Vitamin D Deficiency Behind Many Western Cancers?

twilight30 wrote us with a link to an article in the Globe and Mail. If further study bears out the findings, new research into the causative agents behind disease and cancer may have a drastic impact on the health of citizens in Canada and the US. According to a four-year clinical trial, there's a direct link between cancer and Vitamin D deficiency. "[The] trial involving 1,200 women, and found those taking the vitamin had about a 60-per-cent reduction in cancer incidence, compared with those who didn't take it, a drop so large — twice the impact on cancer attributed to smoking — it almost looks like a typographical error. And in an era of pricey medical advances, the reduction seems even more remarkable because it was achieved with an over-the-counter supplement costing pennies a day. One of the researchers who made the discovery, professor of medicine Robert Heaney of Creighton University in Nebraska, says vitamin D deficiency is showing up in so many illnesses besides cancer that nearly all disease figures in Canada and the U.S. will need to be re-evaluated. 'We don't really know what the status of chronic disease is in the North American population,' he said, 'until we normalize vitamin D status.'"

Comments

now the counter argument... ?

[lems1]

Now I'm waiting for another research showing that the intake of vitamin D causes some other serious illness...

So typical.

Re:now the counter argument... ?

[Bryan Ischo]

Name one race from a northern climate that has brown or black skin. You can't. There aren't any. Now name a race from an equatorial region that has white or light skin. Once again, you can't.

I'd say this is pretty strong evidence for the GP's point. Sure, there will be variations among races at the same latitude, I wouldn't be surprised if some equatorial people were darker than others. But I would also be surprised if there wasn't a STRONG correlation between latitude and skin color. It would seem really, really unlikely that this was "caused by genetic variation of a few settlers." Yeah, the light colored setters just randomly happened to move north, and the darker people stayed south. Sure.

And people weren't in northern europe long enough for evolution to have played a role? OK then how about China? Northern Chinese are very light-skinned, I know this from experience. And surprise, surprise - southern Chinese are alot darker. And don't you think that a 60% greater chance of disease due to vitamin D deficiency would be a strong evolutionary pressure? Strong enough to act over relatively short time periods on the evolutionary scale perhaps?

Anyway, if your evidence for this evolutionary biologists' "dismissal" of skin color's correlation to latitude is one book, that's pretty weak. Of course, it's still more evidence than I can submit.

Re:now the counter argument... ?

[nwbvt]

No one (including the guy you were responding to) used skin cancer the selecting mechanism. Its generally believed among evolutionary biologists that it is vitamins. Some vitamins (such as vitamin D as mentioned here) need UV light to be produced. Others get denatured by too much exposure to UV light. There have been other theories (for instance women with too pale skin might get sunburned nipples which prevents them from breastfeeding), but I have never heard anyone argue skin cancer is one since it is only recently that people have lived long enough for that to be common. Note that in species like humans, there is a selection to help humans live past their breeding age so the elder populations can pass information on down to the younger generations.

Is this as big as I think it is?

[Lord Duran]

60%. That's not a small number. Consider the possibilities: 60% of cancer reduced, just by using a standard vitamin pill. I think I'll head off to the pharmacy.

Not so confusing.

[Hamster Lover]

How is this confusing? Not enough sunlight may cause vitamin D deficiency, too much may cause cancer. Not enough food and you starve to death, too much and you grow obese and suffer related ailments.

Life is about balance.

Vitamin D deficiency? Life style!

[MavEtJu]

Let me see... People roll from their bed into their car (via a door between the house and the garage), drive to work and park under the building. Lunch in the canteen, and in the evening the same path and sitting in front of the TV. 90% of the people in the apartment block I'm living in does live this way and get no direct sunlight for weeks. I think I found the reason why people have a vitamin D deficiency!

Re:60% reduction in risk?

[knapper_tech]

You have yet to read the paper, but you do not agree that Vitamin D deficiency can be responsible for 60% of about cancers. Congratulations. You have a lifetime supply of straw man ashes.

All you did was list reasons why you're skeptical of the results, yet you haven't read the paper. Granted they are plausible reasons, someone who is capable of excercising this kind of critique could do the world a favor by reading the article to either confirm or address their skepticism and then posting their final interpretation of the article.

This post is like reading intial lab notes. I don't care what you're hunch is now if you can follow through on the data (do several hundred more experiments in the lab) and come to something more conclusive. The paper isn't a state secret. Read it.

Re:Go outdoors for a few minutes

[AmiAthena]

Our modern diet is very different from what we evolved to eat. Better in some ways - few Westerners starve - but probably lower in many micronutrients than the ideal. So this type of report is not a surprise. Expect more.

QFT... the evolution of our dietary needs is exactly why so many of us do have weight issues. Everyone who's ever went on a diet or tried to eat healthier has one major complaint: all the stuff that tastes good is bad for you. But there's a reason for that! Cavemen didn't have Twinkies, Haagen-Dazs, and Big Macs. Protein, fat, and sugar/carbs were necessities to the developing human, and they were pretty scarce. Early man had green leafy stuff to eat as far as the eye could see, but it was work to kill something for food. So we evolved to have a greater affinity for these rare essentials.

Up until one or maybe two hundred years ago, this worked fine. Only the wealthy could afford to gorge themselves to dangerous levels of obesity. Today, for maybe $6, I can go to Burger King and get a Whopper, fries (King Size) and a Coke (King Size). According to BK's own meal-builder nutrition info, this meal has 1660 calories (650 from fat), 72 grams of fat, and 117g total sugars. And I didn't even put cheese on that Whopper. (And no Vitamin D as far as I can tell.) This is theoretically one out of three meals, supposedly totaling 2000 calories. In all likelihood, it's more like hald the day's calories than most. Meanwhile, the average modern American doesn't burn nearly as many calories Mr. Caveman did, since we survive by sitting in cubicles instead of hunting and gathering. Clearly, our ability to feed ourselves has improved to the point where the foods we naturally crave due to things coded in our genes thousands of years ago are actually harming us. For all the exotic things we can now eat because of technology, our range of nutrients sucks.

So it's hard to diet because as far as your body knows, that triple fudge brownie might be the the calories you burn not freezing to death tonight. And since you're body's so preoccupied with this now baseless fear of starvation, it forgets to make you want to eat things like broccoli or spinach, which our ancestors were probably eating to pass the time until some meat wandered close enough to kill. Call it evolutionary sabotage- what we needed before is not what we need now, and if we can't stay on top of those changes, we tend to die.

Re:Huh? Do You Know How Inuit Live?

[krbvroc1]

You do know that in addition to sunlight, Fatty fish and Fish Oils, a staple of Inuit diet, is a significant source of Vitamin D? Seems to me that they adapted to get their Vitamin D by an alternative source.

Re:60% reduction in risk?

[adrianmonk]

4) A risk reduction of 60% (= relative risk of 0.4) is epidemiologically very strong and if that was the case, we would have already found such a role of Vitamin D much earlier (like 30 years before or so). There is something called Bradford Hill's criteria for causation in epidemiology which has strength of association as one of the criteria. The rationale for that is if we had a confounder which is actually responsible for the effect, we would have known it before because it is more likely to have a stronger effect. The same principle goes here. We do not know anything that could prevents so many types of cancer with such great attributable fraction. The magnitude of effects of like 2.5 or reduction of risk to 0.4 were the strengths we used to see in the papers of 1970s.

I see where you're going with that. The more obvious things tend to be the ones discovered first. It's not a hard and fast rule because it's quite possible for everyone to miss something obvious for a long time (due to groupthink or just chance), but it is a good rule of thumb.

On the other hand, there's another possible explanation for why this was not discovered in the 1970's when all the other big factors were being discovered: if a variable doesn't change much, it's harder to notice what happens when it does change. The push to wear high-SPF sunscreen didn't occur until after the 1970's and neither did the warnings to stay out of the sun. So it seems possible that the reason this phenomenon wasn't discovered in the 1970's was that it didn't exist in the 1970's. I'm not saying that the (supposed) causal link between vitamin D deficiency and cancer didn't exist; what I am saying is that vitamin D deficiency may have been uncommon enough that the causal link didn't matter because it wasn't being "triggered".

Of course, I'm postulating something about how common vitamin D deficiency is now versus 30-ish years ago, and I don't really have any data to say that difference actually exists, so my whole argument may be BS. Not only that, vitamin D deficiency would have to have been rare enough not just to be uncommon but to actually reduce the effects down near the noise level.

Not magic

[DrYak]

Nobody said that, skin colour of all ethnic groups will automagically instantly adapt to the amount of sunlight they receive in their location.
Nor that you could predict the latitude where some ethnic groups lives, down to 1 precision, based only on skin colour.

What the parent says is that *there seems* to be some variation of skin colour which may follow some pattern which can be put in relationship with some factor like sunlight exposure. Like always with nature, there are never "nevers" or "always". Only "tendencies" and even if there's so much variation between skin colours, you can't deny that paler complexion are a little bit more frequent in region with less sunlight exposure.
Amazon natives MAY be a lot less dark than other people living in the equator, they ARE STILL a little bit more tanned than Swedish people.

Also the whole point of the original poster was to say that this tendency of distribution could be partly caused by the fact that on one hand, too much sunlight kills because UV are cancerigens, and not enough kills too because of Vitamin D deficiency. Thus people will tend to have skin colours grossly adapted to the region where they originate from even if there's a lot of variation (partly due to the fact that all this is recent history and there hasn't been enough time for selection to discriminate more strongly, in fact given the local climate variation and the degree of additional modulable protection produced by clothes it's not necessary that skin colour needs more adaptation for regions).

As a side note, in practical medicine, we do see, for example, occurence of some problems such as osteoporosis (brittle bones due to deficiency in vitamin D) happening with a higher frequency in women originating from northern Africa (skin "somewhat tuned" for high sun exposure by recent evolution, but hiding under too much clothes for religious reasons and not getting enough sun to produce vitamin D) than with european women (wear also a lot of clothes for cold / sunburn protection, but the light that gets through paler skin is a little bit more for Vitamin D synthesis).

Aboriginals are much much darker and further away from the equator than individuals from Malaysia

But on the other hand both gets way much more sun than people in Denmark. Or northern China. Or Siberia.
And happen to be, on the average, darker than those people, even if there's variation than can't be only explained by the amount of sun exposure alone.