
Vitamin D and cancer prevention - fanf2
https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/vitamin-d-fact-sheet
======
DoodleBuggy
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.

~~~
rm999
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.

~~~
rnprince
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...](https://www.acsh.org/news/2017/07/28/sunscreen-ms-and-hard-believe-
scientific-finding-11617)

~~~
tonyedgecombe
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.

~~~
rnprince
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.

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2920915/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2920915/)

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mamoswined
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.

~~~
mattferderer
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/](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.

~~~
mamoswined
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.

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

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chippy
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.

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VeejayRampay
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.

~~~
oicu812
> 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...](https://www.vox.com/2014/11/17/7230641/maps-charts-obesity-
weightloss)

[2] [https://www.mensfitness.com/weight-loss/burn-fat-fast/the-
fi...](https://www.mensfitness.com/weight-loss/burn-fat-fast/the-fittest-and-
fattest-cities-in-america)

~~~
e9
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.

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

[https://www.grc.com/health/vitamin-d.htm](https://www.grc.com/health/vitamin-d.htm)

 _NOTE_ : Steve Gibson is a security researcher and software developer, _NOT_
a doctor, so take the page with a shaker of salt.

~~~
gnu8
I would take Steve Gibson's security advice with a few grains of salt as well

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

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

[https://www.vitamindwiki.com/Cluster+headaches+substantially...](https://www.vitamindwiki.com/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.

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

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sliverstorm
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.

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ausjke
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.

~~~
wutbrodo
> 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.

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Tharkun
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 :-(

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jayess
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.

~~~
sp821543
Do you regularly test your vitamin D levels?

~~~
wutbrodo
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.

~~~
bproven
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

~~~
wutbrodo
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.

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legulere
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](https://www.medicalnewstoday.com/articles/269266.php)

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jryan49
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.

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tdburn
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

~~~
jackmott
there was a recent post here about B12 supplementation _causing_ cancer.

~~~
dawnerd
Not so much cause but increases the risk.

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

~~~
shirro
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.

~~~
jimjimjim
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.

