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Vitamin D supplementation to prevent acute respiratory tract infections (2017)

bmj.com

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Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#101

Post by wdobbels »

BurningFrog wrote: post #88
leto_ii wrote: post #21

I can say from my own experience that the lack of vitamin D can have a significant impact on both mind and body. I suspect that essentially all people living at relatively northern latitudes have some sort of vitamin D deficiency. From what I know you need to have your face and arms exposed to direct sunshine for at least 15 minutes/day to keep healthy vitamin D levels in the body. Good luck with that in the European…

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#102

Post by pygy_ »

wdobbels wrote: post #101
BurningFrog wrote: post #88

Earlier quoted context omitted.

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

Melanin is deposited in the epidermis, vitamin D conversion happens deeper, in the blood vessels of the dermis.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#103

Post by hcarvalhoalves »

wdobbels wrote: post #101
BurningFrog wrote: post #88

Earlier quoted context omitted.

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

Vitamin D synthesis happens underneath the skin, and requires UV B radiation. The dark skin is an adaptation to avoid UV damage from the normal UV levels you get at the less extreme latitudes by filtering out most of it.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#104

Post by BurningFrog »

wdobbels wrote: post #101
BurningFrog wrote: post #88

Earlier quoted context omitted.

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

Yeah, it's confusing.

I think this is how it works: The melanin is not transparent, so it stops the light from penetrating beyond the very surface, and so a smaller volume of skin cells get access to sunlight.

To go a little deeper: Sunlight does two major things in our skin. It creates vitamin D, and destroys folate. Both are essential, so the various skin colors we have reflect the balance evolution has struck in various environments.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#105

Post by ahakki »

wdobbels wrote: post #101
BurningFrog wrote: post #88

Earlier quoted context omitted.

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

IIRC from high school biology, the melanin in the upper skin layer absorbs the sunlight thus preventing it from going any deeper into the skin.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#106

Post by leto_ii »

wdobbels wrote: post #101
BurningFrog wrote: post #88

Earlier quoted context omitted.

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

Nope. Dark skin is an adaptation to exposure to lots of UV rays: https://en.wikipedia.org/wiki/Melanin#Evolutionary_origins

Incidentally you can test this yourself: if you go out in the summer you will tan i.e. your skin will darken. This is adaptation to lower the risk of sunburn and skin cancer.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#107

Post by Raphmedia »

wdobbels wrote: post #101
BurningFrog wrote: post #88

Earlier quoted context omitted.

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I'm probably missing something obvious but... Should white skin not reflect sunlight more, and dark skin absorb it more? I agree that northerners have more need to absorb sunrays and hence make more vitamin D, so shouldn't they be black?

Melanin in dark skin doesn't absorb as much UV radiation. It makes sense for people who live under the sun with relatively little protection to be dark skinned but it wouldn't make sense for people who are rarely exposed to the sun to be resistant to it.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#108

Post by russholmes »

hestefisk wrote: post #26
VBprogrammer wrote: post #4

Earlier quoted context omitted.

Assuming it's the BMJ that I know of that's the 'British Medical Journal' which is highly regarded. https://en.wikipedia.org/wiki/The_BMJ

Yes, together with New England Journal of Medicine and The Lancet, they are the ‘Nature’ equivalent of medical science.

The BMJ is the Daily Mail of medical journals, its target audience is whisky-nosed old buffers. Real doctors read the Lancet.

https://www.dailymotion.com/video/x2nedgv

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#109

Post by alexpotato »

BurningFrog wrote: post #88
leto_ii wrote: post #21

I can say from my own experience that the lack of vitamin D can have a significant impact on both mind and body. I suspect that essentially all people living at relatively northern latitudes have some sort of vitamin D deficiency. From what I know you need to have your face and arms exposed to direct sunshine for at least 15 minutes/day to keep healthy vitamin D levels in the body. Good luck with that in the European…

This is one reason arctic people eat so much (vitamin D rich) fish. The other is of course that a plant based diet is impractical when plants are only alive half the year. White skin itself is an evolutionary adaption for getting enough vitamin D outside of tropical Africa. The extreme "melanin-anemic" blond & blue eyes look of Scandinavia is thought to be because it has a uniquely warm weather for the latitude, whic…

I don't have the source handy but there was a geographic point made about Scandinavia that went something like this:

- Scandinavia is very far north and therefore gets less sun in the winter (obviously)

- Apparently the soil of Scandinavia is well suited to crops that are high in Vitamin D

The soil being good for Vitamin D crops (plus lightening of skin/hair and fish diets etc) was a part of why people were able to live in such far northern climates even if they didn't always have access to fish.

Re: Vitamin D supplementation to prevent acute respiratory tract infections (2017)

#110

Post by funklute »

neuronic wrote: post #69

May I mention the following research on NCBI: https://www.ncbi.nlm.nih.gov/pubmed/28768407 I will simply quote from the abstract: > This could lead to a recommendation of 1000 IU for children 1 year of age, and around 8000 IU for young adults and thereafter. Actions are urgently needed to protect the global population from vitamin D deficiency. Essentially, the recommended intake that pharmacists and labels tell you…

While this is a very interesting paper, I'm a little bit wary of research articles that only have a single author. Are you aware of how accepted this viewpoint is in the wider research/medical community? For example, are there any medical bodies that currently actually recommend adults to take 8000 IU of vitamin D supplement per day, if they are at risk of deficiency? Conversely, are the medical bodies that do not make such a recommendation simply slow, or are they in fact disputing the above findings?
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