An ongoing study is investigating whether ultra-processed foods affect brain chemistry and obesity risk in young people

An ongoing study is investigating whether ultra-processed foods affect brain chemistry and obesity risk in young people

In continuing study in journalism with the magazine Contemporary clinical trialsResearchers are studying how consumption of ultra-processed foods (UPF) affects physiological processes related to energy intake (EI) and reward processing.

Overweight and obesity continue to rise around the world, leading to various health problems such as heart disease. Scientists have found that even young adults (ages 18 to 30) who are at a medically recommended weight are at high risk of transitioning to overweight or obesity within the next quarter century.

Poor dietary practices among adolescents and young adults in the United States have been well documented. It is believed that more than two-thirds of their IQ comes from ultraviolet protection factor (UPF), with little or no whole foods. Scientists are concerned that these foods could alter how people make diet decisions and lead to weight gain and obesity.

Study: Effect of ultra-processed food consumption on reward processing and energy intake: Background, design, and methods of a controlled feeding trial in adolescents and young adults.  Image credit: Celso Bobo/ShutterstockStudy: Effect of ultra-processed food consumption on reward processing and energy intake: Background, design, and methods of a controlled feeding trial in adolescents and young adults. Image credit: Celso Bobo/Shutterstock

UPF foods have high rewards but little nutrition

Research in humans and rats has shown how processed foods can affect the brain’s dopamine system. Mice fed bacon and ice cream quickly gained weight, which was thought to be related to decreased functioning of striatal dopamine D2 receptors (D2R) located in the striatum, an area of ​​the brain associated with moderate food intake and reward.

Animals fed high-sugar diets and humans exposed to foods high in fat and sugar show similar effects. The finding that humans with a high body mass index (BMI) have reduced D2R function suggests a role for UPF in increased EI, which may lead to overweight and obesity.

However, only one trial has examined this relationship in adult humans, and no research has focused on how UPF consumption in early adulthood may alter brain chemistry and modify how people perceive reward from food.

These changes, which occur during the crucial transitional period between childhood and adulthood, have implications throughout an individual’s life as cognitive processes such as inhibitory control mature at this age. Thus, UPF can modify executive function (EF) related to inhibitory control, working memory, and cognitive flexibility, leading people to eat more food when they are not hungry.

Exploring how UPF affects EF in young people

The ongoing clinical trial will recruit participants between the ages of 18 and 25 who are either sedentary or recreationally active. Individuals with food allergies will not be included. During the hiring process, physical examinations and nutritional recall information will be evaluated. Participants will also be scanned through a mock functional magnetic resonance imaging (fMRI) scan to ensure they do not suffer from claustrophobia.

Essentially, researchers will collect data on body weight and composition, perform functional MRI, and ask participants to complete delay discounting tasks and cognitive EF tasks. They estimate that they will need 32 participants at the beginning of the study to account for attrition and to ensure that they have at least 26 participants and sufficient statistical power for causal inference.

All participants will then be put on two diets, each for two weeks. On one diet, participants would get 81% of their EI from UPF, while the other diet would have no UPF. These diets will be designed to be similar in overall quality, nutrients, texture and palatability and are formulated to maintain weight. It will contain 15% protein, 35% fat and 50% carbohydrates.

Participants will eat breakfast in the lab Monday through Saturday and will have food for the rest of the day. Sunday meals will be provided in advance. Any remaining food will be returned to the laboratory, and consumption, deviation and compliance data will be recorded.

In addition to meals, participants will be offered a choice of snacks and buffet meals to rate their preferences between UPF and non-UPF foods. There will be a four-week “washout period” between the two controlled feeding periods. After each feeding period, an fMRI will be performed again, and physical measurements and cognitive performance will be noted. For four days of each diet, participants will wear an accelerometer for physical activity measurements.

Researchers will study the mechanisms by which the UPF modulates reward processing. They will explore the body’s blood oxygen level-dependent (BOLD) response, as well as EI between meals, using statistical methods such as analysis of variance (ANOVA) with mixed effects and generalized linear mixed models.

They hypothesize that foods high in UPF will impair the BOLD response in the ventromedial prefrontal cortex and striatum, the brain’s reward centers. They also expect that the UPF diet will lead to increased preference for food items containing UPF, in addition to EI, between meals. Finally, they hypothesized that foods containing UPF would decrease EF performance by impairing inhibitory control.

Implications of the study

Although emerging research highlights the harmful health effects of ultraviolet protection factor (UPF), commercial food consumption remains widespread in popularity. Researchers believe that these foods are addictive and that they impair our natural ability to regulate emotional intelligence. Understanding how these foods modify decision-making abilities and brain chemistry is key to formulating more effective public health guidelines and regulations for commercial food companies to promote healthy diets.

Magazine reference:

  • The effect of ultra-processed food consumption on reward processing and energy intake: Background, design, and methods of a controlled feeding trial in adolescents and young adults. Rego, MLM, Leslie, E., Capra, P.T., Helder, M., Yu, W., Katz, B., Davey, K.B., Hedrick, V.E., Davey, P.M., DeFelicesantonio, A.J. Contemporary clinical trials (2023). https://doi.org/10.1016/j.cct.2023.107381, https://www.sciencedirect.com/science/article/pii/S155171442300304X?via%3Dihub
    (tags for translation) Adolescents 

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