High-fat foods slow the brain

Nando, 3 June 1996

Fatty foods slow down the brain and impair mental function, nutrition researchers have found. But they also make people more sociable. The researchers found that a high fat content in the digestive system significantly reduces alertness and affects speed and accuracy in tasks requiring sustained attention. Even higher calorie lower fat meals did not reduce mental function when compared to a higher fat meal.

One of the researchers, Anita Wells is reported to have said; Carbohydrates make you feel assertive and alert . . . Although fat makes you more lethargic and impairs mental performance, we found it does make people feel more friendly.

Other research by the Sheffield Centre for Human Nutrition team found that people in simulated clerical jobs can be rapidly rendered inefficient by fat consumption.

Co-ordinating the research Prof. Nicholas Read, thinks the results have particular implications for those in driving jobs or other activities such as air traffic control, where speed of reaction is crucial. Prof. Read is quoted as saying;

Our studies broadly support what people intuitively know, which is why eating habits have changed in recent years . . . A low fat diet helps people to concentrate at work and a higher fat meal helps you relax. That’s why people eat cereal and sandwiches for breakfast and lunch and a heavier meal in the evening.

In fact the research goes further than this! Fat could act as a pain-killing sedative making it a popular opium for the masses. Perhaps this is yet another piece of evidence supporting the existance of addictive drug like experiences and cravings sought by those on the Standard American Diet. Why a higher carbohydrate diet tends to make one less happy needs to be answered as well. It seems that one can become a fat drunkard.

The potential ramifications of these effects are gigantic. High fat eaters (just what is this high and low in relation to?) seem to have the potential to misjudge pain signals, our natural warning system, but are also less attentive so may learn less and make more blunders.

Is this the final explanation for the jovial attitude of some people caught up in miserable jobs who love their greasy breakfast? Is a double cheese burger a stupidity inducer that keeps the masses happy?

John

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abstracts:

Title
Influences of fat, energy, and time of day on mood and performance.

Author
Wells AS; Read NW

Address
Centre for Human Nutrition, University of Sheffield, Northern General Hospital, Sheffield, UK.

Source
Physiol Behav, 1996 Jun, 59:6, 1069-76

Abstract
Paired studies testing the effects of lower energy high-fat, low-CHO meals (3181 kJ, fat:CHO energy ratio 54:41) and higher energy low-fat, high-CHO meals (3599 kJ, fat:CHO energy ratio 7:88) were conducted in 18 healthy males. The meals were eaten at 1030h by group A (nine subjects) and 1230 h by group B (nine subjects). Subjective lassitude increased following ingestion of all four meals, but there was little change in performance. In addition, group A, but not group B, felt significantly less vigorous, imaginative, and antagonistic, and significantly more dreamy, feeble, and fatigued after the lower energy high-fat, low-CHO meal than after the higher energy low-fat, high-CHO meal. These results suggest that in the morning, fat exerts a greater depression on alertness and mood than carbohydrate irrespective of a reduction in energy content, but this effect varies according to the time at which food is eaten, and is less evident at lunch time.

Title
The influence of food on pain perception in healthy human volunteers.

Author
Zmarzty SA; Wells AS; Read NW

Address
University of Sheffield, Northern General Hospital Trust, Centre for Human Nutrition, UK.

Source
Physiol Behav, 1997 Jul, 62:1, 185-91

Abstract
The aim of this study was to investigate if food could reduce pain perception in a group of 16 healthy human volunteers (8 male and 8 female), and to explore the differential effects of macronutrient composition on the response to cold-induced pain. All subjects underwent the cold pressor test (CPT) on 3 occasions in a counterbalanced order, before and after administration of isoenergetic high-fat low-carbohydrate (CHO) and high-CHO low-fat meals, and when no meal was given. The CPT was carried out 4 times on each test day, once before the meal, and 0.5, 1.5, and 2.5 h after the meal, and at the equivalent times on the day when no food was given. Radial pulse and blood pressure measurements and visual analogue scales of mood/emotional state were carried out before and after each CPT. Mean pain scores were significantly reduced following both meals compared with the no-food condition. The maximum reduction in pain occurred 1.5 h after ingestion, and a significantly greater effect was exerted by the high-fat low-CHO meal compared with the high-CHO low-fat meal. These results demonstrate that food, particularly when rich in fat, significantly reduces the pain induced by the cold pressor stimulus in healthy human subjects.

Title
Influences of fat and carbohydrate on postprandial sleepiness, mood, and hormones.

Author
Wells AS; Read NW; Uvnas-Moberg K; Alster P

Address
Centre for Human Nutrition, University of Sheffield, England.

Source
Physiol Behav, 1997 May, 61:5, 679-86

Abstract
Paired studies were conducted in 18 healthy volunteers (9 men, 9 women) to investigate whether differences in mood and daytime sleepiness induced by high-fat-low-carbohydrate (CHO) and low-fat-high-CHO morning meals were associated with specific hormonal responses. Plasma insulin concentrations were significantly higher after low-fat-high-CHO meals, and cholecystokinin (CCK) concentrations were significantly higher after high-fat-low-CHO meals. Subjects tended to feel more sleepy and less awake 2-3 h after the high-fat-low-CHO meal, and ratings of fatigue were significantly greater 3 h after the high-fat-low-CHO meal than after the low-fat-high-CHO meal. The results of the present study are consistent with the hypothesis that there is an association between the lassitude experienced after a meal and the release of CCK.