Our ability to focus may falter after eating a meal high in saturated fat

New research suggests that eating just one meal high in saturated fat may hinder our ability to concentrate. The study, published in the American Journal of Clinical Nutrition, 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 sunflower oil, 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 researchers 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,” said Annelise Madison, lead author of the study and a graduate student in clinical psychology at The Ohio State University, in a press release.

The researchers conducted a secondary analysis of the data 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.

Then, they ate a high-fat meal of eggs, biscuits, turkey sausage, and gravy containing 60 grams of fat, made of 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.

Five hours later, the women retook the continuous performance test. 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 the participating women were, on average, 11% 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.