Protein is an essential part of the diet because it provides amino acids the body needs to function correctly. People need daily protein sources from their food, which they can get from animal or plant proteins.
This article looks at how much protein someone needs each day and why this amount may vary. It also describes amino acids, their role in the body, and the effects of protein deficiency. Finally, it includes sources of protein and tips to get enough protein in the diet.
Protein is a macronutrient, and each gram provides four calories.
Amino acids are the building blocks of proteins in food. In nutrition, amino acids are either essential or non-essential. People need to consume essential amino acids in foods.
When a single protein source contains all nine essential amino acids, nutritionists refer to it as a “complete protein.” Animal-based proteins such as meat are complete sources of protein. People who eat a plant-based diet can obtain all of the essential amino acids by eating a combination of foods.
According to the Dietary Guidelines for Americans 2020-2025, people need different amounts of daily protein depending on their age and sex. Those amounts include:
- 56 grams (g) for adult males
- 46 g for adult females
- 34 g for children aged 9-13 years
- 13 g for children aged 2-3 years
A person who is pregnant or breastfeeding requires 71 g of protein per day.
Experts base guidelines on healthy adults who do minimal activity. People who do more activity or who build muscle through exercise may require more protein in their diet, although recommended amounts vary.
For a person doing moderate to intense physical activity, the recommended intake is between
However, the International Society of Sports Nutrition recommends higher levels of
People can also calculate the amount of protein they need by using the guidelines of
Protein is an essential part of the diet, and the body needs it for numerous processes.
The United States Food and Drug Administration (FDA) advise that protein plays roles in the following aspects of human health:
- ensuring correct growth and development, especially during childhood, adolescence, and pregnancy
- building and repairing cells and body tissues
- maintaining and building healthy skin, hair, nails, muscle, bone, and internal organs
- producing hormones, neurotransmitters, antibodies, and enzymes
- helping blood to clot, balancing fluids, and supporting the immune system
The body incorporates dietary amino acids into skeletal muscle and other tissues as needed. During fasting or stress, the muscles can release the amino acids for the body to utilize.
The Dietary Guidelines for Americans 2020-2025 recommend that people vary the sources of protein they eat, and limit or avoid saturated fat sources such as processed and red meat.
Sources of protein include:
- meat and poultry such as beef, lamb, pork, chicken, turkey, game, liver, and sweetbreads
- chicken and other birds’ eggs
- dairy products, including milk, yogurt, cheese, and cream
- seafood such as white fish, oily fish, scallops, shrimp, crab, and oysters
- nuts and seeds, including Brazil nuts, cashews, hazelnuts, almonds, walnuts, hemp seeds, pumpkin seeds, chia seeds, and sunflower seeds
- beans and pulses such as lentils, chickpeas, black beans, navy beans, butter beans, and cannellini beans
- soy products, including tofu, natto, tempeh, soy milk, and soy yogurt
- plant-based proteins such as seitan and mycoprotein
According to a
The Dietary Guidelines for Americans 2020-2025 suggests that about three-quarters of Americans meet or exceed the recommendation for consumption of meats, poultry, and eggs. However, almost 90 percent do not meet the guidelines for seafood, and more than half do not meet the recommendation for nuts, seeds, and soy products.
A lack of essential amino acids can not only occur in developing countries but also in older adults with inadequate care.
- stunted growth in children
People can get enough protein by including suitable food sources in each meal and snack.
Here are some meal ideas for how a person can incorporate more poultry, eggs, dairy, fish, and lean meats into their diet:
- chicken breast, sweet potato, and greens
- scrambled egg with tomato and spinach
- pancakes with Greek yogurt and fruit
- salmon, purple sprouting broccoli, and sweet potato mash
A person following a vegetarian or vegan diet needs to ensure they get all the essential amino acids by including various types of protein. Here are some suggestions for the kinds of meals that can help a person incorporate sufficient protein:
- Bolognese made with lentils and zucchini noodles
- vegetable soup served with oatcakes
- protein powder smoothie with fruit and oat milk
- crispy tofu bowl
- vegetable and hummus wrap
People can ensure they get enough protein by including varied sources in their diet every day. Meat, fish, and dairy products are complete sources of protein. Eating a variety of different plant sources ensures that people eating a plant-based diet get essential amino acids.
People can add beans, nuts, and seeds to their meals as additional protein sources, or try adding protein powder to smoothies. Consuming up to 2 g of protein per kilogram of body weight a day is safe for healthy adults.