Vitamin D Requirement

[Kasper]

I heard that vitamin D is really important to prevent osteoporosis.

I read somewhere that if we are in the sun, we make something like 10000IU vitamin D in our skin, it's almost impossible to get such a amount from food.
If we are not enough in the sun would you advise to get supplements RRM?

[RRM]

I heard that vitamin D is really important to prevent osteoporosis.

Thats a hypothesis, based on the fact that osteoporosis correlates with low vitamin D levels,
which not at all means that the osteoporosis is caused by the latter.
I will explain after this introduction:

Vitamin D is the precursor of calcitriol, a hormone that plays a role in bone health.
In the new definition of osteoporosis osteoporosis just means a low bone mass, which generally is not a disease, but just a temporary condition,
in as much as a low muscle mass does not have to be an indication for a muscle disease;
it may also be the result of undereating / lack of physical activity, which is readily reversed.
In the old definition of osteoporosis the bone (matrix) building cells (osteoblasts) are exhausted.
Calcitriol increases calcium absorption from food and absorption of calcium into the bones,
and therefore induces death of osteoblasts.
Calcitriol also stimulates deportation of calcium from the bones into the blood.
On the other hand:
Excessive PTH (parathyroid hormone) accelerates aging of the bones, and calcitriol inhibits PTH secretion,
so that calcitriol is protective in such a (excessive PTH) case,
by per saldo decreasing both uptake of calcium into the bones and deportation of calcium from the bones.

In my view, the best thing you can do for your bones, is preventing the intake of excessive calcium (milk etc),
as this will accelerate aging of osteoblasts.

About the osteoporosis-low vitamin D correlation:
· In my view osteoporosis is caused by consuming too much calcium year after year.
The body tries to counteract this by taking up as little calcium as possible.
Vitamin D increases the calcium-absorption rate. So to prevent the uptake of excessive calcium,
the body tries to keep the vitamin D level as low as possible.
· Hyperparathyroidism (excessive PTH) strongly increases both uptake of calcium into the bones and deportation from the bones,
eventually causing osteoporosis. If too little calcitriol is available, the secretion of PTH is not sufficiently inhibited.
Elevated vitamin D levels would have the same effect as hyperparathyroidism.
· If always very, very little calcium is consumed (less than 300 mg / day which is a very hard thing to achieve),
a lack of vitamin D / calcitriol can cause low bone mineral density by making it impossible to increase calcium absorption.
However, in countries where extremely little calcium is consumed, osteoporosis / hip fracture incidence is very low as well.

I read somewhere that if we are in the sun, we make something like 10000IU vitamin D in our skin, it's almost impossible to get such a amount from food.

Regarding the sunlight exposure and osteoporosis incidence correlation:
Though Italy is much sunnier than Poland, hip-fracture incidence in Italy is much higher than in Poland, for example.
And we dont need to be in the sun directly.
Daylight exposure (helped by the reflection of daylight in the snow, for example), is also very effective.

If we are not enough in the sun would you advise to get supplements RRM?

No, you can get all the required vitamin D from fish.
You can also make it a lot easier for our body to make the required vitamin D,
by providing it with a generous level of cholesterol, its precursor.
So that consuming fresh raw egg yolk is a good thing.
We dont need that much vitamin D for keeping PTH in check, for example.
In Saudi women who wear clothing that totally covers their skin, including the face,
in 52% of them their vitamin D level was extremely low, but their bones were not affected.

Too much vitamin D is harmful, so i definitely advice against supplementary vitamin D.
Supplementary vitamin D / calcitriol increases the blood-calcium level,
and this extra calcium can precipitate in arteries and on the outside of the bones,
which may cause arteriosclerosis and bone-deformities.

[Mr. PC]

vitamin D is a hormone? The only info I could find on the Way sites was this. viewtopic.php?f=26&t=258&hilit=vitamin+d+hormone

So, vitamin D is a vitamin, but needed for hormone production, which means the article is false in this regard.

Also on that topic is this link http://www.vivo.colostate.edu/hbooks/pa ... amind.html which I'll quote from here
"The term vitamin D is, unfortunately, an imprecise term referring to one or more members of a group of steroid molecules. Vitamin D3, also known as cholecalciferol is generated in the skin of animals when light energy is absorbed by a precursor molecule 7-dehydrocholesterol. Vitamin D is thus not a true vitamin, because individuals with adequate exposure to sunlight do not require dietary supplementation. There are also dietary sources of vitamin D, including egg yolk, fish oil and a number of plants. The plant form of vitamin D is called vitamin D2 or ergosterol. However, natural diets typically do not contain adequate quantities of vitamin D, and exposure to sunlight or consumption of foodstuffs purposefully supplemented with vitamin D are necessary to prevent deficiencies."

[RRM]

vitamin D is a hormone?

Vitamin D is the precursor of calcitriol, a hormone that plays a role in bone health.

Vitamin D is thus not a true vitamin, because individuals with adequate exposure to sunlight do not require dietary supplementation.

To what extend one can produce vitamin D is individually different,
in as much that it is individually to what extend one can produce vitamin B3, for example.

There are also dietary sources of vitamin D, including egg yolk, fish oil

and fish...

and a number of plants.

Not really.
D2 is found in various mushrooms and alfalfa, though.

The plant form of vitamin D is called vitamin D2 or ergosterol.

Ergocalciferol.
Ergosterol (a sterol) is a precursor to vitamin D2.
Ergosterol is found in fungi, and does not occur in plant or animal cells.

natural diets typically do not contain adequate quantities of vitamin D

So, eating fish and/or egg yolks cannot be part of a natural diet?

[dime]

I think this is a very interesting read about vitamin D, and why supplementation may (or may not) be disastrous. Also some discussion on the paper.

The US FDA currently encourages the addition of Vitamin D
to milk and cereals, with the aim of reducing rickets in
children, and osteoporosis in adults. However, Vitamin D not
only regulates the expression of genes associated with
calcium homeostasis, but also genes associated with
cancers, autoimmune disease, and infection.
...
The FDA docket does not review one single paper detailing the
transcriptional activity of Vitamin D, even though, on
average, one new paper a day is being published on that
topic. Nor do they review whether widespread
supplementation with Vitamin D, an immunomodulatory
secosteroid, might predispose the population to immune
dysfunction. This BioEssay explores how lifelong
supplementation of the food chain with Vitamin D might well
be contributing to the current epidemics of obesity and chronic disease.

FDA staff currently suggest(43) a 25-D level in the 75-80
nmol/L range as “adequate.” This is a level well above the
means of the Chilean and Bangladeshi women, and is based
on a risk-benefit analysis.
The new FDA regulation(7) proposes to allow additional
supplementation of the nation’s food chain. Indeed,
manufacturers who supplement orange juice with Vitamin D
will be able to make the claim that their product “reduces
osteoporosis”.

From the conclusion

The concept that “The Sunshine Vitamin” really is just a
vitamin, with the consequent implication of a linear ‘vitamin
in, benefit out’ model, is clearly no longer tenable. At any
level of molecular analysis, the Vitamin D metabolites are
part of the delicate homeostasis which allows our bodies to
express genes, and to express them when the need arises.

This is in response to the above paper: "The health benefits of vitamin D greatly outweigh the health risks"

[WaiWay]

Hey, my vitamin D requirement according to waidiet nutrient calculator is almost twice as much as I can get in salmon. I know the sample diet says not to eat over 100g of salmon, but I'm 16, 6'1, walk a lot, and work out occasionally with a fast metabolism. Is it alright I eat enough to get my required amount of vitamin D? To obtain my required amount, I would need to consume at least 160g of raw salmon. Is this alright?

[dime]

You also get from egg yolks and sun so no worries about that.

[Rivera]

Is it true that if you put some vegetables under the sun they get more vitamin D ? Sounds very strange to me.

[RRM]

Vegetables dont contain vitamin D, except for D2 (and a tiny bit of D3) in alfalfa and D2 in fungi such as mushrooms.
UV exposure is essential in this.

[WaiWay]

You also get from egg yolks and sun so no worries about that.

Dime, I live in Canada and I've read a lot of articles that it's very easy to become Vitamin D deficient during the winter months. I'm thinking taking a supplement, what do you think?

[dime]

I think it's best if you go to the doctor to first check if you're deficient if you think you are. That's what I did.

[RRM]

Actually, being 'vitamin-D deficient' is quite normal.
Even in sunny countries people on average are low on vitamin D.
viewtopic.php?f=17&t=1569&p=33372#p33372

[dime]

Yeah vitamin D levels seem so variable throughout the population that it's quite impossible to determine what is normal and what is abnormal.

[dime]

http://www.sciencedaily.com/releases/20 ... 085838.htm

Pregnant women should avoid taking vitamin D supplements, new research suggests. Substitution appears to raise the risk of children developing a food allergy after birth.

[dime]

Vitamin D May Lower Diabetes Risk in Obese Children and Adolescents

Peterson and her colleagues studied 35 pre-diabetic obese children and adolescents who were undergoing treatment in the MU Adolescent Diabetic Obesity Program. All of those in the study had insufficient or deficient vitamin D levels and had similar diets and activity levels. Study participants randomly were assigned either a high-dose vitamin D supplement or a placebo that they took daily for six months. Those who took the supplement became vitamin D sufficient and lowered the amount of insulin in their blood.
...
"What makes vitamin D insufficiency different in obese individuals is that they process vitamin D about half as efficiently as normal-weight people," Peterson said. "The vitamin gets stored in their fat tissues, which keeps it from being processed. This means obese individuals need to take in about twice as much vitamin D as their lean peers to maintain sufficient levels of vitamin D."