Now that the warmer weather is here you can get outside and replenish your much-needed stores of vitamin D, the sunshine vitamin.

“20 minutes twice a week” is the usual rule of thumb for getting enough sun to keep your vitamin D levels up. But in real life it’s much more complicated than that. We’ll examine some of the surprising reasons this is so.

But first let’s take a look at why vitamin D is critical to your health.

Vitamin D — What’s It Good For?

Vitamin D is technically not a vitamin, it’s a pre-hormone that’s created when your skin is exposed to sunlight. It’s the only human nutrient that’s created from sunlight. Just like a plant. 

Vitamin D is close to being nature’s cure-all. It’s a fantastic immune system booster. It’s been found to be protective against cancer, diabetes, heart disease, high blood pressure, osteoporosis, and Alzheimer’s.

Studies have shown it can lift your mood, banish depression, improve memory, and increase problem-solving ability. Inadequate levels may contribute to the blues many people feel in the winter.

Surprising Factors Affect Vitamin D Formation

It’s estimated that 80-90% of adults in North America are vitamin D deficient. Here are five surprising factors that affect your ability to manufacture vitamin D.

1. Sunscreen

If you are outside in the sun but wearing sunscreen, you won’t manufacture much vitamin D. I live in the land of perpetual sunshine – southern Arizona – and am outside a lot. So I was shocked to learn I was seriously vitamin D deficient! I know now that’s because I wore sunscreen most of the time.

2. Latitude

If you live in the US draw a line from Los Angeles to Atlanta. If you live north of this line, the sun’s rays are too weak to trigger vitamin D production most of the year except during the summer.

Time for some fun science! Here’s a way to tell if the sun’s rays are strong enough to stimulate vitamin D formation:

Go outside, stand in the sun, and look at your shadow. The more direct the sun’s rays are, the shorter your shadow will be. A good rule of thumb is that if your shadow is your height or longer, the sun’s rays strike at too great an angle to promote vitamin D formation.

3. Skin Color

Our different skin tones evolved depending on how much sunshine our ancestors were exposed to. Light-skinned people from very northern areas evolved to utilize sunshine more efficiently. If you have dark skin, you need even more sun exposure to get adequate exposure levels, up to one hour a day.

4. UV Index

Just because the sun is shining and you’re in it, doesn’t mean you’re producing vitamin D! UV index is affected by season, time of day, cloud cover, air pollution, altitude, and even your surrounding surface. Whether you’re outside in the snow, at the beach, or picnicking on a lawn can affect how much UV radiation is reflected back at you by up to 40 fold.

It is only when the UV index is greater than 3 that the needed UVB wavelengths are present in sufficient amounts. Check a site like Weather.com to find your current local UV index before you take your next vitamin D “sun bath”. There are also some apps that report your local UV index.

5. Bathing

It takes up to 48 hours for your skin to fully absorb all of the vitamin D it makes in the sunshine. About 50% of the total formation occurs within the first few hours so try to hold off showering at least until then. Otherwise your new vitamin D will literally go down the drain.

Here’s a link to a calculator that takes most of these factors – latitude, skin color, altitude, sky conditions and such – into account. It estimates how many minutes of sun exposure you need to produce 25 mcg (the equivalent of 1,000 International Units) of vitamin D. You might not know your latitude and altitude off the top of your head but you can google it.

Know Your Levels, Supplement Accordingly

Vitamin D deficiency symptoms — muscle pain, weak bones, low energy, lowered immunity, depression, mood swings, and sleep problems — can be mistaken for many other health problems.

The only way to know for sure if you need vitamin D supplementation is to have a blood test to check your 25-hydroxy level. You can see your doctor or you can order a vitamin D test online. Online self-testing is a great way to save money, retain your privacy, and have more control over your health.

If your level is found to be low and you can’t get enough sun exposure, you need to supplement.

There are five forms of vitamin D – D1 through D5. Most experts agree the most effective form is D3.

Some foods, like milk, are fortified with the D2 form and mushrooms naturally contain D2, but this form is not very well utilized.

By far the best “food source” of D3 is cod liver oil. Not that most of us would call this “food”!  Fatty fish like salmon and sardines contain some D3, but not nearly as much.

When you choose a vitamin D supplement be sure to buy from a company you can trust. Last year a study on 55 brands of vitamin D supplements found they contained between 9% – 146% of what was listed on the label!

For most of the country, sunbathing days will soon be here. Keep these tips in mind to benefit from the sun exposure you receive. Remember the “20 minutes twice a week” rule of thumb rarely holds true. If you suspect you’re deficient get tested to know for sure.

ABOUT THE AUTHOR:

Deane Alban holds a bachelor’s degree in biology and has taught and written on a wide variety of natural health topics for over 20 years. She teaches the best ways to stay mentally sharp for life at her website BeBrainFit.com. Learn how to protect your brain and optimize your brainpower – sign up for her free e-course 21 Days to a Brighter Brain here.