Sugar and Spice and Everything Not So Nice?

Sugar and Spice and Everything Not So Nice?

 Jim Windell

             A little sugar can’t hurt, right?

            I mean, what’s so bad about a candy bar, a little sugar on our cereal, a dish of ice cream at night, a non-diet soda, maybe a handful of M&Ms or a slice of pie?

            If you’re an adult, maybe there’s nothing terribly wrong with any of those things. A little sugary treat in moderation. It probably won’t alter your brain or cause diabetes.

            But what about your children or grandchildren?

            What effect does sugar consumption have on them?

            A new study sheds some light on these questions.

            New research, recently published in Translational Psychiatry, and led by a University of Georgia faculty member in collaboration with a University of Southern California research group has shown in a rodent model that daily consumption of sugar-sweetened beverages during adolescence impairs performance on a learning and memory task during adulthood.

           Taking into consideration the role the hippocampus plays in a variety of cognitive functions and the fact that the area is still developing into late adolescence, the researchers in this study sought to understand more about the hippocampus’ vulnerability to a high-sugar diet via gut microbiota. In the study, juvenile rats were given their normal chow and an 11% sugar solution, which is comparable to commercially available sugar-sweetened beverages. The researchers then had the rats perform a hippocampus-dependent memory task designed to measure episodic contextual memory. That is, remembering the context where they had seen a familiar object before.

           "We found that rats that consumed sugar in early life had an impaired capacity to discriminate that an object was novel to a specific context, a task the rats that were not given sugar were able to do," commented Emily Noble, assistant professor in the University of Georgia Atlanta’s College of Family and Consumer Sciences.

           Noble, who served as first author on the paper, and the other researchers then ran the rats through a second memory task; this task measured basic recognition memory – a hippocampal-independent memory function that involves the animals' ability to recognize something they had seen previously. In this task, sugar had no effect on the animals' recognition memory.

           One of the conclusions drawn by researchers, says Noble, is that "Early life sugar consumption seems to selectively impair their hippocampal learning and memory."

           Additional analyses, however, determined that high sugar consumption led to elevated levels of Parabacteroides in the gut microbiome. These are the more than 100 trillion microorganisms in the gastrointestinal tract that play a role in human health and disease. But to better identify the mechanism by which the bacteria impacted memory and learning, researchers experimentally increased levels of Parabacteroides in the microbiome of rats that had never consumed sugar. Those animals showed impairments in both hippocampal dependent and hippocampal-independent memory tasks. The research group further showed that changes in the bacteria in the gut may be the key to the sugar-induced memory impairment.

           "Early life sugar increased Parabacteroides levels, and the higher the levels of Parabacteroides, the worse the animals did in the task," said Noble. "We found that the bacteria alone was sufficient to impair memory in the same way as sugar, but it also impaired other types of memory functions as well."

           And what are the implications for youth?

           Sugar practically screams from the shelves of your grocery store, especially those products marketed to kids. As it turns out, children are the highest consumers of added sugar, even as high-sugar diets have been linked to health effects like obesity and heart disease and even impaired memory function.

           The Dietary Guidelines for Americans, a joint publication of the U.S. Departments of Agriculture and of Health and Human Services, recommends limiting added sugars to less than 10 percent of calories per day. But, data from the Centers for Disease Control and Prevention show Americans between the ages 9 and 18 exceed that recommendation, the bulk of the calories coming from sugar-sweetened beverages.

           Although Noble says that future research is needed to better identify specific pathways by which this gut-brain signaling operates, for now, it is reasonable to conclude that the brains of youth will more likely grow in a healthier way if sugar consumption falls below recommended levels. And we can also conclude that high sugar consumption during childhood will affect the development of the hippocampus and may interfere with learning and memory.

           To read the original article, find it with this reference:

Noble, E.E., Olson, C.A., Davis, E., Tsan, L., Chen, W-Y., Schade, R., Liu, C., Suarez, A., Jones, R.B., de La Serre, C., Yang, X., Hsiao, E.Y. & Kanoski, S.E. (2021). Gut microbial taxa elevated by dietary sugar disrupt memory functionTranslational Psychiatry, 11 (1) DOI: 10.1038/s41398-021-01309-7

 

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