Vitamin D is one of the most important underlying factors for human pigmentation. We humans need regular supplies of this vitamin, which is seldom found in diet (fish essentially) and therefore Nature has provided us with sort of a photosynthetic skin, which generates the essential nutrient thanks to the energy of the Sun.
That is why humans loss partly their tan as they migrated northwards, where ultra-violet radiation is scarce, at least in winter.
I have on occasion discussed at my old blog Leherensuge several newly found roles of this critical vitamin besides bone formation: brain development, immune system and cholesterol. I have also mentioned a reason for the dark skin dominant in tropical peoples besides sunburns and skin cancer (vitamin B9, folate).
Well, there is yet another reason for the critical importance of vitamin D in our metabolism and coloring, though maybe not too different from one of the above (immune system): an specific defense response has been linked to vitamin D levels:
Olof Hertting et al., Vitamin D Induction of the Human Antimicrobial Peptide Cathelicidin in the Urinary Bladder. PLoS ONE 2010. Open access.
Abstract
The urinary tract is frequently being exposed to potential pathogens and rapid defence mechanisms are therefore needed. Cathelicidin, a human antimicrobial peptide is expressed and secreted by bladder epithelial cells and protects the urinary tract from infection. Here we show that vitamin D can induce cathelicidin in the urinary bladder. We analyzed bladder tissue from postmenopausal women for expression of cathelicidin, before and after a three-month period of supplementation with 25-hydroxyvitamin D3 (25D3). Cell culture experiments were performed to elucidate the mechanisms for cathelicidin induction. We observed that, vitamin D per se did not up-regulate cathelicidin in serum or in bladder tissue of the women in this study. However, when the bladder biopsies were infected with uropathogenic E. coli (UPEC), a significant increase in cathelicidin expression was observed after 25D3 supplementation. This observation was confirmed in human bladder cell lines, even though here, cathelicidin induction occurred irrespectively of infection. Vitamin D treated bladder cells exerted an increased antibacterial effect against UPEC and colocalization to cathelicidin indicated the relevance of this peptide. In the light of the rapidly growing problem of resistance to common urinary tract antibiotics, we suggest that vitamin D may be a potential complement in the prevention of UTI.
The immune character of Vitamin D is comparable to that of Vitamin C long reputed to have the effect.
ReplyDeleteGiven the immense health benefits of routine low dose asprin (against both cancer and cardiovascular diseases), I wonder if that won't someday be reclassified from being a medicine to being a Vitamin.
There are some differences between vit. C and D. Vit. C can be ingested without limitations because it's quickly removed from the organism (main exception are pregnant women because of "tolerance" effects in the fetus), vitamin D, as most other vitamins can be overdosed.
ReplyDeleteAlso vit. C is readily available in foods (fruits, vegetables, even the humble potato has some), instead vit. D is scarce (fish) and must be metabolized in the skin with solar help.
As for aspirin, I do not have much to say. When it was partly replaced by paracetamol it was also for a reason. However, as Hippocrates said, "there is no poison but dose". And I would add: "and well pondered knowledgeable intent". Everything can be useful when properly utilized but vitamins in excess can be toxic: one should not overdo it ever and should use what nature and chemistry provide carefully and with knowledge.
"ultra-violet radiation is scarce, at least in winter."
ReplyDeleteUV- B is scarce in northern winters but during the summer it is available in massive excess everywhere that humans live. As it's fat soluble and can be stored for the winter. Wherever they live humans in fact get more vitamin D than they need from the sun. Vitamin D supplements would be likely to dis-regulate a finely balanced homeostasis.
A urinary infection is no fun but a kidney stone will have you screaming for morphine.
Vale, Ken. I know your "theories" already.
ReplyDeleteYes it is a lonely battle me against all these experts.
ReplyDeletePROFESSOR Frank Garland, and his brother, Cedric, recommend that every cancer patient should have their vitamin D tested and brought up to a high normal range. This is the natural high level that is found in people who live an outdoor life in sunny countries and can be achieved by taking 50,000 units of vitamin D per week for eight to twelve weeks followed by maintenance on 1,000 to 2,000 units a day”.
ACCORDING to research from the newly published study by Cedric F. Garland, Dr. P.H., FACE, Department of Family and Preventive Medicine and Moores Cancer Center of the University of California, San Diego (UCSD), “It is projected that raising the minimum year-around serum 25(OH)D level to 40-60 ng/ml (100-150 nmol/L) would prevent approximately 58,000 new cases of breast cancer and 49,000 new cases of colorectal cancer each year, and three quarters of deaths from these diseases, in the US and Canada.”
The odds are slightly more in my favor since Frank Garland passed away from cancer of the esophageal junction.
Still there are a few dilettantes who agree with me, for example
Institute of Medicine of the National Academy of Sciences has determined that "While the average total intake of vitamin D is below the median requirement, national surveys show that average blood levels of vitamin D are above the 20 nanograms per milliliter that the IOM committee found to be the level that is needed for good bone health for practically all individuals. These seemingly inconsistent data suggest that sun exposure currently contributes meaningful amounts of vitamin D to North Americans and indicates that a majority of the population is meeting its needs for vitamin D".
There is no benefit to raising vitamin D higher than that. A vitamin D level of over 39 ng/ml increases mortality in older men, here is a quote from that study "The idea that high plasma vitamin D concentrations are related to overall cancer death can at first seem counterintuitive, because vitamin D has potent antiproliferative, pro differentiative, and immunomodulatory functions in a variety of cell types (10). Nevertheless, experimental studies have reported that excessive vitamin D activity could promote cancer (8) and accelerate aging (11). Cancer development may be promoted by the direct stimulatory effects of vitamin D on the oncogenic enzyme CYP24 (13) and insulin-like growth factor I (IGF-I) production (32, 33). Interestingly, vitamin D excess has also been shown to exacerbate premature aging phenotypes in mouse models of aging (11). These mice, however, can be rescued and their life span extended by suppressing IGF-I activities (11), restricting dietary intake of vitamin D, or by ablating the 1a-hydroxylase gene that is essential for biosynthesis of 1,25-dihydroxyvitamin D (32, 33). {...}Greatly increased <enterohepatic cancer death rates were ob- served with both low and high plasma vitamin D concentrations. "
The very latest alarming research:- older women with vitamin D levels over a mere 30 ng/ml had higher odds of frailty at baseline.
Yes it is a lonely battle me against all these experts.
ReplyDeletePROFESSOR Frank Garland, and his brother, Cedric, recommend that every cancer patient should have their vitamin D tested and brought up to a high normal range. This is the natural high level that is found in people who live an outdoor life in sunny countries and can be achieved by taking 50,000 units of vitamin D per week for eight to twelve weeks followed by maintenance on 1,000 to 2,000 units a day”.
ACCORDING to research from the newly published study by Cedric F. Garland, Dr. P.H., FACE, Department of Family and Preventive Medicine and Moores Cancer Center of the University of California, San Diego (UCSD), “It is projected that raising the minimum year-around serum 25(OH)D level to 40-60 ng/ml (100-150 nmol/L) would prevent approximately 58,000 new cases of breast cancer and 49,000 new cases of colorectal cancer each year, and three quarters of deaths from these diseases, in the US and Canada.”
The odds are slightly more in my favor since Frank Garland passed away from cancer of the esophageal junction.
Still there are a few dilettantes who agree with me, for example
Institute of Medicine of the National Academy of Sciences has determined that "While the average total intake of vitamin D is below the median requirement, national surveys show that average blood levels of vitamin D are above the 20 nanograms per milliliter that the IOM committee found to be the level that is needed for good bone health for practically all individuals. These seemingly inconsistent data suggest that sun exposure currently contributes meaningful amounts of vitamin D to North Americans and indicates that a majority of the population is meeting its needs for vitamin D".
There is no benefit to raising vitamin D higher than that. A vitamin D level of over 39 ng/ml increases mortality in older men, here is a quote from that study "The idea that high plasma vitamin D concentrations are related to overall cancer death can at first seem counterintuitive, because vitamin D has potent antiproliferative, pro differentiative, and immunomodulatory functions in a variety of cell types (10). Nevertheless, experimental studies have reported that excessive vitamin D activity could promote cancer (8) and accelerate aging (11). Cancer development may be promoted by the direct stimulatory effects of vitamin D on the oncogenic enzyme CYP24 (13) and insulin-like growth factor I (IGF-I) production (32, 33). Interestingly, vitamin D excess has also been shown to exacerbate premature aging phenotypes in mouse models of aging (11). These mice, however, can be rescued and their life span extended by suppressing IGF-I activities (11), restricting dietary intake of vitamin D, or by ablating the 1a-hydroxylase gene that is essential for biosynthesis of 1,25-dihydroxyvitamin D (32, 33). {...}Greatly increased <enterohepatic cancer death rates were ob- served with both low and high plasma vitamin D concentrations. "
ReplyDeleteThe very latest alarming research:- older women with vitamin D levels over a mere 30 ng/ml had higher odds of frailty at baseline.
There is no benefit to raising vitamin D higher than that. A vitamin D level of over 39 ng/ml increases mortality in older men, here is a quote from that study "The idea that high plasma vitamin D concentrations are related to overall cancer death can at first seem counterintuitive, because vitamin D has potent antiproliferative, pro differentiative, and immunomodulatory functions in a variety of cell types (10). Nevertheless, experimental studies have reported that excessive vitamin D activity could promote cancer (8) and accelerate aging (11). Cancer development may be promoted by the direct stimulatory effects of vitamin D on the oncogenic enzyme CYP24 (13) and insulin-like growth factor I (IGF-I) production (32, 33). Interestingly, vitamin D excess has also been shown to exacerbate premature aging phenotypes in mouse models of aging (11). These mice, however, can be rescued and their life span extended by suppressing IGF-I activities (11), restricting dietary intake of vitamin D, or by ablating the 1a-hydroxylase gene that is essential for biosynthesis of 1,25-dihydroxyvitamin D (32, 33). {...}Greatly increased <enterohepatic cancer death rates were ob- served with both low and high plasma vitamin D concentrations. "
ReplyDeleteThe very latest alarming research:- older women with vitamin D levels over a mere 30 ng/ml had higher odds of frailty at baseline.
Look, Ken: I know that most vitamins can be overdosed and one has to be careful about that. The main exception is vitamin C because it is hydrosoluble and hence quickly eliminated.
ReplyDeleteAnd you are probably right that is the reason the human skin stops producing vitamin D past some point. But precisely that's why skin color is so important to proper vit. D production, not just because of risk of lack of the key element, but also because producing it with the skin, which is fine tuned biologically to each environment, is the safest way to get the appropriate dose.
As I have said often, adults, specially males, are less susceptible to lack of vitamin D. The main risk is for children, who need it for a lot of functions in their development, and this is extended to mothers (and that may be why women almost invariably have a lighter skin color than men of their same population).
Paleolithic people or even most modern people do not go around measuring the exact input of vitamin D, or anything else: they just live where they are born, more or less.
The value of melanin as a sunscreen (2010)" Here we find that epidermal melanin is not a neutral density filter providing no or minimal protection for the induction of erythema at 295 and 315 nm and some protection at 305 and 365 nm."
ReplyDeleteSo it turns out melanin does not really filter the wavelengths of UV (ie UV-B) which synthesize vitamin D. And yes Aficans in Europe have low vitamin D levels but they also have low vitamin D levels when they live in Africa. Africans are supposed to have low vitamin D levels. Blood Vitamin D Levels in Relation to Genetic Estimation of African Ancestry
"African-Americans generally have lower circulating levels of 25 hydroxyvitamin D [25(OH)D] than Whites, attributed to skin pigmentation and dietary habits. Little is known about the genetic determinants of 25(OH)D levels nor whether the degree of African ancestry associates with circulating 25(OH)D.[...]The effect of high vitamin D exposure from sunlight and diet was 46% lower among African-Americans with high African ancestry than among those with low/medium ancestry. " (And diet, think about the implications of that).
"human skin stops producing vitamin D past some point".
It is a lot more complicated than that. The essential point is blood vitamin D levels are optimized for the environment; for Aficans and those tropically adapted blood vitamin D levels should be much lower.
I am having a lot of trouble posting my comment to this site. About a dozen have failed already they seem to work but they disappear. I bet I'm not the only one. It's pretty frustrating.
ReplyDeletehuman skin stops producing vitamin D past some point.
ReplyDeleteIt's not that simple. Yes, Africans and others of tropical ancestry have lower vitamin D levels but the reason has nothing to do with skin color as shown by these two studies
Blood Vitamin D Levels in Relation to Genetic Estimation of African Ancestry.
"African-Americans generally have lower circulating levels of 25 hydroxyvitamin D [25(OH)D] than Whites, attributed to skin pigmentation and dietary habits [...]The effect of high vitamin D exposure from sunlight and diet was 46% lower among African-Americans with high African ancestry than among those with low/medium ancestry. "
"AND DIET" think about the implications of that for a moment please.
What's that you're thinking - the greater amount of melanin in African skin must block UV and result in lower vitamin D. No the above study specifically refutes that but here is some more evidence. Melanin as a sunsceen. "we find that epidermal melanin is not a neutral density filter providing no or minimal protection for the induction of erythema at 295 and 315 nm and some protection at 305 and 365 nm". (vitamin D is produced by UV 280- 315nm). So it turns out that melanin does not filter the vitamin D synthesizing wavelengths of UV after all.
What happens to African who have raised vitamin D levels
Vitamin D Levels Have Different Effects on Atherosclerosis in Blacks and Whites, Study Finds.
"We found that higher circulating levels of vitamin D in blacks were associated with more calcium in the artery walls," Freedman said. "This is the opposite effect of what is felt to occur in white patients and shows that the accepted "normal" range of vitamin D may be different between blacks and whites"
human skin stops producing vitamin D past some point.|
ReplyDeleteIf it was that simple, then it should be just as easy for Africans as whites to raise their vitamin D levels by ingesting vitamin D.
Blood Vitamin D Levels in Relation to Genetic Estimation of African Ancestry
"The effect of high vitamin D exposure from sunlight and diet was 46% lower among African-Americans with high African ancestry than among those with low/medium ancestry." Note it says "and diet". Think about the implications of that for a minute please.
Melanin doesn't make any difference to the amount of vitamin D synthesized The value of melanin as a sunscreen.Here we find that epidermal melanin is not a neutral density filter providing no or minimal protection for the induction of erythema at 295 and 315 nm and some protection at 305 and 365 nm. ( Pro vitamin D is produced in the skin by UV of wavelength 280- 315nm)
Africans have naturally low vitamin D levels they're healthy that way. What happens to African americans with raised vitamin d levels Vitamin D Levels Have Different Effects on Atherosclerosis in Blacks and Whites, Study Finds.
"We found that higher circulating levels of vitamin D in blacks were associated with more calcium in the artery walls," Freedman said. "This is the opposite effect of what is felt to occur in white patients and shows that the accepted "normal" range of vitamin D may be different between blacks and whites"
Global vitamin D levels in relation to age, gender, skin pigmentation and latitude: an ecologic meta-regression analysis.
ReplyDelete"The mean 25(OH)D level was 54 nmol/l (95% CI: 52-57 nmol/l). Women had borderline significantly higher 25(OH)D levels than men, and Caucasians had higher levels than non-Caucasians. [...] There was a significant decline with latitude for Caucasians (-0.69 +/- 0.30 nmol/l per degree, p = 0.02), but not for non-Caucasians (0.03 +/- 0.39 nmol/l per degree, p = 0.14). "
Ponder these studies
Vitamin D Production after UVB Exposure Depends on Baseline Vitamin D and Total Cholesterol but Not on Skin Pigmentation
Speaks for itself really
Pigmentation and Vitamin D Metabolism in Caucasians: Low Vitamin D Serum Levels in Fair Skin Types in the UK
"Contrary to current beliefs based mainly on studies between different ethnic groups, this study shows that fair skin types within a Caucasian population in the UK are most at risk of vitamin D deficiency"
I did already comment in Leherensuge that the main reason for black/brown skin is not skin cancer (likely to have very small fitness cost) but folate (vit. B9).
ReplyDeleteI do not think I can agree that different populations have different needs of vit. D just because of skin color. That makes no sense whatsoever.
"I am having a lot of trouble posting my comment to this site. About a dozen have failed already they seem to work but they disappear. I bet I'm not the only one. It's pretty frustrating".
ReplyDeleteSorry about that: it's the damn new Blogger spam-filter (which I cannot disable). As I get all answers by email, no matter what, I do not notice unless you say. There were seven comments in the spam box and I think all were yours. They should be in their places now.
Link to previous discussion of folate and solar radiation in which you said "Finally 30 ng/ml is just the top risk level for osteoporosis "
ReplyDeleteAccording to the Institute of Medicine of the National Academy of Sciences team of experts who looked at over 100 scientific papers that is 100% wrong Report Questions Need for 2 Diet Supplements
"It is not clear how or why the claims for high vitamin D levels started, medical experts say. First there were two studies, which turned out to be incorrect, that said people needed 30 nanograms of vitamin D per milliliter of blood, the upper end of what the committee says is a normal range. They were followed by articles and claims and books saying much higher levels — 40 to 50 nanograms or even higher — were needed".
For the love of god don't take vitamin D supplements, you'll put your life into fast-forward.
And the simple latitude hypothesis can't be right because it is known the white colour that europen skin now has appeared suddenly 6- 12000 years ago long after entering Europe. here
"And the simple latitude hypothesis can't be right because it is known the white colour that europen skin now has appeared suddenly 6- 12000 years ago long after entering Europe".
ReplyDeleteDo not make false claims, please.
This refers to a single gene which "plays a role" in skin color. This gene has the following SNPs:
- rs 1426654, whose derived allele (A) is dominant in Europeans and Indians and present in all populations.
- rs 16960620, for which Europeans have the ancestral allele A (the derived allele G is found mostly among East Asians, but not as dominant)
- rs2555364, whose European allele is present in all populations
So:
1. It is a gene that does not clearly determine anything
2. Its European alleles are shared with so many other peoples that is most unlikely it evolved any time recently. In fact the alleles are all present in Africa, though in the case of rs 1426654, only in minor apportions but it's almost as dominant in India as is in Europe.
Please get your facts straight before going around confusing people. There's often a lot of hype in the media about things that later happen to be wrong or simply exaggerated for a bit of impact publicity.
We do not know for sure when loss of brownness happened in West Eurasians and East Asians (probably two distinct processes) but it is most likely that it happened as soon as people began taking positions around Turkey and Korea, for instance. 40 degrees north (Spain, Turkey, Uzbekistan, Mongolia, Korea, New York) is already very much non-tropical, believe me. All the population at that latitude (and further north) is what we call white, often with rosy cheeks to maximize UV input, even if they can also tan easily.
I understand that it is impossible in any case for a population to survive for long in places like Altai or much of Europe with dark pigmentation (and I'm talking about damage to babies, not adults), specially if they had to face well adapted competence like Neanderthals. That is... unless their diet was very rich in fish, what may have helped transitioning in some cases.