Diets that limit highly processed foods aren't automatically healthy, study shows

Dr. Zhaoping Li, professor of medicine and director of the Center for Human Nutrition at the David Geffen School of Medicine at the University of California, Los Angeles, advises eating as many fresh, nutritious foods as possible. Photo by Klaus Nielsen/Pexels
1/2 |Dr. Zhaoping Li, professor of medicine and director of the Center for Human Nutrition at the David Geffen School of Medicine at the University of California, Los Angeles, advises eating as many fresh, nutritious foods as possible. Photo by Klaus Nielsen/Pexels
NEW YORK, June 30 (UPI) -- Diets that limit highly processed foods aren't necessarily healthy, and the types of foods people eat may matter more than the level of processing the foods are produced, a new study suggests.

The results were presented Sunday at the annual meeting of the American Academy of Nutrition in Chicago. The researchers compared two menus that reflect a typical Western diet according to the NOVA food classification system: one that emphasizes minimally processed foods and one that emphasizes ultra-processed.

The system categorizes foods into one of four groups based on processing criteria. It was developed by the Center for Epidemiological Studies on Health and Nutrition at the School of Public Health of the University of São Paulo in Brazil.

Meat substitutes may be more heart-healthy than meat

Americans' diets are improving but still unhealthy for many, Tufts study finds

Ultra-processed foods may increase risk of stroke and dementia

The less-processed menus were more than twice as expensive and had a shelf life more than three times faster, without any added nutritional value.

the findings showed that "both ultra-processed and less-processed foods may have less health value." "Moreover, highly processed foods with similar health value as less processed foods have a longer shelf life and cost less," Levine said.

Based on these findings, the researchers noted that people may eat a low-quality meal even if their diet consists primarily of minimally processed foods.

"The results of this study indicate that to create a nutritious meal, it is not enough to consider food processing as defined by NOVA," lead researcher Julie Hess said in a press release.

Last year, the team published a study showing that it is possible to create a high-quality menu that meets dietary guidelines while getting most of its calories from foods classified as highly processed. In the new study, the researchers asked the opposite question: Can we create a low-quality menu that gets most of its calories from "simple" foods?

To answer this question, they created a low-processed menu that gets 20% of its calories from highly processed foods and a high-processed menu that gets 67% of its calories from highly processed foods. The NOVA system determined the processing level of each menu.

The researchers calculated that the menus had a Healthy Eating Index score of about 43 to 44 out of 100, a relatively low number that reflects low adherence to the Dietary Guidelines for Americans.

They estimated that the low-processed menu would cost $34.87 per person per day, compared with $13.53 per person per day for the highly processed menu. They also calculated that the median time to expiration for less processed menu items was 35 days, compared with 120 days for more processed menu items.

The study highlights the contradiction between food processing and nutritional value, the researchers said. Some nutritious packaged foods could be classified as ultra-processed, such as unsweetened applesauce, ultra-filtered milk, liquid egg whites, and some brands of raisins and canned tomatoes.

"When it comes to affordable healthy eating, you can package both nutritional quality and price," said Joan Salge-Blake, R.D., clinical professor and director of the nutrition program at Boston University, who was not involved in the study. Blake recommends using grocery store brochures and apps to find healthy foods on sale, whether they're fresh, frozen, canned or packaged, and planning your meals for the week around those items.

"Instead of being fooled by the level of processing, use the Nutrition Facts panel on the label as a guide to understand the nutritional value of the foods you choose," she said.

But highly processed foods can be a big contributor to obesity and related chronic diseases when they're high in sugar, unhealthy fats and artificial additives and offer little nutritional value, says Dr. Zhaoping Li, professor of medicine and director of the Center for Human Nutrition at the David Geffen School of Medicine at the University of California, Los Angeles.


She advises replacing ultra-processed foods with a variety of fresh, nutritious foods whenever possible. A diet consisting of whole grains, lean proteins, healthy fats, fruits and vegetables "ensures that your body gets the vitamins, minerals and other beneficial compounds it needs," Lee said.


Overall, the study sends the message that the health value of food is more important than how much processing it undergoes before it reaches the consumer, said Liz Weinandy, a registered dietitian and lecturer at The Ohio State University Wexner Medical Center in Columbus.

"But I don't think anyone would disagree that sugary drinks, candy and snack chips have little nutritional value and shouldn't be consumed regularly," Weinandy said. "We don't want to put lipstick on a pig."