Nutrition is the supply of materials i.e. food required by organisms and cells to stay alive. In human medicine, nutrition is the science or practice of consuming and utilizing foods.

Nutrition studies how the body breaks food down (catabolism) and repairs and creates cells and tissue (anabolism) i.e. referred to as metabolism. Nutrition also focuses on how diseases, conditions and problems can be prevented with a healthy diet.

A nutrient is a source of nourishment, an ingredient in a food, e.g. protein, carbohydrate, fat, vitamin, mineral, fiber and water. Macronutrients are nutrients we need in relatively large quantities. Micronutrients are nutrients we need in relatively small quantities. The human body requires seven major types of nutrients:

Carbohydrates - 4 kcal per gram
Molecules consist of carbon, hydrogen and oxygen atoms. Carbohydrates include monosaccharides (glucose, fructose, glactose), sisaccharides, and polysaccharides (starch).

Proteins - 4 kcal per gram
Molecules contain nitrogen, carbon, hydrogen and oxygen. Simple proteins, called monomers, are used to create complicated proteins, called polymers, which build and repair tissue. Proteins are the building block your body uses to create new muscles tissues and repair any injured tissues.

Fats - 9 kcal per gram
Molecules consist of carbon, hydrogen, and oxygen atoms. Fats are triglycerides - three molecules of fatty acid combined with a molecule of the alcohol glycerol. Fats are essential for body to perform many corporal functions.

Fiber
Fiber consists mostly of carbohydrates. Fiber is a crucial part of essential human nutrition.

Water
About 70% of the human body is water. Human body needs between one to seven liters of water per day to avoid dehydration. Water helps in washing out the dangerous toxins that your body takes in, from the air you breathe, the food you eat and the chemicals used in the various products you use on your skin and hair.

Balanced Diet and Health

A balanced diet comprising of healthy foods is a key to promote good health. A nutritious diet while ensuring overall well being, helps to maintain a healthy Body Mass Index (BMI), reduces the risk of several diseases like cancer, cardiovascular ailments, diabetes, osteoporosis and stroke. Thus a nutritious & healthy diet is important for the prevention and cure of various diseases.

It is essential to consume a variety of healthy foods. There are five main food groups:

• Fruits
• Vegetables
• Cereals and Pulses
• Dairy
• Poultry, Fish and Meat products

A healthy balanced diet of these food groups ensures essential vitamins, minerals and dietary fiber. The food group serving size depend on various factors like age, activity level, body size and gender.