Protein
A protein consists of amino acids that act as the body’s main building blocks for tissues, such as muscle, skin, bone, and hair. Proteins also assist in many reactions in the body, including the production of enzymes (the catalysts that keep all body processes running smoothly), hormones, and antibodies. The best protein sources are meats, poultry and seafood, beans and peas, nuts, eggs, and soy products.
Fats
Your body uses fats for energy when carbohydrates aren’t available. You also need fats as insulation, to help your body absorb fat-soluble vitamins, and to protect your organs. Fats come in both liquid and solid forms. The best sources of healthful fats are the liquid monounsaturated and polyunsaturated fats found in olive oil, soybean oil, and avocados, as well as fatty fish rich in omega-3 fatty acids.
Carbohydrates
Carbohydrates are the body’s main energy source and the brain’s only source of fuel. Your body breaks carbohydrates down into glucose, which cells require to create energy. The best sources of carbohydrates are whole grains and foods made from grains, such as whole-wheat bread, bulgur, barley, oatmeal, brown rice, and cornmeal.
Vitamins and minerals
You need vitamins and minerals for numerous physiological functions that help you survive. They're essential for normal growth and development, and each one plays a unique role in helping to maintain optimal health. For example, calcium and vitamin D are necessary for healthy bones, and the B vitamins help support the nervous system. Vitamins and minerals come from a variety of foods, including fruits and vegetables.
Water
You’ve probably heard that you can live for weeks without food but only days without water. That’s because water is the most important essential nutrient. It is involved in many of your body’s vital functions, and it distributes other essential nutrients to your cells.
