As vitamins go, B12 is an important one. It’s essential for nerve and blood cells and helps make DNA. It also staves off a form of anemia that can cause weakness and fatigue.
If you aren’t getting enough, you can experience a medley of problems, from constipation to loss of appetite to trouble concentrating. A recent medical journal article even suggests that a vitamin B12 deficiency may have been the cause of Mary Todd Lincoln’s psychiatric and physical issues, which included a sore mouth and delusions. But can a shortage of B12 really contribute to depression? In a way, yes.
“Low levels will worsen the symptoms of depression” because you need B vitamins to produce and metabolize the mood chemical serotonin, says Joseph Feuerstein, MD, an associate professor of clinical medicine at Columbia University and director of integrative medicine at Stamford Hospital in Stamford, Connecticut. A serious B12 deficit can also lead to psychosis and memory loss. “It’s one of the only reversible causes of dementia,” Feuerstein says. “It’s an incredibly important vitamin.”
When patients come in with depression or anxiety, Feuerstein routinely checks their levels of B12. Even if you’re on the low end of the “normal” range—as many people are—taking a supplement might help improve your mood and give your antidepressant medication a boost. That said, vitamin B12 alone is not a remedy for depression, says Feuerstein.
The average adult should aim for 2.4 micrograms of B12 every day. You’ll find it in a variety of animal products, such as meat, eggs, milk, and cheese. Although some non-animal items are fortified with this vitamin, it can be hard to get enough if you’re vegan; Feuerstein suggests taking a supplement.
While most people who need extra B12 can simply pop a pill (Feuerstein recommends looking for the USP seal), that won’t work for those who have conditions that affect absorption, such as inflammatory bowel disease or pernicious anemia. In that case, your doctor can give you intramuscular injections once a month to ensure that you get what you need.