Children who eat too much junk food may end up harming some of their brain functions like memory, according to a recent study.
Researchers fed one group of rats a Western diet containing high-fat, high-sugar foods during their juvenile and adolescent stages. The other group was fed the usual meal.
Metabolic and behavioral assessments were conducted on rats before and after a healthy diet intervention was made during the early adulthood stage.
Specifically, the hippocampus’ acetylcholine (ACh) signaling was found to have been compromised. The hippocampus relies on such signaling for proper memory function. ACh in the brain is crucial for memory and functions like attention, learning, and involuntary muscle movement.
Moreover, disrupted ACh signaling is a “pathological marker of Alzheimer’s disease.” The memory deficits suffered by the rats persisted despite “healthy diet intervention at the onset of adulthood,” the study said.
Such memory impairments happened even though there were no metabolic or body weight outcomes, suggesting that “early life diet can have critical, long-lasting effects on neural function—independently of obesity.”
“I don’t know how to say this without sounding like Cassandra and doom and gloom … but unfortunately, some things that may be more easily reversible during adulthood are less reversible when they are occurring during childhood,” he said.
Researchers tracked the impact of diets on rats’ brains by looking at ACh levels and engaging the animals through memory tests. They looked at the brain responses of the rats to certain tasks.
One test involved letting the rats explore new objects at different places. Several days later, researchers would reintroduce the rats to a similar setting but with one added object.
The rats raised on junk food showed signs of being unable to remember which objects were seen earlier and where.
In contrast, rats from the other group exhibited familiarity with the place.
“Acetylcholine signaling is a mechanism to help them encode and remember those events, analogous to ‘episodic memory’ in humans that allows us to remember events from our past,” said lead author Anna Hayes.
“That signal appears to not be happening in the animals that grew up eating the fatty, sugary diet.”
Researchers also examined whether the memory alteration could be reversed by using drugs that induce the release of ACh. For this purpose, they used PNU-282987 and carbachol. The two drugs, when given directly to the hippocampus, were found to restore memory ability.
The study also showed that consuming a Western diet in early life “markedly altered the gut microbiome.” However, when the rats were given a healthy diet during adulthood, such alterations “largely reversed.”
Poor Impulse Control, Lower Grades
A March 2020 review paper published in The Lancet detailed how the propensity to consume calorie-dense foods during adolescence heightened the “adverse impact of these foods on brain function.”During adolescence, the prefrontal cortex region of the brain is developing. This region involves decision-making and reward-seeking. Until this region matures, adolescents are likely to engage in impulsive, reward-seeking activities.
Excessive consumption of calorie-dense foods can alter the structure and function of the prefrontal cortex. This includes changing the signaling and inhibition of dopamine—a neurotransmitter released by the brain when the reward system is activated by an action such as eating calorie-dense foods.
When adolescents overstimulate their reward systems by consuming junk foods, unhealthy diets can end up resulting in poor cognitive control and heightened impulsivity as the kids enter adulthood.
“One avenue that we really need to look into is the use of exercise as a way of regulating changes in the brain that can help us make better dietary choices,” said Ms. Lowe.
“There’s evidence that exercise can help improve the brain in terms of cognitive control, but also reduce reward sensitivity to things like food items.”
“Fast food consumption during fifth grade predicted lower levels of academic achievement in all 3 subjects in eighth grade, even when fifth-grade academic scores and numerous potential confounding variables, including socioeconomic indicators, physical activity, and TV watching, were controlled for in the models,” the study said.
“These results provide initial evidence that high levels of fast food consumption are predictive of slower growth in academic skills in a nationally representative sample of children.”
In addition to potentially harming brain function, consumption of fast foods can pose various other medical complications, including diabetes, cardiovascular issues, cancer, liver disease, depression, kidney damage, and dental cavities.
“For decades, we have allowed large corporations in the food and beverage industry to entice children to eat foods loaded with sugar, salt, and saturated fat. This situation has led to an addiction crisis, with ultra-processed foods being as addictive as alcohol and cigarettes,” he said.
Mr. Sanders called for prohibiting junk food ads targeting kids, pointing to similar successful regulations in Quebec, Canada.
