Making the switch to a vegetarian or vegan diet

Several million Americans have abandoned red meat and poultry in favor of a predominantly plant-based diet. One reason some are making the switch is evidence of the health perks from going vegetarian or vegan, reports the May 2014 Harvard Women's Health Watch.

"There's certainly some research on the benefits of the vegetarian diet," says Kathy McManus, director of the Department of Nutrition at Harvard-affiliated Brigham and Women's Hospital. It can help lower or control weight, reduce the chances of developing heart disease, diabetes, and cancer, and possibly lead to a longer, healthier life.

There are a variety of plant-based diets, named largely for what they include or exclude:

• Semi-vegetarians includes meat and other animal-based foods. Many semi-vegetarians eat chicken and fish but not red meat.
• Pescatarians avoid meat and poultry but still eat fish and seafood.
• Lacto-ovo vegetarians skip meat, fish, and poultry but include dairy and eggs in their diet.
• Vegans eat only food from plants. They don't consume any animal-based foods—not even eggs or dairy products.

While vegetarian and vegan diets are generally healthy, they can lack certain nutrients. People who follow these diets may have to use a little creativity to make sure they get enough protein, calcium, iron, and vitamin B₁₂.

Vegetarians can find many of these nutrients in eggs and dairy, and vegans can get them from plant sources. But some people may need an added boost. "Because vitamin B₁₂ is found only in animal sources, if you're a vegan you might consider taking a vitamin supplement," McManus says. Some vegetarians also take omega-3 fatty acid supplements. These can be made from fish or plants like flaxseeds.