Anecdotally, I had this discussion with a cardiovascular interventionist specialist about seven or eight years ago when I was managing a team of cardio theatre orderlies in a private hospital. He made the comment, "mark my words, in about five to ten years time there will be a major scare about needing to absorb more vitamin D".
His opinion was that the increase in sunscreen usage and the push to avoid skin cancer by staying covered up was likely to blame. I find it interesting when articles such as this pop up, because it directly reflects his concerns from those years ago.
For reference, this was the late Dr Geoffrey Mews (who I only just realised has passed on while I was looking for a reference to post. That's made me a bit sad now)
The NIH guys also did a study that said that even in tropical countries, Vitamin D absorption has fallen dramatically because of lifestyle changes. One of the probable factors is the lust for fair skin. I routinely see people covered from head to toe to help them stay fair skinned, even kids are sent to play covered in full sleeve clothing.
When the burn time is less than 10 minutes, you need to cover them up or have them play in the shade. The UV index for tomorrow is just shy of 14 and we are a month or two from the time of year when it’s highest, you would need medical treatment for a child who played in that and was uncovered all day.
Related: I found the old measure (burn time) much easier to use than the new UV index, and while having it standard across countries is good, it’s not straight forward to convert.
That UV index stuff is no joke. My girlfriend spent an hour "sunbathing" in the canary islands and came back with the most incredible sunburn I've ever seen. I'm mega paranoid (SPF 50 all the time in hot countries) and didn't notice anything damaging but she had to be covered in aloe vera creams to numb the pain.. it affected her sleep, it must have been unbearable.
Not sure what the health qualms are with lack of Vitamin D bit I'm certain I don't want to advocate in favour of potentially harming people as much as my girlfriend experienced.
> Not sure what the health qualms are with lack of Vitamin D
Rickets and Osteomalacia are the big ones, I think. Both are a form of softening of the bones. Vitamin D apparently helps regulate the absorption and use of calcium, magnesium, and phosphate in the body.
I never took the time to investigate how accurate this site is, but it seems quite nice since it has uv index, time to skin redness and time to sunburn:
> One of the probable factors is the lust for fair skin.
I think this must be cultural. Certainly in my experience in the United States, the lust is for tanned skin. There are even tanning salons, where one can lie down in a machine which floods one's skin with UV.
Now, I personally love fair skin, and have never understood why others seem to love a tan so much.
It's a cultural thing, and directly related to wealth (or class, if you prefer).
If most people work outside for a living, then the sign of wealth is that you don't have a tan. If most people work in offices, then the sign of wealth is that you have a tan, implying that you went on vacation or otherwise have the available leisure time.
When most people do manual labor, having impractically long fingernails demonstrates that you don't have to do that.
When most people have two or three sets of clothing, changing clothes several times a day demonstrates your wealth.
When most people eat a subsistence diet, being fat is demonstrating wealth. when most people eat fast food, being thin demonstrates your superior resources.
If most people need to pay attention to what they are wearing at their jobs, dressing in a way which signals that you don't have to pay attention is a status marker.
If everybody drives a car, picking an unusual vehicle can be a status marker. What's the difference between a Chevy Silverado 2-door and a Ford F-150 SVT Raptor? They demonstrate different spending priorities.
I live in southern Brazil (one of these tropical countries), where sunlight is not that easy to get; also people dress up and cover themselves much more than in other regions due to not only the weather but also for cultural reasons. In fact, the city where I live (Curitiba) has a huge portion of people who need vitamin D supplements, to the point this deficiency became folkloric. I was quite "happy" to learn last year that after a full decade here my blood exam showed for the first time in 35 years that now I need vitamin D supplements too.
Sure, but higher melanin (ie, darker skin pigmentation) is correlated with lower cancer rates [1][2]. So the point is that cultural changes are causing people who were previously were at lower risk of cancer due to their skin pigmentation/higher melanin, to now have reducing melanin/pigmentation, therefore increasing rates of skin cancer.
Aren't those links about "people with naturally darker skin"? I'm not sure how cultural changes can affect that. Rich people may eat caviar, but eating caviar won't make you rich...
> The tan is caused by an increase in the activity and number of melanocytes, the cells that make the pigment melanin. Melanin helps block out damaging UV rays up to a point,
It's not particularly clearly worded but to me that seems to suggest that tanning increases melanin and that melanin helps prevent cancer regardless of whether your dark skin is natural or tanned.
But if tanning also produces cancer it remains to be determined which effect dominates (unlike for people with naturally dark skin, where the effect can only go in the beneficial sense).
Every source I've seen clearly states tanning always increases your chance of skin cancer. Tanning does provide a small amount of protection against burning (around 3 SPF worth), but no protection against cancer.
They studied based on 2 weeks of tanning which is very minimal.
You clearly get more than SPF 3 with a deep tan as you can spend 8 hours in direct sun without obvious problems. Without any tan you get a burn in under an hour suggesting ~SPF 10+.
Broadly, my understanding is that a major change in skin tone is 'worth' about 15 SPF, so tanning would fall somewhere below that.
For a fixed amount of sun exposure, spreading out the duration is better both to establish a tan and to allow more time for skin recovery. But there isn't really a case where tanning increases safety, because you get the tan via exposure.
It's like saying pilots who practice a lot are safer; for any given flight it might be true, but cumulative risk can only rise.
We know that genetics and environment both play a significant role.
So think about it this way:
If you're genetically predisposed to having very dark skin, you will be able to tolerate more UV exposure without significantly increasing your risk of cancer. And by continuing to be exposed to high UV levels, your body will continue to produce melanin to keep you protected. It's a feedback loop.
If you're genetically predisposed to having pale skin, but then expose your skin to higher levels of UV than your low melanin levels can guard against, you will sustain significant sunburn, and if you do this repeatedly you'll significantly increase your risk of skin cancer. But if you gradually expose yourself to moderate levels of UV you can gradually increase your melanin levels more safely, but only as far as your genetics allow. (This is theoretical of course; we know very well that it's very hard for fair-skinned people to expose themselves to UV light from the sun or tanning beds without overdoing it, hence the widespread occurance of skin cancer.)
My educated guess about the notion that dark skinned people are experiencing higher levels of cancer would be that if a dark-skinned person keeps avoiding UV for long enough, their melanin levels start to decline (due to it not being an optimal use of resources), but then if/when sun exposure happens, the protection isn't as strong and the risk of cancer is higher.
The notion of 'building up a tan' is dangerously wrong advice. Even for people with darker skin it is unwise to have significant bursts of UV exposure.
I'm curious as to whether your educated guess derives from a clinical background, or reddit?
The notion of 'building up a tan' is dangerously wrong advice.
I know, I acknowledged that in my comment.
My main point was only about the extent to which people with genetically high melanin levels are at much lower risk of cancer (which your first link confirms), but how their risk might increase if their melanin levels drop.
I don't dispute that it's a complex and dangerous topic. And as someone with genetically very pale skin, I most certainly steer well clear of direct sunlight and make no efforts to develop a tan.
I'm curious as to whether your educated guess derives from a clinical background, or reddit?
That's a low blow :)
I rarely go anywhere near Reddit, certainly not for anything to do with health. I have spent 10+ years researching health topics for reasons to with serious, chronic, illnesses I've endured, and have now largely overcome thanks to what I've learned.
It was a low blow. Sorry. I've been watching my uncle and father die slowly from melanomas, chunk by chunk cut out of their faces, their backs. My uncle still has a healthy deep tan.
And even last year I heard girls talk about building up a 'base tan' before summer. Roasting like rotisserie chickens under the solarium lamps.
Unless the above poster means “due to their [acquired] skin pigmentation” I don’t see how the comment can make any sense. Why would their rates of skin cancer be higher now?
I've known about the sunscreen misinformation for a long time.
My dad died of malignant melanoma. He wore sun screen all the time. He didn't swim. He would wear sun hats. He was paranoid, and likely had premonition of it. Unfortunately, his prevention methods might have actually exacerbated his odds even further because he was depriving his skin of one of its few natural healing modalities.
I'm sorry to hear you dad died of melanoma. But I can guarantee that reducing his UV exposure did not increase his risk. It's possible that intense and closely repeated sun exposure as a child had already caused DNA damage.
You're right, my father had bad sunburns as a child. Shades and hat are a good tip, as is reducing UV over-exposure.
My point is that moderate sun exposure is healthy and good melanoma prevention. From what I've seen, there is quite a bit of research to back this up.
I think that better education about this would encourage people to develop healthy relationships with the sun at a young age. Right now the conventional wisdom seems to be "just throw sunscreen at it" / "stay out of the sun unless you are wearing sunscreen" and I think this totally misses the point.
My caution is that it's unwise to tell people to avoid sun exposure in total. While sunscreen does seem to be helpful in slowing sun damage, it'd also be unwise to suggest that sunscreen will protect people from overexposure, there isn't really evidence for that. There is a whole body of research. Take a look at some of the studies cited in this article http://m.jabfm.org/content/24/6/735.full
I know you probably meant that as a comment about correlation vs. causation, which is understandable. I agree that this is a complex issue, and that there are more factors than just sun exposure. But just so you're aware, your analogy rubbed me the wrong way. My father's death was definitely related to sun exposure in some way or another, and probably other factors like diet (he ate a lot of sugar), psychology/hormones (he experienced a lot of stress), and yes, genetics.
There is misinformation about sunscreen. I'm not going to go and advocate that people don't use sunscreen, rather, for my own self, I've decided that it's important to have positive, moderate exposure to the sun in order to develop a healthy tan, to avoid overexposure, and to use sunscreen and protective clothing if I'm sure to be out in heavy sun.
It's a complex, dynamical issue and there is conflicting evidence about the effectiveness of sunscreen to just blanket reduce melanoma: https://www.ncbi.nlm.nih.gov/pubmed/22994908
Not only that, there have been some controversies about sunscreens themselves containing questionable ingredients, some of which might actually be carcinogenic. If you're going to market your product as cancer preventative, but go and put carcinogens into that very same product, my trust level in your industry has been reduced by somewhere in the range of 25%-75%.
Somehow, in all this, there are people who think any raw sun exposure is going to cause cancer. That's actually misinformation. Melanin is known to be a protective. How can one go about increasing melanin? By tanning in moderation, letting your skin adapt to the sun. Of course there are people who simply don't tan easily, and yes, they should be cautious. But I'm fortunate to have skin that tans, and I'm going to let it do that!
You are misrepresenting the studies findings. It did not show that sunscreen itself is ineffectual, but that as a population measure for children that it's effectiveness was variable. Anyone who has children will attest to the difficulty of applying and maintaining the required level of sunscreen, especially as it is invisible.
If you have concerns about the chemical sunscreens, please use zinc oxide. It is totally non reactive.
Sun damage is cumulative, a tan is a reaction to damage. People with a tan have sun damaged skin.
Naturally very dark skinned people are different, and also have enhanced mechanisms to allow damaged cells to self-euthanize.
Not quite right? A tan is a reaction to sunlight, independent of damage.
Ah! Research, gotta love it. UVA darkens directly as a result of action on the melanin. UVB damages DNA resulting in long-lasting production of more melanin.
Right, it concluded "there is still no evidence of a protective effect of sunscreen against MN development in children". Melanocytic Nevi are precursors to melanoma, and childhood sunburns give people an early start in developing them.
Here's another study arguing that sunscreen might inhibit the inflammatory response without actually reducing the burn. Their abstract concludes "As such, sunscreens might promote instead of protect against melanoma." : http://journals.lww.com/melanomaresearch/Abstract/2005/02000...
SPF is actually measured by reduction of redness. That study points out that reduction of redness doesn't necessarily come with a reduction of damage!
If people are preventing their body from expressing its natural sun defenses and going out and overexposing themselves to the sun, believing themselves to protected... If that protection is illusory, that's kind of a recipe for disaster. People could be getting burned and not even know it... They won't even know to put aloe on.
Take that one with this one, which postulates that sun exposure isn't what causes malignant melanoma, sunburns are:
> Although there is convincing evidence that nonmelanoma skin cancer is related to cumulative sun exposure, there is less evidence of that association with CMM. If CMM were related to cumulative sun exposure, one would expect that outdoor workers would have a greater incidence of CMM than indoor workers. However, that is not the case. The incidence of CMM is actually increasing among indoor workers who receive three to nine times less solar UV radiation than outdoor workers. Furthermore, there is a higher incidence of CMM among whites living in northern states such Delaware, Vermont, and New Hampshire (>30 per 100,000), which enjoy less year-round sunlight and UV radiation than southern states such as Texas, Florida, Arizona, and New Mexico (<25 per 100,000). In California, whites living in San Francisco had a CMM incidence of 30.5 per 100,000, whereas those living in Los Angeles had an incidence of 24.9 per 100,000.
There are a few studies that suggest that chronic, low-grade exposure to sunlight may be protective against CMM. In one Austrian study, those with chronic sun exposure without sunburn had a reduced incidence of CMM compared with those with recreational sun exposure. In Germany, outdoor activities during childhood, in the absence of sunburn, were associated with a lower risk of melanoma. Chronic, repeated sun exposure may allow the skin to accommodate to UV radiation by increasing melanin production, thereby reducing the risk of sunburn. An English study published in 2011 showed that regular weekend sun exposure had a protective effect against CMM, and the researchers postulated that this may be mediated by photo-adaptation or higher vitamin D levels.
It's going to take a lot to convince me, at 56 and very aware of sun damage to the skin of my friends who spend more time in the sun than I do, that "healthy tan" isn't an oxymoron.
With some SPF30 sunscreen, or sufficiently dark skin, sure. I'm not especially pale, but I'll start burning in under an hour of direct sunlight. "Hours on end" would be a recipe for painfulness.
No for Europe but closer for SE Asia. The South Pacific is worse due to the ozone hole which mainly effects regions below the equator. It has a savage effect on UV that gets through. Obviously a bad year, but check the below image and you’ll get the idea of the pattern.
> If they did, we would know, because workers compensation would be paying for it.
While state workers comp laws vary in ways which make this different from state to state, workers comp is paying for it for some subset of people who work outside.
Many of them (like my uncle a few years ago) don’t last very long, so it isn’t workers comp that you should just look at. It is definitely something that happens.
Yes, they do. My father, a life long outsdoorsman and forest ranger for many years regularly had/has skin cancers removed once he got into his 70's. The cancer causing sun damage from your youth/working years doesn't tend to catch up with you until you're older I believe.
"However, compared with the general population, the rates for certain diseases, including some types of cancer, appear to be higher among agricultural workers, which may be related to exposures that are common in their work environments. For example, farming communities have higher rates of leukemia, non-Hodgkin lymphoma, multiple myeloma, and soft tissue sarcoma, as well as cancers of the skin, lip, stomach, brain, and prostate."
Cancer is a complex, heterogeneous disease caused by varying degrees of interaction between inherited and exposed risks. It's just not as simple as you make it out to be.
Antidotes are not data. We have no reason to believe from your story that your would not have got skin cancer if he had spent all his time in a cave. Or maybe he wouldn't have, because he would have died of something even worse at 45.
Science is trying to work this out, it is complex. We know that sun exposure both protects from and causes skin cancer depending on the study. This is a complex subject, the only thing I think I can safely say is don't get a sunburn.
The 2006 Report on indicators for occupational disease
highlights there was an increase in skin cancer claims per million
employees/persons over a six-year period to 2004. The report
says that given the long latency period associated with exposure
and the onset of skin cancer, it is also likely that compensation
claims greatly understate the real incidence of occupational
skin cancer6
.
That's a bit of a blasé thing to say... I have lost direct family members through melanoma due to their work requiring them to be in the sun all day, and clearly many other people here have too. I can't fathom how you would form such an opinion.
People who work outside generally do not do it in bare skin unless they are idiots (of which we have many, many, many examples). You don't typically see military folks wearing shorts and t-shirts even in the hottest weather unless they are out doing PT because the work they do can be harmful and so they use clothing to protect themselves. This used to be common sense. Why do bedouins wear long, flowing robes in the desert? Same reason.
My father, who worked outdoors most of his life, always wore long pants and long sleeves even on the hottest summer days. I did not understand why when I was younger. I now get it.
Because surely all of those farm hands will be able to prove that it was their outdoors work that caused the cancer 30 years later! And surely the insurance will pay to right those wrongs!
Henry Osiecki in his book The Nutrient Bible, I own the 9th edition published in March 2010, recommends 2000-8000IU for three weeks to reestablish sufficient levels, and a supplementary rage of 400-3000IU a day for maintenance.
I obtained this book while studying clinical nutrition in Australia in 2005.
Clinical nutrition as taught by at least a handful of teaching practitioners in Australia that I'm aware of has been using mega-dose therapy to re-establish nutritional deficiencies since at least before I became aware of it twelve years ago.
This could lead to a recommendation of 1000 IU for children <1 year on enriched formula and 1500 IU for breastfed children older than 6 months, 3000 IU for children >1 year of age, and around 8000 IU for young adults and thereafter. Actions are urgently needed to protect the global population from vitamin D deficiency.
I was already taking 10.000IU a day (in winter) to battle Seasonal Affective Disorder. I live above 51N latitude though, so I practically don't see the sun in winter.
I have been deficient for a few years now and I take ~6000 IU per day, but it doesnt seem to make a big difference in my blood tests. I already thought 6K was a lot...
Yup - it's a fat soluble vitamin - this is a very good point to bring up. I made the "taking it with my low fat meal of the day" (breakfast) and made a change to correct that.
Yeah, it's fat soluble so you can take too much (but you'd have to take a ridiculous amount).
The normal doctor prescription to increase levels is a 50k pill once a week for a couple months. The previous recommended level was 20ng/ml, but they increased it to 30ng/ml.
When I got tested mine was 11ng/ml (and this is in the sunny bay area). To have the recommended value from normal sun exposure you'd need face/legs/arms exposed to sunlight for ~30-45 minutes a day which most people don't get. It's very hard to increase D from food.
I'm also not sure how they determine the recommended amount and there seems to be a ton of pseudoscience around all of this stuff so it's hard to tell what's true.
Interesting. I started taking it since I've started working inside for my day job. Apparently I should be upping my dosage. I take a multi and one or two D tablets and probably get a max of ~5600 from that outside of any absorbed from foods.
I also eat a lot of eggs. My girlfriend will be pleased to know that I'll be upping our egg intake!
Get your current nmol/L value and decide based on that data.
In Germany, you have to pay around €30 for that test. It's not covered by insurance for some reason. Anyhow, if they ask for significantly more than that, they are ripping you off.
Ask your doctor, really. When I got diagnosed with vitamin D deficiency (inside on the computer all the time, I'm quite pale) a few years ago the prescription I got was for pills that had 50,000 IUs each and I was to take one twice a week. I recently got a new doctor and was getting bloodwork done and she saw the mention of the deficiency and she asked if I wanted that tested for... she said she usually doesn't bother because everyone in my state (West Virginia) is deficient, she just recommends people take 1000 IUs a day or so. Personally I take 10,000 IUs about every other day. At least assuming the stuff I ordered off Amazon is at all legitimate (vitamins and such things are such a super sketchy market, companies get busted selling sawdust pills all the time).
One thing that I was not expecting, when I was on that prescription at first I noticed a marked improvement in my hearing (which I had not noticed being degraded at all previously...). I thought I was imagining it but upon doing some research it turns out that hearing loss is one of the possible complications of vitamin D deficiency.
Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at relatively greater risk for vitamin D deficiency.
I saw the quoted text, but missed any explanation. I would love a clarification on whether they claim the skin is not getting exposed to sun or, even when exposed, does not make any vitamin D, which is how I read the above.
This is an honest question -- if it is the first, I am not too concerned. I grew up in a colder climate and, while living far in the shaded area today, routinely wear short sleeves and walk a lot outside from early spring to late fall. If it is the second, I would love to learn the underlying causes at least as a scientific curiosity (and start thinking about vitamin D supplements).
The sun is too low in winter and the atmosphere blocks the UVB rays our skin needs to produce Vitamin D. The same thing happens around sunrise and sunset even in summer. Here's a good explanation from HN's favorite site:
It is silly to go through the trouble of including a map, only to reinforce the imprecision of the parallel approximation. Obviously People in Denver get more sunlight than e.g. people in Nashville, given the altitude and weather patterns. More detailed maps don't limit themselves to drawing a straight line.
If you do need supplementation, then Vitamin D3 (specifically Cholecalciferol) is vastly better absorbed than Vitamin D2. If you want a specific recommendation, buy this: https://www.amazon.com/gp/product/B07234TTCC and take it twice per week (Sunday & Thursday for example), that'll average to about 1400 IU per day.
This could lead to a recommendation of 1000 IU for children <1 year on enriched formula and 1500 IU for breastfed children older than 6 months, 3000 IU for children >1 year of age, and around 8000 IU for young adults and thereafter.
Seems odd, considering cow milk contains virtually no vitamin D. It is often enriched with vitamin D, but that practice likely does not predate the evolution of lactose tolerance.
When it comes to nutrition, the majority of unsourced information on web forums is made-up nonsense. Perhaps not maliciously in bad-faith (i.e. maybe OP really has heard this before)... but usually someone repeating something they heard 3rd or 4th-hand without any real fact-checking.
Milk is high in vitamin D because it's intentionally added. Like iodine in table salt, or fluoride in drinking water. Obviously these things had no role in human evolution before they started in the 20th century.
Vitamin D is only absorbed in the presence of fat in the intestine. Milk is a source of fat. Of course it isn't the only source of fat, but the hypothesized explanation is more plausible than you might think.
I have observed 'seanmcdirmid to be a thoughtful commentator. It would be uncharitable to suggest that he thinks that USDA has regulated milk drinking for millennia.
Most "1st-hand" nutritional research is also wrong. That has been the case for decades, which explains the field's relative lack of progress. The reason is that most nutritional research is funded by large commercial food interests.
Oops. You are right, I was thinking of calcium, which you can get from green veggies as well. I get confused because we had to deal with them all at once when my wife was pregnant.
I know the subthread went in another direction, but: vitamin D increases the absorption of calcium. With minimal vitamin D synthesis from sun exposure in northern Europe, it makes sense that extra dietary calcium would be an evolutionary advantage. Hence, lactose tolerance. So OP's comment made sense even while confusing vitamin d and calcium.
Hah, that's a direction I hadn't considered. That is indeed exactly why vit D is added to milk in the first place. The milk industry claims it's a good source of calcium, but fails to mention it's generally a poorly absorbed source of calcium. Hence the addition of vit D.
Hard cheeses are generally very low in lactose, by the way, but I guess lactose intolerant societies are unlikely to discover this on their own.
Lactose intolerant societies generally have cheese and other forms of curd. Also, babies are generally lactose tolerant regardless, losing this tolerance later.
Lactose tolerance evolved in several different populations independently (including African populations), so I think Vitamin D can only be part of the story. Lactose tolerance gives you access to nutrients from milk, which has a huge impact.
You would need 1) the sun to actually be shining, 2) no cloud cover and 3) probably be naked. Most of us won't get enough vitamin D from being outside for an hour.
1. The key UV for vitamin D production by our skin are UVB rays, optimal between 10am and 2pm, except in the winter at 40+ latitude when the rays travel longer through the atmosphere due to the low solar angle. For instance in Washington state your skin cannot produce vitamin D from November to February.
2. UVB do pass through clouds. (But not through glass windows.)
3. Arms and face exposure are sufficient if you spend 10, 20, or 30 minutes a day depending on UV index of the day (the higher the UV index the less time you need to trigger vitamin D production) and on your skin color. There is some kind of "reservoir" effect that limits production of vitamin D to a maximum, so sun exposure time beyond the above does not have any benefit in terms of vitamin D production.
That's easier said than done for some. A couple of years ago we had an exceptionally bleak November here, with one city for example having only 12 minutes of sunshine in the whole month of November. (I'm not talking about places within the Arctic Circle, although relatively speaking they could almost seem that way for some, of course.)
The average where I live for Nov is about an hour of sunlight per day, but to catch that you'd have to spend all the light hours of day outside (and for sure, November sunshine isn't quite the same as summer sunshine).
It is more complicated than that. A dark cloudy day (no gaps to sky) will not have much UVB. A day with thin high clouds won't block much, and may make it worse (reflecting or scattering).
His opinion was that the increase in sunscreen usage and the push to avoid skin cancer by staying covered up was likely to blame. I find it interesting when articles such as this pop up, because it directly reflects his concerns from those years ago.
For reference, this was the late Dr Geoffrey Mews (who I only just realised has passed on while I was looking for a reference to post. That's made me a bit sad now)