6 ms·

For those who, like me, started to wonder how using sunscreen affects vitamin D production, here's the conclusion of "The effect of sunscreen on vitamin D: a re

For those who, like me, started to wonder how using sunscreen affects vitamin D production, here's the conclusion of "The effect of sunscreen on vitamin D: a review": "There is little evidence that sunscreen decreases 25(OH)D concentration when used in real-life settings, suggesting that concerns about vitamin D should not negate skin cancer prevention advice. However, there have been no trials of the high-SPF sunscreens that are now widely recommended. What's already known about this topic? Previous experimental studies suggest that sunscreen can block vitamin D production in the skin but use artificially generated ultraviolet radiation with a spectral output unlike that seen in terrestrial sunlight. Nonsystematic reviews of observational studies suggest that use in real life does not cause vitamin D deficiency. What does this study add? This study systematically reviewed all experimental studies, field trials and observational studies for the first time. While the experimental studies support the theoretical risk that sunscreen use may affect vitamin D, the weight of evidence from field trials and observational studies suggests that the risk is low. We highlight the lack of adequate evidence regarding use of the very high sun protection factor sunscreens that are now recommended and widely used." https://pubmed.ncbi.nlm.nih.gov/30945275/ https://pubmed.ncbi.nlm.nih.gov/30945275/

49531 5y ago
Fortunately Vitamin D supplements are a safe and effective way to get the recommended amount. UV exposure is the most preventable cause of skin cancer[1] and not worth the risk. EDIT Forgot my link: 1. https://www.hhs.gov/sites/default/files/call-to-action-prevent-skin-cancer.pdf https://www.hhs.gov/sites/default/files/call-to-action-preve...
- gojomo 5y ago
  But, after 50+ years of rising sunscreen use, there's essentially no data showing more sunscreen use reduces skin cancer. Sunscreen definitely prevents sunburns, and almost certainly delays visible skin aging/weathering. Those may be enough benefits for some people. But the people/populations using more sunscreen are also having more skin cancer. Some theories compatible with these observations are: • While preventing sunburn pain, sunscreen doesn't prevent the actual cancer-causing skin damage - and thus by allowing more time to be spent in the sun, actually worsened skin cancer rates. (This may have especially been a problem for the 1960s-1990s, when it was thought that only sunburn-causing UVB contributed to skin cancer - so sunscreens only blocked UBV. That encouraged increased exposure to the mostly-unblocked UVA, now understood as an equal contributor to skin cancer. More recent sunscreens block UVA as well.) • Known carcinogens commonly used in sunscreens, or present as contaminants, are actually causing increased rates of skin cancer. Anyone whose true worry is skin cancer should use shade & limited times of exposure - not sunscreens. (Ensuring a spaced-repetition of gradually-increasing exposure, to develop a natural tan without ever reaching a peeling burn, is also likely naturally protective against skin cancer.) Further, while endogenous Vitamin D production relies on sun exposure, and low Vitamin D is correlated with health problems, oral Vitamin D supplementation may not replace all the benefits of sun exposure. Generally, large population studies show positive effects of moderate sun exposure on many health outcomes, including overall longevity, heart disease, and non-skin cancers. Meanwhile, Vitamin D supplementation studies have usually not found that such supplementation alone reverses the correlations of many diseases with low Vitamin D. Thus, Vitamin D may not be the only mechanism by which sun's benefits are achieved. So rigorous sun-exposure-minimization, even if it does reduce (often benign or increasingly survivable) skin cancers, may increase overall mortality through higher heart disease & other cancers. (Your HHS report mentions 9,000 skin melanoma deaths per year. There are 650,000 heart-disease deaths and 600,000 other cancer deaths.) Get sun. Use shade, clothing, & timing to ensure it's not so much sun that you peel. Use sunscreen sparingly, only when you can't moderate sun exposure other ways.
  - seattle_spring 5y ago
    Can you provide some peer reviewed sources for your claims? Your whole comment reads like that thoroughly debunked "scientists blow the lid off of sunscreen" [1] article that was going around a few years back. [1] https://millerfamilydermatology.com/sunscreen-myth/ https://millerfamilydermatology.com/sunscreen-myth/
    - gojomo 5y ago
      Here's a good recent overview of reasons to doubt the efficacy of sunscreen against fatal skin cancers: https://www.outsideonline.com/2380751/sunscreen-sun-exposure-skin-cancer-science https://www.outsideonline.com/2380751/sunscreen-sun-exposure... (Most recently discussed on HN at https://news.ycombinator.com/item?id=23086211 https://news.ycombinator.com/item?id=23086211) Similar doubts have existed for decades – here's a 1993 variant reporting some of the trends that already didn't add up, back then: https://www.motherjones.com/politics/1993/05/melanoma-sunscreen-use/ https://www.motherjones.com/politics/1993/05/melanoma-sunscr... Another branch reply provides more sources about sunscreen chemicals & sun-longevity correlations: https://news.ycombinator.com/item?id=27520144 https://news.ycombinator.com/item?id=27520144
  - 49531 5y ago
    > • Known carcinogens commonly used in sunscreens, or present as contaminants, are actually causing increased rates of skin cancer. I am curious to see a citation for this claim. > Generally, large population studies show positive effects of moderate sun exposure on many health outcomes, including overall longevity, heart disease, and non-skin cancers. Meanwhile, Vitamin D supplementation studies have usually not found that such supplementation alone reverses the correlations of many diseases with low Vitamin D. Thus, Vitamin D may not be the only mechanism by which sun's benefits are achieved. I am also curious to see these studies, and wonder if they control for other variables like physical activity. I think it's an incorrect framework to say that you have to choose between skin cancer and heart disease, you can avoid both through different lifestyle choices.
    - baumandm 5y ago
- loudtieblahblah 5y ago
  Sunshine is more than just a source of VitD. UVA has also been shown to lower blood pressure. This is probably the result of UVA causing the release of nitric oxide from skin stores, which promotes widening of blood vessels. It also acts as an antioxidant to prevent damage to cells. People who don’t get enough sunlight have altered cellular defense mechanisms that predispose them to excessive inflammation, which can result in autoimmune diseases. One could argue you can supplement to replace VitD, but are you supplementing your children? From what age? How regularly? What's the quality of the supplementation? How do the poor maintain access to supplementation? Then you run into the problem that long term, large(r) doses of Vitamin D causes kidney problems. A study ( https://pubmed.ncbi.nlm.nih.gov/21430082/ https://pubmed.ncbi.nlm.nih.gov/21430082/) found an association between low vitamin D levels and the development of type 2 diabetes. For every ten-unit decrease in blood vitamin D levels, we found a 10% increased risk of developing this form of diabetes over the following five years. when they gave supplements of vitamin D to patients with low vitamin D levels who were already at risk of developing diabetes, there was no overall improvement in their sensitivity to insulin. Nor was there a change in their blood glucose levels compared with those given inactive tablets. I'm betting, not just in this case, but the act of your body making it's own VitaminD creates benefits we are not yet aware - that oral consumption of a pill isn't going to compensate for. nevermind MOST of VitaminD pills use soybean oil or some other horrible Omega-6 ridden, cheap seed oil as it's delivery method. Outside time in the sun is helpful in ways not tied to VitD, as well. circadian rhythms are regulated by bright light exposure. You can't get these lumens by waking up and sitting inside all day. The heat from the sun is capable of reducing physical stresses on the body’s cells and by increasing heat production. Another important potential effect of sunlight is UV-induced suppression of the body’s immune system. Solar radiation does this by altering the activity of the white cells involved in turning on the body’s defence mechanisms. This may seem like a negative, but it's vital for people to reduce inflammation and when considering how the earth's population spreads out autoimmune disorders (higher percentages the more you get away from the equator), this may be a secondary factor on top of VitaminD. IMHO - people need to find a balance with sunscreen and sunshine. if you know you're going to risk a burn, put it on and reapply when necessary. if you're worried about cancer, eat some cruciferous vegetables regularly to make sure you get lots of sulforaphane which protects against skin cancer. Get regular derma checkups. but when looking at auto-immune issues (that once you have one, your supplementation isn't going to undo it), the depression issues, and so forth - isn't worth skipping out on sunshine. Skin cancer may be the most preventable but it's also a fairly unlikely cancer, as far as cancers go - and while it's one of the scarier cancers, catching it early with derma appointments is key to survival. Catching it early has a high survival rate. An auto-immune issue, on the other hand, will shorten your life and make you suffer along the way, increasingly, for the rest of your life. It's not just a death sentence. It's a slow-slog through hell on the way there. Most people never go into a permanent remission of Ankylosing spondylitis or MS. It just slowly destroys you, it handicaps you, and then it kills you. And along with all that suffering, is your kids, parents and partners suffering right along with you. Yay - therapy sessions for everyone. It's not just auto-immune issues. Depression, anxiety, even certain cancers themselves all have some relation to low vitamin d. IMHO - sunlight needs to have it's saturated-fat moment where we realize that a lot of the fear mongering simply wasn't warranted. And that the cures for some diseases end up being the catalyst for many others that are far more likely. How many people are afflicted with an autoimmune issue? how many with debilitating depression? Compare those numbers to skin cancer. Compare the deaths. Compare the suffering. Then try to find a balance.
- nradov 5y ago
  Your risk analysis is not scientifically valid. There is no reliable evidence that moderate sunlight exposure increases all-cause mortality.
loudtieblahblah 5y ago
it should also be noted that consumption of certain antioxidants protect against skin cancer (most notably sulforaphane found in Cruciferous Vegetables). >Nonsystematic reviews of observational studies suggest that use in real life does not cause vitamin D deficiency. yeah, but that's an observational study. I'm not anti-sunscreen and if you burn or get dark/deep freckles easily, I'm even more "pro" sunscreen for you. But when looked at the number of diseases and problems correlated to Vitamin D deficiency and looking at the relatively low risk of contracting melanoma (as scary as that cancer can be if caught late), to me it's a balancing act. Consuming mass amounts of VitaminD over long periods of time, orally, can cause kidney problems. If you look at auto-immune issues globally, the percentage of the populations that have them sky rocket the further you get away from the equator. Depression, anxiety, even certain cancers themselves all have some relation to low vitamin d. Sunlight, the type that allows UV-B to penetrate your skin, is a human necessity. And like a lot of things we need (Vitamin C and E, or polyunsaturated fats, carbohydrates, etc), too much of it will cause you problems and/or kill you, not enough of it will cause you problems and/or kill you. And trying to anecdotally perform some balancing act without constantly running tests on yourself, is difficult. My rule of thumb is put on sunscreen if you are out long enough to risk a burn, re-apply when necessary. Otherwise, soak up the rays.
- pmoriarty 5y ago
  "Consuming mass amounts of VitaminD over long periods of time, orally, can cause kidney problems." What counts as massive? And is consuming massive amounts of Vitamin D necessary to prevent deficiency?
  - loudtieblahblah 5y ago
    if you're like most of the western world, especially if you have an indoor job and indoor hobbies (we spend an awful lot of time binging tv shows, playing video games, working on computers, etc..), you're not outside all that much unless it's to hop in the car and go to another indoor place. and chances are you have a deficiency. Most vitamins tell you to take 2,000 IU. Upper limits are typically stated to be 4,000 IU. But there's been no established harmful upper limit either. This leads a lot of people into thinking more is better, this is doubly true if they have some kind of pre-existing condition that's linked to low VitaminD and they're desperate to heal themselves. They read quack stories on the internet about how 10,000 IU doses help cure MS and they do it too. It's also made worse by so-called "smart" and "qualified" people like Dr Rhonda Patrick essentially turning herself into some pop-health guru and when she tells people what she supplements with (5,000-6,000 IU), many people feel she knows what she's talking about and copies her. But the reality is, she takes A LOT of supplements and she has zero idea how they all mix with each other, especially at the supplementation levels in which she's consuming them. of vitamins that can be abused, VitaminD is mostly safe. But a lot of folks go a bit crazy with it and have hurt themselves. VitD supplements are also, often, in soybean oil, which is horrible for you. VitD needs to be consumed with a fat, so If you're going to supplement, you spend the extra money for it suspended in coconut oil instead.

49531 5y ago

Fortunately Vitamin D supplements are a safe and effective way to get the recommended amount. UV exposure is the most preventable cause of skin cancer[1] and not worth the risk. EDIT Forgot my link: 1. https://www.hhs.gov/sites/default/files/call-to-action-prevent-skin-cancer.pdf https://www.hhs.gov/sites/default/files/call-to-action-preve...

gojomo 5y ago
But, after 50+ years of rising sunscreen use, there's essentially no data showing more sunscreen use reduces skin cancer. Sunscreen definitely prevents sunburns, and almost certainly delays visible skin aging/weathering. Those may be enough benefits for some people. But the people/populations using more sunscreen are also having more skin cancer. Some theories compatible with these observations are: • While preventing sunburn pain, sunscreen doesn't prevent the actual cancer-causing skin damage - and thus by allowing more time to be spent in the sun, actually worsened skin cancer rates. (This may have especially been a problem for the 1960s-1990s, when it was thought that only sunburn-causing UVB contributed to skin cancer - so sunscreens only blocked UBV. That encouraged increased exposure to the mostly-unblocked UVA, now understood as an equal contributor to skin cancer. More recent sunscreens block UVA as well.) • Known carcinogens commonly used in sunscreens, or present as contaminants, are actually causing increased rates of skin cancer. Anyone whose true worry is skin cancer should use shade & limited times of exposure - not sunscreens. (Ensuring a spaced-repetition of gradually-increasing exposure, to develop a natural tan without ever reaching a peeling burn, is also likely naturally protective against skin cancer.) Further, while endogenous Vitamin D production relies on sun exposure, and low Vitamin D is correlated with health problems, oral Vitamin D supplementation may not replace all the benefits of sun exposure. Generally, large population studies show positive effects of moderate sun exposure on many health outcomes, including overall longevity, heart disease, and non-skin cancers. Meanwhile, Vitamin D supplementation studies have usually not found that such supplementation alone reverses the correlations of many diseases with low Vitamin D. Thus, Vitamin D may not be the only mechanism by which sun's benefits are achieved. So rigorous sun-exposure-minimization, even if it does reduce (often benign or increasingly survivable) skin cancers, may increase overall mortality through higher heart disease & other cancers. (Your HHS report mentions 9,000 skin melanoma deaths per year. There are 650,000 heart-disease deaths and 600,000 other cancer deaths.) Get sun. Use shade, clothing, & timing to ensure it's not so much sun that you peel. Use sunscreen sparingly, only when you can't moderate sun exposure other ways.
- seattle_spring 5y ago
  Can you provide some peer reviewed sources for your claims? Your whole comment reads like that thoroughly debunked "scientists blow the lid off of sunscreen" [1] article that was going around a few years back. [1] https://millerfamilydermatology.com/sunscreen-myth/ https://millerfamilydermatology.com/sunscreen-myth/
  - gojomo 5y ago
    Here's a good recent overview of reasons to doubt the efficacy of sunscreen against fatal skin cancers: https://www.outsideonline.com/2380751/sunscreen-sun-exposure-skin-cancer-science https://www.outsideonline.com/2380751/sunscreen-sun-exposure... (Most recently discussed on HN at https://news.ycombinator.com/item?id=23086211 https://news.ycombinator.com/item?id=23086211) Similar doubts have existed for decades – here's a 1993 variant reporting some of the trends that already didn't add up, back then: https://www.motherjones.com/politics/1993/05/melanoma-sunscreen-use/ https://www.motherjones.com/politics/1993/05/melanoma-sunscr... Another branch reply provides more sources about sunscreen chemicals & sun-longevity correlations: https://news.ycombinator.com/item?id=27520144 https://news.ycombinator.com/item?id=27520144
- 49531 5y ago
  > • Known carcinogens commonly used in sunscreens, or present as contaminants, are actually causing increased rates of skin cancer. I am curious to see a citation for this claim. > Generally, large population studies show positive effects of moderate sun exposure on many health outcomes, including overall longevity, heart disease, and non-skin cancers. Meanwhile, Vitamin D supplementation studies have usually not found that such supplementation alone reverses the correlations of many diseases with low Vitamin D. Thus, Vitamin D may not be the only mechanism by which sun's benefits are achieved. I am also curious to see these studies, and wonder if they control for other variables like physical activity. I think it's an incorrect framework to say that you have to choose between skin cancer and heart disease, you can avoid both through different lifestyle choices.
  - baumandm 5y ago
loudtieblahblah 5y ago
Sunshine is more than just a source of VitD. UVA has also been shown to lower blood pressure. This is probably the result of UVA causing the release of nitric oxide from skin stores, which promotes widening of blood vessels. It also acts as an antioxidant to prevent damage to cells. People who don’t get enough sunlight have altered cellular defense mechanisms that predispose them to excessive inflammation, which can result in autoimmune diseases. One could argue you can supplement to replace VitD, but are you supplementing your children? From what age? How regularly? What's the quality of the supplementation? How do the poor maintain access to supplementation? Then you run into the problem that long term, large(r) doses of Vitamin D causes kidney problems. A study ( https://pubmed.ncbi.nlm.nih.gov/21430082/ https://pubmed.ncbi.nlm.nih.gov/21430082/) found an association between low vitamin D levels and the development of type 2 diabetes. For every ten-unit decrease in blood vitamin D levels, we found a 10% increased risk of developing this form of diabetes over the following five years. when they gave supplements of vitamin D to patients with low vitamin D levels who were already at risk of developing diabetes, there was no overall improvement in their sensitivity to insulin. Nor was there a change in their blood glucose levels compared with those given inactive tablets. I'm betting, not just in this case, but the act of your body making it's own VitaminD creates benefits we are not yet aware - that oral consumption of a pill isn't going to compensate for. nevermind MOST of VitaminD pills use soybean oil or some other horrible Omega-6 ridden, cheap seed oil as it's delivery method. Outside time in the sun is helpful in ways not tied to VitD, as well. circadian rhythms are regulated by bright light exposure. You can't get these lumens by waking up and sitting inside all day. The heat from the sun is capable of reducing physical stresses on the body’s cells and by increasing heat production. Another important potential effect of sunlight is UV-induced suppression of the body’s immune system. Solar radiation does this by altering the activity of the white cells involved in turning on the body’s defence mechanisms. This may seem like a negative, but it's vital for people to reduce inflammation and when considering how the earth's population spreads out autoimmune disorders (higher percentages the more you get away from the equator), this may be a secondary factor on top of VitaminD. IMHO - people need to find a balance with sunscreen and sunshine. if you know you're going to risk a burn, put it on and reapply when necessary. if you're worried about cancer, eat some cruciferous vegetables regularly to make sure you get lots of sulforaphane which protects against skin cancer. Get regular derma checkups. but when looking at auto-immune issues (that once you have one, your supplementation isn't going to undo it), the depression issues, and so forth - isn't worth skipping out on sunshine. Skin cancer may be the most preventable but it's also a fairly unlikely cancer, as far as cancers go - and while it's one of the scarier cancers, catching it early with derma appointments is key to survival. Catching it early has a high survival rate. An auto-immune issue, on the other hand, will shorten your life and make you suffer along the way, increasingly, for the rest of your life. It's not just a death sentence. It's a slow-slog through hell on the way there. Most people never go into a permanent remission of Ankylosing spondylitis or MS. It just slowly destroys you, it handicaps you, and then it kills you. And along with all that suffering, is your kids, parents and partners suffering right along with you. Yay - therapy sessions for everyone. It's not just auto-immune issues. Depression, anxiety, even certain cancers themselves all have some relation to low vitamin d. IMHO - sunlight needs to have it's saturated-fat moment where we realize that a lot of the fear mongering simply wasn't warranted. And that the cures for some diseases end up being the catalyst for many others that are far more likely. How many people are afflicted with an autoimmune issue? how many with debilitating depression? Compare those numbers to skin cancer. Compare the deaths. Compare the suffering. Then try to find a balance.
nradov 5y ago
Your risk analysis is not scientifically valid. There is no reliable evidence that moderate sunlight exposure increases all-cause mortality.

loudtieblahblah 5y ago

it should also be noted that consumption of certain antioxidants protect against skin cancer (most notably sulforaphane found in Cruciferous Vegetables). >Nonsystematic reviews of observational studies suggest that use in real life does not cause vitamin D deficiency. yeah, but that's an observational study. I'm not anti-sunscreen and if you burn or get dark/deep freckles easily, I'm even more "pro" sunscreen for you. But when looked at the number of diseases and problems correlated to Vitamin D deficiency and looking at the relatively low risk of contracting melanoma (as scary as that cancer can be if caught late), to me it's a balancing act. Consuming mass amounts of VitaminD over long periods of time, orally, can cause kidney problems. If you look at auto-immune issues globally, the percentage of the populations that have them sky rocket the further you get away from the equator. Depression, anxiety, even certain cancers themselves all have some relation to low vitamin d. Sunlight, the type that allows UV-B to penetrate your skin, is a human necessity. And like a lot of things we need (Vitamin C and E, or polyunsaturated fats, carbohydrates, etc), too much of it will cause you problems and/or kill you, not enough of it will cause you problems and/or kill you. And trying to anecdotally perform some balancing act without constantly running tests on yourself, is difficult. My rule of thumb is put on sunscreen if you are out long enough to risk a burn, re-apply when necessary. Otherwise, soak up the rays.

pmoriarty 5y ago
"Consuming mass amounts of VitaminD over long periods of time, orally, can cause kidney problems." What counts as massive? And is consuming massive amounts of Vitamin D necessary to prevent deficiency?
- loudtieblahblah 5y ago
  if you're like most of the western world, especially if you have an indoor job and indoor hobbies (we spend an awful lot of time binging tv shows, playing video games, working on computers, etc..), you're not outside all that much unless it's to hop in the car and go to another indoor place. and chances are you have a deficiency. Most vitamins tell you to take 2,000 IU. Upper limits are typically stated to be 4,000 IU. But there's been no established harmful upper limit either. This leads a lot of people into thinking more is better, this is doubly true if they have some kind of pre-existing condition that's linked to low VitaminD and they're desperate to heal themselves. They read quack stories on the internet about how 10,000 IU doses help cure MS and they do it too. It's also made worse by so-called "smart" and "qualified" people like Dr Rhonda Patrick essentially turning herself into some pop-health guru and when she tells people what she supplements with (5,000-6,000 IU), many people feel she knows what she's talking about and copies her. But the reality is, she takes A LOT of supplements and she has zero idea how they all mix with each other, especially at the supplementation levels in which she's consuming them. of vitamins that can be abused, VitaminD is mostly safe. But a lot of folks go a bit crazy with it and have hurt themselves. VitD supplements are also, often, in soybean oil, which is horrible for you. VitD needs to be consumed with a fat, so If you're going to supplement, you spend the extra money for it suspended in coconut oil instead.