If any meat alternative is capable of converting carnivores, it’s plant-based burgers. These vegan items are engineered to cook, taste, and even “bleed” like real beef, and they're quickly becoming mainstream, with brands like Beyond Meat and Impossible Foods appearing in supermarkets and fast-food restaurants nationwide. But despite their popularity, the nutritional value of such foods, and even their main ingredients, remain unclear to much of the public. Before making these meatless, plant-based protein sources part of your diet, it helps to know what they’re made of.

What are Beyond Burgers and Impossible Burgers made of?

Both Beyond Burgers and Impossible Burgers are made by manipulating proteins found in plants. Beyond Meat’s process involves heating, cooling, and compressing proteins extracted from peas, rice, and beans to create a fibrous texture that mimics real animal tissue. Plant-based fats and carbohydrates are added to give it flavor and hold everything together, and beet juice gives it its “bloody” quality.

The secret to making Impossible Burgers is something called heme, which is the compound that allows an animal's blood to deliver oxygen to its organs. Plants also use heme, but they don’t contain as much as animals do. When food has a flavor that can be described as “meaty,” heme is usually the source. By genetically modifying yeast to produce the heme found in soybeans, Impossible Foods can produce this substance at a massive scale. Impossible Burgers also contain manipulated protein from wheat and other additives for flavor and texture, but the soy heme-containing protein (or leghemoglobin) is what makes it such a convincing meat alternative.

Are Beyond Burgers and Impossible Burgers healthy?

Plant-based burgers are definitely vegan, but there’s still some debate over whether they qualify as health food. “Just because something is labeled as plant-based or completely vegan doesn't necessarily make it healthier for us,” nutritionist and author Rhiannon Lambert tells Mental Floss. “They can have added salt, sugar, fats, and be lower in key nutrients.”

When comparing beef to meat alternatives, it helps to remember that meat isn't inherently bad for you. It contains protein, iron, vitamin B12, and other nutrients we need to survive. Looking at their vitamin and mineral contents is one way to judge the “healthiness” of plant-based products against meat. “Nutritionally speaking, meat is very nutritious, providing us with a whole array of nutrition from vitamins to protein. However, some vegan alternatives now rival meat on the protein aspect and the nutrition,” Lambert says.

Another way to decide if plant-based burgers are better for you is to see what ingredients they contain that you may already be getting an excess of in your diet. These include sugar, salt, carbohydrates, and fat. Beef also has high levels of cholesterol, so if that’s something you’re looking to cut down on, you should know that Beyond Meat and Impossible Burgers don't have any (though real and plant-based meat contain similar amounts of saturated fat).

Most nutritional points are comparable between real meat and fake meat, but with salt, there’s a big divide: a 4-ounce Beyond Burger patty contains 350 milligrams of sodium, and a 4-ounce Impossible Burger patty contains 370 milligrams. That's compared to a raw beef patty, which could have as little as around 80, depending on the cut. Of course, most people add salt to their meat before eating, but with processed, plant-based foods, you can’t control the amount of sodium in your meal.

There are many reasons to choose the vegan option at the supermarket that have nothing to do with personal health. These new meat alternatives have a smaller carbon footprint than beef (though a significantly larger one than unprocessed vegetables and legumes). They may also appeal to vegans, vegetarians, and flexitarians looking to avoid animal products for ethical reasons. But no matter your reasons for experimenting with meatless protein, doing your research first is key. “It really is a case of reading the labels on these plant-based alternatives,” Lambert says. “Currently there is no superior option if we are strictly speaking nutritional meat alternatives, as it depends what fits into your overall diet and lifestyle.”