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Why Some People Benefit from Vitamin D More Than Others


Vitamin D— the sunshine nutrient! 

Over the last few years, we’ve heard the buzz. Vitamin D is a very important nutrient that our body needs for proper function. However, did you know that most of us don’t have enough vitamin D in our bodies?

It’s true. Studies have shown that roughly 42% of American adults are not getting enough vitamin D. Are you one of those adults? And how can you be sure your cells are actually absorbing enough vitamin D even if you are getting enough? 

It’s a trick question, because most people typically get more than enough vitamin D, but their body isn’t absorbing it.

So, why is this important?

For one excellent reason: vitamin D helps the body run the way it should. If you’re not getting enough, or your body isn’t absorbing the vitamin D you are getting, there could be long term health repercussions. 

Here’s how vitamin D affects your body — and how to get more if you need it.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin produced inside the body. One of its primary roles is to promote absorption of different minerals, such as calcium and magnesium. It is an essential vitamin and supports the body by:


  • Supporting the immune system
  • Modulating the inflammation system
  • Producing adequate hormones
  • Modulating cell growth
  • Boosting mood
  • Building strong bones
  • Reducing muscle aches
Most importantly, vitamin D supports healthy genetic functioning, which results in overall improved health.

The Largest Indicators of Low Vitamin D

Most of the time, people don’t even know they’re vitamin D deficient. However, when adults are not producing, consuming, or absorbing enough vitamin D, their health will likely suffer.

For adults, the largest indicators of low vitamin D include:

  • Fatigue
  • Bone pain
  • Muscle weakness, aches, and cramps
  • Mood changes, including seasonal affective disorder (SAD)
  • Frequent colds
How Vitamin D Is Absorbed in the Body?

The good news! Our skin already has the ability to generate vitamin D in the body. However, this process is activated by the sun’s rays. When our skin is exposed to sunlight, our body is able to take what it needs from the sun and convert it into vitamin D.

This occurs because the sun’s energy turns into a chemical, 7-dehydrocholesterol, when the UVB rays are absorbed by our skin, the largest organ of our body. This chemical is carried to our liver, where it picks up extra oxygen and hydrogen molecules. It then becomes 25-OH (25-hydroxyvitamin D).

When the 25-OH chemical moves to the kidneys, it receives a final pair of oxygen and hydrogen molecules converting it to the active form of vitamin D used by the body: 1,25-dihydroxyvitamin D.

While this is quite a process in itself, even more complex is the genetic component we have that affects how well we absorb vitamin D. Lack of absorption is one of the most common causes of vitamin D deficiency. 

What Prevents Vitamin D Absorption Genetically?

Genetics, specifically the VDR gene, play a major role in how well the body absorbs vitamin D.

The VDR gene provides instructions for making a protein called the vitamin D receptor. This receptor allows the body to respond to vitamin D. Some variants in this VDR gene keep you from having the proper response to vitamin D, which affects how well you can convert and absorb it. Studies have shown that the VDR gene increases serum vitamin D levels by 65% when properly supplemented.

When the VDR gene is working, the vitamin D in your body can do its job: help your body absorb calcium and magnesium so it can operate at its best. But when genetics contain variations in the VDR gene, there are obstacles that will prevent your body from utilizing the vitamin D it is receiving effectively. 

What Prevents Vitamin D Absorption Beyond Genetics?

Genetics is not the only factor that impacts how much (or little) vitamin D people absorb. Lifestyle impacts our vitamin D levels as well.

Sun exposure (in moderation) changes dramatically based on geographic location, season, and sunscreen usage. Geographic location plays a major role. For example, people in Alaska have a higher rate of vitamin D deficiency than people living in Florida. In fact, people who live above 37 degrees latitude north or below 37 degrees latitude south can’t rely on the sun alone to get the vitamin D they need.

People who spend most of their time indoors or avoid sunshine may also lack vitamin D derived from the sun. Even excess sunscreen usage can prevent vitamin D from being absorbed into the body.

Those who realize their vitamin D levels are low may opt for supplements. But even supplement choice needs to be intentional. Genetically, we don’t absorb nutrients in the same way. For this reason, if you’re not taking the correct form of vitamin D, your body may not be absorbing and/or using it effectively. You need to choose a form of vitamin D your body can actually use according to your genetics.

How Much Vitamin D Should You Take?

That is a complicated question with a range of answers. Simply put, it all comes down to you and will depend upon a few factors.

In fact, at least three factors contribute to determining how much vitamin D you need and how you should supplement it. These are:

1. Current Levels of 25-OH

Book a physical with a blood panel! 25-OH is a simple blood test that monitors the levels of vitamin D in your blood. This is an important factor in determining how much vitamin D is in your body and how well it is being absorbed. Speak with your healthcare provider for a 25-OH bloodwork test to determine your vitamin D. 

2. Genetic Contributions

Genetics can contribute to vitamin D absorption! In fact, there is a gene known as VDR gene that will affect the ability of your body to absorb vitamin D when there are variants in this gene. Knowing your genetics will support an understanding of how to effectively absorb vitamin D. 

3. Lifestyle Factors

Geographic location, lifestyle, and diet contribute to how much vitamin D supplements your body will need — and the form you need it in.

The generic, recommended daily allowance is not enough. You need to both understand the variables that are unique to you, your habits and your geographic area and speak to a medical professional to determine the best vitamin D supplements that will meet all your needs. 

Remember, don't overdo it! Vitamin D is fat-soluble, so it can build up in the body if you take too much, which can lead to some complications.

Your Best Form of Vitamin D for Absorption

If you suspect that you have low vitamin D or have been wondering what causes vitamin D deficiency, it may be time for a genetic analysis or visit with your doctor. When you know how your individual body is processing vitamin D, you’ll be able to determine the best form of vitamin D for absorption and supporting your body function as well as it should.

Once you consider how your current levels of vitamin D are affected by both your genetics and lifestyle factors, you’ll be able to discuss the best supplemental form of vitamin D for absorption with your doctor. In addition, your physician may prescribe supplements to aid in absorption of vitamin D.

But what can you do for your vitamin D and your wellbeing? 

One of the best ways to impact your vitamin D absorption is to get it naturally. Spend 10 minutes per day in adequate and safe sun exposure (without sunscreen) to help your body naturally produce vitamin D. 10 minutes! 

That’s all you need for your daily sunshine vitamin D. More than that, you are not absorbing any more vitamin D and can open yourself up to the risks of sun exposure, such as getting a sunburn. 

Vitamin D is an important nutrient for our body and while it is not something we think about, spending a few minutes a day to ensure you are absorbing enough is an important step in your journey toward health.