Despite the calls for consumers to eat less meat in order to fight environmental problems like climate change — as well as research showing that red meat isn’t doing your health any favors — beef consumption in the US has recently been on the rise. This is partly fueled by rapidly expanding sales of grass-fed beef.

Advocates for grass-fed beef say it has health and environmental benefits compared to conventionally-raised beef. Marketers and enthusiasts praise it as a healthy food rich in protein, B vitamins, iron, and other nutrients. And some environmentalists gush over the theory that properly managed grass-fed beef could help sequester carbon in the ground, building topsoil and fighting climate change at the same time.

And consumers are responding. The grass-fed beef market has emerged as a multi-billion dollar industry that shows no sign of slowing down. In fact, the market for grass-fed beef is predicted to grow by $14.5 billion between 2020 and 2024.

But is there truth behind these beliefs about grass-fed beef, or is this just a bunch of hearsay by environmentally conflicted burger-lovers trying to justify their meat habit? Is grass-fed beef really better for you, the animals, or the environment? And if it is, does that mean you should eat it?

Grass-fed beef was the norm in the beef industry before the 1950s. Cattle got to live longer back then, sometimes reaching their 3rd birthdays. In the middle of the 20th century, as the popularity of hamburgers and fast food in the US grew, farmers and ranchers needed a way to fatten up cattle faster, so they started feeding them energy-dense grain and soy instead.

Today, most cattle in the United States start out eating grass, but are fattened — or what the industry euphemistically calls “finished” — on grain and soy for their last 160-180 days of life. (While this accounts for barely a third of their lifespan, more than 50% of their weight gain occurs during this final half-year.) Cattle who are fattened up in CAFOs reach their slaughter weight in as little as 14 months.

Grass-fed cattle, on the other hand, feed on grass and other forage for their entire lives. Since the grass they eat is much less calorie-dense than feedlot grain, they’re sent to slaughter later — usually between one and a half and two years old. Their average weight at slaughter is about 1,200 pounds, compared with about 1,350 pounds for feedlot cattle.

So grass-fed cattle live longer and yield less edible meat than their grain-fed counterparts.

Grass-fed beef is marketed to consumers as being nutritionally-superior to conventional beef. And it is. But that’s not a very high bar. When compared on a per calorie basis, grass-fed beef is higher in B vitamins, iron, phosphorus, zinc, selenium, and vitamins A and E (it’s also touted as being higher in omega-3 fatty acids, but the truth is it still has only a negligible amount of them). Plus, it’s lower in saturated fat.

So grass-fed beef is more nutritious than conventional grain-fed beef. But that doesn’t exactly make it a “health food.” Overall, it’s still high in saturated fat, which is linked to an increased risk of heart diseasetype 2 diabetes, and Alzheimer’s disease. And then there’s cancer. Red meat of all kinds, including grass-fed beef, is labeled a class 2A carcinogen by the World Health Organization, meaning that it’s “probably cancer-causing” to humans.

Recent research also suggests that red meat, grass-fed or not, promotes the body’s production of a compound called TMAO, which can contribute to heart disease and other chronic lifestyle diseases. And all red meat can be a nasty vector for the spread of pathogenic bacteria, which can sneak into meat during processing, grinding, and packaging and cause foodborne illness. While the risk of dangerous bacterial contamination from grass-fed beef is lower, it’s certainly not zero.