Vitamin B12 benefits the central nervous system in many important ways: It helps maintain the health of nerve cells — including those needed for neurotransmitter signaling — and helps form the protective covering of nerves, called the cell’s myelin sheath. This means that when vitamin B12 levels are low, almost every cognitive function can suffer.
Vitamin B12, sometimes also called cyanocobalamin, also helps with digestion and heart health, so a deficiency can lead to both digestive disorders and an increased risk for heart disease.
The National Institute of Health’s (NIH) Dietary Office estimates that somewhere between 1.5–15 percent of people in the U.S. are deficient in vitamin B12. Other studies, like one done by the American Journal of Clinical Nutrition in 2000, indicate that this number might be even higher, with up to 39 percent of the population possibly suffering from a vitamin B12 deficiency.
Animal foods are the best food sources of vitamin B12, including organic grass-fed dairy products, cage-free eggs, grass-fed meat, wild-caught fish, organic poultry and organ meats. According to the NIH, plant foods do not naturally contain vitamin B12 unless they are synthetically fortified.
Vitamin B12 can be found to some degree in fortified plant foods like nutritional yeast, fortified grain products and algae sea vegetables. However, most of these are not thought to be nearly as absorbable as natural animal sources are.
Vitamin B12 Deficiency
Vitamin B12 deficiency can be hard to detect, especially considering how common the symptoms of a vitamin B12 deficiency can be, such as feeling tired or unfocused. A diagnosis of vitamin B12 deficiency is typically based on the measurement of serum vitamin B12 levels within the blood. However, alarmingly, studies show that about 50 percent of patients with diseases related to vitamin B12 deficiency have normal B12 levels when tested.
There are more precise screening options available to detect a deficiency, but these are usually not given to patients unless they have a known case of anemia or heart disease-related symptoms. So if you suspect you might have a deficiency but your initial blood test shows that your levels are normal, you may want to talk with your doctor about performing secondary tests, especially those that check for high homocysteine levels.
Symptoms of a vitamin B12 deficiency can include:
- Constantly feeling tired or chronic fatigue
- Muscle aches and weakness
- Joint pain
- Difficulty breathing or shortness of breath
- Feeling dizzy
- Poor memory
- Inability to concentrate well
- Mood changes, like increased depression and anxiety
- Having abnormal heart problems, such as palpitations
- Poor dental health, including bleeding gums and mouth sores
- Digestive problems like nausea, diarrhea or cramping
- A poor appetite
- A more serious deficiency can also cause a form of anemia called pernicious anemia, a serious condition that can cause memory loss, confusion and even long-term dementia
Who is most at risk for having a vitamin B12 deficiency? Elderly people who tend to have impaired digestion are one of the most susceptible populations. This is because older people tend to produce less stomach acid that is needed to convert vitamin B12 properly.