Every cell in your body contains protein, a macronutrient made up of chains of amino acids, the so-called building blocks of life. It helps keep your body running smoothly, from aiding in digestion and regulating hormones, to speeding up exercise recovery and supplying blood with oxygen.

Yet unlike fats and carbohydrates, the other two nutrients you need most, protein doesn’t get stored in your body, explains Simin Levinson, M.S., a registered dietitian nutritionist and clinical professor in the College of Health Solutions at Arizona State University.

“Humans typically are protein-sparing, meaning that although we can use protein for energy—we have the metabolic pathways to do so—it is preferable that carbohydrates and fats are the predominant sources of fuel,” Levinson tells Fortune. “That’s because protein plays such a critical, functional role…and if that protein isn’t provided, we start breaking down body tissues in order to produce those amino acids.”

Plenty of foods naturally contain protein, but demand for protein supplements continues to surge. The global protein supplement market was valued at $5.8 billion in 2022, with a projected 8% compound annual growth rate through 2030, according to Grand View Research. Below, Levinson and other nutrition experts share three things to consider before buying your next tub of protein powder.

Choose whole foods over protein powder when possible

There’s no denying the convenience of protein powder; you can prepare it in seconds, with no refrigeration or cooking involved. However, the supplement may not fuel your body with the variety of proteins that come from a balanced diet of whole foods, Levinson says: “We have many great sources of protein available in the Western diet.”

Nine of the 20 different amino acids are considered essential, meaning your body can’t make them on its own and they must be obtained through food. Foods that contain all essential amino acids are called complete proteins and tend to be animal-based. Soy, quinoa, and hemp seeds are among the few plant-based complete proteins, which can help vegans and vegetarians round out their protein intake.  

The 2020–2025 Dietary Guidelines for Americans include these protein sources:

• Meats, poultry, and eggs
  • Beef, game meat, goat, lamb, and pork
  • Chicken, Cornish hens, duck, game birds, goose, and turkey
  • Chitterlings, giblets, gizzard, liver, sweetbreads, tongue, and tripe
  • Chicken eggs and other birds’ eggs
• Seafood
  • Anchovy, black sea bass, catfish, clams, cod, crab, crawfish, flounder, haddock, hake, herring, lobster, mullet, oyster, perch, pollock, salmon, sardine, scallop, shrimp, sole, squid, tilapia, freshwater trout, light tuna, and whiting
• Nuts, seeds, and soy products
  • Peanuts and tree nuts
  • Nut butters
  • Chia, flax, pumpkin, sesame, and sunflower seeds
  • Seed butters
  • Tempeh and tofu

Most protein powders on the market contain high-quality proteins, says Roger Fielding, Ph.D., a professor at the Tufts University Friedman School of Nutrition Science and Policy. However, they can also leave key nutrients out.

Whey, for example, is a byproduct of manufacturing cheese. Consuming a whey protein supplement in isolation may fuel you with milk protein, but drinking a glass of milk instead will also provide calcium and vitamin D, Fielding explains.

“We always want to encourage people to get their nutritional requirements from food sources,” Fielding tells Fortune, “largely because there’s probably other components in those foods that are healthy, that also may be important for us to consume.”

FDA doesn’t approve premarket protein powder

Keep in mind protein powder is a dietary supplement, not a substitute, stresses Tyler Becker, Ph.D., an assistant professor in the Department of Food Science and Human Nutrition at Michigan State University. And because it’s a supplement, the Food and Drug Administration (FDA) isn’t authorized to approve it for safety and effectiveness before it hits your pantry.

“You don’t really need protein powder; the average person does not,” Becker tells Fortune. “A lot of athletes do not as well, except under certain situations, and the reason [why] is related to the regulation of it.”

The FDA does regulate such supplements, but usually after they’re on the market, leaving the onus of accurate labeling on manufacturers. Class-action lawsuits have accused some companies of “protein spiking,” using cheaper, free-form amino acids rather than the proteins advertised. The FDA has also sent several companies warning letters, deeming their protein products “adulterated dietary supplements.” 

Some types of protein powders may contain toxins. The nonprofit Clean Label Project in 2018 tested more than 130 top-selling powders for heavy metals and other contaminants. More than half contained bisphenol A (BPA), an industrial chemical that may cause cancer or other health problems. One powder had 25 times the allowed limit of BPA in a single serving.

On the whole, though, protein supplements are safe, says Fielding, who sometimes consumes whey powder himself. Becker recommends consulting a registered dietitian if you plan to incorporate protein powder into your diet—particularly if you’re vegan or vegetarian and don’t want to miss out on necessary nutrients. Because dietary supplements may interact with some medications, the FDA also advises asking your doctor if they’re appropriate.

Healthiest protein powder is unique to you

Protein powders are a dime a dozen, sold in countless flavors, sizes, and protein sources at drugstores, grocery stores, wholesale retailers, and online marketplaces. But buyer beware: The more exotic the flavor, the more likely the powder may contain added sugars or artificial sweeteners.

Powdered supplements are often derived from these proteins:

• Casein and whey, from cow’s milk
• Hemp, from hemp seeds
• Pea, from yellow split peas
• Soy, from soybeans

The options may feel overwhelming, but the best protein powder is the one that complements your taste, diet, lifestyle, and overall health, according to Levinson. Whey protein has long been the gold standard among athletes because of its rapid digestion and assimilation, says Levinson, the consulting sports dietician for the WNBA’s Phoenix Mercury and formerly for the NBA’s Phoenix Suns.

“But nowadays, there are some plant-based protein powders that are formulated so well that they provide a great source and the same amount of protein,” she tells Fortune. “Within the WNBA and within the NBA, there is a trend of athletes choosing more plant-based options for their food and for their supplements.”

The FDA generally recommends consuming 50 grams of protein daily, but you may need more depending on your age, weight, and level of physical activity.

“If you’re physically active, whether you’re doing endurance exercise or weight lifting, you want to think about upping that to maybe 75 to 100-plus grams per day,” Fielding tells Fortune. “Start thinking about where the sources of protein can come from in your diet.

“If you’re trying to get up to that 100-plus grams per day, taking a whey protein supplement where you can get 20 to 25 grams in a scoop…that’s probably not a bad idea.”

For more on incorporating protein into your diet:

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