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Vitamin D and cancer prevention (cancer.gov)
97 points by fanf2 on Nov 13, 2017 | hide | past | web | favorite | 81 comments

Take the extremes; is cancer incidence markedly lower in perpetually sunny cities like Phoenix or Los Angeles compared to perpetually cloudy cities like Seattle or Portland? Surely the data would show if there were a notable difference for people exposed to 11 months of sun versus 10 months of clouds.

That's almost exactly how they found the connection, from the article:

> Early epidemiologic research showed that incidence and death rates for certain cancers were lower among individuals living in southern latitudes, where levels of sunlight exposure are relatively high, than among those living at northern latitudes

An obvious problem is confounding variables, this isn't a controlled correlation in any way. The article goes on to say:

> However, additional research based on stronger study designs is required to determine whether higher vitamin D levels are related to lower cancer incidence or death rates.

This reminds me of autoimmune disease like MS. They are more common in higher latitudes (where there happens to be less sunlight), and there is a connection to low Vitamin D that isn't understood.

While attempting to understand the link better, UW-Madison researchers recently produced data implying that the ingredients of some sunscreen products may provide benefit in preventing MS. https://www.acsh.org/news/2017/07/28/sunscreen-ms-and-hard-b...

There was a piece in the New Scientist a couple of years ago that said type 1 diabetes seems to be correlated with higher latitudes. They suggested it was related to Vitamin D.

Yes, like MS, type 1 diabetes is considered to be an autoimmune disease. It's surprising to me as someone who hasn't studied medicine how related to each other autoimmune issues seem to be. Rheumatoid arthritis and latitude is another one that follows this same pattern. This article from 2010 about rheumatoid arthritis also mentions the link to low vitamin D levels, and that the link isn't understood.


Are there any statistics that low levels of D at northern latitudes decreases life span? Without such decrease even if it will be confirmed that low D causes cancer, it will also imply that higher levels of D causes other problems that just as deadly as cancer.

One example (mentioned elsewhere in this thread) is that incidence of autoimmune disorders goes up as you get farther away from the equator

Edit: I suppose that’s decreased health span more than decreased life span

As D suppresses immune system among many other things one should not be surprised to have such correlation with incidents of autoimmune disorders. On the other hand life span in Canada is few years longer than in US while I got impression that levels of D deficiency is comparable in US and Canada. So I guess it is very open question if low D is really bad.

Additional research such as EPIC series of research? One of which studied the impact of vit. D levels in blood on all cause mortality corrected for many factors?

(Note: EPIC studies Europeans.)

idk, being too sunny also leads to staying indoors more. especially in LA. i rarely get sun around here. just the other day, my doctor told me i have extremely low levels of vitamin D. and i started taking 10k mg doses of vitamin D, this also seem to help me sleep better at night.

Why not just go out and walk more?

Which is a great idea for more than just the sun exposure, but unfortunately at Los Angeles's latitude, there isn't sufficient UVB to trigger vitamin D production in the skin from around the beginning of October through the beginning of March. During these months vitamin D supplementation is pretty much a necessity for anyone who's ordinarily vitamin D deficient.

The root cause here is probably high stress, to which walking more is probably going to be helpful, but for people under chronic stress (as I am from time to time) it can be hard to see how to make the time for that.

I used to walk when I lived in a different neighborhood of a southern city. We get lots of sun, but way more heat & pollution. My neighborhood's simply not great for walking.

You can do both! But if you supplement vitamin D you wouldn't need to worry about making it out for your walk every day. IANA nutritionist, but I also believe GP's prescribed dose would be unfeasible to get reliably from the sun, especially at northern latitudes.

Hmm, I see. I live in Greece, so I don't really have an intuition for how much sun one needs (we get eight months of sun or so). What you say makes sense, thank you.

The Norwegian Institute for Air Research has a fairly simple online calculator: https://fastrt.nilu.no/VitD-ez_quartMED.html

I can't personally vouch for its accuracy though.

Doesn't sun exposure cause skin ageing and increase your risk of skin cancer?

It does - so much so that fair skinned people are suggested to avoid sun exposure and get vitamin d from supplements.

Not unless you overdo it.

Agreed - I think this is another myth that has gone mainstream. The biggest issue from my reading is damage to the skin. If you are constantly getting burned you are increasing your risk. If you slowly increase your exposure and avoid burning you get the benefits of sun plus (almost) none of the drawbacks. I say almost b/c you cannot discount genetic predisposition. Also, time of day is critical too - with mid-day being the best time.

I'm not sure if there are studies that take this variable into consideration. The tin foil hatter in me tends to think the results are probably different than the current common belief. BUT we can't have sunscreen sales dropping to zero ;) BTW I'm also weary of the effects of sunscreen itself - does slathering chemicals on your skin to protect against sun contributing to cancer?

Th truth is there is probably a happy medium somewhere between the "sun is evil! It causes cancer!" and "don't worry worshipping the sun is OK". However we tend to knee jerk react in one direction or the other...

It's not always that simple - in Dunedin, NZ, burn time can be under ten minutes. It's quite similar in Australia, too.

Another consideration is the pollution you're breathing when walking or deeply breathing while running. Particulate matter, ozone, and carbon monoxide could very well cancel out the benefits of receiving that Vitamin D production you get in some months.

>Take the extremes; is cancer incidence markedly lower in perpetually sunny cities like Phoenix or Los Angeles compared to perpetually cloudy cities like Seattle or Portland?

you need to compare not the whole populations of geographies - you nee to look at people who isn't evolutionary adapted (in this particular case - skin color to manage the sunlight and vitamin D level in particular) to the geographies they are currently living at.

For example, children autism is much higher in the Somali immigrant population in Minnesota and Sweden (vs. Somalis in Somali) as this immigrant population has, for obvious reasons, extremely low, frequently almost non-detectable, vitamin D levels.

If cancer rate has negative correlation with vitamin D levels, we'll, unfortunately, see it for sure in like a decade or 2 in those immigrant populations.

I was shocked when I got my vitamin D levels analyzed a couple of years ago. Yeah I work inside most of the time, like most programmers, but I also walk to work and easily get 10000 steps a day, so I thought I'd be OK. Nope, guess it wasn't enough especially since I'm in Chicago. My levels were in the deficient range. I now take supplements daily.

Out of curiosity, do you remember what levels they suggested you be at? I've heard there are a lot of different opinions on this.

Some important factors on receiving Vitamin D from sun exposure are skin color, the amount of clothing you wear & time of day.

Light skin absorbs more than dark skin. Noon gives more Vitamin D than morning or evening. Sun screen & sun screen lotion limit the Vitamin D you get.

Being a fellow northerner, walking outside doesn't do much in the winter when 95% of my body is covered in clothing.

Science Vs did a great podcast on this - https://gimletmedia.com/episode/vitamins-supplements-worth/ (Vitamin D is their first supplement they discuss & the link provides a transcript for skimming)

My personal experience (with no medical background except the Chiropractor's wife who recommended it) finds that Vitamin D supplements (5,000 IU) seems to help prevent & shorten colds & flu-like bugs. I mostly take that dosage when feeling slightly ill or run down.

My levels came back at a 5 ng/mL. Which is somewhere between dead and vampire. It wasn't shocking entirely (nowhere near enough time outside), although they said they had rarely seen levels so low before. I was fortunate to not be suffering any measurable problems from it. It was suggested by my doctor that I should aim for 30 to 60 ng/mL (ideally closer to 50-60). I began taking one-per-day 5000 IU of Vitamin D3. Took care of the deficiency in short order.

From what I can tell the article lists guidelines based on consumption (how much Vit D to take or what is recommended), but seems to fail to mention that absorption can vary by person. I think the better method would be to get a blood test and find out where you are and supplement (or get more sun) as needed to bring levels within normal to optimal ranges. But again, what is normal or optimal? Where is the mention of Vit K?

In my experimentation, it takes about 5000-10,000 IU per day supplementation + outdoor sun exposure 3 days a week for about an hour each day for me to be in the (or what I am hoping is) normal/optimal range (around 60-70 ng/mL). My sun exposure in that hour is hiking outdoors in full/partial sun mid-day with no shirt on. So 75% body exposure I guess? I am assuming that normal or optimal is mid to upper values in the lab results ranges for Vit D. In the case of Labcorp, the range referenced was 30-100 ng/mL with anything around 30ish and under being definitely deficient according to the lab results description of the range. So in my case it does take quite a bit of sun + supplementation to get optimal. Now my results above are based on summer sun exposure. In the winter, obviously that will be reduced (colder less outdoor skin exposure + sun is low in the sky) so I'm curious to see what difference I see on the labs without the sun exposure part.

There are some nice phone apps that helpful in figuring out sun exposure and Vit D. I have used D Minder on the iPhone. You punch in some stats about yourself (skin type, age, % of skin exposure and it asks you a few questions to confirm skin type based on your experience in the sun (do you burn easily, just get red and tan, just tan etc). Then based on your current geo location, sun angle in the sky (winter vs summer and the time of day) and time you want to spend exposed to the sun it calculates Vit D absorption in IU. Granted I'm not sure how accurate it is, but based on my labs and supplementation the biggest eye opener to me was how much sun it really takes to make a difference between deficient and normal/optimal. I do tend to believe now that the old recommendation of "15 min in the sun per day is enough" is false. That might be enough to stave off rickets, but I think more is probably in order for optimal living.

However, with all this said it would be great if there more studies on what the optimal or disease preventing blood levels are - with emphasis on blood levels and not just IUs intake per day.

> Being a fellow northerner, walking outside doesn't do much in the winter when 95% of my body is covered in clothing.

Even if you were naked it wouldn’t help, the sun would be too low.

Took me forever to find (I now digitize and save my records but didn't then) but it was 30 ng/ml. Sounds like that is actually not deficient by most standards. My doctor was a little woo at the time. I started taking 1800 iu.

I do have extremely pale skin, but I yeah, a lot of it ends up covered in the winter.

Hey if you have a minute and don't mind would you tell me a little bit about where you work? I'm graduating in December with a software engineering degree and plan on move to Chicago afterwards, but it obviously isn't quite as well known for tech firms as big cities on the west coast

I think it's OK, there are plenty of opportunities, but I would not do it if I were young. I would do Silicon Valley, get a "big tech" or startup name on my resume and work on cutting edge projects, and then move to Chicago.

The major advantage here is cost of living is so much lower than the valley. Housing is cheap, which leaves a lot of room for money to use to eat out, nightlife, plays, music, etc.

Chicago has a great scene. Some startups, some trading, some big business. Its not a bad place to code.

Me too, actually had tingling in my feet. Doctor prescribed 10000 IU once a week and symptoms went away.

Wow, 10,000IU in one big mega dose?

Vitamin D can be stored by the body. My Doctor also prescribed me one whole bottle every week for a certain period of time, then I switched to 6 drops a day.

Vitamin D defficiency is really a problem, I didn't know I had it till I got a blood test. I was feeling tired all the time, my bones ached, I felt low, dizzy, etc. Getting Vitamin D supplements helped cured all the symptoms, I feel much healthier now.

Yup, I was on that temporarily too. It came in little blue-and-white capsules. I think you have to get a prescription for those since, as the article mentions, large doses can cause problems over time.

I’ve been taking 60,000IU once a week for the last 3 years

Infrequent 50k IU doses are commonly used too.

yeah you can take vitamin d like that. 1 unit a day, or 7 units once a week, doesn't matter.

Instead of taking supplements, you could eat more fish, which contains a lot of vitamin D. This would also give you the necessary DHA and EPA.

You will also get high level of toxins in the form of PCBs, agricultural pesticides, benzene, etc. The pill is probably a safer option

To my knowledge PCBs aren't a significant concern in wild-caught fish. They may be somewhat more prevalent in farm-raised fish, which typically have a lower concentration of vitamin D anyway (and would therefore be of less benefit). Suffice it to say that I don't believe it's accurate to argue that eating "more fish" will result in "high levels of toxins" — if someone is eating little to no fish and integrates some quality fish into their diet, that's very unlikely to result in the consumption of unsafe levels of toxins.

Of course, when it comes to fish, and especially with concern to mercury, over-doing it is very possible.

In that case, you could opt for cod-liver oil from a renowned brand.

I also work in the loop. I found that my mood changes in the winter, and it's greatly helped with Vit D. Just popped one just now.

I’ve also had quite severe mood changes during autumn/winter and this year I’m supplementing 100ug (4000IU) five days a week. It took a few weeks but it feels like I’ve bounced back.

For anyone who understands Swedish this presentation is valuable: https://youtu.be/syRaJVIBNnw Article with the same info: http://www.lakartidningen.se/OldWebArticlePdf/6/6279/LKT0711...

What dosage do you take daily?

But no mention of vitamin K2. Not necessarily for cancer but for calcium regulation and the synergy of working with D3.

In the UK it's impossible to get Vitamin D from the Sun during Winter months, due to the high latitudes (it's above all of the US apart from Alaska, and is also above most of the population of Canada), even if you walk around naked at noon for an hour! Doctors here recommend everyone to take supplements.

From what I recall the season is from mid October to mid March. There's a few Vitamin D online calculators about if you're curious about where you live, also.

They mention that people in the Southern Hemisphere get more sun and have a lower incidence of cancer, but is that also true of Australians? Cause on average, people from the Southern Hemisphere have a lower caloric intake, which has also been linked to lower rates of cancer in general.

That being said, I really enjoy the fact that scientists are following so many rabbits in the war against cancer. This is going to pay huge dividends on the long run.

Listening to many people who are knowledgeable in researching & carrying out science experiments, I've begun to appreciate how impossible of a task it is to get really good data off of an experiment that involves humans & food intake over long periods of time.

This is exactly why nutritional science is such a dumpster fire. It's not a problem with the rigor or talent of nutritional scientists: it's just an almost-impossibly hard task. Medical research is hard enough, and when you remove the feasibility of RCTs for the most part...

> people from the Southern Hemisphere have a lower caloric intake

Do you have a source for this claim? In America, while not in the Southern Hemisphere, the CDC's Obesity Prevalence maps [1] show that obesity is concentrated in the southern states.

2017 Fattest Cities in America [2]: 1. Houston 4. Memphis 5. Tampa 6. Las Vegas 7. El Paso 9. Los Angeles 11. Tulsa 12. Miami

[1] https://www.vox.com/2014/11/17/7230641/maps-charts-obesity-w...

[2] https://www.mensfitness.com/weight-loss/burn-fat-fast/the-fi...

Well, to be fair it's poverty and cheap processed food that drives higher caloric intake in southern states. You can buy a cheeseburger with 600 calories for $1 or you can buy 50 calories worth of organic foods for the same price. If you are on minimum wage the choice is pretty clear.

I don't have source for this claim no. I was just observing that huge swaths of the southern part of Africa and South America face tough economic circumstances that may have a direct impact on the ability to live in "caloric security".

Linking to Steve Gibson's amateur page on Vitamin D. Worth a read:


NOTE: Steve Gibson is a security researcher and software developer, NOT a doctor, so take the page with a shaker of salt.

I would take Steve Gibson's security advice with a few grains of salt as well

I know it's not exactly the place to discuss this in detail, but could you elaborate?

Either elaborate or don't say anything at all.

Every time someone mentions the man someone says "hurr durr XP raw sockets something something" and links to that page that calls him a charlatan or snake oil seller.

For what is worth Cluster headaches substantially reduced by 10,000 IU of Vitamin D in 80 percent of people


I got results right away last time I had a cluster. I am crossing my fingers that this is it.

Wow, that's good to know. Hope you won't have to go through that again.

Vindication of my long-held opinion that the skin cancer groups, with their very extreme advice befitting milk-white Victorian ladies or photophobic vampires (always cover all skin at all times, avoid going outside whenever possible, wear a thick layer of sunscreen always), were taking things way too far.

I am in the deficient range for years even though I walk under the sun a few times per week for about 15 minutes each time, that's still far from enough it seems. I will take supplements now.

> even though I walk under the sun a few times per week for about 15 minutes each time,

This is a very very low amount of exposure to the sun, isn't it (esp depending on your latitude)? I'm asking because it sounds like you're phrasing it as if you think it's a decent amount.

It's honestly only recently that I'm realizing how little sun exposure most people enjoy/are used to. I feel like something's wrong if I don't get sun+fresh air much more frequently than you're describing.

Grab an app like dminder. There's a lot of variables, some you can control and some you can't.

In a bathing suit in Mexico in summer, a fair skinned person will produce their entire daily allotment in just a few minutes.

But that same person with pants and short sleeves might need an hour or more in Michigan in spring.

I took a vitamin D supplement once, and had the worst migraine of my life hours later. Could have been a coincidence, but I'm in no rush to repeat the experience :-(

I started taking vitamin d because I have a family history of colon cancer, and it has been shown to reduce such instances. My doctor said it is one of the few vitamin supplements that has strong clinical evidence to support its use. A happy side effect was that vitamin d also nearly totally made my acne go away. I take on 5000IU in the morning and one at night.

Examine.com offers a good roundup of research on Vitamin D, see https://examine.com/supplements/vitamin-d/

Do you regularly test your vitamin D levels?

This is sort of my concern. I had extremely low vitamin D, so I started megadosing on the advice of my doctor (50000IU/week). The problem is, without regular tests, I don't really know when I should be stopping. Vitamin D is fat soluble, and at some point, I'll in theory have levels that are too high.

True - you should just schedule a blood test. In most US states you can do it yourself without a physician via online lab ordering companies. You will pay out of pocket (or you can use health savings). I usually do this b/c its easier for stuff like this if I am curious about blood levels and procrastinate too much on setting up doctor appts ;)

EDIT: Wanted to mention that a Vit D test is usually around 30-50 bucks, so not too expensive

Ah thank you, this is something I would've looked into when I felt it had been long enough but this is pretty much exactly what I'm looking for.

I wonder if those studies that link latitudes with cancer accounted for cold weather? A quick google search revealed that there seems to be a relation there: https://www.medicalnewstoday.com/articles/269266.php

I was super deficient being a programmer inside all the time. My levels were literally zero when I went in because I felt like I was dying, bones hurt, extreme fatigue. 10,000 IU 3 times for three weeks fixed it. I've been taking 2000IU every day ever since, and my serum levels still don't go above 20.

My opinion, the two most important vitamin levels to check are vitamin D and B12. Many people are easily deficient of both.

Some say 60-80 blood serum level is the optimal (80+ is possibly toxic) while others point to 40-50 as healthy

there was a recent post here about B12 supplementation causing cancer.

Not so much cause but increases the risk.

If you live in the southern hemisphere continue to stay out of the sun. Take vitamin D tablets if you have to.

Thats the advice I give my kids. They don't go outside without sunscreen and hats. But I am beginning to wonder if it isn't an oversimplification. There is no doubt sun exposure is harmful but there is an absolutism that precludes public debate on the benefits and relative risks. I know my skin can't moderate its immune system without some sun damage and oral vitamin D has no equivalent benefit. Not that my experience should be the basis for public health advice, but it is enough to raise some doubts in my mind about the amount of balance in the discussion.

yeah, but it's so difficult to get the general population to do anything that may benefit their health and that leads to oversimplifications.

I worry that some people just read a headline and can't cope with details (or don't remember) and end up ignoring the initial good advice.

there's a reason why 99% of australia knows the word melanoma.

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