The question of whether plant-based diets are healthy depends on what foods the individual eats. Just eliminating all meat does not necessarily mean that you are on a healthy diet.

Eliminating meat from a terrible diet doesn’t really make it any healthier, according to a study released today in the Journal of the American College of Cardiology.
In fact, the study found that participants whose mostly-plant-based diets (think vegetarian or vegan) included a lot of processed foods, such as sugary beverages and French fries, were more likely to develop heart disease or die during the study period than people who avoided processed food—even if that meant eating a little meat.

Previous studies have found that people who adhere to vegetarian or vegan diets have better cardiovascular health. President Bill Clinton, who was once famous for jogs that detoured through McDonalds, went vegan to cope with heart disease. But those studies tend to lump all plant-based diets together into one group. The real world is a little more complicated.

Are Plant-Based Diets Healthy?

According to the researchers: “These studies of vegetarian and vegan diets haven’t distinguished between different qualities of plant food,” says lead author Ambika Satija, a postdoctoral fellow at Harvard T. H. Chan School of Public Health.

“Certain plant foods, like whole grains and fruits and vegetables, are associated with lower risk of type 2 diabetes and cardiovascular disease. But other plant foods, such as sugar sweetened beverages, are actually associated with increased risk.”

What the Evidence Says on Question of Are Plant-Based Diets Healthy

• The researchers analyzed longitudinal data from the Nurses Health Study, which included 73,000 women, the Nurses Health Study 2, which included 92,329 women, and the Health Professionals Follow-up Study, which included 43,259 men.
• These studies work, in part, by asking participants every two to four years what they eat and how much.
• Using this data, the researchers created three groups of participants.
• The first, those on a healthful plant-based diet, contained randomly selected individuals who adhered to a plant-based diet, defined for the sake of the study as including under six servings of meat and other animal products each day.
• The second category, those who ate an overall plant-based diet, included those who ate lots of whole grains, nuts, fruits, and vegetables, but not much in the way of meat, animal fat, potatoes, or sugar sweetened beverages.
• The third group had an unhealthy plant-based diet, and consumed a lot more sugar, juices, and refined grains.
• The groups were analyzed to determine how many developed heart disease, had a heart attack, or died of heart disease during the course of the study.
• They found that people in the first group who adhered to a healthful plant-based diet had a reduced risk of heart disease and heart attacks compared to those in the other groups.

Conclusions About Plant-Based Diets from the Research

• The researchers concluded that not all veggie-centric diets are created equal.
• People who followed a healthful plant-based diet but included more animal foods (still staying below six servings a day) were less likely to die than those who followed the highly processed unhealthful plant diet.
• “The study is encouraging in the sense that you don’t have to completely eliminate all animal foods from your diet in order to get a heart benefit.”
• “We found that modestly reducing your animal food intake by a couple of servings a day could maybe lower your risk of heart disease.”
• “More people would be able to adopt these moderate dietary changes and hopefully benefit from them rather than extreme changes.”

Of course, heart health isn’t the only reason to avoid too many hamburgers: folks worried about their contributions to climate change can drastically cut down on carbon emissions by reducing their meat and animal product consumption.
Focusing on eating unprocessed vegetables and the like as much as possible—with some meat and animal products sprinkled in—could be a much more sustainable plan for Americans accustomed to the omnivorous lifestyle.

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