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What are nutritional deficiencies?

The body requires many different vitamins and minerals that are crucial for both body development and preventing disease. These vitamins and minerals are often referred to as micronutrients. They aren’t produced naturally in the body, so you have to get them from your diet.

A nutritional deficiency occurs when the body doesn’t absorb or get from food the necessary amount of a nutrient. Deficiencies can lead to a variety of health problems. These can include digestion problems, skin disorders, stunted or defective bone growth, and even dementia.

The amount of each nutrient you should consume depends on your age. In the United States, many foods that you buy in the grocery store — such as cereals, bread, and milk — are fortified with nutrients that are needed to prevent nutritional deficiency.

But sometimes your body is unable to absorb certain nutrients even if you’re consuming them. It’s possible to be deficient in any of the nutrients your body needs.

Keep reading to learn about some common nutritional deficiencies and how to avoid them.

The most widespread nutritional deficiency worldwide is iron deficiency. Iron deficiency can lead to anemia. This is a blood disorder that causes fatigue, weakness, and a variety of other symptoms.

Iron is found in foods such as dark leafy greens, red meat, and egg yolks. It helps your body make red blood cells. When you’re iron-deficient, your body produces fewer red blood cells. The red blood cells it produces are smaller and paler than healthy blood cells. They’re also less efficient at delivering oxygen to your tissues and organs.

According to the World Health Organization (WHO), over 30 percent of the world’s population is anemic. Many of these people are anemic due to iron deficiency.

In fact, it’s the only nutritional deficiency that’s prevalent in both developing and industrialized countries. Iron deficiency anemia affects so many people that it’s now widely recognized as a public health epidemic.

Vitamin A is a group of nutrients crucial for eye health and functioning and reproductive health in men and women. It also plays a part in strengthening the immune system against infections.

According to WHO, a lack of vitamin A is the leading cause of preventable blindness in children. Pregnant women deficient in vitamin A have higher maternal mortality rates as well.

Beta carotene is a nutrient that functions as an antioxidant. It’s found in red, orange, yellow, and dark green produce. Beta carotene can be converted to vitamin A in the body when needed.

For newborn babies, the best source of vitamin A is breast milk. For everyone else, it’s important to eat plenty of foods high in vitamin A. These include:

Another common nutritional deficiency occurs with thiamine, also known as vitamin B-1. Thiamine is an important part of your nervous system. It also helps your body turn carbohydrates into energy as part of your metabolism.

A lack of thiamine can result in:

Thiamine deficiency can also lead to nerve and muscle damage and can affect the heart.

In the United States, thiamine deficiency is most often seen in people with excessive alcohol use. Alcohol reduces the body’s ability to absorb thiamine, store thiamine in the liver, and convert thiamine to a usable form. Thiamine deficiency is a common cause of Wernicke-Korsakoff syndrome. This is a form of dementia.

Many breakfast cereals and grain products in the United States are fortified with thiamine. Other good sources of thiamine include:

  • eggs
  • legumes
  • nuts
  • seeds
  • wheat germ
  • pork

Niacin is another mineral that helps the body convert food into energy. It’s also known as vitamin B-3.

A severe deficiency in niacin is often referred to as pellagra. Niacin is found in most animal proteins but also in peanuts. As a result, this condition is rare in industrialized countries or in meat-eating communities.

Symptoms of pellagra include diarrhea, dementia, and skin disorders. You can usually treat it with a balanced diet and vitamin B-3 supplements.

Shop for vitamin B-3 supplements.

Vitamin B-9 helps the body create red blood cells and produce DNA. It’s often referred to as folate. Folate also helps brain development and nervous system functioning. Folic acid is the synthetic form found in supplements or fortified foods.

Folate is especially important for fetal development. It plays a crucial role in the formation of a developing child’s brain and spinal cord. Folate deficiency can lead to severe birth defects, growth problems, or anemia.

You can find folate in the following foods:

  • beans and lentils
  • citrus fruits
  • leafy green vegetables
  • asparagus
  • meats, such as poultry and pork
  • shellfish
  • fortified grain products
  • whole grains

While beans can provide a great amount of folate, the folate content in canned beans is about half of what cooked, dried beans offer.

Most people in the United States get enough folate. But pregnant women and women of childbearing age sometimes don’t consume enough folate for a healthy pregnancy.

The National Institutes of Health (NIH) recommends that women who are pregnant or who may become pregnant consume up to 400 micrograms of folic acid each day — over and above the folate they’re getting from food naturally — to help prevent birth defects.

There’s also research showing that some people have genetic mutations that prevent their body from methylating folate, or converting it to a form the body can use. In these cases, while folate intake might be adequate, a supplement of methylated folate may be necessary to prevent deficiency.

Vitamin B-12 is a B vitamin that’s responsible for assisting the body in making enough healthy red blood cells. Deficiency in this vitamin is common among people who:

  • are vegans
  • have had gastric surgery
  • are over 60 years old
  • have diabetes and take metformin (Glucophage)
  • have a long history of antacid use
  • lack intrinsic factor

Intrinsic factor is a transport protein secreted by the stomach cells. It binds to B-12 and takes it to the small intestine for absorption. This is the way the body is able to absorb and utilize B-12.

Adequate calcium intake at meals is required for intrinsic factor to assist in B-12 absorption in the small intestine.

A deficiency in this vitamin may cause pernicious anemia. This is a type of anemia caused by a decreased ability to absorb B-12 efficiently. Pernicious anemia is more common in people with autoimmune disorders and inflammatory or digestive diseases.

Symptoms of vitamin B-12 deficiency include:

  • fatigue and weakness in extremities
  • dizziness
  • shortness of breath
  • weight loss
  • nausea or poor appetite
  • sore, red, or swollen tongue
  • pale or yellowish skin

Left untreated for too long, vitamin B-12 deficiency may cause irreversible damage to the nervous system. More severe symptoms include:

  • difficulty walking
  • muscle weakness
  • irritability
  • dementia
  • depression
  • memory loss

Your doctor can order a variety of blood tests to check for vitamin B-12 deficiency. Blood tests can check for:

  • levels of vitamin B-12
  • methylmalonic acid
  • intrinsic factor antibodies

Treatment may be provided in a variety of ways, including:

  • increasing vitamin B-12 sources in the diet
  • taking vitamin B-12 supplements
  • receiving vitamin B-12 injections
  • blood transfusions

Vitamin B-12 is commonly found in red meat and animal products. Vegetarian sources include fortified plant-based milks and nutritional yeast.

According to Harvard’s School of Public Health, about 1 billion people worldwide don’t get enough vitamin D. People with darker skin tones are at a higher risk of vitamin D deficiency.

Vitamin D is essential for healthy bones. It helps the body maintain the right levels of calcium in order to regulate the development of teeth and bones. A lack of this nutrient can lead to stunted or poor bone growth. Osteoporosis, caused by a lack of calcium and vitamin D, can lead to porous and fragile bones that break very easily.

Vitamin D is only found naturally in a few foods. Foods with vitamin D include:

Many dairy products and plant milks in the United States are fortified with vitamin D.

The best source of vitamin D is sunlight. According to the NIH, some research suggests that 5 to 30 minutes of midday sun exposure twice a week on the face, arms, neck, or back can provide you with enough vitamin D.

Although recommended, sunscreen does hinder vitamin D absorption from sunlight through the skin. Spend a few minutes in the sun prior to sunscreen for optimal vitamin D absorption.

Calcium helps your body develop strong bones and teeth. It also helps your heart, nerves, and muscles work the way they should.

A calcium deficiency often doesn’t show symptoms right away, but it can lead to serious health problems over time. If you aren’t consuming enough calcium, your body may use the calcium from your bones instead. This leads to bone loss.

While some experts believe that calcium deficiencies may be related to low bone mass and weakening of bones due to osteoporosis, it’s a topic of much debate. According to WHO, evidence does support the importance of calcium with vitamin D for bone health in older populations. Evidence is weaker for younger populations.

Population study research by WHO also reveals that countries with lower calcium intake don’t have high rates of bone diseases. But countries with higher calcium intake have higher rates of hip fractures. In these countries, like the United States, high protein intake and lack of exercise can contribute to poor calcium status and bone health.

Calcium deficiency can lead to convulsions and abnormal heart rhythms. These can even be life-threatening. Postmenopausal women experience greater bone loss due to changing hormones and have more trouble absorbing calcium.

The best sources of calcium are:

  • dairy products, such as milk, yogurt, and cheese
  • calcium-set tofu
  • small fish with bones

Vegetables such as kale and broccoli also have calcium. Many cereals and grains are calcium-fortified.

The main causes of nutritional deficiencies include a poor diet that lacks essential nutrients, a disease or medication that impairs absorption, or both. The body is able to store some nutrients, so a deficiency may not be caught until the body has been without the nutrient for some time.

A number of diseases and conditions can lead to an iron deficiency. These include:

Pregnancy can also cause an iron deficiency if the body diverts iron to the fetus.

Researchers have found associations between bariatric surgery, which reduces the size of the stomach to achieve weight loss, and nutritional deficiency.

People who are candidates for bariatric surgery may already be nutrient-deficient due to poor diet. Talk to your doctor and dietitian before and after the surgery to set up a thorough nutrition plan.

The symptoms of a nutritional deficiency depend on which nutrient the body lacks. However, there are some general symptoms you might experience. These can include:

You may display all of these symptoms or only groups of them.

Over time, most people adapt to the symptoms. This can cause the condition to go undiagnosed. Schedule a checkup with your doctor if you experience prolonged periods of fatigue, weakness, or poor concentration. These symptoms could be a sign of the beginning of a serious deficiency.

Your doctor will discuss your diet and eating habits with you if they suspect you have a nutritional deficiency. They’ll ask what symptoms you’re experiencing. Make sure to mention if you’ve experienced any periods of constipation or diarrhea, or if blood has been present in your stool.

Your nutritional deficiency may also be diagnosed during routine blood tests, including a complete blood count (CBC). This is often how doctors identify anemia.

The treatment for a nutritional deficiency depends on the type and severity of the deficiency. Your doctor will find out how severe the deficiency is as well as the likelihood of long-term problems caused by the lack of nutrients.

Before deciding on a treatment plan, they may order further testing to see if there’s any other damage. Symptoms usually fade when the correct diet is followed or nutrient is supplemented.

Dietary changes

A doctor may advise you on how to change your eating habits in the case of a minor deficiency. For example, people with iron deficiency anemia should include more meat, eggs, dark meat poultry, vegetables, and legumes in their diet.

Your doctor may refer you to a dietitian if your deficiency is more severe. They may recommend keeping a food diary for a few weeks. When you meet with the dietitian, you’ll go over the diary and identify any changes you should make.

Typically, you’ll meet with your dietitian regularly. Eventually, you may have a blood test to confirm that you’re no longer deficient.


The United States’ official dietary guidelines recommend that you get most of your nutrients from food. In some cases, you may need to take supplements or a multivitamin. It may also be necessary to take an additional supplement to help your body absorb the supplements, such as taking calcium and vitamin D together.

The frequency and dosage of a supplement depends on how severe the deficiency is. Your doctor or dietitian can determine this.

Talk to your doctor before taking any nutritional supplements.

Parenteral administration

In very severe cases — such as when a nutritional deficiency doesn’t respond to oral medications or vitamins — it may be necessary to give the nutrient parenterally, or through the veins or muscles. This can carry the risk of additional side effects. It’s usually done in a hospital.

Parenteral iron, for example, can cause side effects that include:

In rare cases, it can even cause a severe allergic reaction.

Once you’ve been given the treatment, your doctor will have you do a repeat blood test to confirm that it was successful. You may need to attend the hospital for repeat appointments until you’re no longer deficient.

Most problems caused by nutritional deficiencies stop once you’re no longer deficient. But in some cases, there may be lasting damage. This usually only occurs when the deficiency has been severe and has lasted a long time.

For example, a prolonged thiamine deficiency can be associated with stunted growth or depression. Nutritional deficiencies in children can be serious and lead to lasting negative health outcomes.

If you’re experiencing symptoms and are concerned that you’re not obtaining enough of a certain nutrient, talk to your doctor. They can discuss your diet with you and help you figure out whether you should make some dietary changes or start taking supplements. If you don’t already have a primary care doctor, the Healthline FindCare tool can help you find a physician in your area.