Oak Street Health is part of CVS Healthspire™

Signs of Vitamin B12 Deficiency: What You Need To Know

Written by 
Lacey Ramburger

Article at a glance

  • Vitamin B12 is an essential nutrient that helps create DNA and maintain healthy blood and nerve cells.

  • B12 deficiency is fairly common amongst all ages and can result in side effects such as fatigue, poor concentration, muscle weakness, etc.

  • Vitamin B12 deficiency can be countered through changes in diet, consuming dietary supplements, or administering specific medications to regulate vitamin B12 levels.

What Is Vitamin B12?

Vitamin B12 is a vital nutrient that helps maintain healthy red blood cells, as well as brain and nerve cells. It is also critical in the body’s ability to form DNA. It is available in both food/​beverages as well as supplements and is most commonly found in animal products.

When food containing vitamin B12 is eaten, hydrochloric acid in the stomach helps to separate vitamin B12 from its food source. Once the vitamin is separated, it binds with what is known as the intrinsic factor, which helps the vitamin to be fully absorbed into the body.

What is Vitamin B12 Deficiency Anemia?

When your body is deficient in vitamin B12, it can lead to a deficiency of red blood cells. Vitamin B12 is what the body needs to create red blood cells that carry oxygen throughout the body. With less B12 comes fewer red blood cells, meaning that the body is working harder and that it has become anemic. Folate is another type of B vitamin (otherwise known as folic acid) that can cause anemia if there is a deficiency of it in the body. In fact, folate deficiency and vitamin B12 deficiency comprise the two types of megaloblastic anemia that distort the shape of the body’s red blood cells and reduce the bone marrow’s production of them.

Importance of Vitamin B12

Outside of its important role in creating DNA, vitamin B12 also helps in the prevention of certain conditions, such as

  • Megaloblastic Anemia: a blood condition that causes tiredness and weakness in people.

  • Cancer: research is still needed to fully understand the effects, but some research shows that those with lower levels of Vitamin B12 may be at a higher risk for cancer.

  • Heart Disease and Stroke: vitamin B12 supplements have been linked to reducing levels of homocysteine, a compound that is often associated with an increased risk of a heart attack or stroke (however, there is no formal evidence that proves the supplement automatically prevents cardiovascular issues).

How Much Vitamin B12 Does a Person Need?

The amount of vitamin B12 a person needs is dependent on a few factors, namely age and whether a person is pregnant. According to the National Institutes of Health and Human Services, this is the amount of vitamin b12 (measured in micrograms) a person requires each day:

  • Birth to 6 months: 0.4 mcg

  • Infants 7–12 months: 0.5 mcg

  • Children 1–3 years: 0.9 mcg

  • Children 4–8 years: 1.2 mcg

  • Children 9–13 years: 1.8 mcg

  • Teens 14–18 years: 2.4 mcg

  • Adults: 2.4 mcg

  • Pregnant teens and women: 2.6 mcg

  • Breastfeeding teens and women: 2.8 mcg

How Common Is Vitamin B12 Deficiency?

In most cases, people are able to adequately consume enough vitamin B12 to meet the recommended doses. However, even if consumed, some may have difficulty absorbing vitamin B12, which can lead to lower levels of vitamin B12. The National Institutes of Health state that up to 40% of Western populations experience lower levels of Vitamin B12 or even vitamin B12 deficiency.

Conditions Causing B12 Deficiency

While vitamin B12 is found in several types of food and there are supplements available, there are several reasons why a person may experience vitamin B12 deficiency (also referred to as folate deficiency). 

Plenty of conditions can set the stage for vitamin B12 deficiency, including:

  • Inability to Produce Hydrochloric Acid: hydrochloric acid helps separate vitamin B12 from whatever protein it is attached to (such as in food-based products) so it can be absorbed.

  • Lack of Intrinsic Factor: a protein in the stomach that bonds with vitamin B12 to help the body properly absorb the nutrient.

  • Pernicious Anemia: a specific type of megaloblastic anemia that doesn’t allow the body to properly absorb vitamin B12, which can lead to other symptoms and health problems down the road.

  • Stomach/​Intestinal Disorders: diseases such as Crohn’s or celiac disease can make it difficult for the small intestine to absorb vitamin B12.

Signs of Vitamin B12 Deficiency

There are several symptoms related to vitamin B12 deficiency that can range across multiple areas.

Physical Symptoms of Vitamin B12 Deficiency

  • Fatigue: due to the lack of healthy red blood cells that results from vitamin B12 deficiency, a person may find themselves feeling consistently tired and fatigued.
  • Pale/​Yellow Skin: due to a lack of healthy red blood cells, a person’s skin may appear yellowish or pale over time.
  • Headaches: lack of vitamin B12 may result in consistent headaches or migraines. In some situations, those who have headaches as a result of a vitamin B12 deficiency received relief after their vitamin B12 levels were regulated.
  • Stomach/​Weight Issues: some stomach issues, such as weight loss, diarrhea, bloating, or nausea may develop in response to vitamin B12 deficiency (though it’s important to note that these side effects can be attributed to other conditions or factors as well).
  • Muscle Weakness: in some cases, vitamin B12 deficiency has been linked to potential muscle weakness and cramps, due to its ability to impact sensory nerve functions.

Neurological Symptoms of Vitamin B12 Deficiency

Multiple studies have been done that link vitamin B12 deficiency to neurological problems, such as:

  • Memory loss
  • Difficulty concentrating/​focusing
  • Forgetfulness
  • Pins and needles” in hands and feet
  • Difficulty walking
  • Difficulty speaking

Psychological Symptoms of Vitamin B12 Deficiency

Vitamin B12 deficiency can potentially affect cognitive skills and may cause issues such as:

  • Depressive symptoms
  • Personality changes
  • Irritability

In many cases, those who receive the appropriate amounts of vitamin B12 often report improvement in their mental well-being—like in this study.

Risk Factors For Vitamin B12 Deficiency

There are a few types of people who may be at higher risk for vitamin B12 deficiency, including:

  • Stomach Surgery Patients: if a person has an operation on their stomach, such as weight loss surgery (gastric bypass surgery) or to remove cancerous tumors, it can affect the body’s ability to retain vitamin B12.
  • Those Taking Certain Medications: some medications, such as proton pump inhibitors, that are used to treat acid reflux can reduce stomach acid, making it difficult to absorb vitamin B12. Additionally, medications for conditions such as diabetes, seizures, or infections can also cause issues with vitamin B12 absorption.
  • Vegans or Vegetarians: the majority of foods naturally containing vitamin B12 are animal-derived, so those who adhere to a strict vegan or vegetarian diet may develop a vitamin B12 deficiency over time.
  • Older Adults: as a person ages, they have the potential to develop atrophic gastritis, which causes the body to not make enough hydrochloric acid and can reduce the amount of vitamin B12 absorption.
  • Family History With B12 Deficiencies: Those with a family history of vitamin B12 deficiency may be more likely to develop this condition.

Vitamin B12 Deficiency in Older Adults

While different groups of people can experience vitamin B12 deficiency, older adults are specifically at a higher risk of experiencing it. 

Age itself is a factor in a lack of vitamin B12, most notably because older adults are at a higher risk for conditions that contribute to vitamin B12 deficiency, including:

  • Diabetes

  • Crohn’s disease

  • Atrophic gastritis

  • Pernicious anemia

  • Food-cobalamin malabsorption syndrome

Additionally, as a person ages, their diet may not be as well-rounded as it once was, or a lack of appetite may prevent older adults from eating the types of food and beverages that would provide an adequate amount of vitamin B12. Certain medications may also interfere with the person’s ability to absorb vitamin B12.

How To Treat Vitamin B12 Deficiency

In order to determine whether a person has a vitamin B12 deficiency, they should visit their healthcare provider. A primary care provider may schedule a blood test to get a reading on how high or low the vitamin B12 levels are. Additionally, if a person shows a high risk for vitamin B12 deficiency, they will administer routine blood tests—known as a complete blood count (CBC) and a vitamin B12 blood test level—to check the amount of vitamin B12 present.

If vitamin B12 deficiency is detected, there are a few different treatment options available, including:

  • Vitamin B12 shots or Folic Acid Pills: these are typically used in severe cases of vitamin B12 deficiency and are administered in weekly doses to help regulate vitamin B12 levels.

  • Dietary Supplements: in less severe cases, taking supplements that contain vitamin B12 (including multivitamins) can help provide the appropriate amount of vitamin B12.

  • Fortified Foods: particularly for those on a vegan or vegetarian diet, certain foods and beverages that are fortified with vitamin B12 can help make up for the lack of the nutrient that is typically found in most animal products.

Sources of Vitamin B12

There are plenty of foods and beverages that contain higher amounts of vitamin B12. These are typically divided into two categories: foods that contain B12 naturally and those that artificially include B12 for added nutrients known as fortified foods.

Foods That Naturally Contain Vitamin B12

Some examples of foods that naturally contain the nutrient include:

  • Beef liver

  • Clams (without shells, cooked)

  • Tuna

  • Citrus fruits

  • Salmon

  • Eggs

  • Beef

  • Milk

  • Yogurt

  • Cheese

  • Turkey

  • Kidney beans

  • Spinach

Fortified Foods That Contain Vitamin B12

Some examples of fortified foods that artificially contain the B12 nutrient include:

  • Nutritional yeast

  • Non-Dairy milk (certain ones)

  • Fortified breakfast cereals

  • Tofu

  • Fortified fruit juices

  • Some meat substitutes

  • Dairy-free yogurt (certain ones)

When To Speak To Your Healthcare Provider

One of the larger issues surrounding vitamin B12 deficiency is how subtle the symptoms can be. The human body does store a large amount of vitamin B12, meaning that even when you are not actively absorbing the nutrient from food or supplements, it can take years for a vitamin B12 deficiency to make itself known.

With symptoms that can also be mistaken for other conditions or illnesses, it can be difficult to know when to see a physician. Here are some things to keep in mind:

  • Contact your doctor if you are experiencing multiple symptoms of vitamin B12 deficiency: regardless of the cause, if you are dealing with consistent symptoms such as nausea, difficulty focusing, or muscle weakness, it’s important to contact your healthcare provider and see about taking a blood test to determine your vitamin B12 levels.
  • If you experience new or worsening symptoms: if your doctor has already informed you that you have low levels of vitamin B12 and you develop new or worsening symptoms, contact your healthcare provider immediately.


Are folate deficiency and vitamin b12 deficiency the same?

Folate deficiency anemia commonly occurs alongside Vitamin B12 deficiency and while they are frequently linked, they are different deficiencies. However, if you have a folate deficiency it is likely you're deficient in vitamin B12 as well and should speak with a care provider about treatment. To learn more about folate deficiency anemia, visit this source.

Become a patient

Experience the Oak Street Health difference, and see what it’s like to be treated by a care team who are experts at caring for older adults.

Related articles

View all articles

Get access to care, right in your neighborhood.