Are Plant-Based Diets Healthy? A Scientific Guide to Eating Vegan

Plant-based diets are on the rise, as new studies emerge every week about the health benefits of following a vegan or vegetarian diet. Whether you want to try a plant-based diet for sustainability, ethical treatment of animals or the sake of lowering your risk of disease, the science supports the fact that staying away from meat and dairy is one of the best things you can do for your health.

Here’s the bonus: While you’re preparing your plant-based recipes to eat healthier, you're also helping the planet, as a plant-based diet is optimal for lowering your individual impact on climate change. Animal agriculture is one of the biggest manmade contributors to greenhouse gases, both methane (from the animals) and CO2 (from the equipment). So whether you are in it for the ethical treatment of animals, the sustainability of our environment, or for health reasons, here's where start your healthy vegan or plant-based journey.

The unequivocal answer is yes, plant-based diets free of meat and dairy and high in fiber-rich foods are better for your health. “Because the main foods of a plant-based diet are fruits, vegetables, whole grains, beans, and legumes, it’s one of the healthiest diets on the planet,” says Anna Herby, RD, nutrition education program manager for the Physicians Committee for Responsible Medicine.

U.S. News & World Reports ranks the healthiest diets each year, and for five years in a row, the Mediterranean Diet has topped the list as the healthiest diet. A Mediterranean diet is focused on eating more plant foods and fewer animal products, with the exception of fish.

What is a plant-based diet?

One that focuses on foods that grow from seeds, rather than being raised as animals:

A healthy plant-based diet includes only minimally processed foods such as tofu, seitan, and those oils that you could press from plant foods such as olive, avocado, and sesame seeds. On a whole-food plant-based diet, you try to avoid meat, dairy, and animal products as well as highly processed foods, including packaged snacks, chips, cookies, and other foods that included added sugar and fat.

You can get all the nutrients you need on a plant-based diet, including protein, iron, and calcium.

When you adopt any new diet, you’re usually doing it because of your health or to lose weight. Often these are tied together since losing extra weight is one way to be heart healthier. Yet when you eat a plant-based diet, even if you don’t change anything other than what you’re eating, you’re probably going to lose weight because of the high fiber content of fruits, vegetables, legumes, whole grains nuts, and seeds.

Plant foods such as fruit, vegetables, legumes, whole grains, and nuts and seeds are the most nutrient-dense foods you can eat because they are high in vitamins, minerals, antioxidants, and fiber, the one nutrient most Americans don’t eat enough of. “Most people are getting 10 grams of fiber a day if they’re lucky, but we recommend consuming up to 40 grams a day,” Herby says.

Fiber is found only in plants, and if you’re eating the Standard American Diet, high in red meat, full-fat dairy, and added oils and sugar, with very few whole plant foods, you’re not getting the fiber you need. Less than 1 in 10 Americans eat the recommended five servings of fruit and vegetables a day, so just by adding in more plant foods, you will increase your fiber intake.

Fiber is crucial for digestion, gut health, blood sugar, and cholesterol levels. It is also vital to your immune system and weight. Unlike meat, dairy, poultry, and other animal products, which contain things like cholesterol and saturated fat, both of which can clog blood vessels and damage your heart, plants contain no cholesterol and have a low amount of saturated fat.

Americans face an onslaught of chronic diseases, chief among them being heart disease, which remains the number one killer, accounting for about 680,000 deaths a year. Other top diseases that afflict Americans include cancer, Alzheimer’s disease, type 2 diabetes, and chronic kidney disease. Many of these could be reduced by eating less meat and dairy and focusing on a plant-based diet.

“Because a plant-based diet is anti-inflammatory, high in fiber, water, and lower in calories, it can reduce the risks for these chronic diseases,” Dana Ellis Hunnes, R.D., assistant professor at the UCLA Fielding School of Public Health in Los Angeles and author of Recipe for Survival says. “But a good amount of studies also now demonstrate that plant-based diets can help reverse some of these chronic diseases – not cancer, though it may slow down its progression – but certainly type 2 diabetes, heart disease, and obesity.”

The unifying factor behind all of these conditions is inflammation, which is your body's response to injury or when you are eating a diet that is unhealthy, such as one heavy in red meat, full-fat dairy, and refined carbs. Inflammation becomes a problem when it’s chronic.

“Many of our lifestyle habits, like staying up too late, drinking too much alcohol, and eating too many processed foods are inflammatory in nature,” explains Dr. Katie Takayasu, author of Plants First and integrative medicine physician in Stamford, Ct.

When inflammation becomes chronic, the immune system responds, and over time, the body's ability to fight off disease is weakened. This can lead to many physical and mental health conditions that shorten longevity. A new study just found that a plant-based diet can lengthen the average expected lifespan by as much as 14 years among people who give up meat and focus on a vegan or vegetarian diet.

One way to tamp down that inflammation is to eat foods that are anti-inflammatory, such as plant foods. “Plants allow the body to function best,” Dr. Takayasu says. Compare a plant food like almonds to something like chicken.

When you eat almonds, you’re not only getting a healthy combination of fat and protein but also melatonin, calcium, zinc, and all of the other natural nutrients that benefit your body. Chicken includes saturated fat that drives up inflammation. “When you choose more plants, they work for you while inflammatory foods work against you,” Dr. Takayasu says.

Curious how plants work against three of the most common diseases? Lowering inflammation is only the start, as experts explain.

You have miles of blood vessels in your body that are lined with a layer of tissue called your endothelial cells. “You want that layer to be like Teflon so that nothing sticks,” Herby says. When you’re eating an animal-rich diet, however, those vessels get sticky, more like velcro, and the fat in the bloodstream hardens, eventually showing up as plaque, which causes inflammation. Eventually, those plaques can reduce blood flow and oxygen to the heart or brain, causing heart attacks and strokes.

`On a plant-based diet, those blood vessels are smoother, and inflammation is reduced. Take note: Among adults aged 18 to 30, eating a plant-based diet lowered the risk of heart disease by 52 percent, according to research from the Journal of the American Heart Association.

There are cases of people who change their diets, go plant-based, and reverse heart disease, saving their own lives. Doug Schmidt was one of the many people who credits a plant-based diet with saving his life. He completely reversed his heart disease by removing meat and dairy from his diet after having an unexpected heart attack at 49 years old. "All the research showed that if I didn't change my eating habits, I would have another heart attack within five years," he said.

It’s impossible to say that you won’t get cancer if you’re eating a plant-based diet. “But your risk is significantly reduced,” Herby says. A new study out of the UK found that you can lower your cancer risk by 14 percent by eating mostly plant-based.

Eating plant-based can bring down your cancer risk even lower for certain hormonal cancers, like breast cancer and prostate cancer, since those are associated with high-fat diets rich in saturated fat. One reason? With more fiber in your body, excess hormones that cause these cancers instead bind to the fiber, which gets carried out of the body as waste.

Studies have found that diets high in meat, dairy, and processed foods with added sugar and fat are associated with a higher risk of Alzheimer's disease and dementia. Research suggests that a plant-based diet may reduce the risk of developing Alzheimer's disease, which is why people are showing so much interest in an approach known as the MIND diet.

Eating more plant-based while avoiding meat, dairy and processed foods have been shown to slow brain aging by 7.5 years and lower the chances of developing Alzheimer's disease, according to the Mayo Clinic.

8 healthy foods to eat on the MIND diet for brain health

While all of the above benefits are reason enough to start a plant-based diet, there may be an even more compelling and timely one. Recent research shows that a plant-based diet can reduce the risk of getting infected with a severe case of COVID-19 and serious symptoms.

A plant-based diet has been linked with a 9 percent lower risk of COVID-19 infection overall, and a 41 percent lower risk of severe COVID-19 cases, according to research from PCRM. Plus, when health care workers who had exposure to COVID-19 followed a plant-based diet, they had a 73 percent lower risk of developing moderate to severe COVID-19.

Existing underlying health conditions also can make COVID infection worse, including heart disease, high blood pressure, type 2 diabetes, and obesity. By eating a plant-based diet, you can lower your risk of these co-morbidities, Herby says. Doctors have recommended patients at risk for severe COVID-19 switch to a plant-based diet to lower their risk of severe infection.

Eating a plant-based diet comes with many health benefits, including:

Starting a plant-based diet might seem overwhelming at first. Below, experts offer seven strategies to make it easier to go plant-based, even if you want to ease into it over time.

Focus on Vegetables. Make meat the sideshow. If changing your diet overnight feels too tough, ease into it by piling your plate with vegetables and other plant foods and reducing the animal-based foods, Hunnes says.

Follow the 1-2-3 rule:  Have one serving of vegetables (either half cup cooked or one cup raw) at breakfast, two at lunch, and three at dinner. Why focus on veggies? “Vegetables are where you’ll get the most nutrients,” Dr. Takayasu says.

Consider simple substitutions: Think about places where you can swap out plant-based products for animal-based products and start there, Hunnes says. For instance, use plant-based yogurt instead of dairy yogurt, plant milk instead of dairy milk, and vegan bacon for pig bacon.

Rethink your plate: Divide your plate into four quarters and then make a meal that is equally divided between fruits, vegetables, legumes, and whole grains. These four food groups will give you all the nutrients you need to eat a healthy, balanced, plant-based diet.

Use vegan foods as a transition: Vegan alternatives to your favorite foods are flooding the market, and although many of them aren’t considered healthy, they do serve as good transition foods. If you love to eat a burger, try one of the plant-based ones. “These foods will help you get your foot in the door,” Herby says. Eventually, though, you want to minimize them since they are highly processed and not as healthy as whole food options like bean or lentil burgers.

Go slowly: If you’re not used to eating much fiber, you may wind up with some unexpected consequences like bloating, diarrhea, or gas. “Your gut bacteria need time to adjust,” Dr. Takayusu says. Add plants to your diet slowly and don’t forget to drink more water as you go.

Supplement with vitamin B12: You can get all of the nutrients you need on a plant-based diet with the exception of B12, which is often added to foods. “If you’re eating 100 percent plants, you’ll need to supplement with vitamin B12,” Herby says. B12 recommendation for most people 18 to 65 years old is 100 micrograms (mcg) per day or 1,000 mcg twice per week; if you’re older than 65, you’ll need 500 to 1,000 mcg per day.

The best plant-based recipes to start your journey

There are many scientifically proven health benefits to going mostly plant-based, or eating a totally vegan diet. If you are eager to get started, try eating plant-based at least one meal a day and ease into it. You will see the benefits to your health both now and later.