin D production in some small number of cases, the benefits far outweigh the effect. (not sure if they have anything to say about very high spf 30+ sunscreens)

The BAD article links to this: https://pmc.ncbi.nlm.nih.gov/articles/PMC6899952/

Let's analyse it quickly, though.

They analyzed serum vitamin D but do not tell us anything about their diet or supplementation, both of which contribute to vitamin D serum levels. The error factor of this alone can be anywhere between 1-20% or over if anyone was supplementing or consuming a lot of oily fish, as for example we also know some people consume things like Huel, smoothie powders or fish oil pills which tend to have vit. D added. We can assume they did not overall, it's what I would assume, but I also do not know enough about their possible diets in Tenerife to infer it, all I can do is hope they considered it.

Factor 2: The control group did not go to Tenerife, but stayed in Poland. The countries have vastly different UV charts... My problem with Tenerife is the principle of the study. Being by the seaside in sunny weather and above 20 temperatures gives you excess vitamin D the body doesn't actively use. I read somewhere (and you're welcome to try and find such info) that 2 hours by the seaside in sun, in skimpy bath suits, gives you the equivalent of 10,000 IU. Blocking Vitamin D may be significant if your vitamin D levels are borderline, and you cannot afford to run naked on a beach, on the other hand.

Modifying factor number 2: They were not followed by the team of scientists on whether or not they kept applying the cream on all the time... I'd assume most people wouldn't apply it all the time unless they were scientists themselves.

You all need to go back to the maps I linked, showing a clear trend. As we know, the reality is better than random studies with highly variable control factors, although they do remain useful and interesting for society nonetheless.

Let's focus on trying to explain why higher UV and olive tan do not correlate with high skin cancer rates. Suncare use by buying power does not correlate with lower cancer rates either in developed countries... although we should assume that's because it is also applied improperly. Now, I explained to you why, my logical theory.

Edited August 15Aug 15 by FreeStyle

6 hours ago, FreeStyle said:

Where did you see this recommendation? I keep seeing it on pages that need to make sales or are funded by such companies, which isn't always bad, except when it is.

Have you checked out the references I provided? There are also synthesis statements based on those and other papers from medical field that I could pull up, assuming that this is a good faith question.

6 hours ago, FreeStyle said:

They analyzed serum vitamin D but do not tell us anything about their diet or supplementation, both of which contribute to vitamin D serum levels. The error factor of this alone can be anywhere between 1-20% or over if anyone was supplementing or consuming a lot of oily fish, as for example we also know some people consume things like Huel, smoothie powders or fish oil pills which tend to have vit. D added. We can assume they did not overall, it's what I would assume, but I also do not know enough about their possible diets in Tenerife to infer it, all I can do is hope they considered it.

It also suggests given all the other elements such as diet, the use of sunscreen (at least up to SPF 30 ish) does not provide evidence for enhanced risk for vitamin D deficiency. Recommendations are typically based this whole assessment as folks want to know the outcome given everything that a person does. This will inevitably have areas of uncertainty. There are a handful for intervention style studies, too (Australia has been mentioned).

6 hours ago, FreeStyle said:

Let's focus on trying to explain why higher UV and olive tan do not correlate with high skin cancer rates. Suncare use by buying power does not correlate with lower cancer rates either in developed countries... although we should assume that's because it is also applied improperly. Now, I explained to you why, my logical theory.

Can you explain exactly what your hypothesis (I don't really see a theory here) is as it reads still very unspecific to me.

On 8/15/2025 at 7:04 AM, FreeStyle said:

The BAD article links to this: https://pmc.ncbi.nlm.nih.gov/articles/PMC6899952/

Let's analyse it quickly, though.

Maybe true but B.A.D. also looked at 75 peer reviewed studies (mostly British) on vitamin D production during sunscreen use, including the most recent 3, to reach their conclusions. I can't believe they would ignore anything that was peer reviewed and contradicted the official line.