Study also looks at effect of leaky gut on concentration
Ohio State University
Fatty food may feel like a friend during these troubled times,
but new research suggests that eating just one meal high in saturated fat can
hinder our ability to concentrate -- not great news for people whose diets have
gone south while they're working at home during the COVID-19 pandemic.
The study compared how 51 women performed on a test of their
attention after they ate either a meal high in saturated fat or the same meal
made with sunflower oil, which is high in unsaturated fat.
Their performance on the test was worse after eating the
high-saturated-fat meal than after they ate the meal containing a healthier
fat, signaling a link between that fatty food and the brain.
Researchers were also looking at whether a condition called
leaky gut, which allows intestinal bacteria to enter the bloodstream, had any
effect on concentration. Participants with leakier guts performed worse on the attention
assessment no matter which meal they had eaten.
The loss of focus after a single meal was eye-opening for the
researchers.
"Most prior work looking at the causative effect of the diet has looked over a period of time. And this was just one meal -- it's pretty remarkable that we saw a difference," said Annelise Madison, lead author of the study and a graduate student in clinical psychology at The Ohio State University.
Madison also noted that the meal made with sunflower oil, while
low in saturated fat, still contained a lot of dietary fat.
"Because both meals were high-fat and potentially
problematic, the high-saturated-fat meal's cognitive effect could be even
greater if it were compared to a lower-fat meal," she said.
The study is published in the American Journal of
Clinical Nutrition.
Madison works in the lab of Janice Kiecolt-Glaser, professor of
psychiatry and psychology and director of the Institute for Behavioral Medicine
Research at Ohio State. For this work, Madison conducted a secondary analysis
of data from Kiecolt-Glaser's study assessing whether high-fat meals increased
fatigue and inflammation among cancer survivors.
Women in the study completed a baseline assessment of their
attention during a morning visit to the lab. The tool, called a continuous
performance test, is a measure of sustained attention, concentration and
reaction time based on 10 minutes of computer-based activities.
The high-fat meal followed: eggs, biscuits, turkey sausage and
gravy containing 60 grams of fat, either a palmitic acid-based oil high in
saturated fat or the lower-saturated-fat sunflower oil. Both meals totaled 930
calories and were designed to mimic the contents of various fast-food meals
such as a Burger King double whopper with cheese or a McDonald's Big Mac and
medium fries.
Five hours later, the women took the continuous performance test
again. Between one and four weeks later, they repeated these steps, eating the
opposite meal of what they had eaten on the first visit.
Researchers also analyzed participants' fasting baseline blood
samples to determine whether they contained an inflammatory molecule that
signals the presence of endotoxemia -- the toxin that escapes from the
intestines and enters the bloodstream when the gut barrier is compromised.
After eating the meal high in saturated fat, all of the
participating women were, on average, 11 percent less able to detect target
stimuli in the attention assessment. Concentration lapses were also apparent in
the women with signs of leaky gut: Their response times were more erratic and
they were less able to sustain their attention during the 10-minute test.
"If the women had high levels of endotoxemia, it also wiped
out the between-meal differences. They were performing poorly no matter what
type of fat they ate," Madison said.
Though the study didn't determine what was going on in the
brain, Madison said previous research has suggested that food high in saturated
fat can drive up inflammation throughout the body, and possibly the brain.
Fatty acids also can cross the blood-brain barrier.
"It could be that fatty acids are interacting with the
brain directly. What it does show is the power of gut-related
dysregulation," she said.
The statistical analysis accounted for other potential
influences on cognition, including depressive symptoms and the participants'
average dietary saturated fat consumption. The women in the study ate three
standardized meals and fasted for 12 hours before each lab visit to reduce diet
variations that could affect their physiological response to the high-fat
meals.
The findings suggest concentration could be even more impaired
in people stressed by the pandemic who are turning to fatty foods for comfort,
Kiecolt-Glaser said.
"What we know is that when people are more anxious, a good
subset of us will find high-saturated-fat food more enticing than
broccoli," she said. "We know from other research that depression and
anxiety can interfere with concentration and attention as well. When we add
that on top of the high-fat meal, we could expect the real-world effects to be
even larger."
This work was supported in part by the National Institutes of
Health.
Additional co-authors, all from Ohio State, included Martha
Belury, Rebecca Andridge, M. Rosie Shrout, Megan Renna, William Malarkey and Michael
Bailey.