Every cell in your body contains protein -- your muscles, skin, organs and glands, even most of your body fluids. Proteins are made of amino acids, often referred to as "building blocks" because your body uses them to repair cells, make new cells and for growth and development. The amount of protein you need is determined by your age, gender, activity level and body weight.
The Importance of Protein
Protein is one of the three macronutrients. When you eat protein, your body breaks it down into different amino acids. These amino acids are used to generate new cells, maintain your immune and respiratory systems, create hormones such as adrenalin and can be used for energy if glucose isn't available. There are two types of protein -- complete proteins that include all essential amino acids and incomplete proteins that contain only some of the essential amino acids.
Female Protein Requirements
The Centers for Disease Control and Prevention recommends that females ages 14 to 70 years old consume 46 grams of protein daily. This is a very general guideline; a more comprehensive way to determine your protein requirement is to eat 0.4 grams of protein for every pound of body weight. Divide your body weight in half and subtract 10. An average 140-pound woman would need 60 grams of protein daily. You can also calculate your protein needs as a percentage of your total calorie consumption -- eat 10 to 15 percent of your calories from protein. If you eat 1,800 calories daily, 180 to 270 calories should come from protein. Each gram of protein has 4 calories, so that amounts to 45 grams and 68 grams of protein daily.
The Dangers of a High-Protein Diet
Many popular low-carb diets recommend eating up to 35 percent of your calories from protein -- a much higher protein consumption than suggested by federal guidelines. The American Heart Association says that high-protein diets can be dangerous because of their high saturated fat content and limited dietary fiber and vitamin content. Consuming large amounts of high-fat animal proteins increases your risks of high cholesterol and coronary artery disease. Diets low in fiber and essential nutrients, from a lack of grains, legumes and other plant foods, can lead to high blood pressure because of a lack of calcium, potassium and magnesium. Perhaps the biggest concern with high-protein diets is the effect of protein digestion on your kidneys.
Protein and Kidney Disease
Your kidneys filter waste from your body and help to digest both fats and protein. People in good health can safely consume 20 to 25 percent of their calories from protein and not harm their kidneys. However, the American Diabetes Association recommends that no more than 10 percent of your calories come from animal protein if you have kidney disease.
- Medline Plus: Protein in Diet
- Centers for Disease Control and Prevention: Protein
- American Heart Association: High-Protein Diets
- MSN Health Today; Protein 101 -- How Much Do You Need?; Aug. 29, 2006
- Harvard School of Public Health: The Nutrition Source -- Protein
- National Institutes of Diabetes and DIgestive and Kidney Disease: Kidney DIsease of Diabetes