MEET THE NUTRIENTS

 

The Energy-Yielding Nutrients

Foremost among the six classes of nutrients in foods is water, which is constantly lost from the body and must constantly be replaced.  Of the four organic nutrients, three are energy-yielding nutrients, meaning that the body can use the energy they contain. The carbohydrates and fats (fats are also called lipids) are especially important energy-yielding nutrients.

Carbohydrates

Carbohydrates usually provide the greater part of the energy in a normal diet, but no individual carbohydrate is an essential nutrient in the sense that the body needs it but cannot make it for itself from other nutrients. If the carbohydrate intake is less than 100 g per day ketosis is likely to occur

Fat

Fat provides the most concentrated source of energy, with 9 calories per gram. Healthy adults should get 20 to 35 percent of total calories from fat, which equates to 44 to 77 grams of fat per day on a 2,000-calorie diet, according to the 2010 Dietary Guidelines from the U.S. Department of Health and Human Services. Unsaturated fats, such as from olives, nuts, canola oil and avocados, are considered healthier than saturated fats, which come from full-fat cheese, fatty meats, butter and coconut oil.

Protein

Protein provides 4 calories per gram, and the 2010 Dietary Guidelines from the U.S. Department of Health and Human Services recommend getting 10 to 35 percent of your total calories from protein. This equals approximately 50 to 175 grams on a standard 2,000-calorie diet. Along with providing energy, protein is an essential nutrient for maintaining your lean muscle mass, promoting a strong immune system and allowing chemical reactions in your body to occur. Good sources of protein include meat, poultry, seafood, eggs, dairy products, tofu and beans. 

 
Vitamins and Minerals
 

The fifth and sixth classes of nutrients are the vitamins and the minerals. These provide no energy to the body. A few minerals serve as parts of body structures (calcium and phosphorus, for example, are major constituents of bone), but all vitamins and minerals act as regulators. As regulators, the vitamins and minerals assist in all body processes: digesting food; moving muscles; disposing of  wastes; growing new tissues; healing wounds; obtaining energy from carbohydrate, fat, and protein; and participating in every other process necessary to maintain life. Later chapters are devoted to these six classes of nutrients.

The Concept of Essential Nutrients

When you eat food, then, you are providing your body with energy and nutrients. Furthermore, some of the nutrients are essential nutrients, meaning that if you do not ingest them, you will develop deficiencies; the body cannot make these nutrients for itself. Essential nutrients are found in all six classes of nutrients. Water is an essential nutrient; so is a form of carbohydrate; so are some lipids, some parts of protein, all of the vitamins, and the minerals important in human nutrition.