3 Reasons You May Not be Getting Enough Vitamin D this Summer
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.
2. You Slather on Sunscreen
Do you dutifully slather your body with sunscreen before heading outdoors, and then assume your vitamin D levels are fine because you spend plenty of time in the sun? This, too, is a risk factor for deficiency, because sunscreens effectively block the type of ultraviolet light – UVB -- needed in order for your body to produce vitamin D in response to the exposure.
According to vitamin D researcher Michael Holick:4
“ … a sunscreen with a sun protection of 15 absorbs 99% of the incident UVB radiation, and, thus, when topically applied properly will decrease the synthesis of vitamin D3 in the skin by 99%.”
3. You’re Sunbathing in the Wrong Place
While laying on a glass patio or soaking up rays through a window may feel good on your skin, the warmth that comes through is deceiving because vitamin D-producing UVB rays cannot pass through glass. So you’ll get absolutely no boost to your vitamin D levels if the sunlight passes through a window before hitting your skin.
Worse still, the skin-damaging UVA light, which penetrates your skin more deeply than UVB, and may be a much more important factor in photoaging, wrinkles and skin cancers, does pass through glass. This means that getting sun exposure through a window gives you none of the beneficial UVB, and all of the cancer-causing UVA!
A study in Medical Hypotheses5 even suggested that indoor workers may have increased rates of melanoma because they're exposed to sunlight through windows, and only UVA light, unlike UVB, can pass through window glass. At the same time, these indoor workers are missing out on exposure to the beneficial UVB rays, and have lower levels of vitamin D.
How to Maximize Your Vitamin D from Safe Sun Exposure
Occasional sunlight exposure to your face and hands is not sufficient for vitamin D nutrition for most people. To optimize your levels, you need to expose large portions of your skin to the sun, and you may need to do it for more than a few minutes. Contrary to popular belief, the best time to be in the sun for vitamin D production is actually as near to solar noon as possible (you need to figure in Daylight Saving Time, which typically pushes solar noon to 1 p.m. for most).
This is because while UVA rays are quite constant during ALL hours of daylight, throughout the entire year, UVB are low in morning and evening and high at midday. So to use the sun to maximize your vitamin D production and minimize your risk of skin damage, the middle of the day (roughly between 10:00 a.m. and 2:00 p.m.) is the best and safest time. During this UVB-intense period you will likely need the shortest sun exposure time to produce the most vitamin D.
As far as the optimal length of exposure, you only need enough to have your skin turn the lightest shade of pink. This may only be a few minutes for those who have very pale skin.
Once you have reached this point your body will not make any additional vitamin D and any further exposure will only result in damage to your skin. Most people with fair skin will max out their vitamin D production in just 10-20 minutes, or, again, when their skin starts turning the lightest shade of pink. Some will need less, others more. The darker your skin, the longer exposure you will need to optimize your vitamin D production.
The skin around your eyes and your face is typically much thinner than other areas on your body and is a relatively small surface area so will not contribute much to vitamin D production. It is strongly recommended to protect this fragile area of your body, as is at a much higher risk for cosmetic photo damage and premature wrinkling. You can use a safe sun block in this area or wear a cap that always keeps your eyes in the shade, which is what I do when I am outside seeking to increase my vitamin D levels.
From a health perspective it doesn't make much sense to expose your skin to the sun when it is lower than 50 degrees above the horizon because you will not receive any valuable UVB rays, but you will expose yourself to the more dangerous and potentially deadly UVA rays. UVA's have a longer wavelength than UVB and can more easily penetrate the ozone layer and other obstacles (like clouds and pollution) on their way from the sun to the earth. So while it will give you a tan (mainly by oxidizing melanin instead of producing new melanin), unless the companion UVB rays are available you're likely doing more harm than good and should probably stay out of the sun to protect your skin.
During the times of the year when UVB rays are not present where you live you essentially have two options: You can use a safe tanning bed or you can swallow oral vitamin D3.
What are the Optimal Levels to Aim For?
I would strongly encourage you to have your blood level checked to confirm that your sun exposure is putting you at the right level, as there are many variables that can influence this, including the darkness of your skin, your age and your geographical location. If it isn't, or if sun exposure is not a practical option for you, then you should consider supplementing with oral vitamin D3. Remember, unless you get a deep dark tan, which is a pretty good indicator that your vitamin D levels are where they need to be, it is wise to get your blood levels checked -- that is the only way to know for certain you have reached therapeutic levels.
Please do take this information seriously, and share it with your friends and family, as correcting a vitamin D deficiency is simple, and it may cut your risk of dying by more than half, according to an analysis conducted last year.6 People with low levels of vitamin D were found to be more likely to have diabetes, high blood pressure, and diseased heart muscle -- and were three times more likely to die from any cause compared to those with normal levels. Vitamin D is also emerging as a key player in the fight against cancer, so it is very much to your advantage to get your levels up where they need to be.
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