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Do you really need Vitamin D?

It's estimated that 35% of adults are deficient in Vitamin D in the United States and almost 50% are at insufficient levels. Areas further away from the equator in the winter months are at significantly higher risks of lower levels. Vitamin D has a bunch of health benefits and although it is unclear if Vitamin D can help with Seasonal Affective Disorder, low levels have been found in people with S.A.D.

So do you actually need Vitamin D? Well let's learn a few things and I hope to teach you enough that you feel comfortable making that call for yourself!

Where Do We Get Vitamin D From?

  • Natural process in our body from sun exposure, supplements, some foods

Contrary to popular belief, we don’t actually “get” Vitamin D from the sun! If you just learned something, keep reading to learn why getting some extra D will be beneficial for you. So where does that belief that we “get” Vitamin D from the sun come from? 

We convert cholesterol in our body into 7-dehydrocholosterol… don’t worry there won’t be a vocab quiz at the end. The important thing to note is that when we are exposed to UVB radiation, like we get from the sun, that gets converted into Vitamin D3. When it is processed through the liver and kidneys, it becomes usable D3 in our body. The extra cool thing is that the UVB radiation also helps to break down excess levels of Vitamin D3 in our body.

photo credit: Precision Nutrition:

During the warmer weather months we can get more than enough UVB by spending 20-30 being outside. Wearing sunscreen and being behind regular glass will block out nearly all that valuable UVB radiation. So as cooler temperatures roll in, we not only get less direct exposure to the sun, the angle that the sun hits us makes the amount of Vitamin D we get naturally nearly non-existent. 

We can also get Vitamin D from supplementation, cod liver oil, mushrooms, liver and eggs, fortified milk and cereals.

Why do we need vitamin D?

  • Better Brain Function

  • Strong Bones and Teeth

  • Keep Muscle Strength and Mass

  • Decreased Risk of Cancer

  • Improved Immunity

  • Lower Blood Pressure

  • Reduce Risk of Developing Diabetes

Activated vitamin D is required to absorb dietary calcium that is essential in signaling between brain cells, and development of bones and teeth. Low levels of vitamin D in the body are associated with increased loss of muscle strength and mass, increased risk of cancers, lower levels of immunity, higher blood pressure, the development of neurological disorders, and development of diabetes. As we age, our ability to make vitamin D can be reduced by up to 75%... so it is especially important for aging populations. 

Before you run out to the store to slam bottles of vitamin D, remember this is a fat soluble vitamin, meaning it can be stored in our fat cells and having levels that are too high can be toxic to your system. 

So how do you tell how much is enough? 

  • ~800 IU daily or blood serum levels of 20-50 ng/mL.

Well without investing into vitamin D tests or frequent trips to your doctor, we don’t really know how much each individual needs. What we do know is that a recent study in Maine found that 800 IU per day was enough to reach adequate blood levels during the winter for most women.

Some expert recommendations for the general population can come up to 10,000IU per day! Other things to consider are your current level of body fat, physical activity levels, baseline vitamin D and calcium, use of oral contraceptives, race and ethnicity. So with such a big range, without getting direct blood work for you, it is safe to say that 1,000-2,000IU in a daily supplement or 20-30 minutes of mid-day sun from February - November in northern areas.  


So do you "need" Vitamin D? I'll let you make the call, but if you live in the north, for optimal health I would make a plan to get enough vitamin D this Fall and Winter! This can include frequent trips to areas below Georgia for sun exposure, eating a lot of cod liver oil, mushrooms, liver and eggs, fortified milk and cereals or just taking a supplement like this trusted one from Thorne labs ( 


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