By now you’ve definitely heard of (and probably tried) Beyond Meat and Impossible Foods burgers. These brands shook up the fast food world with alt-beef. Now, a growing number of big food names are joining the alt-meat ranks to go…beyond beef, so to speak. Taco Bell is testing using “pulled oats” for vegan pulled chicken in certain locations in Europe. Canned tuna giant Bumble Bee just announced a partnership to distribute and market the vegan alt-fish brand Good Catch. And Nestlé announced its own vegan tuna salad in partnership with food science brand Burcon.

“Alt-meat is having a huge moment, and it’s going to grow,” says Brigitte Zeitlin, MPH, RD, a New York City-based nutritionist.

There’s a reason for all of the excitement: Decades of research has linked red meat consumption to heart disease, and the World Health Organization labels red and processed meats as carcinogenic. A panel of international health and climate experts published a recommendation in the journal The Lancet last year to eat less than 50 grams (about 1.8 ounces) of eggs, fish, sugar, and meat a day to combat climate change.

But do all alt-meat products necessarily trump their real-world counterparts in terms of nutrition and environmental sustainability? The reality is nuanced.

Are meat alternatives better for the environment?

Plant-based products are generally better for the environment than animal meat, says Sujatha Bergen, the director of health campaigns for the National Resources Defense Council. Animal farming requires huge amounts of land, grains, and water. In fact, the livestock industry accounts for 14.5 percent of all human greenhouse gas emissions, according to the Food and Agriculture Organization.

Bergen reviewed Beyond Burger’s and Impossible Burger’s proprietary environmental impact assessments and says that, taking the reports at face value, they have a much lower climate impact and water and energy use than conventional beef burgers. For now, she’s not aware of independent research on other types of alt-meats—likely because they are so, so new to the market.

But alt-meat companies may be solving one set of ecological problems by adding to another: systemic issues in food production. Soy, for example, is a common ingredient in alt-meat burgers, and in the U.S. it’s largely genetically modified and grown on monoculture farms. Monoculture farms plant the same crop year in and out on the same land—a practice that has been noted to degrade soil quality so that farmers need to use more fertilizers and pesticides (which, by the way, are made with fossil fuels) to grow their crops. “That creates un-resilient farms that can’t withstand climate change,” says Bergen.

As these companies grow, it’s critical that they work with farms that follow sustainable or regenerative agriculture practices like crop rotation to avoid adding to environmental issues, rather than just coasting on the idea that by not using meat, they’re doing good enough for the environment. “I hope these companies will put real thought into their options,” Bergen says.

Are alt-meat burgers better for your health than the real thing?

The nutritional argument for alt-meat is more complex. Eating too much animal protein, especially red meat, can be problematic because it’s high in heart-unhealthy unsaturated fat. However, many alt-meat products use coconut oil—which is equally high in saturated fat, note nutritionists. “I’m wary of alt stuff, because you think you’re doing something healthier for yourself when you’re not,” says Zeitlin.

You’ll also get a lot more sodium— upwards of 400 or 500 mg—per serving in alt-meat than animal meat, since salt helps preserve shelf life and boosts flavor. “Salt is a huge contributor to high blood pressure,” says Zeitlin, and it can increase inflammation throughout your body. The American Heart Association recommends 2300 mg of sodium total daily, which adds up quickly.

Alt-meats also often contain soy, pea, or wheat protein isolate, wheat gluten, and a touch of sugar. “I wouldn’t look say these ingredients are bad or dangerous for you, but you’re not eating whole, simple foods,” says Lisa Moskovitz, RD, the CEO and founder of New York Nutrition Group. “You’re getting such a mix of additives and preservatives…in order to make it taste good.”

Thus, when you choose any alt-meat product, check the ingredients list. The first three ingredients, which make up the bulk of the product, should be whole foods you recognize, like tofu, whole grain rice quinoa, and beans. If not (and especially if one of those ingredients is salt or sugar), skip it, suggests Zeitlin. Aim for at least three to five grams of fiber per serving, she suggests, and avoid products made with coconut oil. And use potato chips—an inherently salty food—as a reference point for sodium: a single serving contains 170 to 180 mg.

So how do alt-meats stack up?

Want to add a bit of alt-meat to your diet? Here’s how the various alt-meat options stack up:

Beef or sausage: your best alt-meat swap

If you want to swap just one alt-meat product for environmental and health reasons, experts say choose beef. Beef is the biggest greenhouse gas contributor in our diets. Some research suggests that every calorie of beef we consume requires 28 times more land and 11 times more water than the average of other livestock products (dairy, poultry, pork, and eggs). “Beef production is so climate-intensive that replacing it with almost anything else is better from a climate perspective,” says Bergen. “One of best things can do in your individual life to tackle climate change is to cut your beef consumption.”

From a nutrition perspective, red meats and processed meats (like sausage) are high in saturated fat, which raises blood cholesterol and puts you at greater risk of heart disease. That’s not to say there aren’t health benefits to occasionally enjoying lean red meat: It’s a good source of iron, zinc, B vitamins, and complete protein. But experts agree it’s safest to eat it once or twice per week max (less if you’re at higher risk of heart disease). If you’re currently eating red meat more than once per week, Moskovitz says it’s a good idea to switch to an alt-meat option (or better yet, fresh lean poultry or fish).

For more on how healthy these alt-beef products are, check out this video from a top dietitian:

Chicken: an OK alt-meat swap once in a while

Poultry farming has a lesser climate impact than cattle farming, notes Bergen; chickens require less land and food, and they don’t produce the same methane gases. However poultry farming creates water pollution that has been linked to dead zones in the Chesapeake Bay.

Like red meat, poultry is a great source of bio-available iron, zinc, B vitamins, and complete protein, and it’s generally lower in heart-unhealthy saturated fat than beef—so nutritionists typically don’t put the same restrictions on poultry consumption as they do for red meat. If you’re craving alt-chicken, enjoy it once in a while. Just don’t assume it’s doing your health many favors—unless you’re eating it in place of dark meat poultry or fried chicken.

Fish: you’re mostly better off eating the real thing

Nutritionists want us to eat more fish, since most of us don’t get enough—and the omega-3 fatty acids in fish actually help lower your cholesterol levels, and plant-based sources of omega-3s (which are added to many alt-fish products) are often less bioavailable than those found in animals. We should aim for at least 8 to 12 ounces of fatty fish (that’s two to three servings) per week. Moskovitz says unless you’re pregnant and need to watch mercury levels in some types of fish, there really are no limits on fish unless it’s fried.

While fish overall has a smaller climate impact than cattle or poultry, the seafood industry negatively impacts ocean ecosystems. “Many species of tuna are endangered by overfishing,” says Bergen. Reducing your consumption of certain types of seafood makes a big difference; check out the Seafood Watch’s or Marine Conservation Society’s lists to learn more about the types of fish to avoid.

Otherwise, for a healthier and more plant-based diet, you’re better off eating more whole foods: nuts, seeds, whole grains, beans, tofu, peas, and lentils. Miss meat patties? Cook up your own using fish, beans, or lentils. “If you’re making it yourself, you don’t need extra salt to preserve shelf-life,” says Zeitlin.