The growth of the plant-based meat sector started to take hold a decade back. Thanks to rapidly increasing sales, even traditional meat companies—those of the animal protein world—want in on the game. But as the sector matures, many people are beginning to ask tougher questions about the long-term potential of the trend, the nutritional value of the products, and whether faux meat production can really help reduce the harm traditional meat production causes the environment.

While companies that produce plant-based meat substitutes are pushing money into telling the public about the benefits of their products, the data behind the environmental and long-term health impacts of the products are just beginning to trickle in.

The Good Food Institute reports that the current retail market for plant-based foods is valued at $5 billion. In 2019, plant-based meats accounted for $939 million of those billions, a 38% jump from 2017.

And according to IRI, 14% of U.S. households are buying plant-based meat, driven primarily by growth in the refrigerated segment.

Still, plant-based meats make up only 1% of all dollar sales of total retail meat, according to the Good Food Institute.

Recent moves by animal-based meat producers make it clear that they see room for themselves in the plant-based market. “It’s still very early, which is exciting because there is so much growth still,” Jennifer Lamy, a sustainable seafood initiative manager with the Good Food Institute, told Fortune. “The big meat companies that are jumping into the space are indicating, either through their investments or their own product lines, that this is being perceived in the industry as a whole as an enormous shift, not just a fad.”

And it’s not just vegetarian millennials buying up the products.

During an earnings call with analysts, Beyond Meat CEO Ethan Brown said the company’s core customers are “people who are over 40” and are driven by health concerns, as well as environmental factors and animal welfare.

Other reports suggest that the majority of consumers of plant-based meats still like to chow down on beef burgers on other nights. According to the NPD Group, 90% of the consumers buying plant-based meat are neither vegans nor vegetarians.

“Building on the incredible success of the latest generation of plant-based burgers, we're seeing rapid product innovation across a wide variety of plant-based meat products from startups, leading [consumer packaged goods] companies, and even the world's largest meat companies,” said Good Food’s Bushnell. “This is a tipping point, with so much product innovation yet to hit the market.”

Big (faux) meat

What Beyond Burger, Impossible Foods, and other plant-based companies have accomplished in the past decade is no small feat.

Wall Street investors are paying attention; the big meat companies are watching their every move (Tyson Foods invested in Beyond Meat back in 2016); and new competitors continue to come on the scene.

A public company, Beyond Meat is the most heavily scrutinized player in the plant-based space. “One of the most interesting aspects of Beyond is the amount of money they spend on R&D, compared to an average food company. In some ways they are more like a tech company,” said Nigel Barrella, regulatory counsel at the Good Food Institute.

Beyond Meat’s promise is similar to that of a lot of venture capital darlings that pledge to make the world a better place. But, when it comes to environmental impact, the Good Food Institute rates the company the runner-up against the other big name in plant-based meats, Impossible Foods.

Launched in 2011, Impossible wants to eliminate animals from the food production system by 2035. “Animal agriculture is a prehistoric technology to turn plants into delicious protein. It’s also the most destructive technology on earth. There is a better way: meat from plants,” said an Impossible spokeswoman. The company closed on a $500 million funding round earlier this week, bringing the total for outside investment to $1.3 billion since 2011.

Beyond Meat declined to comment for this story.

As for expansion, during the investor call, Beyond’s Brown said the company is still just “scratching the surface” of the U.S. restaurant market and remains optimistic about moving into Europe, Asia, and the Middle East, despite concerns about the coronavirus outbreak.

“We continue to focus on Asia with the goal of producing in the region before the end of 2020, pending some level of resolution of the coronavirus crisis,” Brown said on the recent earnings call. “The magnitude of the opportunity merits significant investment. We believe that the core price in Asia provides an unprecedented opening to introduce new production models for meat.”

Beyond Meat reported a gross profit margin of 34% for the last quarter, meeting analysts’ projections, although a decline from the previous quarter’s gross profit margin of 35.6%. Sales during the fourth quarter of 2019 came in at $98.5 million, topping analyst estimates.

Despite concerns about margins and aggressive expansion risks, many Wall Street investors and industry analysts view Beyond Meat’s outlook favorably. “Beyond Meat should be a major beneficiary of PBM (plant-based meat) growth, given its first-mover advantage, and the brand’s strong performance in taste tests (consistently second only to privately held Impossible Foods),” said a research note from Morningstar. “Beyond has significant opportunity to expand into new product offerings (bacon, chicken nuggets) and geographies (Europe and Asia).”

There are still questions, however, about whether or not the company will be able to control consistency of its products as sales grows, in particular to fast-food chain restaurants across the United States. Fast-food chains that already sell Beyond Meat products include McDonald’s, KFC, Starbucks, and Dunkin’.

Also, while the marketing of many plant-based companies focuses on what they say is the nutritional superiority of their products compared to conventional meat, there is still little comprehensive independent data to back up a lot of these assertions.

According to Morningstar: “Beyond Burger’s relative lack of health benefits as compared with lean beef may garner increased consumer attention as the category gains additional retail and food-service distribution, limiting PBM product adoption. Consumers have been shifting away from products with long ingredient lists (such as Beyond’s fare), opting toward fresh, natural products, which could also limit ultimate demand.”

And though Impossible’s spokesperson said the company’s production process could potentially “turn back the clock on climate change,” there are plenty of people who remain unconvinced of those claims.

“Plant-based meat can be just as dirty as a T-bone steak, depending on how it’s produced. In both cases, pesticides enter the environment, novel genetic material is passed from crop to livestock to the environment, workers and communities are drained of their wealth and vitality,” said Alan Lewis, a director of special projects at Natural Grocers by Vitamin Cottage who focuses on government affairs and food and agriculture policy. “Impossible Foods has far more in common with JBS, Purdue, and Cargill than with a small holder grass-fed rancher.”

And those companies are starting to add meat alternatives to their protein lineups. A JBS USA spokesperson said the company is launching new products in response to consumer cravings.

JBS has previously tested its plant-based products in Brazil, the U.K., Europe, and Australia. And, in April, the company will start distributing its Ozo brand in the U.S.

Get ready for lab-grown meats

Smaller startups that produce lab-derived meat alternatives have started to join the category. The companies claim that their production processes beat both traditional and plant-based meat companies on the environmental front.

And they often cite population statistics—and the need to feed the world’s fast-growing population—as a reason for their faster-to-create products to win out over anything that starts out growing in or walking on the ground. Current estimates put the global population at 10 billion people by 2050, which will require a 70% increase in the demand for food production, according to the World Resource Institute.

“This means an increased need for land and resources to meet this need, both of which are not realistic with our current supply chains,” said Lisa Dyson, CEO of Air Protein. Dyson’s company, which was spun off from a space tech startup, is in the early stages of developing “air-based meat” made of carbon, wind, and microbes.

“Current food production accounts for over 20% of greenhouse gases,” she added, “more than all of transportation combined, and uses over 37% of the planet’s land mass—the amount of land equivalent to the size of both Africa and South America.”

Dyson said her company’s goal is to compete by using a much smaller environmental footprint.

“Our innovation enables a path to producing meat from air in a way that’s far cheaper than meat from cows or even meat from soy—that’s because air-based meat production starts with air, water, and renewable energy,” said Dyson. “It takes two years to grow a steak, which is an extremely costly process that’s both taxing on the environment and resource inefficient. Our way of producing meat [takes just a few days and] doesn’t require the use of arable land, which has even more exciting upsides for a sustainable food system and bottom lines.”

Some meat sectors, however, have made clear that they’ve made strides in reducing their own environmental footprint. According to the National Chicken Council’s “Chicken Check In” site, the environmental impact of chicken production decreased by 50% since 1965, including the reduction of resources needed to raise a chicken. Farmland dropped 72%, water 58%, and fossil fuels 39%.

For lab-derived meat substitutes, there’s still a good deal of regulatory oversight to put in place, as well as finding ways to win over consumers on taste, something Impossible and Beyond took years to do.

“We may need an actual example of a product getting approval to get the full outline of what regulators are going to require,” said Good Food’s Barrella.

In the meantime, companies including Air Protein, Memphis Meat, and Sustainable Bioproduct as well as plant-based companies like Beyond Meat and Impossible Foods remain “entirely outside the USDA/FDA framework,” he said.

And constant innovation, multiple core ingredients, sourcing, distribution, and packaging practices can be confusing for consumers in the absence of the kind of public watchdog that is proactive in other countries.

What’s the real cost?

For companies built on offering alternatives to animal products, it’s time to back up claims of environmental and health benefits with proof. Beyond Meat offered few details on either front during the earnings call.

“The problem is not whether we can mimic nature, it’s about unintended consequences,” said Shen Tong, a founder of the FoodFutureCo accelerator for food tech startups. He argued that historically the promise of processed food, driven by lower costs and profitability, didn’t turn out so well in terms of long-term nutritional value. The allure of plant-based food presents the same risk.

“That’s where you get into dangerous territory," said Tong. "You start playing God.”