Your body is like a very complex, organized factory. Even the billions to trillions of cells making up your body are incredibly complicated, with many interacting components. The building blocks of cells, tissues and organs are chemicals. Most of these are supplied by the diet. Chemicals ingested in the diet are also used to a great degree for the utilization of energy. While our knowledge of nutrition is evolving, the USDA has set guidelines for a healthy diet. However, a healthy diet may vary from one person to another, depending on age, weight, energy expenditure and disorders. Consult a physician or other health-care professional regarding dietary decisions and the diagnosis and treatment of disease.
Protein
The building blocks of protein, called amino acids, are used as energy or to build the proteins of the body. These proteins have myriad functions, such as supporting structures holding cells together and increasing the rates of chemical reactions, according to "Lehninger Principles of Biochemistry" by David L. Nelson and Michael M. Cox. Protein-rich foods include meat and dairy products. The USDA recommends a diet consisting of 10 to 35 percent protein for most people.
Carbohydrates
Carbohydrates are primarily used for energy. Simple carbohydrates are basic sugars such as fructose or glucose. Complex carbohydrates are the same molecules as simple carbohydrates, but the sugars have been linked like the rungs on a ladder. This is important because it takes longer for the body to break down the sugars in the intestine, resulting in more stable and steady blood sugar. Fiber includes complex carbohydrates that cannot be digested, as found in fruits, vegetables and whole grain foods. The USDA recommends 45 to 65 percent of calories come from carbohydrates.
Fats
Fats, including cholesterol, help to form signaling molecules, such as stress and sex hormones, and the outer layer of cells, and are necessary for health. They also provide energy and help to absorb vitamins A, D, E and K. Trans and saturated fats have been associated with diseases such as heart and blood vessels disorders, while mono and polyunsaturated fat are healthier. The USDA recommends 20 to 35 percent of calories be derived from fat.
Vitamins and Minerals
Vitamins and minerals are called micronutrients -- as opposed to the macronutrients listed above -- because they are needed in small amounts. These include the water-soluble B vitamins and vitamin C, and the fat-soluble vitamins A, D, E and K. Vitamins play numerous roles in the body, mostly by binding to and helping enzymes to function. Enzymes are special proteins that speed up the rates of chemical reactions in the body. They help the cells to function properly and perform work.
Minerals include sodium, potassium and magnesium. While small amounts promote health, large doses can be dangerous. For example, moderate sodium intake balances the fluid in the body and helps nerves and muscles function. Excessive sodium intake leads to high blood pressure.
References
- "Lehninger Principles of Biochemistry, 4th ed."; David L. Nelson and Michael M. Cox; 2004
- USDA: Dietary Reference Intakes: Macronutrients
- "Nutrition Concepts and Controversies, 11th ed."; Frances Sizer and Ellie Whitney; 2007
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