Protein serves as the building block of all your body's cells. It helps repair and build new cellular tissue, oxygenates your blood and plays an indirect role in numerous other functions. Protein is one of three macronutrients you need to consume in sufficient amounts to support your energy needs. The Institute of Medicine lists the recommended daily protein intake as 56 grams for men and 46 grams for women. This is a base amount, and an active bodybuilder may need well over 100 grams of protein per day, according to Columbia University. Harvard School of Public Health reports that there is no "one size fits all" formula for protein intake.
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Recommended Dietary Allowance
Recommended Dietary Allowances for all nutrients are set by the Institute of Medicine. The RDA for protein for adults over the age of 18 is 10 to 35 percent of your total calories. The RDA for children aged 4 to 18 is 10 to 30 percent of their total calories. Children aged 1 to 3 should consume 5 to 20 percent of their calories from protein. There is no RDA for protein for infants.
Calculating Protein Needs
You can determine your protein needs by first calculating your total caloric needs. Calculate your caloric needs using an online calculator that takes into account your age, sex and activity level. The average American adult typically needs about 2,000 calories a day. If 10 to 35 percent of your total calories should come from protein, you would then need 200 to 700 protein calories each day. Protein contains 4 calories per 1 gram, so this caloric value amounts to 50 to 175 grams of protein per day. A protein intake of 100 grams a day would be appropriate for adults who consume anywhere from about 1,200 to 4,000 calories a day.
There is no defined level at which excessive amounts of protein are associated with adverse health effects, according to the IOM. Any protein you consume that your body doesn't need is excreted through bodily waste. Too little protein in the diet, however, is called protein-energy undernutrition, and it can lead to severe impairment of your vital organs, dehydration, problems dispelling bodily waste and possibly death. A diet consisting of 10 percent protein should be thought of as the minimum amount necessary to maintain health.
Protein exists in both animal and plant sources. The best way to ensure adequate protein intake is to consume a wide range of meats, grains and vegetables. Fish and poultry are generally better than red meat because they have similar protein content but much less fat. Dairy products offer plenty of protein but can also be high in saturated fat and cholesterol. Try to consume low-fat dairy products when possible. Legumes, beans and whole-grain products are the best plant sources of protein, particularly soy.
- MedlinePlus: Protein in Diet
- KidsHealth: Learning About Proteins
- Institute of Medicine: Dietary Reference Intakes; Macronutrients
- Merck Manuals: Protein-Energy Undernutrition
- Harvard School of Public Heath: Protein
- Columbia University: Go Ask Alice: Do Bodybuilders and Weight Lifters Need More Protein?
- Centers for Disease Control and Prevention: Protein