Your body needs protein—that’s a fact. The macronutrient performs many critical roles in the body, including helping to enable your cells, tissues, and organs to function. So yes, you need to eat foods that contain it, because while the body synthesizes many amino acids that make up protein chains, there are some the body can't produce,
After that, there's a lot of back and forth about how much your body needs, in what form (animal, vegetable or vanilla-flavored white powder poured in a giant plastic container to be sold at ye olde supplement shoppe) and whether the macronutrient itself can help you lose more weight or build more muscle. “The National Academy of Medicine also sets a wide range for acceptable protein intake—anywhere from 10% to 35% of calories each day,” Harvard's T.H. Chan School of Public Health Nutrition Source says. “Beyond that, there’s relatively little solid information on the ideal amount of protein in the diet or the healthiest target for calories contributed by protein.”
That leaves a lot of room for misconceptions to bloom. To help clear up some of the confusion, we went to the experts.
Myth #1: There’s no such thing as too much protein.
The truth: There are multiple reasons not to overdo it. While a high-protein diet may seem like a no-brainer, digesting protein raises blood levels of the waste product uric acid, which your kidneys help flush out of your body. Eat way more than you need (about 46 g per day for a 130-lb woman) and you can overtax the kidneys, leading to damage and conditions like gout, says Steven Gundry, M.D., director of the International Heart & Lung Institute for Restorative Medicine.
For most people, though, the issue is that keto- and Atkins-type diets consist of a lot of meat and eggs, which tend to be high in saturated fat and cholesterol, says Ruby Lathon, Ph.D., a nutritionist in Washington, DC, and those may up risk of heart disease and cancer. Plants are the best way to get protein—a 2020 study in BMJ found that replacing some red meat with protein from high-quality plant sources like beans, nuts, and soy might reduce risk of coronary heart disease. As for protein as a magic bullet for weight loss, whether excess calories come from beef or brownies, they “get converted to sugar, which gets stored as fat,” Dr. Gundry says.
Myth #2: You can’t get enough complete protein just from plants.
The truth: You can. Experts used to think you had to pair certain plant proteins to get a complete protein—that is, one containing all nine of the essential amino acids your body can’t make on its own. Now we know that you don’t have to combine plant proteins perfectly within one meal as long as you eat from a variety of food groups during the day. In fact, a 2019 review found that vegetarians who ate enough protein-rich food got more than enough protein and amino acids. Beans, nuts, and seeds can satisfy your daily requirements just as well as animal products (a cup of cooked black beans has 16 g, about 35% of your daily needs; a cup of edamame has 18 g, compared with 29 g in a 4-oz beef burger). Veggies contain less protein but do have some—especially broccoli, bean sprouts, green peas, and spinach.
Myth #3: Eating cheese is a great way to get protein.
The truth: If only. Listen, Brie babes: While cheese is high in protein (just 1.5 oz of Cheddar has 10 g), it has lots of sodium, calories, and cholesterol-raising saturated fat. The American Heart Association recommends limiting saturated fat to about 13 g a day (on a 2,000-calorie-per-day diet) and sodium to 2,300 mg a day, so having just 1.5 oz of Cheddar (an amount about the size of three dice) would give you more than half your saturated fat and use up more than 10% of your sodium budget for the day. Your best bet is to pick lower-fat options (think feta, mozzarella, and cottage cheese), says Ginger Hultin, a registered dietitian nutritionist at Champagne Nutrition, or keep portion sizes of the richer stuff petite. Either way, cheese shouldn’t be your main protein source.
Myth #4: Animal protein causes cancer.
The truth: It’s not that simple, and the good news for meat-eaters is that not all meats are created equal. When doctors talk about the connection between meat and cancer, they’re mostly referring to red meat and processed meats such as bacon, sausage, ham, and jerky. The World Health Organization considers processed meat a Group 1 carcinogen, which means there’s evidence to show that it can cause colon cancer in humans. Red meats like beef, pork, veal, and lamb are labeled as Group 2 carcinogens, with some evidence suggesting that they can up cancer risk. If you eat animal protein, Dr. Gundry recommends focusing on wild fish and shellfish, some chicken and duck, and eggs—foods that don’t have the Neu5Gc sugar molecule, which has been linked with cancer—rather than beef, pork, and lamb. Eating a diet rich in fruits, veggies, and fish, meanwhile, can actually reduce your risk of colorectal cancer by 43%, a JAMA Internal Medicine study found.
Myth #5: Protein powders and bars are a great way to up your protein intake.
The truth: Not so much. Many protein bars and powders are highly processed, with added sugars or other sweeteners, colors, and preservatives, Hultin says. And the more processed they are, the more sluggish they can make you feel, because processed foods can clog the mitochondria, the tiny organelles that turn food into energy for the body’s cells, says Dr. Gundry. Plus, it’s optimal to get protein from whole food sources so that you’ll also get other nutrients, like calcium and fiber, Lathon says.
Still, the occasional bar or powder can be convenient, says Hultin. Look for bars with at least 3 g of fiber and short, simple ingredient lists featuring items like fruits and nuts along with natural sweeteners like monk fruit and dates. Whatever name sugar is listed under (even if it’s honey or maple syrup), “be sure sugar isn’t the first ingredient,” Lathon says. “If it is, you’re pretty much eating a candy bar.”
This article originally appeared in the October 2021 issue of Prevention.