Nutrition is a science that examines the relationship between diet and health. Dietitians are health professionals who specialize in this area of study, and are trained to provide safe, evidence-based dietary advice and interventions.Deficiencies, excesses and imbalances in diet can produce negative impacts on health, which may lead to diseases such as cardiovascular disease, diabetes, scurvy, obesity or osteoporosis.Many common threats and their symptoms can often be prevented or alleviated with better nutrition. The science of nutrition attempts to understand how and why specific dietary aspects influence health.