Protein supports muscle growth, helps with transport of oxygen to the blood and is intrinsic to the development of skin, hair and nails. The Harvard School of Public Health notes that consuming an inadequate amount of protein causes growth failure, degradation of muscle mass, poor immunity and decreased function of the heart and respiratory system. The minimum amount of protein you should eat per day, according to the Institute of Medicine, is 10 percent of your daily calories. Choose lean protein sources to minimize your intake of saturated fat.
Meat and Fish
Meat, like beef, pork, lamb and bison, is an excellent source of protein. When choosing meat, it is important to consider what comes along with the protein, however. Six ounces of porterhouse steak provides 38 grams of protein, but it is exceptionally high in saturated fat. Over-consumption of saturated fat can put you at risk for the development of chronic diseases like diabetes and cardiovascular disease. Select lean cuts such as tenderloin and flank steaks. Consider limiting your overall intake of red meat to only once or twice per week, and consume a portion of 6 ounces or less. Fish is a good source of protein that also provides heart-healthy omega-3 fatty acids, vitamin D and selenium. Omega-3 fatty acids help improve heart health. In an article surveying 20 studies about fish consumption and heart health, the "Journal of the American Medical Association" reported that there is strong evidence that eating one or two 3-ounce servings of fatty fish a week reduces your risk of dying from cardiovascular disease by 36 percent. Salmon, mackerel, anchovies and sardines offer the most benefits.
Soy is the only vegetable that offers a complete amino acid profile. Soy protein is available in the form of soybeans -- like edemame -- tofu and meat “substitutes.” The Harvard School of Public Health recommends eating two to four servings of soy per week. Evidence that soy is a "wonder food," offering help with menopause symptoms, preventing some cancers and helping with weight loss, is still inconclusive.
Eggs are an inexpensive, versatile source of protein. One large egg contains 6 grams of protein, 4 grams of which are contained in the white. Eggs do have a lot of cholesterol, but recent research -- as noted by the nutritionists at Harvard -- suggests that dietary cholesterol does not strongly affect human blood cholesterol. The fact that eggs contain a number of important nutrients like vitamins B-12 and D and minerals such as riboflavin and folate make them a good addition to any diet. If you are concerned about cholesterol, make the most of your egg dishes with the whites. Eggs also offer greater satiation and can contribute to weight control as evinced by a study in the "Journal of the American College of Nutrition" in 2005. When researchers compared participants’ sensations of fullness after eating either a bagel-based breakfast or egg-based breakfast, it was noted that the egg breakfast induced greater satisfaction and led to less overall short-term food intake.
Nuts, Seeds and Legumes
Nuts, seeds and legumes are major sources of protein, especially if you consume a vegetarian diet. According to a report from Nutrition for Life, nuts and seeds contain 10 to 25 percent protein, and some of the best sources to choose are pumpkin, sesame and sunflower seeds and almonds, Brazil nuts and pistachios. The legume family consists of beans, peas and lentils. They are not only packed with protein, they are a high source of fiber and other important nutrients. Legumes are also low-glycemic, which means they do not raise blood sugar levels if you have, or are at risk, for diabetes.