OPC - The Foundation Of Human Health 

By Dr. Mercola

While mainstream media continues to blast health warnings about the dangers of sun exposure, the news reports have it all wrong―instead of too much sun, it’s likely most people are not getting enough.

Even though summer is a time when more people are outside―and theoretically exposed to more sun, which is the ideal way to boost your vitamin D levels―there are three good reasons why you still many not be getting enough …

Three Reasons Why You May be Vitamin D Deficient

It's estimated that over 95 percent of U.S. senior citizens may be deficient in vitamin D, along with 85 percent of the American public. Researchers have noted that vitamin D deficiency is prevalent in adults of all ages who have increased skin pigmentation (such as those whose ancestors are from Africa, the Middle East, or India), or who always wear sun protection or limit their outdoor activities.1

The truth is that many are under the false impression that they’re getting enough vitamin D, when their levels are seriously deficient. Three major reasons for this are:

1. Relying Too Much on Vitamin-D Fortified Foods or Poor-Quality Supplements

First of all, it is my firm belief that we were not designed to swallow our daily dose of vitamin D we were designed to absorb it from the sun. There are very few foods that actually have therapeutic levels of vitamin D naturally. It is a great backup to have the ability to absorb it orally, but it is my belief that oral vitamin D is significantly inferior to vitamin D derived from the sun.

Having said that, dairy processors producing pasteurized milk have been fortifying milk with vitamin D since 1933. Today, about 98 percent of the milk supply in the U.S. is fortified with approximately 400 International Units (IU) of vitamin D per quart. While dairies used to fortify their milk with vitamin D2, most have now switched over to the far superior D3.

Because of this fortification, many people believe that drinking milk is enough to support healthy vitamin D levels, but it is very difficult to get enough vitamin D from food sources alone. As I mentioned, very few foods naturally contain vitamin D -- and those that do will not contain enough to optimize your levels, even if you include fortified foods into the mix.

Additionally, it's important to realize that not all food sources provide the same kind of vitamin D. Plant sources provide you with D2. The more beneficial D3 can only be had through animal-based sources such as salmon, which has about 450 IUs per serving. While other animal-based foods do contain some naturally occurring vitamin D, it is typically at very low levels. One large egg yolk, for instance, contains just 41 IUs of vitamin D.

So, again, consuming these foods is not likely to give you enough vitamin D, as it appears as though most adults need at least 8,000 IU's of vitamin D a day in order to raise their serum levels to healthy levels.2

As for supplements, while safe sun exposure or safe tanning bed use are the best ways to optimize vitamin D, oral supplementation can be used. However, many are taking vitamin D2 (the type used in many prescription vitamin D supplements), unaware that this form is unlikely to give you the health benefits you’re seeking.

Vitamin D3 is approximately 87 percent more potent in raising and maintaining vitamin D concentrations and produces 2- to 3-fold greater storage of vitamin D than does D2.3

Regardless of which form you use, your body must also convert it into a more active form, and it is estimated that vitamin D3 is converted 500 percent faster than vitamin D2. Vitamin D2 also has a shorter shelf life, and its metabolites bind poorly with cellular receptor sites, further hampering its effectiveness. So if you decide to supplement with an oral form of vitamin D, make sure it’s D3, not D2.