Written by Anne Jacobson, MD, MPH | Reviewed by Karla Robinson, MD
Vitamin B12 is an essential nutrient that does its job quietly and efficiently inside the body. Vitamin B12 helps to make new DNA and keep nerve and blood cells healthy. It also helps our cells break down proteins and fats for energy.
Most people get enough vitamin B12 in their diet and absorb it through the digestive system. But some diets and certain health conditions may lead to a deficiency of this important vitamin, especially as you get older.
What is vitamin B12?
Vitamin B12, also called cobalamin, is one of the B-complex vitamins. It’s not made by the body, so we need it in our diet. Vitamin B12 is not made by plants, either. It’s found in animal products, in foods where B12 has been added, or in supplement form.
Teens and adults need about 2.4 mcg of vitamin B12 every day. Pregnant people need around 2.6 mcg, and those who are breastfeeding need 2.8 mcg of vitamin B12 per day. Infants and children need 0.4 mcg to 1.8 mcg, depending on their age.
Common symptoms of vitamin B12 deficiency
Not having enough vitamin B12 can cause complications in multiple body systems. That’s because vitamin B12 is needed for making certain cells, proper cell function, and repair. Having a vitamin B12 deficiency can affect how well your body makes new blood cells, nerve cells, and DNA.
Let’s take a closer look at four common symptoms of vitamin B12 deficiency.
1. Anemia
Low B12 levels cause a kind of anemia, or low blood count. Sometimes, the blood cells become large, or macrocytic, before a person becomes anemic.
Symptoms of anemia might include:
- Feeling tired or having low energy
- Pale skin
- Feeling short of breath, especially with movement
- Having less of an appetite or losing weight without trying
- Headaches
- Feeling dizzy or like you might faint
- Fast or irregular heartbeat
Some people with B12 deficiency also have mouth sores or a swollen, painful tongue.
