Monday, February 28, 2011




















J. A. Deep said...

Any guess as to whether (or why) HDL or LDL, might correlate with Vitamin D production?

Also, does this finding run contrary to the big pharma push to reduce cholesterol with statins?

Great post! I've tried to read extensively on Vitamin D and sun, and would have never guessed at this.

Jake said...

I know that saturated fat consumption is necessary for Vitamin D production as it is for all hormones.

Saturated fat raises HDL and so it would raise total cholesterol.

The correlation then is the lack saturated fat consumption with the lack of Vitamin D production.

I believe the lack saturated fat consumption is one of the main drivers of Vitamin D deficiency in 70% of Americans.

Anonymous said...

Since Vit D production isn't better in light-skinned people, why did lighter skin evolve when people left Africa?

Ned Kock said...

Hi J.A. I think LDL particles play a positive role, as they seem to do also with cardiovascular disease:

It doesn’t look like HDL is the only good guy around, fighting against disease the ravages of the evil LDL particle …

Ned Kock said...

Hi Anon. Perhaps for the same reason that birds evolved all kinds of weird ornaments eh?

Ole Darwin was right about so many things, maybe he got this one right too:

Ned Kock said...

This may require a separate post, but I should point out that sexual selection is the “venture capitalist” of evolution.

Let’s say a few hundred ancestors reached a new land thousands of years ago. All it would take would be a single high-fertility man to have developed a preference for a trait, by chance, with the trait being coded by a genotype that was also present in female offspring. (This is only one of many possible scenarios.)

As a result, the preference and trait could easily spread to the entire population descending from that initial population. This new population may have grown to millions of people displaying both the preference and the trait.

Fisher was probably the first to fully describe this process mathematically. The process is sometimes called “runaway sexual selection”.

Runaway sexual selection may even lead to the evolution of traits that are costly. These are traits that impair survival – e.g., the male peacock’s train.

malpaz said...

thats interesting... i get REALLLL tan in the summer with no effort whatsoever on my part and dont really lose it in the winter...but seems it isnt correlated either way with vitamin D level in me. i took vitamin D in the winter this year b/c i get a massive hate for life when it gets cold and it did seem to keep me sane. i still had problems, but no relapse for the first time in like 6 years!

Jack C said...

Ned and Ted,

Great post! Of particular interest to an old guy like me is that there was no correlation between age and delta vitamin D. Fat guys would be interested that no correlation was found between delta vitamin D and BMI. It appears, according to the article, that the decreased vitamin D synthesis from sun exposure that has been attributed to age, obesity and darker skin color is mainly due to sun habits.

I was surprised at their conclusion, based on other studies, that statins do not decrease vitamin D status. Really? That conclusion seems inconsistent with the finding that reduced cholesterol levels result in decreased delta vitamin D synthesis from sun exposure.

The study found that at 56 degrees latitude 30 minutes of summer noontime sun exposure can provide adequate vitamin D. That equates to the sun exposure in mid March at 31 degrees latitude where I live.

I was amused by the fact that the authors, who are dermatologists, do mot recommend sun exposure to maintain vitamin D status because of "cancer risk", but instead recommend vitamin D supplements. That conclusion is expected as they need to keep their jobs!

Ned Kock said...

Thanks Mal for sharing, as always.

Ned Kock said...

Hey Jack, now you know why I like to look at numbers. Sometimes the text entirely contradicts what the numbers say.

Ned Kock said...

Btw, Jack - old guy!? I thought you were a young lad in his 20’s who happened to have a PhD in biochemistry ;-)

Ned Kock said...

Another interesting thing about this article is the use of the term “sun worshippers”. I don’t know if this is common in dermatology research, but it sounds funny to me, especially in an academic journal article.

David Csonka said...

Interesting theory, though there are so many confounding factors it will be hard to determine if it is just the vilification of saturated fat which is the cause, or is it the reduced sun exposure, or decrease consumption of milk for soft drinks, etc.

Helen said...

My cholesterol seems genetically low, which my doctors love (with just the "right" spread between HDL and LDL). I'm soon to find out my vitamin D status. It being early March, this would be mainly from supplementation. Maybe I should wait until the summer for my test, though, to see what I make on my own.

I wonder if those who have less cholesterol need less vitamin D? Any information on this possibility, or is that just wishful thinking on my part? There seem to be ethnic differences between ideal amounts - maybe there are individual differences, too.

Ned Kock said...

Hi Helen. I suggest you wait for the tests and keep in mind that there are major individual variations even in the sample in the study.

Even though TC and delta D are strongly correlated, the second highest delta D in the sample is for a person who seems to be in the first tercile of TC levels. You can see that on the plot of delta D against TC.

Also, since TC is measured after an overnight fast it completely ignores the contribution of chylomicrons. These are lipoproteins that transport some cholesterol from dietary sources to tissues as well, even though their content is mostly triglycerides.

David Isaak said...


Umm, actually, there has been some speculation that the only benefits of statis are that they somehow preserve or increase Vitamin D levles, and that cholestrol has nothing to do with it.

Google 'statins' "Vitamin D" and 'pleiotropic.'

You can't get at the whole Grimes editorial in the Lancet here, but check out:

It's pretty funny becasue iot casually mentions that no serious researchers any longer accept the cholesterol-heart disease hypothesis, even though it persists in public health and "folklore."

Says it all.

Kris @ Health Blog said...

Vitamin D3 is produced from cholesterol in the skin, I never knew though that low cholesterol levels would actually impair the production of D3.

This is an interesting point and definitely a good argument on one of the shortfalls of having too low cholesterol levels.

PK said...

In regards to sexual selection and skin tone, perhaps it was only when we moved to higher latitudes that the preference for lighter skin could become successful. Perhaps our ancestors in Africa who were born with lighter skin ability to survive long enough to reproduce well were too adversely affected by the inability to block UV rays as much as others. But once migration began, people lighter skin mutations could do fine in the new climate and even be selected for and reproduce more than the average.

Anonymous said...

can u tell me how uv light can effect the vitamin process?

sorry if i'm off the topic. rly curious. help me please? :)

gwarm said...


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India Pharmacy said...

The effects of this kind Vitamin D production can be terrible for our body!

EyeWearBuzz said...

UV rays is very harmful to eyes as well! Thanks for sharing this info. Godbless to your blog.