Living organisms are primarily divided into two groups based on their source of food. Plants can make their own food and are autotrophic, but all animals need to consume food and are therefore heterotrophic. The food that an animal consumes is called its diet.
The diet of a person is extremely important for their health. A poor diet can have an adverse effect on health and cause deficiency diseases like scurvy, beriberi, hypothyroidism, etc, or chronic systemic disorders such as heart disease and diabetes, or health-threatening conditions such as obesity.
Nutrition is the provision of essential nutrients to cells and organisms in the form of food.
There are seven major classes of nutrients- carbohydrates, proteins, fats, minerals, vitamins, fiber and water. They are classified into two types- macronutrients and micronutrients. Macronutrients are needed in comparatively larger amounts than micronutrients. Macronutrients are carbohydrates, proteins, fats, fiber and water, while vitamins and minerals are the micronutrients. Macronutrients are needed in relatively larger amounts than the micronutrients.
Of the macronutrients, carbohydrates, proteins, and fats provide energy. One gram of carbohydrates and proteins provide approximately 4 Calories or 17 kiloJoules of energy each. One gram of fats provides approximately 9 Calories or 37 kJ of energy. Water is of course essential in large quantities for every organism since much of their bodies is made up of water. Fiber provides roughage which helps heterotrophic organisms to digest their food and excrete the undigested food from their bodies.
Micronutrients vitamins and minerals are also essential since certain vitamin and mineral deficiencies cause certain diseases. There are also some other categories of nutrients such as antioxidants and phytochemicals which are essential for the bodies of heterotrophic organisms.
