Nutritional Effects of Cognition and Flight Performance

Glenda N. Lindseth, Ph.D. and Paul D. Lindseth, Ph.D.; University of North Dakota; PRMRP Investigator-Initiated Research Award

About 70-90% of aircraft accidents happen because of human error or human factor kind of problems and when we speak of human factors, we’re meaning things like fatigue, being tired, maybe not having good nutrition, not having good sleep habits, those kinds of issues. One of the top stressors for the airline pilots was not having proper nutrition ,in other words, the right kinds of food or the meals at the right time. We pursued a research study with other colleagues that I have. We recruited about 90 pilots to our study and then we randomized for selection so we picked about half of those people to be in the study. They were student pilots that were enrolled in a professional aviation program at a four-year institution. They had to have some kind of instrument experience because we put them in a GAT-2 simulator where they had to fly some instruments but they weren’t rated instrument pilots but they knew enough about how to fly an instrument approach. We fed the pilots different types of meals over a 14-week time frame. We started off doing baseline assessments of the pilots. We measured things like what was their cognitive performance at base, in other words, at baseline measurement, how did they perform cognitively when we did different psychological exams, how did they perform when we did different types of flight testing and then some of the blood lab values that they might have to see what their health condition was like at the time. And then we brought them into a study we randomized again to see which kind of diet they should have on a particular week. So you might have some pilots eating the protein diet that week, some pilots eating a high carbohydrate diet that week, some pilots eating high fat diet and some eating a control diet on a particular week. After having 4 days of diets in the laboratory setting, they were put in the simulator for the flight test to test their cognitive flight abilities while flying this GAT-2 simulator. And basically what we ran them through is a 16-minute regimen of what we call an instrument approach where we simulate that the aircraft is above the clouds and they have to bring the aircraft down to the ground to an airport. We recorded all heading, altitude, and airspeed deviations for the 16-minute flight. The deviations were for every second off altitude, airspeed and heading and what we got was an overall performance score when we added the three different parameters together to get an overall performance score. Our results showed with the flight performance that they actually had two diets that were significantly better than all the rest. That was the high carbohydrate and the high fat diet. That was confirmed again with our psychological exams. When they did the memory test, we found that they did the best using the carbohydrate diet and the fat diet again. There was no significant difference between carbohydrate and fat, they performed well on both of those. The one that they did the worst on—the high protein diet. Another words they made the most mistakes when they flew. The Atkins Diet is similar to what the high protein diet that we fed in this particular study as far as the percentage of protein, it’s very similar to the Atkins Diet. One of the other things that we did was we had them wear what we called sleep and activity watches, they were an actiwatch. It’s a watch that they wear all the time while they were in the study and that told us how much physical activity they did and also how much sleep they had per night. We found that they went to sleep the quickest using the carbohydrate diet, in other words, they had the best rested sleep. The memory test they performed the best on when they had the high fat and the high carbohydrate diet. The other thing that we looked at was we did what we called predictors or hierarchical regression, in other words, if we were to predict how people might do what you put into that statistical equation—it’s sort of the strongest test that we had. When they had the high protein diet, we found the serotonin, irritability, and protein contributed the most to the poorest placed scores. In other words, they were going to perform the worst when they were irritable, when they had a high protein diet. So in conclusion I guess we’re thinking that having a high protein diet, you would perform the worst. If you had a high fat or high carbohydrate diet, you’d perform the best, and this is important for people to know when they’re in a situation such as flying or a combat situation and you need to make high-speed snap decisions and you’re under stress, you might want to pick a diet that has a not so high protein but higher carbohydrates or fats.