After you watch “Forks Over Knives” and decide to adopt a plant-based diet, does it matter if you spend your dollars in the produce department or buy a stack of vegan frozen pizzas, coconut milk ice cream, and soy burgers with chips and fries? While the increasing availability of factory-produced vegan prepared food is staggering, if you are eating for health, the difference in how you spend your dollars and what you put in your body is enormous. This is made crystal clear by a new study from the Harvard School of Public Health that examines which type of plant-based diet is best for avoiding heart disease—the No. 1 killer in the United States—and which diet you should work hard to avoid, even at a young age.

Researchers examined data from over 200,000 health professionals, free of heart disease at the beginning of the study, followed for over 25 years. Participants filled out repeated food questionnaires. Researchers developed two dietary patterns. One was called the healthful plant-based diet index (hPDI) and was defined as eating more whole grains, fruits and vegetables, nuts, legumes, teas, coffee, and vegetable oils (as compared with butter and lard). The other dietary pattern was called the unhealthful PDI (uPDI) and was defined as one with increases in juices, sweetened beverages, refined grains, sweets, and fried potatoes.

During the study, 8,631 subjects developed coronary heart disease (CHD) like a heart attack or needing heart bypass surgery. Adhering to any plant-based diet lowered the risk of CHD by about 8 percent overall during the study. Then the researchers took it a step further and analyzed the risk of CHD based on the quality of the diet. The good news was that the benefit was much stronger for those following the hPDI, where the risk of developing CHD was slashed by 25 percent. These data are a huge confirmation that eating a whole-food, plant-based diet is a powerful tool to prevent that first heart event that may be fatal. The bad news was that for those who followed the uPDI pattern, there actually was an increase in the risk of developing CHD, perhaps as much as a 30 percent increase! Clearly eating junky food, even if plant-based, makes for a junky body and a junky heart.

A database this large, that includes so many years of follow-up information on participants, by a major research center is uncommon and provides important insight into what we should be putting on our plates. The overall finding that plant-based diets lower the risk of CHD is not new but confirmed in this mega study. The importance of the quality of the plant-based diet on heart health outcomes may be obvious, but here it is dramatically demonstrated.

The food industry has responded with the creation of many plant-based processed food and drink choices that would easily fit the uPDI pattern. As delicious and convenient as these foods may be, they should either be avoided or enjoyed rarely. The majority of the food we eat should be from the produce department at local stores, the farmer’s market plant-based choices, or our own gardens. For health, the quality of the food we choose and the closer it is to the earth make all the difference. I’d even like to see the term “plant diet” instead of “plant-based” used to make it clear that it should be plants, not processed morsels made in food company plants, that fuel our health.