By Carolyn Crist

(Reuters Health) – Although doctors and nutrition experts have recommended “eating a variety of foods” for decades, there’s a lack of agreement on what exactly that means and whether it really is a healthy option, according to a new American Heart Association Science Advisory.

Recent studies suggest that diet diversity is associated with poor eating habits that include processed foods, refined grains and sugary drinks and not eating minimally-processed foods such as fish, fruits and vegetables. Diet diversity could lead to weight gain and obesity, the AHA Behavioral Change for Improving Health Factors Committee writes in the journal Circulation.

“While selecting a wide range of healthy foods remains important for good nutrition, expanding food choices to include less-healthy foods such as donuts, chips, fries and cheeseburgers, even in moderation, may translate into eating too much of too many unhealthy things far too often,” said lead advisory author Marcia de Oliveira Otto of the University of Texas Health Science Center at Houston.

The group emphasized the American Heart Association Dietary Recommendations and the Dietary Approaches to Stop Hypertension (DASH) diet as two examples of healthy eating patterns.

“The focus should shift to emphasizing eating adequate amounts of healthy foods such as fruit and vegetables, protein, low-fat dairy products, vegetables oils and nuts, while limiting intake of less-healthy foods such as sweets, beverages with added sugar and red meats,” de Oliveira Otto told Reuters Health by email.

The committee looked at studies around diet variety, eating patterns and obesity since 2000 to provide an updated perspective for doctors and nutritionists. First introduced in the early 20th century, the concept of promoting “variety” was based on the premise that eating different foods would help people avoid nutrient and mineral deficiencies. During the past two decades, however, more junk food is on the market that ever before, and more diversity doesn’t mean quality.

The committee found there’s no evidence that greater overall dietary diversity leads to healthy eating habits or a healthy weight. In fact, they found some evidence that a wider variety of food options in one meal may delay people’s feeling of fullness and may increase the amount of food they eat.

They also found evidence that greater diet diversity is associated with eating more calories, poor eating patterns and weight gain.

Consumers could use this information to reduce unhealthy snack behaviors. For example, keeping one flavor of cookies in the house instead of three may reduce the number of cookies being overconsumed, said Megan McCrory of Boston University. McCrory, who wasn’t involved with this advisory, has researched dietary variety and energy balance.

“Another example is buffets and potlucks – everyone who has been to a buffet or potluck is familiar with the idea that it’s difficult to limit the number of items put on their plate because they all look so good, and it’s tempting to taste them all,” she told Reuters Health by email.

Future studies should look at whether diet diversity in certain food groups, such as fruits and vegetables, is related to healthier diet habits or weight control, said Maya Vadiveloo of the University of Rhode Island in Kingston, who wasn’t involved in the study.

Researchers are looking at how these behaviors develop in different groups of people and how to encourage them to adopt healthier diet patterns, she said. Dietary diversity could play a role alongside environmental factors such as availability of food, cost, taste and sustainability.

“The research community is in agreement that it is overly simplistic to recommend overall variety as a strategy to promote healthful diets and weight control,” she told Reuters Health by email. “Even more so, researchers recognize how difficult it is for most Americans to adhere to healthful patterns.”

Vadiveloo and colleagues begin a study in September that will offer people targeted coupons based on their current grocery choices to encourage more healthy options. They hope to shift the typical ways nutrition experts promote healthy diets.

“While the idea that ‘variety is the spice of life’ does not apply to promoting healthy diets and weight control across the board, we may still find that variety is good if we apply it to fruits, vegetables and whole grains,” she said.

SOURCE: Circulation, online August 9, 2018.