What is Vitamin D Deficiency Symptoms?

Known as the “sunshine vitamin”, vitamin D is one of the most important, yet often overlooked, nutrients in human health. It acts more like a powerful hormone in our body rather than just a vitamin. Getting enough vitamin D is crucial for keeping bones, teeth and muscles healthy. It also plays a vital role in modulating immune function, cell growth, neuromuscular functioning and reducing inflammation.

Vitamin D Deficiency Symptoms

Vitamin D deficiency has reached epidemic proportions worldwide, with an estimated 1 billion people deficient globally. According to a large-scale study, 41.6% of American adults are deficient in this critical vitamin. But because symptoms are usually subtle, many people do not realize they have a deficiency until it progresses to the point of triggering serious illness.

This in-depth guide will cover the major causes, risk factors and reveal the most common signs and symptoms of vitamin D deficiency. Recognizing these cues early on can help prevent long-term health consequences down the road.

What Causes Vitamin D Deficiency?

Vitamin D deficiency occurs when our bodies do not have enough of this nutrient in circulation to carry out vital functions. There are three main causes behind insufficient vitamin D levels:

  • Inadequate sun exposure
  • Inadequate dietary intake
  • Malabsorption issues

Our bodies produce vitamin D when our skin is directly exposed to sunlight. Ultraviolet B (UVB) rays from the sun trigger vitamin D synthesis. But due to widespread sun avoidance and overuse of sunscreen, rates of deficiency are skyrocketing. Higher latitudes also receive less intense sunlight which reduces vitamin D production capabilities.

Very few foods naturally contain or are fortified with vitamin D. Key food sources include:

  • Fatty fish like salmon, tuna and mackerel
  • Fortified milk, yogurt, orange juice and cereals
  • Beef liver
  • Egg yolks
  • Mushrooms

Those following restrictive diets are also at a much higher risk of deficiency.

Certain health conditions like celiac disease, Crohn’s disease, cystic fibrosis and gastric bypass surgery can impair vitamin D absorption. Deficiency is also commonly seen in those with liver or kidney disorders.

Am I At Risk for Vitamin D Deficiency?

Here is a table outlining key risk factors that make certain groups more likely to develop a vitamin D deficiency:

Risk Factor Explanation
Older Adults Ability to synthesize vitamin D from sunlight declines with age
Indoor Occupations Office workers, night shift workers get less sun exposure
Darker Skin Tones Increased melanin reduces vitamin D production from sunlight
Obesity Vitamin D gets trapped in fat cells
Exclusively Breastfed Babies Breastmilk low in vitamin D
Digestive Disorders Conditions impacting nutrient absorption
Certain Medications Glucocorticoids, anticonvulsants, others interfere with vitamin D metabolism

Some key groups face a higher risk, but deficiency can happen at any age. Testing vitamin D levels and addressing any deficiencies is important for long-term health. Let me know if you need any other details!

Many of these factors can compound together to severely reduce vitamin D levels. For example, an elderly, dark-skinned, obese individual working an office job would be at very high risk.

Recognizing Vitamin D Deficiency Signs and Symptoms

In the early stages of deficiency, symptoms tend to be subtle which makes it easy to miss. Without an active vitamin D test, millions suffer from a deficiency without realizing it for months or even years.

Here are some of the most common signs and symptoms signaling low vitamin D levels:

Physical Symptoms

  • Bone and back pain
  • Muscle pain or weakness
  • Frequent sickness/infections
  • Fatigue and low energy
  • Bone loss and fractures
  • Impaired wound healing
  • Hair loss
  • Muscle cramps

Mood-Related Symptoms

  • Depression
  • Irritability and mood swings
  • Impaired brain function
  • Lethargy and lack of motivation

Long-Term Dangers Left untreated over longer time periods, vitamin D deficiency poses some major health risks:

  • Osteoporosis – bone loss and fractures
  • Cancer – increased risk of many types
  • Autoimmune disorders
  • Heart disease
  • Diabetes
  • Hypertension
  • Multiple sclerosis
  • Dementia

Testing and Treatment Options

Getting tested is critical to catch a deficiency early before complications set in. A simple blood test called the 25(OH)D test measures vitamin D levels.

Optimal values fall between 50–80 ng/ml while deficiency is defined as anything under 30 ng/ml. Borderline deficiency occurs in the range of 30-50 ng/ml. Testing allows tailoring of proper dosage and forms of supplementation.

To treat deficiency, the most common route is taking oral vitamin D3 supplements. Dosage guidelines to correct deficiency are:

  • Mild deficiency – 1,000−2,000 IU/day
  • Moderate deficiency – 5,000 IU/day
  • Severe deficiency – 10,000+ IU/day

Always consult your physician before self-prescribing. In more severe cases, a high-dose prescription formula may be needed requiring closer medical oversight.


Vitamin D deficiency has reached epidemic scales yet often goes undetected for too long. Knowing the major causes along with recognizable physical and mental signs are key to catch this “silent epidemic”. Getting blood testing is critical for confirmation and allows proper treatment dosing before health consequences occur. With the right testing and supplementation regimen guided by your doctor, reversing deficiency is absolutely within reach.


Here are answers to some frequently asked questions about vitamin D deficiency:

What are the first signs of vitamin D deficiency?

Some early signs include frequent sickness and infections, tiredness and fatigue, bone and muscle pain, mood changes like depression, and slower wound healing.

What does vitamin D deficiency cause?

Deficiency contributes to a range of serious illnesses like osteoporosis, heart disease, diabetes, autoimmunity, multiple sclerosis and even certain cancers. It also causes bone pain, muscle weakness, impaired immunity and mood changes.

How can you tell if your vitamin D is low?

The only way to confirm deficiency is through a blood test measuring 25(OH)D levels. Anything below 30ng/ml indicates deficiency. Ideal values fall between 50-80ng/ml.

Can low vitamin D cause weight gain?

Emerging research shows vitamin D helps regulate fat accumulation and distribution. Deficiency alters metabolism which leads to increased fat mass and obesity.

Can vitamin D deficiency cause hair loss?

Yes, deficiency contributes to a type of hair loss called telogen effluvium. Vitamin D helps regulate hair follicle cycling. Low levels interrupt the cycle causing shedding.

How do you treat low vitamin D?

Treating deficiency involves oral vitamin D3 supplementation along with sensitively increasing sun exposure. Dosage depends on severity level which requires testing to determine. Moderate to severe cases may need prescription formulas.


My name is Selina, a medical specialist blogger helping people access treatment for 5+ years. Although blogging awhile, only recently deeply engaged. This past year my most productive, providing hospital reviews and info on symptoms, diagnoses and diseases. Also offer guidelines to help readers navigate healthcare. Goal to continue increased content pace to assist many. Aim to facilitate treatment and empower advocacy through writing.

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