2The B-complex vitamins are a family of nutrients that play multifaceted and essential roles in health and preventing disease. They are needed to make and repair DNA and increase energy levels-both key steps for slowing the aging process. Some B vitamins are needed to make mood-enhancing neurotransmitters, such as serotonin, and can have powerful antidepressant benefits. The B vitamin folic acid reduces blood levels of homocysteine, a known risk factor for heart disease, stroke, cancer, and Alzheimer's disease. Vitamin B12 is needed for normal mental function, and low levels can mimic senility. This book explores the remarkable benefits of these and the rest of the B-complex family of vitamins.