Want to go vegan? Explore the pros, cons of the lifestyle.

Veganism has attracted millions of participants for decades, which is especially impressive when you learn just how restrictive a vegan diet can really be. And while there are certainly overlapping foods that both vegetarians and vegans avoid, most vegans go a lot further than most vegetarians in terms of what they choose not to eat.

Here's what veganism is, what benefits it provides and some of the downsides associated with practicing the lifestyle. Though it may be declining ever-so-slightly in popularity, its supporters are anything but quiet.

What is vegan? What do vegans eat?

While all vegans share the same goal of wanting to avoid animal products in their diet, their motivations, dietary decisions and overall approach to veganism "can vary from person to person," says Dr. Uma Naidoo, director of nutritional and lifestyle psychiatry at Massachusetts General Hospital and the Harvard-trained nutritional psychiatrist behind "Calm Your Mind with Food." In other words, some vegan diets are most strict and restrictive, while others are more casual and flexible.

Generally, though, vegans opt exclusively to eat a plant-based diet – choosing to not only avoid eating animal meat (as vegetarians do) but to also avoid any foods that come from animals, including dairy products and eggs. Even honey is usually avoided, as it's produced by bees.

Vegans also often avoid foods that many people don't think of as being associated with animals. "These include animal-based ingredients like gelatin (used in Jello, supplement capsules, marshmallows, etc.), casein, whey proteins (because they are milk-derived) and food colorings like cochineal – a red pigment made from crushed red beetles that's used in food colorings, candies and alcoholic beverages," says Jen Messer, a nutrition consultant and registered dietitian at Jen Messer Nutrition. "Other tricky examples that take careful label reading include kimchi (fish sauce, fish paste), Worcestershire sauce (anchovies) and Caesar dressing (anchovies)."

Naidoo says that some vegans also go beyond dietary restrictions by also avoiding the use of any cosmetics that were tested on animals or animal-derived clothing such as leather belts, shoes or fur coats.

Overall, "vegans eat plenty of fruits, vegetables, grains, beans, nuts and seeds," says Lisa Young, a registered dietitian nutritionist, author of "Finally Full, Finally Slim" and an adjunct professor of nutrition at New York University.

Vegans also commonly eat plant-based substitutes "such as tofu, tempeh, seitan and textured vegetable protein; opt for vegan dairy options like almond, soy or oat milk; and choose plant-based oils, herbs, spices and sweeteners such as maple syrup and agave," adds Messer.

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What are the health benefits of being vegan?

A vegan diet can be healthy, Messer says, because it is rich in beneficial nutrients that are low or missing from a standard American diet. "Vegan diets tend to be high in dietary fiber from the high intake of legumes, fruits, vegetables and whole grains," she explains; "and they are rich in vitamins and minerals such as vitamin C, potassium and magnesium." Plant-derived phytochemicals and antioxidants commonly consumed in vegan diets also help reduce inflammation and support overall health.

Messer says that plant-based diets can also lower one's risk of chronic health issues like heart disease, type 2 diabetes, hypertension, certain cancers and obesity due to a "lower intake of saturated fat and a higher focus on nutrient-dense foods."

"And veganism can be beneficial for healthy weight management, due to a high intake of fiber-rich, nutrient-dense foods that are both low in calories and filling," adds Young.

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Are there any downsides to being vegan?

At the same time, a vegan diet requires careful planning to avoid downsides that come from completely cutting out too many food groups. "Veganism is a form of an elimination diet and with any elimination diet, there are risks of nutrient deficiencies," says Naidoo.

For instance, vegan diets can be low on levels of protein, vitamin B12, iron, calcium, omega-3 fatty acids, vitamin D and zinc, says Young. This usually requires vegans to eat fortified foods or take a variety of supplements, especially for nutrients like vitamin B12, which is only found in animal products.

Beyond nutrition gaps, there are other downsides of the lifestyle to consider including cost, "as many specialty vegan products like meat substitutes can be expensive," says Messer, "and adopting a vegan lifestyle might be more time-consuming." What's more, "dining out or attending social events can be more challenging to find suitable options, but a bit of planning can mitigate these challenges," she adds.

"While veganism comes with potential downsides, including nutrient deficiencies and lifestyle adjustments," says Messer, "it can be a healthy and ethical choice with proper planning."

This article originally appeared on USA TODAY: What do vegans eat?