Western-Style Diet Impairs Memory and Learning and Leads to Over-Eating

A study from the Royal Society of Open Science aimed to find out if a western-style diet has an effect on the brain. One hundred and ten healthy human adults were recruited for the study. All participants were screened before enrolment to ensure they were lean, fit, and currently consuming a nutritious diet.

Then they were assigned randomly into 2 groups. One group continued their regular healthy diet, and the other group ate a western-style (WS) diet.

The Healthy Diet Group Ate the Following

On Days 1 and 8, these participants received a laboratory breakfast consisting of a toasted sandwich and a milkshake. All low in saturated fat and added sugars. (total KJ = 2954; 13% fat [5% saturated], 29% carbohydrate [10% sugar] and 58% protein)

On Days 2–7, they were asked to maintain their healthy regular diet.

The Western-style Diet Group had a Diet that is High in Saturated Fat and Added Sugar

On Days 1 and 8, the WS group received a laboratory breakfast of a toasted sandwich and a milkshake that is high in saturated fat and added sugar. (total KJ = 4023; 33% fat [19% saturated], 51% carbohydrate [29% sugar] and 16% protein)

On Days 2–7, participants were instructed to eat two Belgian waffles for breakfast or dessert on 4 days (total KJ for two waffles = 3376; 28% fat [15% saturated], 65% carbohydrate [31% sugar] and 7% protein)

The main meal and drink/dessert were from a set of options from a popular fast-food chain on the other 2 days. (total KJ per average meal/drink/dessert = 4127; 27% fat
[15% saturated], 46% carbohydrate [25% sugar] and 27% protein)

Gray739-emphasizing-hippocampus (1) — By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body

Tests Done

Before and after the test, neuropsychological tests were done like the wanting and liking test to measure appetite control.

Another is the test to measure Hippocampal-Dependent Learning and Memory (HDLM)

Results

The group that had a western-style diet tend to overeat based on the wanting and liking check.
WS-diet induced a decline in memory and learning.
Both the tendency to overeat and decline in memory and learning reflects changes in the hippocampus.

The reason is that WS meals generate repeated mild inflammatory responses, caused in part by their effect on blood glucose and damage to the cells.

Can the Damage to the Brain be Reversed?

The good news is that the damage is reversible. Three weeks after the study, they retested learning, memory, and tendency to overeat, and they found no difference between the two groups.

However, it may be reversible because the exposure to the high saturated fat and added sugar diet was only for 1 week.

Reference:

Richard J. Stevenson, Heather M. Francis, Tuki Attuquayefio, Dolly Gupta, Martin R. Yeomans, Megan J. Oaten, and Terry Davidson. Hippocampal-dependent appetitive control is impaired by experimental exposure to a Western-style diet. Royal Society Open Science. Published:19 February 2020

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