Nutrients are food components that are necessary to maintain normal life activities. The study of nutrients in modern nutrition is mainly aimed at the nutrient needs of human beings and livestock. Nutrients are divided into seven categories: protein, lipids, carbohydrates (sugars), vitamins and minerals (inorganic salts), water and cellulose.

The nutrients needed by living things are composed of a large number of elements, including hydrogen, oxygen, nitrogen and carbon. These are the main elements that make up the protein of organisms and store energy. In addition, there are a small amount of sulfur, phosphorus, calcium, magnesium, potassium, sodium, chlorine and various trace elements. Some trace elements are only trace in organisms.

Organisms from low to high, from single-celled organisms to higher animals and plants, from living in water to living on land, live in different environments and have different ecology. As a result, the nutrients needed and the way of ingesting nutrients are also different.

Extended data:

Nutritional requirements

A reasonable diet is necessary to form and maintain a healthy body and meet the great energy needs of physical and mental work. A person's daily demand for essential nutrients is determined by age, sex, height, weight, metabolism and activity. Based on the analysis of research data, the requirements of 45 essential nutrients in food have been evaluated. The Food Nutrition Committee of the National Academy of Sciences and the agricultural department of the United States regularly issue the recommended daily dietary nutrient supply (RDA) to calculate the dietary needs of healthy people.

The U.S. Department of Agriculture has proposed that a balanced diet consists of four basic foods. They are: dairy products, meat and plant protein, bread and grains, and fruits and vegetables. A new and optimized pyramid dietary suggestion is put forward to help people choose a diet that can supplement essential nutrients and reduce the incidence of many diseases, such as cancer, hypertension, coronary heart disease and stroke.

This suggestion depends on the different calorie consumption of each person (from1600 to 2400 kcal or more). For example, a person who needs 1600kcal should eat 6 portions of cereal and 3 portions of protein food every day, while a person who needs 2400kcal should eat 10 portion of cereal and 5 portions of protein food. Generally speaking, the intake of fat should be reduced to 30% of the total calories, while the intake of fruits, vegetables and cereals should be increased.

References:

Baidu Encyclopedia-Nutrition (nutrients ingested by living things)