Nutrition can be defined as the science of food, its composition, utilization, and its effects on an individual's health and diseases. Molecular biology, biochemistry, genetics, as well as feeding science, are utilized by nutritionists to investigate the effect of nutrients on human physiology. They also examine the impact of diet on lowering disease rates, the consequences of nutrient over-ingestion or under-ingestion, and the mechanisms of allergens.

Energy-giving and health-protecting food substances; food is important because nutrients aid in sustaining the body’s health. The basic ones are sources of proteins, carbohydrates, fats, vitamins, and minerals, fiber, and water. Each nutrient plays a specific role: proteins replenish tissues, carbohydrates serve as energy sources, fats are essential for cells, vitamins, and minerals act as factors for biochemical reactions, fiber is for digestion and water is for all other bodily functions.

There must be a balance of these nutrients to prevent excessive assimilation of one nutrient at the expense of the others. Nutrient deficiency may cause different diseases, for instance, malnutrition, a less robust immune system, and frequent illnesses. Similarly, having too much of some things is not good for your health; for example, obesity, diabetes, cardiovascular diseases, and others.

Such persons are nutritionists and dietitians. People out there are given guidance in enabling them to make suitable food choices for the proper functioning of their bodies. Clinical dietitians generally practice in outpatient departments where they design meals specially for patients suffering from particular diseases. Nutritionists generally intervene in large-scale interventions and may advise on a healthy diet and disease prevention. Knowledge on nutrition enables people to make better choices of what they eat so that they can get what their bodies need.