Dr. Mercola's Comments:
If I told you there was something you could do to cut your risk of 15 types of cancer by 50 percent -- and it wouldnít cost you a dime -- would you do it?
Well there is, and itís called sun exposure.
This simple thing is so widely overlooked in the United States, despite the fact that only smoking is a bigger risk factor for cancer. After that, Dr. Grant, who is one of the top experts in the world on this topic, believes that your ability to get proper sun exposure is the next largest variable in whether or not youíll get cancer.
Vitamin D, the sunshine vitamin, is different from other vitamins in that it influences your entire body -- receptors that respond to the vitamin have been found in almost every type of human cell, from your brain to your bones.
In fact , your organs can actually convert vitamin D in your bloodstream into calcitriol, which is the hormonal version of vitamin D. Your organs then use it to repair damage, including that from cancer cells.
Some physicians are even experimenting with extremely high doses of vitamin D -- upwards of 50,000 international units (IU) a day -- to help advanced cancer patients heal (which is not something Iíd recommend doing without very close supervision from an experienced health care provider).
And according to Dr. Grant, about 30 percent of cancer deaths
-- which amounts to 2 million worldwide and 200,000 in the United States -- could be prevented each year with higher levels of vitamin D.
How Much Vitamin D do You Need?
Getting about 2,000 IU to 4,000 IU a day of vitamin D can help you to reduce your cancer risk by up to 50 percent
. However, most people only get 250-300 IU a day from their diet.
This means you simply need some sun exposure if you want to get enough vitamin D. Your body is capable of producing about 10,000 IU of vitamin D each day when youíre out in the sun, but depending on how much skin you have exposed, cloud cover, location, skin color and other factors, you may make much less than that.
As Dr. Grant pointed out, if you only have 10 percent of your body exposed to the sun you can make about 1,000 IU per day, and if half your body is exposed you can make 5,000 IU.
Keep in mind also that as you age your bodyís ability to produce vitamin D decreases significantly. Typical unhealthy adults over 60 actually have just one-quarter the production rate of vitamin D than do younger people, so if youíre over 60 youíll need to stay out in the sun longer to get enough vitamin D.
The best thing about getting your vitamin D from the sun is that itís impossible to overdose, and it just feels so good!
In the winter months if youíve had your vitamin D levels tested and found them to be low, a vitamin D3 supplement
(cholecalciferol), which is the type of vitamin D found naturally in foods like eggs, organ meats, animal fat, cod liver oil, and fish, can be used. Continue to have your vitamin D levels monitored
during this time, though, so you donít overdose.
So How Much Sun Should You Get?
A common myth is that occasional exposure of your face and hands to sunlight is "sufficient" for vitamin D nutrition. For most of us, this is an absolutely inadequate exposure to move vitamin levels to the healthy range of 45-55 ng/ml.
You need to expose large portions of your skin to the sun, and you need to do it for more than a few minutes.
In Caucasian skin, an equilibrium occurs within 20 minutes of ultraviolet exposure. It can take three to six times longer for darkly pigmented skin to reach the equilibrium concentration of skin vitamin D. So, bearing in mind that you need to gradually increase your time, starting in the spring, you should be aiming toward exposing large areas of your skin to the sun, anywhere from 20 minutes at a time to two hours at a time, depending on your skin type and environmental factors.
A light-skinned person fairly far from the equator (such as in the UK or the northern U.S.) needs at least three of these 20-minute sessions per week, in bright midday sunlight and with few clothes. Longer will be needed if sunbathing occurs at off-peak times for ultraviolet light (before 12 p.m. or after 3 p.m.) or at the beginning or end of the summer (April or September) when the sun is lower in the sky for most of the day. A dark-skinned person, of course, should be outside significantly longer.
What You Need to Know About the Sun and Sunscreen
The sunís rays contain two primary wavelengths: ultraviolet A (UVA) and ultraviolet B (UVB).
UVB is the more beneficial of the two, as this is what converts into vitamin D. UVA, meanwhile, is now believed to be a primary risk factor for cancer.
UVB has a wavelength that is more easily filtered through the atmosphere, so on a cloudy day you wonít get as much of that beneficial radiation on your skin to make vitamin D. However, UVA does not get filtered as well and will penetrate the atmosphere more easily, so it will STILL increase your risk of cancer on cloudy days, in the early morning and late afternoon.
Now, if you think you can protect yourself from UVA by using sunscreen, think again.
Many of the sun lotions on the market do not screen for UVA. Unless it specifically says so on the label, assume it doesnít. What most sunscreens end up doing, then, is screening out the beneficial UVB, and therefore limiting your vitamin D, while allowing the dangerous UVA to filter through!
If youíre using sunscreen, please make sure you use a product that protects you from both UVA and UVB rays, and contains non-toxic ingredients
Even then, I only recommend using it when you know youíll be outdoors for a long period and wonít be able to cover up. Ideally, get out in the sunshine with no sunscreen just long enough to get your vitamin D (this can vary from 15 minutes to two hours depending on the factors I mentioned earlier), then cover up with some loose clothing and a hat.