What to Know About Vitamin Deficiencies: Symptoms, Signs, and Causes

Medically Reviewed By Adam Bernstein, MD, ScD
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Vitamin deficiencies result from lacking any of the 13 essential vitamins that your body needs in small amounts to work optimally. Depending on which vitamin you are lacking, you may notice symptoms. By eating a balanced diet that contains a variety of foods, you can ensure that you are getting the vitamins you need to remain healthy.

This article explains what vitamin deficiencies are and why vitamins are vital for optimal health. It also details the signs of vitamin deficiencies to look out for and what can cause them.

What is a vitamin deficiency?

there is a selection of fruits and vegetables on a white table
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Vitamins are substances that are essential to our overall functioning, health, and wellness.

The 13 essential vitamins are:

  • vitamin A
  • vitamin C
  • vitamin D
  • vitamin E
  • vitamin K
  • thiamine
  • riboflavin
  • niacin
  • pantothenic acid
  • biotin
  • B6
  • B12
  • folate

Sometimes, our levels of certain vitamins may drop, and we may develop a vitamin deficiency. Causes of vitamin deficiencies may include:

  • having certain medical conditions that mean you cannot absorb some vitamins as easily
  • having bariatric or weight loss surgery
  • being unable to eat particular foods

According to the World Health Organization (WHO), deficiencies in iron, vitamin A, and iodine are the most common worldwide.

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What are signs and symptoms of a vitamin deficiency?

Different vitamins have different functions. These include:

  • helping your body to fight infections
  • maintaining nerve health
  • enabling the body to produce blood clots
  • helping the body produce enzymes, hormones, and other proteins that your body needs to function well
  • contributing to your energy levels and mental function

Symptoms and signs of a vitamin deficiency depend on which vitamins you are lacking. For example, vitamin D deficiency may lead to bone pain. Vitamin A deficiency may lead to weak vision in dim light.

Depending on the vitamin deficiency, signs and symptoms may include:

  • developing certain medical conditions, such as scurvy or anemia
  • developing vision problems
  • developing issues with bone health
  • developing issues with brain, blood, and nerve health

What causes a vitamin deficiency?

Your level of certain vitamins may fall for different reasons. These include:

  • Changes in diet: A diet low in fruit, vegetables, meat, fish, dairy products, and fortified foods may lead to vitamin deficiencies.
  • Having excess weight: Research from 2017 shows that excess fat tissue may lead to changes in body function and vitamin deficiency.
  • Weight loss surgery: This surgery may reduce the size of your stomach or bypass part of your small intestine. This may limit your body’s ability to absorb sufficient quantities of certain vitamins.
  • Kidney or liver failure: This may prevent your body from adequately processing vitamin D.
  • Intestinal conditions: Cystic fibrosis, Crohn’s disease, and celiac disease cause inflammation of the intestines. This can prevent your intestines from absorbing enough vitamin D.
  • Stomach conditions: Pernicious anemia is an autoimmune condition that affects your stomach and makes it difficult for your body to absorb vitamin B12.

What are complications of a vitamin deficiency?

Depending on which of the 13 essential vitamins you are missing, you may experience a range of complications.

Vitamin A deficiency

A deficiency in vitamin A may result in the following complications:

Vitamin A deficiency is rare in developed countries, but it is common during pregnancy in developing countries.

Vitamin C deficiency

A deficiency in vitamin C may result in the following complications:

  • developing scurvy, a potentially fatal condition resulting in loss of teeth, depression, anemia, and subcutaneous bleeding
  • easy bruising
  • poor wound healing

Vitamin D deficiency

A deficiency in vitamin D may result in the following complications:

Your skin produces vitamin D when you are in the sunlight. Without exposure to sunlight, you may develop a vitamin D deficiency.

Vitamin E deficiency

A deficiency in vitamin E may result in the following complications:

  • nerve complications
  • muscle damage
  • loss of body movement control
  • weak immune system
  • vision problems

Vitamin E deficiency is rare.

Vitamin K deficiency

A deficiency in vitamin K may result in the following complications:

  • osteoporosis
  • poor bone development
  • an increase in the risk of cardiovascular disease
  • bleeding disorders

Vitamin K deficiency is rare in adults.

Vitamin B deficiency

The B vitamins include thiamine, riboflavin, niacin, pantothenic acid, biotin, B6, folate, and B12. Complications or deficiencies may include:

  • B1 or thiamine: memory loss, irritability, disturbed sleep, and abnormal motor function
  • B2 or riboflavin: fatigue and brain dysfunction
  • B3 niacin: depression, anxiety, memory loss, paranoia, psychotic symptoms, and aggression
  • B5 or pantothenic acid: behavioral changes
  • B6 or pyridoxine: irritability, depression, cognitive decline, and dementia
  • B9 or folate: cognitive decline, psychosis, Alzheimer’s disease, and vascular dementia
  • B7 or biotin: depression, lethargy, hallucinations, and seizures
  • B12 or cobalamin: cognitive decline, Alzheimer’s disease, and vascular dementia

Most vitamin B deficiencies are rare in developed countries. However, the main source of B12 is in meat and dairy products, so vegans are at risk for B12 deficiency.

When should you contact a doctor?

Many signs and symptoms above can point to a deficiency in essential vitamins. Contact your doctor for further dietary information and advice.

How can you prevent a vitamin deficiency?

Over-the-counter supplements may help treat or prevent a vitamin deficiency, but eating a balanced diet is your best option. Before taking supplements to prevent or treat a deficiency, consult with your doctor or dietitian.

A balanced diet includes:

  • whole grains
  • legumes, nuts, seeds
  • fresh fruit and vegetables
  • seafood, lean meats, and poultry or vegan and vegetarian alternatives such as tofu and tempeh
  • eggs
  • minimum amounts of sugar, sodium, saturated fats, and trans fats

Try to include fruits and vegetables of different colors. By eating a variety of colors, you can get an array of vitamins, minerals, and phytochemicals.

Read more about the benefits of eating fruits and vegetables.


Your body needs small amounts of different vitamins to function optimally. Symptoms of a vitamin deficiency vary according to the vitamin you may be lacking.

Eating a balanced diet that contains a variety of foods is the best way to prevent a vitamin deficiency. Most individuals can get all of the necessary vitamins and minerals through eating nutrient-dense foods. 

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Medical Reviewer: Adam Bernstein, MD, ScD
Last Review Date: 2022 Nov 8
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.