Niacin helps convert food into energy. It helps the body make various sex and stress related hormones. Some symptoms of niacin deficiency is indigestion, fatigue, canker sores, vomiting and depression. Severe deficiency is a condition known as pellagra (cracked, scaly skin, dementia and diarrhea). Niacin is fast acting and can provide a healthy boost of energy and proper metabolism of a meal. Niacin has been shown to help boost energy and mood within 30 minutes after consumption.