Vitamin B12 is essential for positive brain function. Many years ago, the traditional treatment for psychotherapy was high doses of B12 and other B vitamins. Unfortunately, this successful form of treatment has gone by the wayside in favor of chemicals. B12 is obtained from red meat and liver so if you are vegetarian or eat very little meat, you may want to supplement this nutrient. There are two kinds of B12 and the one I recommend–methylcobalimin–is the most easily absorbed.