A very large study recently published in the Journal of the American College of Cardiology is a case in point. The study, by a team from Harvard’s T.H. Chan School of Public Health, examined the relationship between plant-based diets of varying quality and the risk of developing coronary heart disease among more than 200,000 health professionals. The participants, who started the study free of chronic disease, were followed for more than two decades, submitting their dietary patterns to the researchers every two years.
Based on their responses on food-frequency questionnaires, the participants’ diets were characterized by the team as an overall plant-based diet that emphasized plant foods over animal foods; a healthful plant-based diet emphasizing healthful plant foods; or an unhealthful plant-based diet. Any of the diets could have included various amounts of animal products.
Healthful plant foods like whole grains, fruits and vegetables, nuts and legumes, as well as vegetable oils, coffee and tea, received a positive score, while less-healthful plant foods like juices, sweetened beverages, refined grains, potatoes and fries, and sweets along with animal foods were assigned a negative rating.
The more closely the participants adhered to a healthful plant-based diet, the less likely they were to develop heart disease in the course of the study. Those with the least healthful plant-based diet were, on average, 32 percent more likely to be given diagnoses of heart disease. In a prior study, the researchers found a similar reduction in the risk of Type 2 diabetes of a healthful plant-based diet.
The team, led by Ambika Satija of Harvard’s Department of Nutrition, concluded that “not all plant foods are necessarily beneficial for health.”
Interestingly, the Harvard finding was nearly identical to one from an 11-year European study that found a 32 percent lower risk of coronary heart disease among vegetarians than among nonvegetarians, although no health-based rating was given to the quality of the participants’ vegetarian diets.
The more detailed Harvard study, which examined gradations of adherence to a plant-based diet, found that “even a slightly lower intake of animal foods combined with a higher intake of healthy plant foods” was associated with a lower risk of developing heart disease.
In other words, you don’t have to become a strict vegetarian to protect your heart. Simply reducing your dependence on animal foods, and especially avoiding those high in fat, is helpful. In fact, “a diet that emphasized both healthy plant and healthy animal foods” was associated with a coronary risk only slightly higher than a diet based almost entirely on healthy plant foods, the researchers found.
On the other hand, overdoing “less healthy plant foods” and less healthy animal foods like red and processed meats, the study showed, significantly increased the risk of developing heart disease.
The Harvard findings lend further support to the most recently released Dietary Guidelines for Americans that urge people to consume large amounts of “high-quality plant foods,” the researchers noted. They added that the recommended diet “would also be environmentally sustainable” because plant-based food systems require fewer resources than those that rely heavily on animal foods.
Thus, the more plant foods and the fewer animal foods you eat, the lower your carbon footprint and the less you would contribute to animal suffering. But to be truly beneficial, the plant foods you choose must be rich in nutrients.
Although most Americans rely heavily on animal foods for needed protein, it’s not difficult to get quality protein on a vegetarian diet that contains dairy foods and eggs. Pescatarians, who add fish to such a diet, get a nutritious bonus of healthful omega-3 fatty acids along with high-quality protein from fish and shellfish.
Those choosing a strict vegan diet — one devoid of all foods from animals — face a greater challenge because the protein in plants is not complete and must be balanced by consuming complementary sources, like beans and grains. A sandwich of almond butter or peanut butter on whole-grain bread is totally vegan and an excellent example of balanced protein in a high-quality plant-based diet. Vegans also must supplement their diet with vitamin B-12.
Short of becoming a vegan, you can improve your diet, protect your health and add variety to your meals by a few simple dietary adjustments. For example, as Dr. Hena Patel and Dr. Kim Allan Williams Sr., cardiologists at Rush University Medical Center in Chicago, suggested in a commentary on the Harvard study, you might choose one day a week to be meatless and gradually add more meatless days while adding one or more new plant-based recipes each week.
I bet you’ll be pleasantly surprised at how much more delicious and varied your meals will be.