Aro2220

Hi,

I'm trying to find some information on tanning beds and sunlight in general.

How does tanning bed light compare with natural sunlight?
Is natural sunlight 'better' in that you would choose sunlight over tanning light?

How do skin cancer rates compare between tanners from tanning beds and tanners from natural sunlight in cases of low, moderate and over use?

As for vitamin D, how is it produced by sunlight? What does vitamin D do in the body? If it is produced in the skin, what does it do there? Does it get into your blood? If sunlight allows the human body to create much more vitamin d3 than is safe to get through supplements, then why don't people experience vitamin d overdosing when getting 'too much' sunlight?

While my questions may seem specific (especially with the vitamin D paragraph), they really are generic questions. Answer them in any way you like and as specific as you care to be.

I live in Canada, and we don't have the kind of weather you'd want to sun bathe in for the better part of the year. I find sunlight helps with energy levels, mood, and helps to clear up skin and give it a more healthy appearance. It sure would be nice if I could crawl into a tanning bed and get the same benefits as being outside on a nice summer day.

I look forward to reading any replies,
Thanks :)

billable

Wow! You are asking enough in that post that I could sit here answering for the next hour and not give you complete answers. I suspect that you are "computer literate" enough to search this forum (think positive about UV) and find the answers to almost all of your questions. Pay particular attention to the Dana-Farber study as well as the latest 2 or 3 studies referenced in this forum.

I feel confident that you will find all your answers by following the links provided and you will have much more confidence in the information that you find than you would if I just told you that tanning beds provide the same tanning rays that sunlight provides or that your body has a natural mechanism for regulating the amount of vitamin D it produces via UV so you can't overdose on vitamin D from UV exposure, etc.

Good Luck and feel free to come back to discuss more specific questions in more detail. You will find there are many people here that can help you with the more technical questions.

eileen

Hi,

I'm trying to find some information on tanning beds and sunlight in general.

How does tanning bed light compare with natural sunlight?
Both sources can produce Vitamin D in your body.

Is natural sunlight 'better' in that you would choose sunlight over tanning light?
Sunlight can be more sporadic in how
much is actually getting through to you. A tanning beds output will be more consistant and take less overall time to produce.

How do skin cancer rates compare between tanners from tanning beds and tanners from natural sunlight in cases of low, mooderate and over use?
To date I don't believe there is a scientific study with any results of this available. If you happen to find one please email the information.

As for vitamin D, how is it produced by sunlight? What does vitamin D do in the body? If it is produced in the skin, what does it do there? Does it get into your blood?
Vitamin D is the only Vitamin to act as a steroid hormone. Some more information below with the link to the source:
http://www.vivo.colostate.edu/hbooks.../vitamind.html

Bioactive vitamin D or calcitriol is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, and in mineralization of bone. More recently, it has become clear that receptors for vitamin D are present in a wide variety of cells, and that this hormone has biologic effects which extend far beyond control of mineral metabolism.

Structure and Synthesis

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 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.
Vitamin D, as either D3 or D2, does not have significant biological activity. Rather, it must be metabolized within the body to the hormonally-active form known as 1,25-dihydroxycholecalciferol. This transformation occurs in two steps, as depicted in the diagram to the right:

1. Within the liver, cholecalciferal is hydroxylated to 25-hydroxycholecalciferol by the enzyme 25-hydroxylase.
2. Within the kidney, 25-hydroxycholecalciferol serves as a substrate for 1-alpha-hydroxylase, yielding 1,25-dihydroxycholecalciferol, the biologically active form.

Each of the forms of vitamin D is hydrophobic, and is transported in blood bound to carrier proteins. The major carrier is called, appropriately, vitamin D-binding protein. The halflife of 25-hydroxycholecalciferol is several weeks, while that of 1,25-dihydroxycholecalciferol is only a few hours.
Control of Vitamin D Synthesis

Hepatic synthesis of 25-hydroxycholecalciferol is only loosely regulated, and blood levels of this molecule largely reflect the amount of amount of vitamin D produced in the skin or ingested. In contrast, the activity of 1-alpha-hydroxylase in the kidney is tightly regulated and serves as the major control point in production of the active hormone. The major inducer of 1-alpha-hydroxylase is parathyroid hormone; it is also induced by low blood levels of phosphate.
The Vitamin D Receptor and Mechanism of Action

The active form of vitamin D binds to intracellular receptors that then function as transcription factors to modulate gene expression. Like the receptors for other steroid hormones and thyroid hormones, the vitamin D receptor has hormone-binding and DNA-binding domains. The vitamin D receptor forms a complex with another intracellular receptor, the retinoid-X receptor, and that heterodimer is what binds to DNA. In most cases studied, the effect is to activate transcription, but situations are also known in which vitamin D suppresses transcription.
The vitamin D receptor binds several forms of cholecalciferol. Its affinity for 1,25-dihydroxycholecalciferol is roughly 1000 times that for 25-hydroxycholecalciferol, which explains their relative biological potencies.
Physiological Effects of Vitamin D

Vitamin D is well known as a hormone involved in mineral metabolism and bone growth. Its most dramatic effect is to facilitate intestinal absorption of calcium, although it also stimulates absorption of phosphate and magnesium ions. In the absence of vitamin D, dietary calcium is not absorbed at all efficiently. Vitamin D stimulates the expression of a number of proteins involved in transporting calcium from the lumen of the intestine, across the epithelial cells and into blood. The best-studied of these calcium transporters is calbindin, an intracellular protein that ferries calcium across the intestinal epithelial cell.
Numerous effects of vitamin D on bone have been demonstrated. As a transcriptional regulator of bone matrix proteins, it induces the expression of osteocalcin and suppresses synthesis of type I collagen. In cell cultures, vitamin D stimulates differentiation of osteoclasts. However, studies of humans and animals with vitamin D deficiency or mutations in the vitamin D receptor suggest that these effects are perhaps not of major physiologic importance, and that the crutial effect of vitamin D on bone is to provide the proper balance of calcium and phosphorus to support mineralization.
It turns out that vitamin D receptors are present in most if not all cells in the body. Additionally, experiments using cultured cells have demonstrated that vitamin D has potent effects on the growth and differentiation of many types of cells. These findings suggest that vitamin D has physiologic effects much broader that a role in mineral homeostasis and bone function. This is an active area of research and a much better understanding of this area will likely be available in the near future.

If sunlight allows the human body to create much more vitamin d3 than is safe to get through supplements, then why don't people experience vitamin d overdosing when getting 'too much' sunlight?
A supplement is a foriegn source entered into the body. UV light is the natural way the body was developed to produce vitamin D....your body naturally knows when to stop producing Vitamin D.

While my questions may seem specific (especially with the vitamin D paragraph), they really are generic questions. Answer them in any way you like and as specific as you care to be.

I live in Canada, and we don't have the kind of weather you'd want to sun bathe in for the better part of the year. I find sunlight helps with energy levels, mood, and helps to clear up skin and give it a more healthy appearance. It sure would be nice if I could crawl into a tanning bed and get the same benefits as being outside on a nice summer day.

I look forward to reading any replies,
Thanks :)

I hope this sheds some light on what you are asking....there is a wealth of information right here on tantalk.
:)

Marca

Way to go Eileen!

engfant

yeowza! That's a keeper post!

__________________
"And shut your mouth pussycat e fammi un macchiato, pronto!"

http://www.youtube.com/watch?v=UhHhXukovMU

tanfixr

If sunlight allows the human body to create much more vitamin d3 than is safe to get through supplements, then why don't people experience vitamin d overdosing when getting 'too much' sunlight?

A supplement is a foriegn source entered into the body. UV light is the natural way the body was developed to produce vitamin D....your body naturally knows when to stop producing Vitamin D.

The potential for vitamin D overdosing is vastly overstated. The current recommended upper limit of 2000 IU, and recommended daily dose of 200 IU are little more than arbitratry guesses made decades ago, and it is generally accepted now that both of these numbers are not correct. In fact, most serious vitamin D researchers now think that the optimal daily dose of D3 is between at least 1000 IU and 4000 IU. And hypervitaminosis D is unlikely to occur in adults from anything less than longterm oral doses of 10,000 IU or more.

It is impossible to get too much vitamin D from UV induced cutaneous production of D3. The skin doesn't necessarily "stop producing" vitamin D. We can easily synthesize 20k to 40k IU of D3 from sun or tanning bed exposure. What happens though, is that D3 that is converted from 7-DHC suffers from UV-induced degradation. There is no in-vivo vitamin D degradation action spectrum that I know of, but it's widely claimed that it is mostly UVA that causes this.

The true measure of an individual's vitamin D is the blood serum level. The kinetic path shown in the posted chart is missing a branch where other byproducts are produced by additional UV light. Vitamin D that is already produced by UV exposure gets broken down into other byproducts before being seen in corresponding levels in the blood. Therefore, no vitamin D toxicity.

Also, many vitamin D supplements are still the plant derivative D2, which is not as effective as D3.