5-MTHF (5-Methyltetrahydrofolate) is a biologically active form of folic acid that helps treat anxiety and depression in people with a genetic defect that limits their body's ability to metabolize folate.   The body uses MTHFR to convert homocysteine into methionine, which is used to make neurotransmitters like serotonin, dopamine, and norepinephrine. These neurotransmitters are important for mood and cognitive function. If you have an MTHFR deficiency, you may have low levels of these neurotransmitters, which can increase your risk of mood disorders like anxiety.   5-MTHF is effective for people who have had unexplained anxiety or depression for a long time. It may also be beneficial for people with the MTHFR polymorphism, a genetic error that limits the body's ability to metabolize folate.