This article explains why protein is important in the diet and discusses recommended intake levels. This article also lists 10 high quality sources of protein that can help you meet your daily nutritional needs.
Protein is a macronutrient, a type of nutrient which the body needs in large amounts to maintain the healthy function of the body. Other macronutrients include carbohydrates and fats.
At least 10,000 different types of protein contribute to the body’s structure and function. As a result, protein is an essential component of a healthy, balanced diet.
Protein is made up of substances called amino acids. When you eat protein, your digestive system breaks down the protein into amino acids. Your body absorbs and uses the amino acids for functions such as building and repairing muscles and bones, and producing and regulating hormones and enzymes.
While there are many amino acids, there are nine specific amino acids that the body cannot make itself and that must come from food.
What are the benefits of eating protein?
Eating high quality, high protein foods helps you meet the daily nutritional demands of your body to help you:
- recover after exercise or injury
- support muscle growth
- build lean muscle
- maintain a healthy weight
- curb hunger
- Maintain muscle mass during aging
Not having enough protein results in protein deficiency. Complications of protein deficiency include:
- sarcopenia, muscle wastage or shrinkage
- loss of muscle strength or function
- edema, the buildup of fluids
- slow growth
A 2015 meta-analysis of the role of protein benefits in weight loss and maintenance suggests that a high protein weight loss diet provides concerning body weight and fat mass. Additionally, researchers suggest that higher protein diets may improve risk factors for cardiometabolic disease.
Read on here for more information about muscle weakness.
How much protein do you need?
The current recommended dietary allowance (RDA) for healthy adults with minimal physical activity is about 0.8 grams of protein per kilogram of body weight (g per kg BW) per day. So, for example, a person weighing 75 kg (166 pounds) would need to eat a minimum of 60 g of protein per day.
However, this requirement may increase as people age or increase their activity levels.
A 2016 review suggests that for minimal, moderate, and intensive physical activity, you need a dietary protein intake of 1.0, 1.3, and 1.6 g per kg BW, respectively.
Up to 2 g per kg BW per day may be safe for most healthy adults. Consuming more than this for a long time may be harmful to your health.
Children have different nutritional requirements. These requirements will vary depending on individual factors such as age, sex assigned at birth, BMI, and recommended calorie intake.
The table below summarizes the current average recommended dietary reference intakes of protein for children.
Infants younger than 1 year old may typically meet their protein requirements from breast milk or formula.
Healthy sources of protein
Protein is present in both animal-based and plant-based foods. Sources of protein that contain all nine essential amino acids are “complete” proteins. These include:
- blue-green algae
The Department of Agriculture (USDA) and the Department of Health and Human Services (HHS) recommend eating foods from a variety of subgroups to include a broad variety of nutrients.
The USDA and HHS note that many people in the United States eat close to the recommended amounts of protein. However, almost 90% of people do not meet the target recommendation for specific protein subgroups. These subgroups include:
- meat, poultry, eggs
- nuts, seeds, soy products
The USDA and HHS suggest that about 3 out of 4 Americans exceed the recommendation for meat, poultry, and eggs, while not meeting the recommendations for nuts, seeds, and soy products.
The USDA and HHS also note that protein intake ideally should not be from processed meats.
The National Health Service recommends eating no more than 70 g per day of red or processed meat.
Many clinicians specify the intake of “high quality” protein to satisfy the body’s nutritional needs. High quality protein foods have all of the essential amino acids, and, if meat, are lean cuts.
Following are 10 foods that are good sources of high quality protein and examples of how much protein they provide.
Fish is a lean source of protein. Some examples of lean fish and their protein content per 100 g portion (about 3.5 oz) are:
- cooked salmon, 22.1 g
- canned light tuna, drained, 25.5 g
- steamed or boiled shrimp, 17.4 g
- smoked haddock, 25.2 g
For a 100 g portion, these poultry options provide the following amount of protein:
- cooked, skinless chicken breast, 32 g
- ground turkey, 27.1 g
- turkey sausages, 16.7 g
Meats other than poultry, such as beef, pork, and lamb, are high in protein. However, they also can be high in fat. For a meat option that is high in protein and lower in fat, choose leaner cuts of meat or trim any visible fat.
Ground beef (93% lean meat) and roasted ham offer between 26–29.4 g of protein per 100 g.
While processed meats are high in protein, they can be lower quality protein sources. Frankfurter hot dogs contain about 7 g of protein per hot dog, or 57 g serving. Three pork links contain about 8 g of protein. Two fried slices of bacon offer about 5 g of protein.
Ounce for ounce, cottage cheese has more protein than milk and some other dairy products.
Half a cup of low fat cottage cheese contains about 12 g of protein.
Add cottage cheese to salads, pasta dishes, dips, and even pancake batter to enhance the protein content and taste.
5. Soybeans and other legumes
The Food and Drug Administration (FDA) and World Health Organization (WHO) give soybeans the highest possible score for protein quality.
Cooked soybeans provide as much as 14 g of protein per half cup serving.
Other legumes include fresh and dried beans, peas, lentils, chickpeas, and peanuts. Some examples of the protein provided in a 100 g portion are:
- dry kidney beans, 25.9 g
- boiled peas, 5.3 g
- boiled lentils, 9 g
- raw peanuts, 26 g
One 2016 study also suggests that heating legumes, such as chickpeas, improves the protein quality. The heating process can inactivate some anti-nutritional components.
Legumes offer diverse ways of providing protein in the diet. Preparations such as chickpea hummus offer 14 g of protein per four tablespoons.
This thick and creamy variety of yogurt has more protein than regular yogurt.
Plain whole-milk Greek yogurt offers more than 8 g of protein per 100 g. Nonfat Greek yogurt offers more than 10 g of protein.
Pumpkin seeds are especially rich in protein. Unsalted, shelled pumpkin seeds offer about 8.5 g of protein per ounce.
Other nuts and seeds, such as walnuts, almonds, and sunflower seeds, are a healthy addition to the diet as they contain many important nutrients.
Many seeds and nuts contain 20–21 g of protein per 100 g serving.
In addition to cottage cheese, many other cheeses are a great source of protein.
Cheddar cheese provides nearly 4 g of protein per slice (17 g portion). If you do not like the texture of cottage cheese, whole milk ricotta cheese is a good substitute. Ricotta cheese provides about 10 g of protein per half cup.
Eggs contain many nutrients and are high in protein. One large egg provides about 6 g of protein when scraped, hard-boiled, or fried.
Although the yolks are high in cholesterol, eating an average of one egg per day can be part of a healthy diet.
Grains are not particularly rich in protein, yet they can help meet your daily protein needs.
Quinoa, an ancient grain from the Andes, is higher in protein than most grains. One cup (about 185 g) of cooked quinoa has about 8 g of protein, more than twice the amount in a cup of white rice.
Protein supplements can provide extra protein in your diet, if you need it. Protein supplements are made from milk, eggs, peas, rice, hemp, soy, and other foods.
Before taking supplements, it is important to check with your doctor to see if supplements are a good choice for you. Supplements may have side effects or interact in a harmful way with medications you are taking.
Protein is an essential nutrient for the health of the body due to the amino acids it contains. These amino acids contribute to tissue formation and repair, energy, oxygenation, and hormone and enzyme regulation.
You can meet your daily protein requirements with high protein foods. These requirements vary depending on your weight, condition, age, and other factors.
The best dietary sources of protein include fish, lean meats, products, legumes, seeds, nuts, and eggs.
Talk with your doctor for advice on eating a healthy, balanced diet and what your daily dietary needs are. Always follow the advice of a doctor when implementing changes to your diet.