Strength for Her

Protein is the building block for all matter in the human body. Our tissues, organs, and muscles are composed of protein, and protein plays an important role in running all cellular processes in the body. The body needs protein to create new cells and tissues and to function as a whole. Protein can be found in both animal and plant sources. Examples of protein rich foods include meats, poultry, fish, eggs, cheese, milk, yogurt, soy, beans, seeds and nuts.

Proteins are composed of chains of small molecular building blocks, called amino acids. Although there are thousands of different proteins in the body, they are all made up of combinations of only 20 different amino acids. When we consume proteins, the body breaks them down to into their amino acid components by digestion. It then reassembles those amino acids to form whichever other proteins the body needs at the time.

The body can not only build proteins, but it can also make some of the amino acids. It can manufacture 11 of them 20 amino acids. These are referred to as non-essential amino acids. This name can be somewhat confusing – the amino acids are essential for the body itself, but because the body can make them it isn’t essential that they be consumed in the diet. The other 9 amino acids cannot be produced by the human body, and are referred to as the essential amino acids. This is because it is essential to get these amino acids from protein sources in the diet.

If a protein source contains all of the essential amino acids, it is called a complete protein source. Otherwise, it’s an incomplete protein source. Complete proteins are found in animal sources like meats, fish, eggs, and milk, and also soy protein. Plant sources of protein are incomplete, lacking at least one of the essential amino acids.

Is it necessary to worry about complete versus incomplete proteins? Not usually. If you’re a meat-eater, you most likely get all of the essential amino acids your body needs from your diet. Vegetarians need to pay a little more attention to the protein sources in their diets. Since most plant proteins aren’t complete, a vegetarian can’t get all their essential amino acids from one protein source alone (an exception is soy protein, which is complete). This problem is easily taken care of by eating a variety of plant-protein sources. That way, all of the essential amino acids are consumed one way or another. Rice and beans are a good example of combining protein sources to form a complete protein.

How much protein does the body need?

There are many theories on the best ratio of carbohydrates to fat to protein in the diet. Most dietitians tend to agree that a healthy diet should have between 20%-30% of its calories coming from protein. In a 2000 calorie diet, that would mean about 400 calories, or 100 grams of protein (protein has 4 calories per gram). Another simple way to roughly estimate protein needs is to halve your body weight. For instance, a woman weighing 120 pounds should probably be getting around 60 grams of protein per day. This will vary between individuals depending on their goals – some athletes may require more protein than the average woman.

Protein is clearly labeled on nutritional information, in grams. The biggest sources of protein are meats and fish. Because developed countries consume so much meat, protein deficiency is rarely a problem. A chicken breast or a salmon fillet contains about 30 grams of protein. A cup of milk contains 8 grams. Other sources of protein are soy (soybeans, soy nuts, tofu and other soy derivatives), dairy products (cheese, yogurt, and milk), eggs, nuts, and beans.

Protein can be used as energy by the body, like carbohydrates and fat. However, this is the body’s last resort. Carbs are the easiest to convert into instant energy. Fats require a little more effort, but work well too for energy stores. The body doesn’t really want to use protein as energy, but it will if it gets desperate and doesn’t have another source readily available.

Healthy Protein choices

There are good and bad protein choices as well. Many foods high in protein are also high in fat as well. Therefore, the healthiest protein choices are those that have either minimal fat or heart-healthy fats. Chicken breast, canned tuna, cottage cheese, and skim milk are all relatively low in fat, and can be considered lean protein choices. Salmon has more fat, but it’s the good kind of fat. Nuts provide some protein as well as heart-healthy fats. Legumes provide carbohydrates in addition to protein, but they are full of fiber and are a healthy protein choice. Food preparation must always be considered also. If you have a healthy chicken breast and deep fry it in unhealthy oils, you’ve added a lot of bad fats and additional calories. We’ll talk more about healthy food preparation methods in the future.

 This concludes the Nutrition 101 series. See more examples of carbohydrates, proteins, and fats here.