An Overview of Vitamin Deficiency

Your body needs 13 essential vitamins that you can get from eating a variety of foods. Because these vitamins each have a different role in the body, vitamin deficiencies can have a number of health effects, depending on which vitamin (or vitamins) you are lacking.

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You can develop a deficiency due to low vitamin intake, and several medical conditions can predispose you to vitamin deficiency. Vitamin deficiencies can be detected with blood tests. And they can be corrected with oral (by mouth) or injected vitamin supplements.

The 13 essential vitamins are:

  • Vitamin A
  • Vitamin D
  • Vitamin E
  • Vitamin K
  • Vitamin C
  • Vitamin B1 thiamine
  • Vitamin B2 riboflavin
  • Vitamin B3 niacin
  • Vitamin B5 pantothenic acid
  • Vitamin B6 pyroxidine
  • Vitamin B7 biotin
  • Vitamin B9 folate
  • Vitamin B12 cobalamin


There are a number of different symptoms of vitamin deficiency. Usually, noticeable effects do not begin to develop until you have had several months of low vitamin levels.

Common symptoms of vitamin deficiency include:

  • Fatigue, low energy
  • Loss of bone density
  • Dry skin and hair
  • Depression
  • Irritability
  • Easy bruising or bleeding
  • Poor wound healing (sores that last for a long time)
  • Predisposition to infections
  • Skin color changes (usually small, flat, light patches on your skin)

Anemia, which is decreased red blood cell count and/or function, is a common consequence of vitamin B12 or folate deficiency. It can cause symptoms such as fatigue and irritability.


Prolonged vitamin deficiency can cause more serious health issues that may not improve, even with treatment.

Severe vitamin deficiencies can cause:

  • Decreased sensation of the hands and feet
  • Weakness of the toes and fingers
  • Vision loss
  • Memory loss
  • Behavioral changes
  • Shortness of breath
  • Tachycardia (a rapid heart rate)

Vitamin deficiency during pregnancy can be a serious problem, resulting in developmental problems that affect the growing baby. In fact, vitamin deficiency can have major effects during the first 10 weeks of pregnancy, when most mothers do not even know they are pregnant.

Rare Effects

There are a few symptoms that may be associated with vitamin deficiency, but they are not very common.

Rare effects of vitamin deficiency include:


Often, vitamin deficiency is related to your diet. Vitamins are complex molecules present in fruit, vegetables, grains, meat, poultry, and seafood. Each vitamin is found in more than one type of food, and some foods are fortified with vitamins. For example, milk naturally contains calcium (which is a mineral, not a vitamin) and it is fortified with vitamin D. Pasta, rice, and cereal are often fortified with a variety of vitamins.

In addition to dietary factors, medical conditions can affect your absorption of vitamins, even if your dietary vitamin intake is adequate.

Dietary Risk Factors

Some diets can make you prone to vitamin deficiency. Vitamin B12 is found in meats—a vegan or vegetarian diet can increase the risk of vitamin B12 and biotin deficiency. If you are dairy-free, then you may be at risk of becoming deficient in vitamin D.

A gluten-free diet is a diet low in grains, which are naturally rich in vitamins and are also often fortified with vitamins. So a gluten-free diet can make you deficient in many vitamins, including folate, and thiamine.

A diet that is high in processed foods and low in fresh fruits and vegetables can result in vitamin E and vitamin K deficiency.

It is absolutely possible to avoid vitamin deficiency if you are vegetarian, vegan or gluten-free. However, avoiding vitamin deficiencies when you are on a restrictive diet requires careful planning.


Vitamin D is found in foods such as seafood, eggs, and dairy products. But sunlight is also an important source of vitamin D. And lack of sun exposure can result in vitamin D deficiency. In geographic regions that have a cold climate, this is fairly common during the winter,

Medical Illness

A number of medical problems make it hard to properly absorb and metabolize vitamins. This can lead to vitamin deficiencies.

Common medical causes of vitamin deficiency include:

Pernicious anemia is a confusing term for most people. It is a type of autoimmune disease that affects the small intestine—decreasing absorption of vitamin B12—and ultimately leading to anemia.


Some vitamin deficiencies cause more than one symptom, and some symptoms (like sleepiness) can occur as a result of a few different vitamin deficiencies. Because symptoms do not always clearly correlate with the specific vitamin deficiency, diagnostic testing is the only way to confirm a vitamin deficiency.

The diagnosis of vitamin deficiencies can take some time. That is because it is not routine to test for vitamin levels. Your healthcare provider may consider testing if you have symptoms or if your physical examination identifies issues like bruises, wounds, skin discoloration, and neuropathy.

Neuropathy is a condition in which nerve function is impaired. It is associated with a lack of vitamin B12. It can cause you to have decreased sensation, diminished reflexes, and muscle weakness. Very early neuropathy might not cause these changes, but an electromyography (EMG) or nerve conduction study (NCV) can often detect early stages of neuropathy that have not yet caused signs or symptoms.

Blood Tests

Blood tests can show signs of vitamin deficiency and can be used to measure your vitamin levels. A complete blood count is the most common screening test. A low red blood cell count or a pattern of enlarged red blood cells (megaloblastic anemia) is a common sign of vitamin B12 deficiency.

In some instances, your vitamin levels may be measured with a blood test. Vitamins that can be measured with a blood test include folate (vitamin B9), vitamin D, and vitamin B12.

Interventional Tests

If there is a concern that you could have a digestive problem causing vitamin malabsorption, your healthcare provider may order a test to examine the internal appearance of your stomach or intestines.

An endoscopy is used to examine the appearance of your stomach and the upper portion of your small intestine using a camera that is inserted down your throat. A colonoscopy is used to examine the internal appearance of your large intestine using a camera that is inserted into the rectum.

These tests can be uncomfortable, so they are done with an anesthetic medication. Your healthcare provider can identify problems such as Crohn's disease and some types of malabsorptive syndromes with these interventional examinations.


Treatment for vitamin deficiency involves vitamin replacement. If a medical condition is the cause of your vitamin deficiency, then treatment of that condition is necessary as well.

Dietary Changes

In many instances, even if a medical condition is contributing to your vitamin deficiency, long term dietary changes can help correct and prevent the deficiency from worsening. You can learn which foods contain the vitamins you need so that you can pay attention to getting an adequate amount of these vitamins.

You may benefit from meeting with a dietitian, who can help you identify which foods you could consider including in your diet. You may also need help with creating a healthy meal plan.

Vitamin Replacement

There are several ways to make sure that you get adequate vitamins. Vitamin supplements can be an option. You may be given a recommendation for an over-the-counter (OTC) or prescription supplement. Sometimes when there is a problem with absorption, supplements such as vitamin B12 need to be injected instead of taken orally.

Medical Management

If you have a medical condition such as irritable bowel syndrome or inflammatory bowel disease, you will benefit from getting treated for that condition. There are a number of medical and surgical treatments for gastrointestinal conditions.

Some illnesses, such as liver failure, may not be treatable at late stages. Long term injected vitamin supplementation may be necessary.

A Word From Verywell

Vitamin deficiency can gradually worsen, causing vague symptoms. Nutrition is an important part of health. Paying attention to getting adequate nutrition helps prevent vitamin deficiency.

However, it is important to be careful with supplements. Most of the time, your body can get rid of excess vitamins. But excessive amounts can be harmful, and supplements can interfere with the intended actions of your medications and with your ability to absorb other nutrients in your food. Talk to your healthcare provider about the right supplements and doses for you—more is not necessarily better.

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11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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