Fundamentals of Nutrition

Protein
Proteins form the body's main structural elements and are found in every cell and all tissue. Your body uses proteins for growth, as well as to build and repair bone, muscles, connective tissue, skin, internal organs and blood. Hormones, antibodies and the enzymes that regulate the body's chemical reactions are all made of protein. Without the right proteins, blood won't clot properly and cuts won't heal. And, if carbohydrates and fat can't meet your energy needs, proteins can be broken down and used as a source of emergency energy.

The average person needs 50–65 grams of protein each day. In addition to meat, poultry and fish, significant amounts of protein are found in beans, milk, eggs, dairy foods, seeds, nuts, grains and soy products. Most Americans get more than enough protein in their diet. As you can see from the list below, it's not hard to fill your daily protein quota: In fact, an average single serving of meat supplies half of your daily requirement!

• Four ounces of lean meat, poultry or fish (about the size of a deck of cards) contain 25 to 35 grams of protein.
• One cup of cooked beans or lentils contains about 18 grams.
• One cup of low fat cottage cheese contains 28 grams.
• Two ounces of solid cheese contain about 16 grams.
• One cup of low fat milk contains 8 grams.
• Two tablespoons of peanut butter contain 8 grams.
• One serving of grain foods (barley, pasta, cereals, whole wheat bread, for example) generally contains 3 to 6 grams of protein.
• One serving of vegetables ranges from 1 to 3 grams.

The Skinny on Carbohydrates: What They Are and Why We Need Them
For too many Americans, carbohydrates—or carbs—have become something to avoid in the daily diet. But as nutrition experts know, carbohydrate is an essential macronutrient that provides fuel for the brain and muscles and contains the fiber needed for proper gut function. Moreover, many foods primarily composed of carbohydrates have been demonstrated through numerous scientific studies to lower the risk for certain cancers, stroke, heart disease and high blood pressure. In addition, these foods play an important role in the control body of weight, especially when combined with exercise. This is why the leading medical and nutrition authorities recommend weight loss programs that are rich in foods containing carbohydrate, such as from whole grains, fruits, vegetables and low-fat dairy products.

What Are Carbohydrates?
Carbohydrates are found in a wide variety of foods and are one of the three major macronutrients (along with fat and protein) that supply the body with energy. But, unlike fat and protein, carbohydrates are efficiently converted into glucose, which is used directly by the muscles and brain. That is why the Institute of Medicine (IOM), part of the National Academy of Sciences, recently issued a recommendation that children and adults get a minimum of 130 grams of carbohydrate per day to maintain maximum brain function. This amount is more than six times more than what the initial phase of the Atkins Diet allows (20 grams of carbohydrate per day).

In addition to being the most easily accessible energy source for muscles and organs of the body, carbohydrates play an important role in the construction and maintenance of the body's tissues, organs and cells, including nerve cells. At the same time, carbohydrates are present in a wide range of foods that bring a variety of other important nutrients to the diet, such as vitamins and minerals, phytochemicals, antioxidants and dietary fiber. A diet high in these nutrients has been associated with a lower risk for certain cancers, cardiovascular disease, stroke and diabetes, among other medical conditions.

Carbohydrates are grouped into two main categories: 1) simple carbohydrates, which contain simple sugars, such as glucose and fructose, found in fruits, berries, some vegetables, table sugar and honey; and 2) complex carbohydrates, found in many plant-based foods, whole grains and low-fat dairy products. For optimal health, nutrition and public health authorities recommend consuming a wide range of carbohydrate-containing foods, with an emphasis on fruits, vegetables, whole grains and low-fat dairy products. For both weight control and good health, experts advise caution in over-consuming processed foods where sugar has been added, such as soft drinks, pastries and other sweets.

How Much Do We Need?
Recognizing the many health benefits associated with carbohydrates—and especially diets rich in fruits, vegetables, whole grains and low-fat dairy foods—the Dietary Reference Intakes Report, issued by the Institute of Medicine in 2002, recommended that Americans get the majority of their calories each day from carbohydrates. Specifically, the IOM report states that:
"Adults should get 45 percent to 65 percent of their calories from carbohydrates, 20 percent to 35 percent from fat, and 10 percent to 25 percent from protein."

The minimum amount of carbohydrate that children and adults need for proper brain function is 130 grams a day.
Added sugars should comprise no more than 25 percent of total calories consumed. The IOM report was designed for normal-weight individuals; overweight people need far less.
For adults 50 years and younger, the recommended total intake for dietary fiber is 38 grams for men and 25 grams for women. For those over 50, it is 30 grams and 21 grams respectively.