Although a vitamin B12 deficiency is often discussed in relationship to vegetarian and vegan diets, anyone can become deficient in this essential vitamin. In fact, this deficiency affects between 1.5% and 15% of the American population. It is most commonly found in animal products, but there some plant-based sources of the vitamin that come directly from nature too. Here are the key facts that you need to know about Vitamin B12 and how to make sure you’re getting enough of it in your daily meals.

What Does Vitamin B12 Do?
One of the main functions of Vitamin B12 is to protect the body’s central nervous system. This vitamin also makes up your red blood cells and DNA and helps red blood cells divide as they are supposed to. It is also known to prevent megaloblastic anemia, which makes you feel weak and fatigued. Your body can’t produce vitamin B12 on its own, so it must rely upon the foods you eat and supplements you take.
According to the National Institutes of Health, the recommended amounts for different ages and stages of life are as follows:
Life Stage: Recommended Amount
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
Causes of Vitamin B12 Deficiency
There are many factors that can cause a vitamin B12 deficiency that go far beyond a decision to not eat meat. For vitamin B12 to be absorbed in the body, hydrochloric acid in the stomach separates it from food protein and then attaches it to a protein naturally made in the stomach. These are some of the most common causes of the deficiency:
- Thinning stomach lining
- Immune system diseases
- Heavy alcohol use
- Pernicious anemia
- Long-term use of anti-acid drugs for upset stomach
- Weight loss surgery
- Aging
Symptoms of a Vitamin B12 Deficiency
Some of the first signs of a vitamin B12 deficiency are fatigue and tingling of the hands and feet. If a deficiency is left untreated, blindness, deafness, and dementia have been known to occur. These are some other symptoms associated with the deficiency.
- Pale skin
- Shortness of breath
- Constipation or diarrhea
- Soreness of the mouth and tongue
- Depression

Foods Rich in Vitamin B12
How many of these vitamin B12-rich foods are you getting in your daily diet?
- Beef liver
- Clams and mussels
- Fish
- Poultry
- Eggs
- Milk
- Swiss, Parmesan, feta, and mozzarella cheeses
- Tempeh
- Miso
- Seeweed
- Fortified breakfast cereals
- Nutritional yeasts

Medical Consultation
In serious and symptomatic cases, it may be necessary to consult a medical professional for treatment. Vitamin B12 treatments include injections, oral supplements, and nasal therapy. It’s important to know that vitamin B12 can interact with other medications and supplements that you are taking and discuss potential interactions with your doctor. For example, certain prescription antibiotics (like Choloamphenicol), proton pump inhibitors (like Prilosec), and diabetes drugs (like Metformin) can prohibit your body from absorbing vitamin B12 from the foods you eat.
To learn more about vitamin B12, take a look at the National Institutes of Health dietary supplement fact sheet.