“How Poor Diet Shapes the Brain”
by Stacy Lu
Proto, March 8, 2018
The vicious cycle of SAD, brain health and obesity
Obesity can be hard on the brain. Research over the past decade suggests that people who are obese have reduced brain functions, including attention, verbal memory, decision making, and motor control.
What fewer people know is that the high-fat, high-sugar standard American diet –SAD — that contributes to obesity also damages our brains in ways that can make it harder to avoid these foods going forward.
Based on a new line of studies, scientists suspect that the SAD diet assaults the blood-brain barrier, a layer of cells that protect the brain from potentially harmful substances. This in turn makes the hippocampus, which controls learning and memory, more vulnerable to inflammation. People on such a diet have less ability to sense internal body cues such as hunger and fullness. Instead, they respond more readily to external cues – readily available food – and overeat in an environment where junk food is all too plentiful.
“It’s a vicious cycle. You eat these diets that that mess up regulatory control, and that causes you to eat more,” says Terry Davidson, PhD, a psychologist at American University who has studied these brain effects for a decade.
Scott Kanoski, PhD, who researches neurobiology and food intake at the University of Southern California, is looking into the SAD influence on the gut microbiome. “Western diets reduce production of short-chain fatty acids in the gut that are important to brain health,” he says.
Effects kick in fast. In a study published in February, researchers in Australia found that a Western diet starts to affect human brains in at little as four days. People who ate a sugary breakfast every day were less sensitive to hunger and fullness cues. Further, they performed worse in hippocampal-dependent learning and memory tasks.
The BBB deterioration can lead to other ills. A leaky blood-brain barrier also affects levels of brain-derived neurotrophic factor, a protein that influences appetite, executive functions and decision-making, and is important to neuron development and long-term memory. A less well-protected brain may also be more vulnerable to environmental toxins like some chemicals, lead and pollution; developing brains are particularly vulnerable.
Scientists don’t yet know if the BBB can heal itself. So what’s to be done? Psychologists are studying the effects of computerized inhibitive control training exercises that train participants to make refusing junk food a habit. These may be as simple as repeatedly pressing a “stop” button in front of, say, a picture of a Big Mac.
Results show some promise, but it’s an uphill battle. As Davidson says, “Until we can get people off this diet, we’re not going to see anything different. It’s not like we can tell people to stop eating high fat diets. People have known they shouldn’t eat these things, but the brain changes they produce are preventing them from making changes.”
[Note: I also included a brief bio and links to clips at the bottom of the pitch.]