Proteins are often called the body’s building blocks. Protein forms the major structural components of muscle, the brain, nervous system, blood, skin and hair. It aids in fighting infection because proteins form enzymes that help to create antibodies. Proteins serve as the transport mechanism for iron, vitamins, minerals, fats and oxygen.
Proteins are made up of small units called amino acids. Twenty amino acids are needed in the diet of healthy adults. Nine amino acids are essential, meaning the body can’t make them so they must be ingested from the foods we eat.
Proteins are classified as complete or incomplete. A complete protein contains all of the essential amino acids in amounts proportional to need. Animal products, such as chicken and eggs (with the yolk), are examples of complete proteins. Incomplete proteins are low in one or more essential amino acids. Plant foods, such as beans and nuts are examples of incomplete proteins.
A food that supplies an incomplete protein doesn’t make it a poor food choice. It simply means that it does not contain the essential amino acids. Eating a variety of foods throughout the day allows a person to obtain an adequate supply of all essential amino acids. Below are some examples.
Complete Proteins
- Meat (beef, pork, lamb)
- Poultry (chicken, turkey, duck)
- Fish and seafood
- Eggs (with the yolk)
- Dairy (milk, cheese, yogurt)
- Soy foods
- Quinoa
- Chia seeds
Incomplete Proteins
- Nuts and seeds
- Grains
- Vegetables (broccoli, spinach, asparagus, artichokes, potatoes, sweet potatoes, brussels sprouts)
- Beans (garbanzo, black, kidney, pinto)
- Peas
Current government guidelines for adults recommend 0.8 grams of protein per kilogram of body weight. Adults over 65 may need higher levels of protein. One study published in the American Journal of Physiology (2015) showed adults age 52 to 75 who increased protein consumption showed increased rates of muscle protein synthesis (the process cells use to build muscle).
To calculate how many grams of protein is recommended by weight in pounds, divide weight by 2.2 to convert to kilograms and multiply by 0.8.
Example:
Person weighing 175 pounds:
175 / 2.2 = 79.55 kilograms
79.55 X 0.8 = 64 grams of protein recommended daily
With age comes a natural loss in some muscle mass and strength. This gradual loss of muscle mass, termed sarcopenia, decreases physical function and increases risks of falls and bone fractures. While many factors influence the rate of sarcopenia, an increase in quality protein may positively contribute to an increase in muscle mass.
While higher amounts of protein are beneficial for older adults, too much protein or excess protein required for daily functions, may be stored as fat or converted to glucose and stored as glycogen. This is more likely to occur when overeating during a meal. Spreading the intake of protein throughout the day, as opposed to consuming most protein with the evening meal, is the best way to stimulate muscle protein synthesis and enhance the benefits of exercise. Older adults should strive to eat protein at each meal and with snacks to maintain and build muscle.
General information regarding recommended daily allowances for nutrients and information on the Dietary Reference Intakes (DRIs) will be discussed in Unit 3.
Amount of protein in some foods (represented in grams)
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Brussels sprouts (1/2 cup) 2g
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Broccoli (1 cup) 3g
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Avocado (1 cup) 3g
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Long brown rice (1 cup) 4.5g
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Almonds (1/4 cup) 5g
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Egg (1) 6g
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Hummus (1/3 cup) 6g
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Whole milk (1 cup) 8g
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Quinoa (1 cup) 8g
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Tofu (1/2 cup) 10g
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Oatmeal (1/2 cup raw) 13g
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Hamburger patty (4 oz) 15g
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Greek yogurt (1 cup) 17g
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Salmon (3 oz) 18g
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Lentils (1 cup) 18g
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Lean beef (3 oz) 22g
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Cottage cheese (1 cup) 22g
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Turkey breast (3 oz) 24g
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Chicken breast (3 oz) 26g
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Beef, sirloin (3 oz) 26g
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Tuna (1 cup canned) 39g
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Steak (8 oz) 60g
SilverSneakers instructors can be a positive influence in helping class participants improve their protein consumption. Encourage class participants to increase quality protein throughout the day. Explain how healthy food choices before and after class can benefit muscle development and improve strength.