Six Basic Nutrients and Their Functions

There are six classes of essential nutrients necessary for human survival: carbohydrates, proteins, lipids, vitamins, minerals and water. The best way to get these nutrients is by following a varied, healthy diet featuring plenty of fresh vegetables and fruits, whole grains, lean proteins, nonfat dairy products and healthy fats. Dietary requirements vary with age and sex. Consult your physician or a registered dietitian about the diet that is best for you.

Carbohydrates are a major energy source. Along with providing fuel for physical activity, they also power the body's involuntary functions, including heartbeat, breathing and digestive processes. Food sources of carbohydrates include grains and grain products, vegetables, fruits, legumes, dairy products and sugars. Carbohydrates should supply 40 to 60 percent of the average person's caloric intake.

Skin, muscle and bones depend on dietary protein for normal growth, development and maintenance. Getting enough protein is rarely a problem in industrialized countries such as the U.S. Complete proteins from animal sources contain all the amino acids your body needs for normal functioning. Plant sources only contain incomplete proteins, meaning some amino acids are missing. If you do not eat much meat, poultry, fish or other animal products, eat a variety of protein-rich plant foods such as beans, nuts and whole grains to ensure an optimal combination of amino acids.

You may think of lipids, or fats, as dietary enemies, but they are as necessary to the body's normal functioning as the other essential nutrients. Dietary fat helps the absorption of vitamins, supports cell membrane health and helps maintain the immune system. Not all fats are equal. Choose healthy unsaturated fats such as olive oil and nut oil instead of saturated fats from fatty meats.

Vitamins are micronutrients, meaning the body needs them in small quantities. Vitamins are organic compounds produced by living beings, while minerals are inorganic elements that originate in the earth. Vitamins and minerals support the body's biochemical processes. Each of the vitamins and minerals has a distinct function, including regulating metabolism, guarding the cells from oxidative stress and synthesizing hormones.

Comprising 60 percent of your body weight, water is vital for the normal functioning of all your body's systems. It helps cleanse your body of wastes and toxins, carries essential nutrients to your cells, lubricates your joints and helps maintain your body temperature. While the rule is to drink eight glasses of water daily, this maxim is not supported by scientific evidence, according to MayoClinic.com. If your urine output is about 6 cups per day, your urine is slightly yellowish or clear and you don't often feel thirsty, your water intake is likely adequate.