Sunday, June 26, 2011

Which Industry Funds Your Study? Sun Exposure and Vitamin D

I decided after reading up about Vitamin D the other day, and hearing that it may prevent sunburns as well, that I would look for more articles on that. Well, I found an article that made me want to laugh when I read the abstract. In fact, if it weren't for the erroneous statement they made, I probably wouldn't have bothered reading it. I found more erroneous propositions in it of course. And these people call themselves researchers? This is the problem with medical research in this country today. Seemingly educated people make stupid assumptions and it gets translated into "common knowledge." So what has irked me so? This from this article, about how terrible the sun is for you:

"When nature gave man the appealing capacity for vit D photosynthesis, the expected lifespan was far less than 40 years."

And these people are "educated"? First of all, average lifespan during the paleolithic is arguable. Secondly, the "average" is dragged down by infant mortality. During the paleolithic if one lived past the age of five and did not succumb to infection disease, one probably had just as much chance to live to eighty as they do now. So the whole "expected lifespan" is irrelevant to their argument. Completely irrelevant. I learned this in introductory archaeology.

Secondly, when evolution chooses for something, it has to be before child bearing age. In other words, it has to happen before you pass it onto your offspring. So, things that are bad for us later in life, are not evolutionarily chosen for. This is basic biology. Who are these people? And who is paying them to write this crap?

"The causal role of UV irradiation in both non-melanoma skin cancer (NMSC) and melanoma has been suspected by experienced clinicians and epidemiologists for well more than a century and was demonstrated repeatedly in studies of hairless mice and other animal models beginning in the 1920s."
Yes because we're genetically altered hairless mice. And they suspect UV irradiation causes skin cancer, so therefore it must be true. Wait. What? This doesn't convince me of anything except that whoever wrote this article has the critical thinking skills of a dung beetle. What's even more amusing is they cite an article from 1928. Yes, I'm not making that up. In 1928, they had just figured out that Pellagra wasn't an infectious disease. Incidentally, that's the same year that Alexander Fleming discovered penicillin. My, how far we've come. I need a sarcasm font, but I digress.
"Photoaging changes, even aside from the strongly associated skin cancer risk, is a source of distress for a majority of fair-skinned adults beyond the age of 40–50 years and has spawned a multi-billion dollar skin rejuvenation market. The cause-and-effect relationship between UV exposure and photoaging, like the relationship with skin cancer, has been well documented in mouse models."

Again, I'm not a mouse. I've heard of this type of argument before, it's called an appeal to the vain. Someone should make a snark font, I could use it now. I'm sorry, but no one's skin looks very good at 70, sun or no, unless they've got a plastic surgeon on call. And what does this have to do with cancer?
"...the attractiveness of a tan became embedded in the public psyche and remains there to this day, nearly a century later, despite the revised medical and scientific perception of a tan as a DNA damage response and widespread appreciation that UV exposure often leads to skin cancer."

So now we're at the museum. One of my favorite pieces that I have an appreciation for is Meindert Hobbema's Avenue at Middelharnis. It gives the perception that one is standing, looking down a road in 17th century Holland. Are we in Art History class or doing medical research? I call shenanigans.
"In the 1980s, studies employing normal human volunteers and multiple narrow band UV light sources determined the relative efficacy of different wavelengths of light in producing sunburn and suntan as well as epidermal DNA damage."

In other words, they stuck people under artificial UV light sources. Not the sun. I would think that makes the study pretty irrelevant when it comes to actual sun exposure. How is artificial light the same? I know that it could be composed of the same UV rays, but is it the same? Might there not be some difference, that without doing an actual study where you, oh I don't know, put people in the sun, you'd never know there was a difference? But what do I know, I'm just an artist.

This article has a real problem with what they call the "tanning bed" industry. However, I'm thinking that since they put a large plug in for sunscreen, I believe I know where their funding came from.
"If 2–8 min of unprotected summer sun exposure is required to optimize cutaneous vit D synthesis..."
Except it's not. If 2-8 minutes of sun were enough then no one would be deficient in Vitamin D. What the rest of that sentence goes onto say, is that 10-20 minutes is plenty if wearing sunscreen. Yeah, you can't make this stuff up.
"The confusing and misleading media coverage of the “vit D controversy” over the past few years has unfortunately indeed undermined the campaign to reduce the current excessive sun exposure in our society."

Is that anything like the low-fat campaign? I'm to the point that if authority figures tell me I should do something, I believe I should do the opposite.

Friday, June 24, 2011

Vitamin D deficiency and Type 2 Diabetes

In the early part of the 20th century, a disease called Pellagra was thought to be caused by a virus or bacteria. It was common in the lower classes, but also did show up on occasion in more wealthy people. It was thought to be a "dirty" disease, and there was a stigma attached to contracting it. One of the people who contracted Pellagra was my husband's great-great grandmother. She died at a hospital in Dallas in 1922 from the disease. However, her death, and thousands of others were completely preventable. It turned out that Pellagra was a vitamin B3 deficiency.

Now we blame obesity and type 2 diabetes solely on what people are eating, but what if the catalyst for obesity and T2D is really something else entirely? What if it's a vitamin D deficiency? I found the following article at Science Direct:

The role of vitamin D deficiency in the pathogenesis of type 2 diabetes mellitus

Vitamin D can be obtained either through dietary intake or produced endogenously. It is found in foods such as oily fish (salmon, sardines, mackerel), egg yolks and fortified milk and juice; however dietary intake only accounts for about 30% of the vitamin D obtained. The primary route via which people obtain vitamin D is through exposure to ultraviolet B (UVB) sunlight at wavelengths between 290–315 nm, occurring predominantly in the summer months (June–July) in the Northern hemisphere (latitude >= 42° N).

In other words, if you're not getting a lot of sun, you should probably be supplementing Vitamin D3. I find it interesting that the pushing of the use of sunscreen coincides with the rise of obesity and diabetes in this country. Of course that's when our sugar intake increased too. Maybe it was the perfect storm?

Sunscreen wasn't in widespread use until the 1980s. Prior to that, beach goers might put zinc oxide on their noses, but that was about it. Then with the erroneous idea that the sun causes malignant cancer, enter the sunscreen industry. Like many things, drugs, food, etc. most research about sunscreen is funded by the sunscreen industry. They're out to sell you a product. If you die in twenty years because of it, well, they've made their money.

Glucose sensors located on β-cells sense increases in blood glucose levels despite increases in insulin secretion; the persistent hyperglycemia triggers a series of events which ultimately leads to an increase in β-cell expression, β-cell mass and enhanced secretory capacity of the pancreas. This compensatory increase in insulin secretion explains why some highly insulin resistant individuals never develop T2DM. In a study which examined pancreatic tissue from obese, non-diabetic individuals, relative β-cell volume of the pancreas was 50% greater in obese individuals than in their lean, non-diabetic counterparts (2.6 ± 0.39% vs. 1.71 ± 0.28%, P = 0.05), suggesting that these obese individuals did not progress to T2DM because they were able to increase their insulin production capacity by increasing β-cell mass. Individuals with T2DM do not experience this increase in β-cell mass, in fact there is a significant decrease in β-cell mass.
So long as your body can continue to manufacture insulin to store fat, you will probably not develop Type 2 Diabetes. It is only when this system fails that T2D occurs. Some morbidly obese people do not develop diabetes and it is because they can continue to get fat. A deficiency in Vitamin D may make it difficult for your β-cells to fucntion properly. Another explanation for why some obese people may not develop diabetes is because they're not vitamin D deficient, or if they are, for some reason they require less vitamin D than others.

The identification of the 1α(OH)ase in β-cells suggests that 1,25(OH)2D3 may play a role in overall β-cell function. In vitro and in vivo studies have ascertained that 1,25(OH)2D3 is essential for insulin secretion and glucose homeostasis. VDR mutant mice show a significant decrease in insulin mRNA levels when compared to controls, suggesting that 1,25(OH)2D3 may be required for insulin synthesis.
This isn't just something they've tried in a test tube. In vivo studies show that Vitamin D3 is essential for keeping blood sugar levels normal.

Lastly, obese individuals are often vitamin D deficient due to a decrease in the bio-availability of vitamin D metabolites which may explain why obesity is a risk factor for developing T2DM, although this association is only speculative...

Vitamin D deficiency increases peripheral tissue insulin resistance in addition to decreasing insulin secretion from pancreatic β-cells.

I would argue that they've forgotten that correlation is not causation. Say it with me, correlation is not causation. Associations are also not cause. Did it occur to them that (besides eating way too much sugar and way too many processed vegetable oils) that a deficiency in Vitamin D3 may be a catalyst for obesity? Obesity and insulin resistance go hand in hand. One may cause the other, or both may be caused by something else entirely. Or it's a chain reaction. Something causes insulin resistance which in turn causes obesity. I'm voting on that last one.

Another interesting article I found that has to do with how vitamin D deficiency may lead to breast, cervical and ovarian cancer. If you're not getting enough sun, I think it's a good idea to supplement Vitamin D3. It's cheap and the pills are small and easy to swallow.