Getting enough protein is essential to eating a healthy diet. Protein comes from two sources: animals and plants. Why is this macronutrient important, and which food sources are best?
Why Is Protein Important to a Proper Diet?
Protein serves many functions in the body, including building and repairing tissue such as muscle, skin and blood. It also plays a key role in supporting the immune system and hormone function, as well as providing essential enzymes, vitamins, and blood-clotting factors.Your body can use protein for energy as well. Because it is essential to other important body functions, you must consume enough carbohydrate and fat so all of your protein intake is not used for energy. This is why nutrition experts recommend eating a balance of the three main macronutrients: fat, protein, and carbohydrates. Balancing the macronutrients allows you to eat healthfully to support your body's energy, growth, and repair needs.
Which Sources Are Best?
Proteins are made up of smaller particles called amino acids. There are nine amino acids your body cannot make on its own, so you must take them in through food. These are called essential amino acids.
Animal sources of protein are considered high quality because they contain all of the essential amino acids your body needs. Some animal sources include:
- Meat, such as beef, pork, lamb, and game meats
- Dairy and whey
Plants can provide a full complement of protein if you combine plant sources so you get all nine essential amino acids. For instance, combining legumes with grains or corn makes a complete protein. Plant sources include:
Many people receive macronutrients from animal sources. Because animal sources sometimes have a high amount of saturated fat and cholesterol, which can lead to heart disease, the USDA recommends eating proteins from lean sources such as fish, white meat poultry, shellfish, soy, egg whites, and combined plant foods.
In addition to protein, plant sources provide fiber and phytochemicals. Both animal and plant sources provide minerals such as magnesium, iron, and zinc. As long as various sources are included in the diet, you shouldn't have any trouble getting all of the amino acids your body needs. Vegetarians and vegans who limit or eliminate animal based foods may experience more difficulty getting adequate protein. Because of this, they should seek high-quality sources of plant protein, such as soy, and carefully plan meals to ensure they get all of the amino acids their body needs for tissue growth and repair.
According to the National Academies of Science, Engineering and Medicine, you should eat about 10 to 35 percent of your daily calories from protein. Based on a 2000-calorie diet, this is approximately 200 to 700 calories of protein, or about 50 to 175 grams (6.25 ounces). If you need fewer calories, you should eat less protein, while athletes may need more protein to help repair muscle tissue. Remember that three ounces is about the size of a deck of cards.
Too Much Protein
Experts express varying opinions about getting too much protein in the diet. Some low-carbohydrate dieters exist on mostly animal protein and leafy greens, for instance. Many experts, including MayoClinic, caution against high protein diets, suggesting high-protein diets:
- Are low in fiber, which can lead to bowel problems
- Are high in saturated fat, which may lead to heart disease
- May create too much load on the kidneys, which can lead to kidney problems
Other experts, including Dr. Robert Atkins and Drs. Michael and Mary Dan Eades suggest eating protein more closely resembles how our hunter-gatherer ancestors ate, so it may be a healthier way of eating for today's human beings.
If you are not sure how much protein you need to support your nutritional needs, talk with your doctor or a nutritionist. Getting a little professional advice can help shine light on the nutritional strategy best for you.