Encouraging people to eat a wide variety of foods to ensure they meet all their dietary needs may backfire, according to a new scientific statement from the American Heart Association that provides an overview of recent scientific studies.

"Eating a more diverse diet might be associated with eating a greater variety of both healthy and unhealthy foods" said Marcia C. de Oliveira Otto, Ph.D., lead author of the statement published in the American Heart Association journal Circulation. "Combined, such an eating pattern may lead to increased food consumption and obesity.

"Eating a variety of foods" has been a public health recommendation in the United States and worldwide for decades. While some dietary guidelines highlight greater diversity of recommended foods, there is little consensus about what so-called dietary diversity is, how it is measured and whether it is a healthy dietary goal. The statement authors conducted a thorough scientific literature review of articles published between January 2000 and December 2017. They concluded:

There is no evidence that greater overall dietary diversity promotes healthy weight or optimal eating.

There is some evidence that a wider variety of food options in a meal may delay people's feeling of satiation (fullness), increasing the amount of food they eat.

Limited evidence suggests that greater dietary diversity is associated with eating more calories, poor eating patterns and weight gain in adults.

Instead of telling people to eat a variety of foods, the statement authors conclude that dietary recommendations should emphasize adequate consumption of plant foods, such as fruit, vegetables, beans and whole grains, low-fat dairy products, non-tropical vegetable oils, nuts, poultry and fish, and limit consumption of red meat, sweets and sugary drinks. The American Heart Association Dietary Recommendations and the DASH Diet (Dietary Approaches to Stop Hypertension) are both examples of healthy eating patterns.

"Selecting a range of healthy foods, which fits one's budget or taste, and sticking with them, is potentially better at helping people maintain a healthy weight than choosing a greater range of foods that may include less healthy items such as donuts, chips, fries and cheeseburgers, even in moderation," said Otto, who is also assistant professor of epidemiology, human genetics and environmental science at The University of Texas Health Science Center at Houston, Texas.