With all the praise for plant-based diets, it’s easy to think that a vegan or vegetarian diet guarantees that your diet is healthful and nutritious. But does it? The research in support of plant-based diets is bountiful, which is likely because they include higher levels of vitamins, minerals, phytonutrients and fiber and lower levels of saturated fat.

However, a limitation of early plant-based research was that it often tended to assume plant-based diets as equal without assessing food quality, even though when people focus on avoiding certain foods, they aren’t necessarily making sure the rest of their diet is nutritionally adequate. Then, in 2017, researchers from the Harvard T.H. Chan School of Public Health found that when it comes to the plants you eat, quality does count.

Plants Types? In the study of over 200,000 adults who reported their diets, researchers measured what proportion was plant-based, and whether those plant foods were healthful (vegetables, fruits, whole grains, pulses, nuts and seeds, vegetable oils) or unhealthful (sweetened beverages, refined grains, sweets).

They found that a diet rich in healthful plant foods is associated with substantially lower risk of developing heart disease, while a plant-based diet that emphasizes less-healthful plant foods is associated with increased risk of heart disease. Those eating a nutritious plant-based diet while also being more physically active fared even better. Ultimately, healthy plant-based diets reduce the risk of cardiovascular disease, Type 2 diabetes, metabolic syndrome, and cognitive health, while unhealthy plant-based diets increase risk.

Not seeing the forest for the trees

A vegan diet excludes all animal-based foods, while a vegetarian diet allows eggs and dairy. But focusing too intently on those exclusions can lead to dietary tunnel vision. Logically, a vegan diet that is full of refined grains, potato chips, sugar-sweetened beverages, and soy ice cream isn’t terribly healthful. This is one of the perils of demonizing specific foods — it’s your overall eating pattern that matters most for health and well-being. Unless carefully planned, a vegan diet can lead to nutritional deficiencies over time.

The Harvard studies — and subsequent research — supports the value of a plant-rich diet even for omnivores. Individuals who ate the least plant foods were eating about five or six servings of animal foods per day, while those with the most plant foods were eating three servings of animal foods. This means that reducing animal foods even slightly while increasing healthy plant foods has benefits for preventing heart disease and diabetes. This allows a lot of flexibility with eating.

Final food for thought

Overall, what you do eat matters as much as, if not more than, what you don’t eat. Plant-based diets can take many forms, from vegan to vegetarian to flexitarian to omnivore. The common denominator is that they make plant foods the focal point of the plate.

(Environmental Nutrition is the award-winning independent newsletter written by nutrition experts dedicated to providing readers up-to-date, accurate information about health and nutrition in clear, concise English. For more information, visit www.environmentalnutrition.com.)

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