Vitamin D is one of the most basic needs our bodies have, yet the common tech-driven lifestyles of the 21st century make deficiencies more common than before.

According to, some of the most common situations that can lead to a Vitamin D deficiency include:

  • Not spending enough time outdoors in the sunlight
  • Being overweight
  • Having a darker complexion
  • Being over 50
  • Not consuming enough fish or milk

The point about skin complexion has to do with the skin’s ability to absorb Vitamin D from sunlight. Dr. Mark Hyman recommends spending 1/4 the time it takes to turn skin red (sunburn) outside in sunlight for optimum Vitamin D absorption. Darker complexions require more sunlight for this to happen.

How Can I Tell If I Have A Vitamin D Deficiency?

Boiler plate disclaimer: always check with your doctor if you’re experiencing serious symptoms. Sites like this are not a substitute for actual medical care.

That said, some common symptoms of not having enough Vitamin D in your body are:

Frequent Illness. Most people associate Vitamin C with immune system strength and fighting off colds. However, studies have shown that Vitamin D helps autoimmune function as well as staving off infection. Nutritionists I’ve spoken to personally second this.

Dr. Jeff Blair, nutritionist, states “I’ve found Vitamin D is at least as important as C for keeping your immune system healthy.”

Frequent fatigue. Some degree of occasional fatigue is normal. However, if you’ve noticed that you feel tired or worn out on a regular basis and aren’t sure why, a lack of Vitamin D may be responsible. Much like the above point, most people associate B vitamins with energy. However, research has continued to show that D plays an important role in energy as well.

Ongoing muscular and skeletal pain. This is reinforced in many notable health websites, including Dr. Mercola’s blog. If you’re noticing aches and pains you didn’t have before, and they’re persisting for a period of time with no other apparent cause (such as injury or overuse of muscles), it’s possible that it’s caused by a Vitamin D deficiency.

Depression. As Dr. Hyman points out, Vitamin D is actually a hormone. Given that depression often has a great deal to do with hormonal imbalances, it makes sense that too little D in the bloodstream can affect emotional stability. Anecdotally as someone who has dealt with chronic depression, I can say that Vitamin D supplementation along with other lifestyle changes has lessened the frequency and severity of depressive feelings.

Notably, Dr. Mercola also references studies in which low levels of prenatal Vitamin D can cause birth defects and even increase the likelihood of schizophrenia (source).

Further, Mercola says that incidences of cancer are more prevalent in people with Vitamin D levels lower than 40ng/mL. When levels go above 40ng/mL, such as 60-80ng/mL which is considered healthy, incidences of cancer drop 67% (compared to levels of 20ng/mL).

A Study Published To The Contrary About Vitamin D

A recent headline published is largely about how a government study showed that the hype around Vitamin D was baseless and did not bear out in trials.

However, if you read the article you’ll see that the criticism is that fish oil and Vitamin D did not meaningfully reduce incidences of heart disease in study groups.

While that may be a significant finding for fish oil, grading Vitamin D’s effectiveness based on its inability to prevent heart disease is pretty misleading.

To my knowledge, Vitamin D has never been marketed to prevent heart disease. A study that seemingly only tested it in terms of heart disease therefore proves nothing in terms of Vitamin D’s main purported benefits.

It’s not clear if the author of that article was simply clickbaiting with a misleading frame of the study, but given that an article on NPR was so easily dispelled it bears mention.

Tips For Improved Vitamin D Absorption

Most doctors and nutritionists agree that whenever possible, getting your vitamins and nutrients from food is preferable. This is because it’s easier for your body to actually absorb the nutrients from within food.

If you do take Vitamin D supplements, there are a few things to bear in mind to ensure your body absorbs a good portion of what you’re taking.

  • Always take a Vitamin D supplement with food. It’s fat soluble, meaning it absorbs best when in the presence of fats. If you take Vitamin D without food and on an empty stomach, it’s likely that much of the D contained in the pill will not be absorbed.
  • Vitamin D is available as a liquid in dropper form. This form also tends to absorb more readily into the body.
  • When in doubt, stick with a 2000-3000iu dosage for supplementation. Otherwise, consult your doctor to have your blood levels tested so he or she can determine the strength of supplementation best for you.

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