Eat your veggies, but do it right

A vegan diet can be healthy, as long as it isn’t junk food, a study finds.

Cutting meat and dairy out of your diet is hard. Staying healthy while you do it can be harder.

The wrong kind of exclusively plant-based diet, one that includes a lot of refined grains and sweetened beverages, can actually increase the risk of coronary heart disease, according to a new study from Harvard University. On the other hand, reducing your intake of animal products while boosting your consumption of fruits, vegetables, and whole grains, and continuing to indulge modestly in animal foods, can do you nearly as much good as a healthy vegan diet — and even more good than one that includes a lot of French fries and pasta.

“Less healthy plant foods and animal foods were both associated with increased risk, with a potentially stronger association for less healthy plant foods,” according to the study, published in the Journal of the American College of Cardiology.

The study reviewed data from two iterations of the Nurses’ Health Study and one from the Health Professionals Follow-Up Study.

Each involved tens of thousands of adults who tracked their lifestyles, health behaviors, and medical histories through questionnaires completed every two years. This gave the researchers, at Harvard’s T.H. Chan School of Public Health, more than 4.8 million person-years of followup data to analyze.

Using these data, the authors created three diet indexes. One was an overall plant-based diet index in which plant foods got a positive score and animal foods got a negative score. Another was a healthy plant-based diet index, assigning positive scores to whole grains, fruits, vegetables, nuts, legumes, oils, tea and coffee, and negative scores to juices and sweetened beverages, refined grains, potatoes and fries, and sweets. Then there was an unhealthy plant-based diet, with positive scores for the unhealthy plant foods and negative scores for the healthy plant and animal foods.

The researchers found that the people with a higher adherence to the general plant-based diet index had an inverse association with coronary heart disease, and that this relationship got even stronger for the healthy plant-based diet index.

The unhealthy plantbased diet index had a positive association with coronary heart disease.