Vegetarianism continues to be a popular diet among Americans.
A 2020 survey conducted by Gallup showed that nearly 1 in 4 people in the U.S. reported eating less meat than the year before, with 70% of respondents citing health concerns as a major reason for reducing their meat consumption.
In addition to personal health, concerns about the environment, food safety and animal welfare topped respondents’ list of major reasons for either refraining from eating — or completely eliminating — meat in their diets.
While there is no singular vegetarian diet, there are various forms of vegetarianism — each with its own set of advantages, disadvantages and restrictions.
If you’re interested in adopting a more plant-based lifestyle, it’s important to know the differences.
[READ: 12 Health Benefits of a Plant-Based Diet.]
Why Choose a Vegetarian Diet?
Being a vegetarian means eliminating animal meat, fish, seafood and poultry from your diet.
People may choose a vegetarian diet for environmental reasons, primarily related to the effects of livestock farming on climate change.
Research by the Food and Agriculture Organization of the United Nations has shown animal agriculture accounts for an estimated 14.5% of global greenhouse gas emissions. In fact, if global producers and consumers gradually replaced a carnivorous diet with a plant-only diet over the next 15 years, it would reduce enough greenhouse gas emissions to offset emissions from other sectors — including transportation and energy — for the following 30 to 50 years, according to 2022 research published in PLOS Climate.
However, one of the main reasons people choose a vegetarian diet is for health reasons. Plant-based diets have been linked to a lowered risk of chronic diseases, including heart disease, hypertension and Type 2 diabetes.
“Whatever your reason, or reasons, may be to eat vegetarian, there’s no wrong answer when considering meatless meals,” says Lisa Jones, a registered dietitian based in Philadelphia.
A well-rounded vegetarian diet emphasizes these foods:
— Plant-basedmeatless “meats,” tofu, tempeh or seitan.
— Whole grains.
[READ: Tips to Adjust to a Plant-Based Diet.]
Studies Support the Benefits of Vegetarianism
Plant-based diets are densely packed with nutrients — such as fiber, healthy unsaturated fats, protein, vitamins and minerals — that have been clinically shown to lower LDL (“bad”) cholesterol, reduce inflammation and boost your immune system.
Plant-based diets are associated with:
— Reduced risk of Type 2 diabetes.
— Reduced risk of certain types of cancers.
In a 2018 study published in the journal Progress in Cardiovascular Diseases, researchers found that vegetarian dietary patterns reduced cardiovascular disease mortality and coronary heart disease risk by 40%. Their findings further confirm the benefits of a vegetarian diet on lower blood pressure, lower blood lipids and diabetes management.
Research also shows that a vegetarian diet could be beneficial to our health in other ways. In a 2019 study published in the journal Nutrients, researchers followed 4,839 participants over an average of six years to evaluate the association between a vegetarian diet and gallstone disease. Their findings showed that a vegetarian diet was associated with a decreased risk of gallstone disease in women by lowering cholesterol, which — at high levels — has been identified as a risk factor for the disease.
Depending on what foods you exclude from your diet, a vegetarian eating regimen may be lacking in these nutrients that are naturally present and more abundant in animal food products than other food sources:
— Vitamin B12, which is naturally found in poultry, meat, fish and dairy products.
— Calcium, which often comes from milk and dairy products but can also be found in nondairy products, such as leafy greens.
— Iron, which is highest in meat, poultry and seafood.
— Zinc, which is naturally present in meat, fish and seafood, especially oysters, beef and eggs.
Although a common myth is that vegetarians can’t get enough protein without meat, people can consume adequate amounts of this essential nutrient by incorporating vegetarian-friendly protein sources into their plant-based diet. Popular high-protein foods for a vegetarian diet include:
— Almonds: 6 grams of protein per serving.
— Pinto beans: 2.6 grams of protein per serving.
— Chickpeas: 2.4 grams of protein per serving.
— Lentils: 1.1 grams of protein per serving.
— Tofu: 10 grams of protein per serving.
— Edamame: 11 grams of protein per serving.
— Sunflower seeds: 10 grams of protein per serving.
— Tempeh: 19 grams of protein per serving.
— Quinoa: 8 grams of protein per serving.
— Greek yogurt: 10 grams of protein per serving.
— Cottage cheese: 13 grams of protein per serving.
— Fat-free milk: 8.4 grams of protein per serving.
“If well-planned, these nutrients can be obtained, whether naturally and/or with supplemented products,” says Kaylee Jacks, a registered dietitian with Texas Health Sports Medicine in Dallas.
While many vitamin and mineral supplements are commercially available in pill form, experts agree that the best way to get these nutrients is by consuming whole foods. For example, one-quarter cup of nutritional yeast is packed with 17.6 micrograms of vitamin B12 and 8 grams of protein, and almond milk can be fortified with calcium and vitamin D.
If you’re concerned about making sure you’re getting adequate amounts of these key nutrients, it’s a good idea to consult with your primary care doctor or a registered dietitian about certain nutritional supplementsto make sure your vegetarian regimen is well-balanced and healthy.
“Seeking out a health care professional to discuss supplementation is beneficial for any vegetarian diet,” says Betsy Fears, a registered dietitian nutritionist at The Polyclinic in Seattle, Washington.
Types of Vegetarian Diet
There are several versions of the vegetarian diet:
— Lacto-ovo vegetarian.
The flexitarian diet, a portmanteau of “flexible” and “vegetarian,” is the least restrictive vegetarian eating regimen. People who follow this semi-vegetarian eating pattern occasionally consume meat, fish, poultry and other animal products — however, most of their meals are plant-based.
“Flexitarians prioritize plant-based foods but can include small amounts of all animal products when they choose,” Fears says. “The ability to occasionally consume animal products can make plant-based eating more sustainable for many people.”
Research suggests the flexitarian diet, like other vegetarian eating regimens, can improve people’s overall health while helping them reduce the risk of chronic illnesses, such as cardiovascular disease, Type 2 diabetes and cancer.
[See: What to Know About Becoming Semi-Vegetarian.]
Lacto-Ovo Vegetarian Diet
This diet eliminates meat, poultry and fish but allows dairy and egg products. For most people, this is a healthy diet.
Advantages of the lacto-ovo vegetarian diet include:
— A wide array of options for consuming protein, including eggs, cheese, milk and yogurt.
— Less risk of low intake ofvitamin B12, vitamin D and iron compared to some other vegetarian diet options.
— Getting enough calcium shouldn’t be a concern.
Disadvantages of the lacto-ovo diet:
— Although the risk is lower, you still need to make a conscious effort to include enough iron and vitamin B12 in your diet. This may include adding iron- and B12-rich foods to your plate or taking over-the-counter supplements.
You’ll need to watch your intake of saturated fat. The lacto-ovo diet includes cheese and milk, which can be high in saturated fat. Research suggests saturated fat can contribute to heart disease, says Amy Kimberlain, a registered dietitian based in Miami and national spokesperson for the Academy of Nutrition and Dietetics.
This diet eliminates meat, poultry, fish and eggs but does allow dairy products, such as cheese, milk and yogurt.
“It’s important to get the low-fat or fat-free versions of these dairy products because full-fat dairy is high in saturated fat,” says Jacks.
Reducing saturated fat is important. A diet that is high in saturated fat is associated with an increased risk of cardiovascular disease.
Advantages of the lacto-vegetarian diet include:
— A wide array of options for consuming protein, including cheese, milk and yogurt.
— With dairy included, it’s not difficult to get an adequate amount of calcium.
Disadvantages of the lacto-vegetarian diet include:
— Getting enough vitamin B12 and iron are of high concern.
— Possible higher intake of saturated fat, depending on what forms or how much dairy you consume.
An ovo-vegetarian diet eliminates meat, poultry, fish and dairy, but it does include eggs and any foods containing egg.
“This diet has all the benefits of a vegan diet and the benefits from including eggs,” Jacks says.
Advantages of the ovo-vegetarian diet:
— One whole egg provides 6 grams of high-quality protein.
— Eggs are a source of iron and vitamin B12.
— Egg yolk is a good source of vitamin D.
Disadvantages of the ovo-vegetarian diet:
— Eggs contain a significant amount of cholesterol, with one large egg containing about 186 milligrams of cholesterol, so you’ll have to watch your intake.
For most healthy adults, one to two eggs a day should be healthy and safe, as long as eggs are part of a well-balanced and varied diet that emphasizes fruits, vegetables, whole grains, nuts, seeds and lean protein sources.
In previous years, experts and dietary guidelines recommended consuming no more than 300 milligrams of dietary cholesterol daily for cardiovascular health. However, due to a lack of evidence between dietary cholesterol and cardiovascular risk, nutritional guidance was inconsistent.
As a result, the American Heart Association published a 2019 science advisory recommending healthy dietary patterns — in lieu of setting a specific dietary cholesterol limit — for optimal heart health.
“A recommendation that gives a specific dietary cholesterol target within the context of food-based advice is challenging for clinicians and consumers to implement,” researchers wrote in the statement. “Hence, guidance focused on dietary patterns is more likely to improve diet quality and to promote cardiovascular health.”
A pescatarian diet is a plant-based eating regimen that typically excludes meat, poultry, dairy and eggs but includes seafood as a main protein source, Fears says.
Some pescatarians include dairy and eggs, according to their personal preference.
“Consuming seafood can make getting omega-3 fatty acids and protein easier than other vegetarian diets,” she says. Omega-3 fatty acids are polyunsaturated fats, which research suggests help reduce harmful inflammation and keep cholesterol and blood pressure levels in the healthy range. This can help reduce the risk of heart disease.
Advantages of a pescatarian diet:
— Research suggests this eating regimen reduces the risk of chronic disease, including Type 2 diabetes, heart attack and stroke.
Disadvantages of a pescatarian diet:
— You may have trouble getting enough calcium.
— Overconsumption of fish with high mercury levels may negatively affect your brain health. This is a particular concern for pregnant women and young children.
Fish with high mercury levels include cod, mackerel, marlin and swordfish. Instead, the U.S. Food and Drug Administration and the U.S. Environmental Protection Agency recommend pregnant and breastfeeding women consume no more than one to two servings, or about 4 ounces, and children, depending on age, between 1 and 4 ounces of low-mercury fish.
The best choices for fish that contain lower levels of mercury include:
— Atlantic mackerel.
This is the most restrictive version of a vegetarian diet.
The vegan diet eliminates all animal products, including:
“A vegan diet consists of foods strictly from plants, such as fruits, vegetables, nuts and grains,” Jacks says.
These foods are typically low in calories and high in fiber, vitamins and minerals.
Advantages of a vegan diet:
— Possible weight loss. Research suggests that people who follow vegetarian diets consume fewer calories than individuals who don’t.
— Reduced risk of heart disease.
Disadvantages of a vegan diet:
— It may be challenging to get enough important essential nutrients, including protein, vitamin B12, vitamin D, calcium and iron.
— Its restrictive nature can make this diet hard to follow in the long run.
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Update 03/07/23: This story was previously published at an earlier date and has been updated with new information.