Today, we are going to talk about protein. I’m sure you know that your muscles contain protein, and you probably know that there is protein in your hair, bones, skin and all of your other body parts, too.
Proteins do a lot of important things in addition to their structural roles in things like your muscles and bones. They make the antibodies to fight off illness, enzymes to make the everyday chemical reactions like digestion go smoothly, messengers to coordinate biological processes and transporters to carry atoms and smaller molecules to where they are needed. Our bodies make all these different types of proteins we need to stay alive, which may leave you wondering what are proteins and what are they made of.
Proteins are very large molecules that are made up of chains of many smaller and relatively simple molecules called amino acids. There are nearly 300 different amino acids that occur in nature, but there are only 20 that your body needs to make the thousands of different proteins doing all the different types of jobs in your body.
Your body can make many of the amino acids you need either from scratch or by modifying the ones you get from eating. There are nine that you have to get from the foods you eat. When you eat foods that contain protein, your body breaks it down into amino acids and uses them to make the proteins that it needs.
Proteins are found in meat and other animal products as well as in plant foods like vegetables, beans, nuts, seeds and grains. All food contains protein, but some foods are richer sources than others. All 20 of the amino acids you need are found in any one meat or other animal product, whereas different plant-based sources will be missing a few and not always the same ones from plant to plant. That is why it is important for vegetarians and vegans to eat different types of plant-based proteins. A general rule is that grains and beans are “complementary” protein sources and that eating both are important if you choose to get your protein from plant foods. You don’t need to eat them in the same meal, but I recommend that they be eaten in the same day if they are your main source of protein.
It’s recommended that adult women get about 46 grams of protein per day and men get 56. Exactly how much you need will vary based on your size and activity levels. If you are doing intense exercise you will need more. It is also recommended that older adults eat a little more protein to prevent age related loss of muscle. How do you get that protein? As an example, to get 20 grams of protein you could eat 3 ounces of meat or fish, 12 ounces of yogurt, a half cup of tofu, 3 eggs or 8 ounces of beans. A cup of skim or whole milk has 8 grams of protein. It takes a lot of milk to get a substantial amount of protein, so I don’t recommend it as a major protein source.
I recommend that a good share of your protein come from plant-based sources to help you maintain a healthy weight and cholesterol level. Whether you choose to get your protein from meat, dairy or plants it is important to eat a variety of foods: plenty of vegetables, some fruit, lots of fiber and to vary to foods that you eat. If you tend to eat the same thing every day it is more likely that you will be lacking in one or another nutrient. You have all heard that man cannot live on bread alone. It turns out that he can’t live very well on meat or beans and rice or any other narrow choice of foods either.
Bob Riggs is a family medicine physician practicing at Kaiser Permanente’s Riverfront Medical Center. His column appears biweekly in The Spokesman-Review.