An Overview of Vitamin Deficiency

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Vitamin deficiency can cause a range of symptoms such as fatigue, irritability, and changes to your skin and hair. The specific symptoms depend on which vitamin(s) are at low levels, as each one plays a different role in your body.

For example, a vitamin D deficiency can lead to weak bones and fractures, while a folate deficiency can lead to anemia, which causes fatigue and weakness.

You can develop a deficiency due to low vitamin intake or certain medical conditions. They're usually treated with vitamin supplements in either oral (by mouth) or injected forms.

This article covers the symptoms and complications common to vitamin deficiencies, the causes and risk factors, and how vitamin deficiencies are diagnosed and treated.

A man who can not fall asleep
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Vitamins You Might Be Lacking

Your body produces many of the vitamins it needs. But your health depends on 13 vitamins that your body can't make, so you need to get them through diet or supplements.

These 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)

Symptoms of Vitamin Deficiency

Vitamin deficiency can cause a number of symptoms, including fatigue, dry skin and hair, depression, poor wound healing, and more. While they can vary between deficiencies, many of them overlap.

Usually, noticeable effects don't begin to develop until you've had low levels for several months.

Fatigue and Weakness

If you feel sleepy or sluggish all the time, you may be deficient in vitamin D, any of the B vitamins, and/or vitamin C.

Vitamin D helps with bone and muscle strength, so when you don't have enough, you may feel weak and lack energy. Some research suggests that vitamin D deficiency is linked to fatigue and that taking vitamin D supplements can improve this symptom.

Vitamin C and all B vitamins except folate (B9) are involved in producing energy in your cells, so being deficient in any of them can leave you feeling wiped out. It can also have a major impact on your metabolism and overall health.

Folate deficiency can lead to fatigue and weakness by causing anemia. In that condition, your body doesn't have enough red blood cells, which carry oxygen to your tissues. That oxygen is essential for proper function and energy.

Dry Skin and Hair

Dry skin and hair are common symptoms of deficiencies in:

  • Vitamin A
  • B vitamins
  • Vitamin C
  • Vitamin D

Some of these vitamins are commonly used in skincare and haircare products. Ask your healthcare provider whether dietary sources, supplements, or topical (on the skin) use is best for improving skin and hair health.

Use caution with vitamin A (retinol) products, however. High levels can actually harm your skin.


Vitamin deficiencies can sometimes be associated with clinical depression. They include:

  • Vitamins B1, 3, 6, 9, 12
  • Vitamin C
  • Vitamin D

Supplements may help alleviate depression, but they're not a replacement for antidepressants. Don't stop taking your medication or add supplements to your regimen without first talking to your healthcare provider.

Easy Bruising or Bleeding

Easy bruising and bleeding can happen due to problems with blood clotting, poor healing, or collagen formation. (Collagen gives strength to the walls of blood vessels.)

Essential vitamin deficiencies that can contribute to easy bruising or bleeding are:

  • Vitamin C
  • Vitamin K, especially in newborn babies

Deficiencies of these vitamins are fairly uncommon, however. If you start bruising or bleeding easily, don't just assume a deficiency is causing it.

Poor Wound Healing

Poor wound healing means that your sores take especially long to heal. A lot of essential vitamins contribute to the healing process. Some aid in collagen creation, others help with re-building different types of cells or tissues, and others promote cellular health through antioxidant activity.

Vitamin deficiencies that can contribute to poor wound healing include:

  • Vitamin A
  • B vitamins
  • Vitamin C
  • Vitamin D (when combined with zinc and arginine)
  • Vitamin K

Drawbacks of Vitamin E

Vitamin E (a non-essential nutrient) might have a negative impact on wound healing. It can hamper collagen synthesis and antioxidant activity and may worsen inflammation. Research also suggests it may counter the benefits of vitamin A that's taken to help with wound healing.

Predisposition to Infections

Some vitamin deficiencies affect your immune system and can make you more likely to get infections and infectious diseases. These include:

  • Vitamin A
  • Vitamin C
  • Vitamin D

A vitamin A deficiency is particularly dangerous when it comes to infection risk. It can predispose you to:

  • Diarrhea
  • Malaria
  • Measles
  • Respiratory disease
  • Chronic ear infections

Bone Fractures

Essential vitamins that keep your bones strong and healthy include vitamins A, B6, B9, B12, C, D, and K.

While research shows deficiencies in any of these vitamins can lower your bone density and lead to fractures, it's not clear whether nutritional supplements lower the fracture risk.

Talk to your healthcare provider about the best ways to protect your bone health.

While enough of Vitamins A, B6, and B12 is important for strong bones, too much may actually lower your bone density and increase your risk of breaking bones, according to research.

Skin Color Changes

Skin color changes due to vitamin deficiency can manifest in a few different ways: loss of pigmentation in spots, darker pigmentation in spots, or generally pale skin.

Loss of pigmentation and light-colored spots may result from deficiencies in:

  • Vitamin D (in light-skinned people)

Darker pigmentation can be due to:

  • Vitamin B12
  • Vitamin D (in dark-skinned people)

Deficiencies that can cause generally pale skin include:

  • Vitamin C
  • Vitamin B6, 9, 12

Complications of Vitamin Deficiency

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 people do not even know they are pregnant.

Rare Effects

A few uncommon symptoms may be associated with vitamin deficiency, including:

Causes of Vitamin Deficiency

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, this does require careful planning. Advice from a registered dietitian can help guide you.


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:

What Is Pernicious Anemia?

Pernicious anemia is a type of autoimmune disease that affects the small intestine, decreasing absorption of vitamin B12. This results in an insufficient amount of healthy red blood cells.

Diagnosis of Vitamin Deficiency

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 of Vitamin Deficiency

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.

Nutritional supplements aren't safe for everyone. They may have side effects, negative effects on medical conditions, dangerous interactions with medications, or unwanted effects during pregnancy or breastfeeding. Always talk to your healthcare provider about a supplement before you start taking it.

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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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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Additional Reading

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.