There are undoubtedly many eating approaches and diet trends, but the one diet that continues to be popular among Americans is the vegetarian diet.
According to an August 2023 Gallup poll on consumption habits, 4% of Americans identify as being vegetarian. While that number has remained relatively stable over the years, the trend toward more plant-based eating is on the rise. A 2020 survey also 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.
Why Choose a Vegetarian 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 shows that 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 lower 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:
— Fruits.
— Legumes.
— Nuts.
— Plant-based meatless “meats,” tofu, tempeh or seitan.
— Seeds.
— Whole grains.
[READ: Why a Plant-Based Diet Isn’t Complete Without This]
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 non-dairy 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 vegetarians include legumes (such as beans, chickpeas and lentils), tofu, tempeh, Greek yogurt and cottage cheese.
“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, instead of taking calcium supplements, making sure you consume enough high-calcium foods — such as calcium-fortified plant-based milk, yogurt and cooked kale — will help you meet your recommended dietary intake.
However, if you’re concerned about getting adequate amounts of key nutrients, it’s a good idea to consult with your primary care doctor or a registered dietitian about certain nutritional supplements to 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.
[Read: Plant-Based Diets for Athletes.]
Types of Vegetarian Diet
There are several versions of the vegetarian diet:
— Flexitarian diet.
— Lacto-ovo vegetarian diet.
— Lacto-vegetarian diet.
— Ovo-vegetarian diet.
— Pescatarian diet.
— Vegan diet.
Flexitarian Diet
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 flexitarian 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.”
With the flexitarian diet, you reap all the health benefits of a vegetarian diet without making too many dietary changes. It’s no wonder, then, that the flexitarian diet ranked No. 2 in U.S. News’ Best Diets Overall.
Health benefits
Advantages of a flexitarian diet include:
— 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.
Health risks
There are no known health risks of disadvantages associated with the flexitarian diet.
Foods to eat
— Fruits.
— Vegetables.
— Nuts and seeds.
— Legumes.
— Whole grains.
— Meat, dairy and eggs — in limited amounts.
Foods to avoid
The beauty of the flexitarian diet is that it doesn’t eliminate any foods or food groups. It simply encourages people to moderate intake of meat, dairy and egg products.
[READ: Hybrid Foods for a Flexitarian Diet.]
Lacto-Ovo Vegetarian Diet
Stemming from the Latin word “lacto” for milk and “ovo” for egg, this vegetarian diet allows the consumption of dairy and egg products, while eliminating meat, poultry and fish. For most people, this is a healthy diet.
Health benefits
Advantages of the lacto-ovo vegetarian diet include:
— Less risk of low intake of vitamin B12, vitamin D and iron compared to some other vegetarian diet options.
— Getting enough calcium shouldn’t be a concern.
Health risks
Disadvantages of the lacto-ovo vegetarian 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 from cheese and milk. These foods can high in saturated fat, which research suggests can contribute to heart disease when consumed in high quantities.
Foods to eat
— Fruits.
— Vegetables.
— Nuts and seeds.
— Legumes.
— Whole grains.
— Dairy or plant-based milk products, including milk, cheese and yogurt.
— Eggs.
Foods to avoid
— All animal meat.
Lacto-Vegetarian
This vegetarian diet eliminates meat, poultry, fish and eggs but does allow dairy products.
“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,” Jacks says.
Health benefits
Advantages of the lacto-vegetarian diet include:
— A wide array of options for consuming protein, including cheese, milk and yogurt.
— Because dairy is allowed, it wouldn’t be difficult to get an adequate amount of calcium.
Health risks
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.
Foods to eat
— Fruits.
— Vegetables.
— Nuts and seeds.
— Legumes.
— Whole grains.
— Dairy or plant-based milk products, including milk, cheese and yogurt.
Foods to avoid
— All animal meat.
— Fish and seafood.
— Eggs.
Ovo-Vegetarian Diet
If you love scrambled eggs but could go without dairy, an ovo-vegetarian diet may be right for you. This version of a 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.
Health benefits
Advantages of the ovo-vegetarian diet:
— Eggs are a good dietary source of iron, vitamin B12 and protein. One whole egg provides 6 grams of high-quality protein.
— Eggs are one of the richest sources of choline, a nutrient that helps the body’s brain and nervous system. One large, hard-boiled egg provides 27% of your daily value, with 147 milligrams per serving.
— Egg yolks are a good source of vitamin D.
Health risks
Disadvantages of the ovo-vegetarian diet:
— Egg yolks contain a significant amount of cholesterol, with one large egg containing about 186 milligrams of cholesterol, so you’ll have to watch your intake.
Foods to eat
— Fruits.
— Vegetables.
— Nuts and seeds.
— Legumes.
— Whole grains.
— Eggs.
Foods to avoid
— All animal meat.
— Fish and seafood.
— Dairy products.
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.
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 heart-healthy dietary patterns — in lieu of setting a specific dietary cholesterol limit — for optimal heart health.
Pescatarian Diet
A pescatarian diet is a plant-based eating regimen similar to the lacto-ovo vegetarian diet, but the main difference is that it includes seafood as a main protein source.
“Consuming seafood can make getting omega-3 fatty acids and protein easier than other vegetarian diets,” Fears says.
Omega-3s 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.
Health benefits
Advantages of a pescatarian diet:
— Research suggests this eating regimen reduces the risk of chronic disease, including Type 2 diabetes, heart attack and stroke.
— Fish, dairy and eggs are excellent sources of lean protein and provide many other vitamins, minerals and nutrients.
Health risks
Disadvantages of a pescatarian diet:
— Overconsumption of fish with high mercury levels may negatively affect your brain health. This is a particular concern for pregnant women and young children.
Foods to eat
— Fruits.
— Vegetables.
— Nuts and seeds.
— Legumes.
— Whole grains.
— Eggs.
— Dairy products.
— Fish and seafood.
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:
— Anchovies.
— Atlantic mackerel.
— Catfish.
— Clams.
— Crab.
— Crawfish.
— Flounder.
— Oysters.
— Salmon.
— Sardines.
— Scallops.
— Shrimp.
— Squid.
— Tilapia.
— Trout.
Foods to avoid
— All meat.
Vegan Diet
The vegan diet is the most restrictive version of a vegetarian diet, as it eliminates all animal-derived foods, including meat, fish, eggs and dairy products. It also excludes foods produced by insects, such as honey, and supplements that use capsule shells made of gelatin from animal parts, usually from cows or pigs.
“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.
Health benefits
Advantages of a vegan diet:
— Lower cholesterol.
— Possible weight loss. Research suggests that people who follow vegetarian diets consume fewer calories than individuals who don’t.
— Reduced risk of heart disease.
— High intake of fiber, vitamins and minerals from plant sources.
Health risks
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.
Foods to eat
— Fruits.
— Vegetables.
— Nuts and seeds.
— Legumes.
— Whole grains.
— Plant-based meat replacements, including tofu, tempeh, seitan, jackfruit and breadfruit.
Foods to avoid
— All meat and animal-derived products such as honey
— Fish and seafood.
— Eggs.
— Dairy.
The Bottom Line
There are several versions of the vegetarian diet — each with their own set of restrictions. When deciding on which type of diet to follow, it’s important to take into consideration your lifestyle, values, reasons for switching to a vegetarian diet and sustainability over the long term.
Remember: There’s no right or wrong answer when it comes to choosing a plant-based eating approach. You should feel free to experiment with the different types of vegetarian diets until you find one that works best for you.
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6 Types of Vegetarian Diets Explained originally appeared on usnews.com
Update 09/14/23: This story was previously published at an earlier date and has been updated with new information.
