Vitamin D deficiency: an overview and more


Vitamin D is often called the "sunshine vitamin" because your body makes it when your skin is exposed to the sun. Since vitamin D helps maintain bone strength, a deficiency can lead to softening of the bones and subsequent bone pain and fractures.

What does vitamin D have to do with multiple sclerosis?

While vitamin D deficiency is unfortunately very common, the good news is that this health condition can be diagnosed with a simple blood test and treated with supplements.

Symptoms of vitamin D deficiency

Most people with vitamin D deficiency have no symptoms. Only with a severe and prolonged deficiency do symptoms occur.

The main function of vitamin D is to absorb calcium and phosphorus from the intestines to build and maintain bone mass. With a vitamin D deficiency, this cannot happen correctly. If the deficiency is severe, softening of the bones may develop (a condition called osteomalacia in adults and rickets in children).

With osteomalacia and rickets, a person may experience pulsating bone discomfort, muscle weakness, and pain. Osteomalacia also increases the likelihood of bone fractures, falls, and trouble walking.

In addition to bone and muscle symptoms, fatigue and depression also related to vitamin D deficiency.


Because it needs sun exposure to produce vitamin D, populations most at risk for vitamin D deficiency include those who spend a lot of time indoors (such as the elderly and people who are not attached to the house) and those with dark skin (since they absorb less sunlight than lighter skin).

Other populations at risk for vitamin D deficiency include:

  • Those who do not consume enough vitamin D foods (such as canned tuna and fortified cow's milk)
  • Patients with conditions that affect the intestinal absorption of vitamin D (such as celiac disease and Crohn 's disease).
  • Patients with conditions that affect the metabolism of vitamin D to its active form (eg, chronic kidney disease or liver disease)
  • For those who are obese (excess adipose tissue hides vitamin D, rather than flushing it into the bloodstream)
  • Those who take medications that increase the breakdown of vitamin D (such as anticonvulsants )

Interesting associations

In addition to its primary role in calcium metabolism, vitamin D may play a role in reducing inflammation and weakening the body's immune function. This may be why studies have found a link between vitamin D deficiency and various autoimmune diseases such as multiple sclerosis , rheumatoid arthritis , and type 1 diabetes .

Heart disease and cancer are also linked to vitamin D deficiency. In fact, studies have shown that heart attacks are more common in winter. (when people go out less and therefore have lower levels of vitamin D) and that people tolerate cancer better in the summer months (when they have higher levels of vitamin D).


If you have one or more risk factors for vitamin D deficiency, for example if you are obese, have chronic kidney disease or intestinal malabsorption syndrome, your healthcare provider should test you for vitamin D deficiency.

Certain symptoms can also prompt your healthcare provider to test for vitamin D deficiency, such as more frequent falls, especially if you are older.

However, screening for vitamin D deficiency in asymptomatic people is not currently recommended.

A simple blood test called 25-hydroxyvitamin D or 25 (OH) D can be used to diagnose vitamin D deficiency.

While there is no definitive consensus on normal and healthy levels of vitamin D, the Institute of Medicine (IOM) defines it as follows:

  • Normal : 25 (OH) D level greater than 20 ng / ml
  • Insufficient: 25 (OH) D level 12 to 20 ng / ml
  • Deficiency : 25 (OH) D level less than 12 ng / ml

Watch out

Treatment of a vitamin D deficiency depends on several factors, such as the severity of the deficiency and the presence of certain underlying health problems.

However, in the vast majority of cases, vitamin D deficiency is treated with supplements.


There are two main forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), the latter of which is used in most supplements.

There is currently no standard treatment for vitamin D deficiency. However, a typical plan might include 50,000 international units (IU) of vitamin D2 or D3 by mouth once a week for eight weeks or 6,000 IU daily followed by a maintenance dose. 1,500 to 2,000 IU of vitamin D3 per day.

Note that higher doses will be needed to treat people with medical conditions that affect the absorption of vitamin D from the intestines and those who take medications that affect vitamin D metabolism.

Vitamin D toxicity

Too much vitamin D can cause symptoms associated with high blood calcium levels, such as muscle weakness, pain, heart arrhythmias, and kidney stones. That's why it's important to take vitamin D supplements only as directed by your healthcare professional.


The diet is a supplemental, albeit unreliable, source of vitamin D and is therefore generally not recommended for treating a deficiency. However, it can be beneficial in maintaining healthy vitamin D levels.

Foods that contain vitamin D include:

  • Fatty fish (such as salmon and swordfish)
  • cod liver oil
  • Walnuts
  • Grains and dairy products fortified with vitamin D
  • Cheese
  • Eggs
  • Mushrooms
  • Cow liver


Sunlight is a third source of vitamin D. Like diet, it is generally not recommended for treating vitamin D deficiency. This has been linked to an increased risk of skin cancer associated with sun exposure.


Although the amount of vitamin D a person needs varies depending on factors such as skin color and sun exposure, general IOM guidelines are that people between the ages of 1 and 70 should take a supplement that contains 600 IU of vitamin D up to date. After age 70, a person should take 800 IU of vitamin D per day.

These preventive vitamin D recommendations are for the general population, not for people diagnosed with vitamin D deficiency. People with vitamin D deficiency require therapeutic doses of vitamin D.

In addition to or instead of taking supplements, your healthcare provider may recommend that you eat or drink foods that contain vitamin D and / or get some sunlight (but not too much).

Get the word of drug information

Treating a vitamin D deficiency is important for maintaining strong bones and can improve the health of other systems and tissues in your body, such as the immune system and the heart.

However, before making any major changes, first talk with your doctor to decide which treatment plan is best for you.

Related Articles
Foods to Avoid If You Have Dry Mouth From Radiation

Dry mouth (xerostomia) is a common side effect of radiation therapy for people undergoing treatment for head and neck cancer. Read more

Thyroid adenoma: Causes, Treatment, and Diagnosis

The thyroid is a small, butterfly-shaped gland in the front of your throat that produces hormones affecting a number of Read more

NSAIDs and You Thyroid Function

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most frequently taken over-the-counter medications. Due to their systemic or whole body effects, it's Read more

How Doctors Are Failing Thyroid Disease Patients

The thyroid disease community has continually mentioned the lack of support they experience and the difficulty they have navigating the Read more