Vitamin D Deficiency – Why You’re Not Getting Enough From the Sun

In the heart of Winter, it’s easy to start day dreaming about spring and summer, and feeling the warmth of the sun once again. If you’ve found yourself getting lost in thought about about basking in the sun and increasing your outdoor activities, Vitamin D might be just what you’re craving.

While there are many benefits to increasing outdoor activities and getting sun exposure, one of the chief benefits is vitamin D production. Yet, even in peak summer months, it is estimated that over half of the U.S. population is vitamin D deficient and that number increases during the winter.

But, before we dive into why so many are vitamin D deficient, let take a look at some of the risk factors of vitamin D deficiency.

Why Vitamin D Deficiency Matters?

Vitamin D deficiency carries some serious health risks.   This includes poor bone health, rickets, and osteomalacia, but recent studies have found that vitamin D deficiency is also associated with an increased risk of certain cancers, type I diabetes, multiple sclerosis, tuberculosis, rheumatoid arthritis, osteoporosis, muscle weakness and pain, depression, hypertension, pregnancy complications, and even the seasonal flu.

Vitamin D unquestionably has a significant influence on health and wellbeing and plays an important role in many body systems.  Scientists have identified nearly 3,000 genes that are influenced by vitamin D levels, and getting enough vitamin D is crucial for your health.

The Problem

As mentioned, even in peak summer months, when direct sunlight is most abundant, over half of the U.S. population is still vitamin D deficient.  Why?   Here are a few reasons:


Sunlight is composed of about 1500 wavelengths, but the only wavelengths that help your body produce vitamin D are UVB rays.  Vitamin D production only occurs when UVB rays shine directly on unexposed skin.

UVB rays from the sun actually have to pass through the atmosphere to reach us on the surface of the earth. Physics also plays a role in vitamin D production, as UVB rays will only penetrate the atmosphere when the sun is above an angle of about 50 ° from the horizon.  When the sun is lower than 50 °, the ozone layer reflects UVB rays, but lets through UVA rays.  UVA ray’s have a longer wavelength than UVB rays and can more easily penetrate the ozone layer and other obstacles, like clouds and pollution, on their way from the sun to the earth.  UVA rays are more dangerous and potentially deadly (chronic exposure to UVA rays dramatically increases your risk of skin cancer, photoages your skin, etc.).

UVB rays help the body produce vitamin D, while UVA radiation destroys vitamin D. The reason for this is balance. It’s one of the body’s protective mechanisms to avoid overdosing on vitamin D when we’re outside.  So when we’re exposed to sunlight through our car, office window, or other barriers, we get UVA rays, but no beneficial UVBs.


Every year, when spring and summer roll around, people tend to stock up on sunscreen.  Stores around the nation are filled to the brim with sunscreen and we lather it on for protection.   While sunscreen does help protect against skin cancer, it also blocks out approximately 97% of UVB rays, and thus, our body’s ability to produce vitamin D from sunlight.


It is very difficult, if not impossible, to get all the Vitamin D we need from our diet alone, as there are only small amounts of vitamin D found in very few foods.

Age & Skin Color

Aging skin produces less vitamin D.   As an example, the average 65 year-old produces only 25% of the vitamin D that a 20 year-old does.   Skin color also makes a difference as people with darker skin produce less vitamin D.   The reason — it’s harder for the UVB rays to penetrate tan-to-dark skin.

Where Should I Get Vitamin D?

For most people, the best way to get adequate-to-optimal levels of vitamin D is through supplementation.   Unfortunately, most over-the-counter multivitamins and many stand-alone vitamin D products either have vitamin D levels that are too low (400 IU or lower), or the vitamin D is in a form that your body can’t absorb.   On this point, the main active form of vitamin D that can be absorbed by your body is vitamin D3 (cholecalciferol).   Many vitamins, and even prescription form vitamin D, contain vitamin D2, which is not biologically active.

Thus, taking the right type of vitamin D at the right levels is key.

Action Steps

You’re now aware of the risk of vitamin D deficiency and some of the challenges of getting vitamin D through sun and food alone.   So what’s the next best step?   The answer is supplementation.   Take at least 2,000 IU per day as vitamin D3.   You can take this as a stand-alone product or in a multivitamin.       You may want to consider a high quality multi vitamin as some studies suggest that people who are vitamin D deficient may also have other deficiencies that have not been diagnosed or discovered.

Of course, as always, you want to make sure that the supplements you’re taking are pharmaceutical grade. So, as you dream of the sun, warmer weather and getting back to outdoor activities, keep in mind Vitamin D and the role it plays on your health. Are you getting enough during these winter months? The benefits are easily accessible and there for the taking.   Now’s the time to take action and improve your health?


David’s passion for optimal health, wellness, and prevention started as a research analyst covering the industry. David specialized in nutritional supplements, pouring over clinical studies, touring manufacturing facilities, and immersing himself in the supplement and wellness industry on all levels. He developed a passion for the industry and educating people, and became driven to start Previnex. Previnex is a prevention-based health and wellness company committed to using science, clinically-tested ingredients and going above and beyond the testing and production standards required to bring to life nutritional supplements products of unparalleled quality, safety, and effectiveness.

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