Sources:

Medical Hypotheses 72: 2009; 434-443

Dr. Mercola’s Comments:

At this point, you’re probably wondering how exposure to sunshine could possibly decrease your vitamin D levels… If you’re a regular reader of this newsletter, you know I’ve made it a point to educate you on the incredible value of safe sun exposure to increase your vitamin D levels

I have regularly stated that the ideal way to obtain your vitamin D is from safe exposure to sunshine As it turns out, there is a major caveat, which affects nearly anyone living in a modern day civilization.

But first, I want to review something that’s even more surprising – the connection between exposure to sunshine, vitamin D3, and showering!

What Does Showering Have to Do With Your Vitamin D Levels?

First, it’s important to understand that vitamin D3 is an oil soluble steroid hormone. It’s formed when your skin is exposed to ultraviolet B (UVB) radiation from the sun (or a safe tanning bed). When UVB strikes the surface of your skin, your skin converts a cholesterol derivative in your skin into vitamin D3.

However, the vitamin D3 that is formed is on the surface of your skin does not immediately penetrate into your bloodstream. It actually needs to be absorbed from the surface of your skin into your bloodstream.

The critical question then is: how long does it take the vitamin D3 to penetrate your skin and reach your bloodstream?

If you’re thinking about an hour or two, like I did until recently, you’re wrong. Because new evidence shows it takes up to 48 hours before you absorb the majority of the vitamin D that was generated by exposing your skin to the sun!

Therefore, if you shower with soap, you will simply wash away much of the vitamin D3 your skin generated, and decrease the benefits of your sun exposure. So to optimize your vitamin D level, you need to delay washing your body with soap for about two full days after sun exposure.

Now not many people are not going to bathe for two full days.

However you really only need to use soap underneath your arms and your groin area. , so this is not a major hygiene issue. You’ll just want to avoid soaping up the larger areas of your body that were exposed to the sun.

So, How Exactly Does Sunshine Lower Your Vitamin D Levels?

First, there’s an important distinction that must be made. There are two primary forms of ultraviolet radiation from the sun: UVA, and UVB, and they have different wave lengths and impact your body in different ways.

UVA has a wavelength of about 320 to 400 nanometers, and UVB has a wave length of about 280 to 320 nanometers.( A wavelength is simply the distance a wave has to travel before it starts repeating itself, and a nanometer is a millionth of a meter.)

Because the UVA has a longer wavelength, it penetrates materials more easily, such as the earth’s atmosphere and window glass.

Most of us living in contemporary culture are modern day cavemen. We work inside and don’t spend much time outdoors. It really wasn’t until the industrial revolution that we had the development of mass produced windows. Prior to that time, windows were very costly and only the very wealthy could afford them. So people working indoors were not exposed to sunlight filtered through window glass.

The key point here is that window glass will effectively filter out the majority of UVB radiation, but it minimally filters out UVAs.

What’s the significance of that, you ask?

It’s important to realize that vitamin D3 is formed from exposure to UVB rays, whereas UVA radiation actually destroys vitamin D.

This helps keep your body in balance; it’s one of the protective mechanisms your body has to avoid overdosing on vitamin D when you’re outside. However, when you’re exposed to sunlight through windows — in your office, your home or your car — you get the UVA but virtually none of the beneficial UVB.

This can lead to significant health problems, because in addition to destroying vitamin D3, UVA’s also increase oxidative stress.

UVA is one of the primary culprits behind skin cancer, and it increases photo aging of your skin. It’s also what causes you to tan. You can actually get vitamin D without significantly darkening your skin, because the UVB wavelength does not stimulate the melanin pigment to produce a tan.

Normally, of course, when you get tanned from outdoor sun exposure you’re getting both UVA and UVB at the same time, so it’s not a problem. But when you are indoors and expose yourself to sunlight filtered through window glass, you are increasing your risk of a variety of conditions, primarily skin cancer, because the UVA’s are effectively destroying your vitamin D3 levels while you’re getting none of the benefits from UVB.

The Connection Between Cholesterol and Healthy Vitamin D Levels

As I said earlier, one of the precursors for vitamin D is cholesterol. So if you’re taking drugs statin drugs, or proton pump inhibitors like Prilosec or Prevocid, which are typically used to treat ulcer conditions, you’ll naturally lower your cholesterol levels.

This in turn will decrease your body’s ability to manufacture vitamin D.

This is yet another potential reason your vitamin D levels may be low, or why you may have trouble optimizing your vitamin D levels.

Key Messages

It may seem confusing, and admittedly there are a lot of pieces to this puzzle, which is why I seek to share as much of this information as possible.

But the key take-home points here are:

• To optimize your vitamin D levels, get safe outdoor sun exposure or use a safe tanning bed, being careful not to get sunburned.

If for whatever reason you’re unable to do that, then clearly you’re going to want to use an oral or sublingual vitamin D3, which can also eliminate the whole issue of absorbing the vitamin D3 from your skin. However, beware that anytime you use oral vitamin D you’ll want to get your vitamin D levels checked regularly, using a qualified lab such as LabCorp, to make sure you’re within the optimal range and to avoid overdosing.

• If you’re going to shower after spending time outdoors in the sun, don’t use soap for at least two days, to maximize the absorption of vitamin D in your skin.

The benefits of vitamin D are staggering, and the optimal way to get your vitamin D is through safe exposure to the sun. I’ve written extensively on this topic over the past year, but if you need to refresh your memory, please review the related articles listed below. It is worth the extra effort to apply this information so you and your family can get all the vitamin D benefits they deserve.

So remember, making sure you’re spending plenty of time outdoors this summer can help you reap the incredible health benefits of this essential nutrient.

source: Mercola.com