Nutrition Basics


Any healthy man can go without food
for two days -- but not poetry.

Charles Baudelaire


Your body is made up of billions of atoms and molecules arranged in ways that give you life. Most of the atoms and molecules that make up your body today were not even part of you a few weeks ago. You, like all living things, exchange matter with your environment. You take in food to provide chemicals for life, and you excrete chemicals that are no longer needed.

Your body can manufacture nearly every chemical it needs from 40 basic chemicals called essential nutrients. You must obtain adequate amounts of the 40 essential nutrients in order to be healthy. This is rarely a problem if you consume a variety of foods and eat in accordance with the Healthy Eating Pyramid or the Mediterranean or DASH diets.

Food is composed of seven types of chemicals
  1. protein, consisting of smaller units called amino acids. Amino acids are not stored in the body in appreciable amounts, so you must consume about 60 grams of high-quality protein, called "complete" protein, a day to replenish the amino acids your body has used up in keeping you alive. Animal protein (meat, dairy, fish, poultry) is complete. Vegetable protein is not complete. Vegetarians must combine different sources of protein (eg: corn and beans) to get the protein they need. Dietary protein that is not utilized to keep the body functioning is broken down; some of it is stored as body fat and some is excreted as waste.
  2. carbohydrates, consisting of small chemicals called simple sugars (glucose, fructose, sucrose, lactose), large chemicals called complex carbohydrates (starch and glycogen), and non-digestible chemicals called fiber. Simple and complex carbohydrates provide about 60% of the energy you need to live.
  3. fats (also called lipids), consisting of storage fat (called triglyceride or saturated fat), unsaturated fats, cholesterol, some vitamins, and other fats that make up the membranes of cells. Storage fat is supposed to be your friend; it keeps you alive when food is scarce. When you store lots of fat, you risk ill-health. The body uses cholesterol to manufacture hormones and to cement biological particles together. Two of those particles are referred to as "good cholesterol" (high-density lipoprotein, or HDL) and "bad cholesterol" (low-density lipoprotein, or LDL). Good cholesterol is good because it helps keep blood vessels clear of junk, called plaque, thus reducing your risk of heart attack and stroke. Bad cholesterol is bad because it increases the risk of heart disease and stroke. More on good and bad cholesterol
  4. vitamins are worker-chemicals that allow your body to manufacture and utilize other chemicals. Like workers in a factory, vitamins are not used up when they make something, so you don't require very much of them in your daily diet. You must have sufficient amounts of all of them for your body to function, however. That's the reason nutritionists recommend taking a multivitamin as a form of "dietary insurance."
  5. minerals, consisting of chemicals such as sodium, potassium, calcium, magnesium, and chlorine. (list of minerals, part 1 and list of minerals, part 2)
  6. phytochemicals, consisting of a variety of chemicals that are not essential nutrients but that enhance human health.
  7. water. Your body is about 60% water. You acquire water directly from the environment and in food. You eliminate water (and the waste materials it carries) from the body in urine, sweat, breath, and feces. You must acquire the same amount of water that you lose each day in elimination, which is about 8 glasses. You don't have to drink 8 glasses since you get water in food. You know if you need water because you feel thirsty.