New study postulates the role of dietary
advanced glycation end products in the risk
of Alzheimer's
2 February 2015
Our new paper published in the Journal of
Alzheimer's Disease provides evidence that
cooking foods at high temperatures increases the
risk of Alzheimer's disease. This study looked at
the content of advanced glycation end products
(AGEs) in national diets and clinical studies
comparing and compared total AGEs to
Alzheimer's disease rates.
AGEs are a group of compounds that are
combinations of sugars and proteins and other
large molecules. They can be formed in the body,
and there is a large body of literature on AGEs and
Alzheimer's disease. However, AGEs are also
formed when food is cooked at high temperatures
or aged for a long time such as in hard cheese.
AGEs increase the risk of various chronic diseases
through several mechanisms including increased
inflammation and oxidative stress. They can also
bind to the receptor for AGEs (RAGE). RAGE
transports beta-amyloid proteins across the bloodbrain
barrier and contributes to the development of
Alzheimer's disease.
Our newly published paper is the first that
estimated the AGE content of diets from
observational studies in various countries, which
estimated the link between dietary factors and risk
of Alzheimer's disease. For this purpose, the
values for AGE for many types of food were taken
from a study by researchers at the Mount Sinai
School of Medicine in New York. They cooked 549
foods by different methods and measured the AGE
content of the cooked food. They found that the
higher the cooking temperature, the higher the
AGE content. For example, 100 grams of raw beef
had 707 kU of AGEs, but 100 grams of roast beef
had 6071 kU.
To use their findings in our study, we obtained
information from observational studies in which diet
was assessed using food frequency questionnaires
or from national dietary supply values from the
Food and Agriculture Organization of the United
Nations. We then used either a range of cooking
temperatures or methods for the observational
studies or an estimate of average cooking methods
and temperatures for the national dietary supply
data.
In typical national diets, we found that meat made
the highest contribution of AGEs, followed by
vegetable oils, cheese, and fish. Foods such as
cereals/grains, eggs, fruit, legumes, milk, nuts,
starchy roots, and vegetables generally make low
contributions to the total amount of AGEs in a diet,
either because they are generally prepared at low
temperatures or since they comprise smaller
portions of diets.
According to Drs. Jaime Uribarri and Weijing Cai of
The Icahn School of Medicine at Mount Sinai, "This
epidemiological study supports our previous
findings in animals and humans of an important role
for dietary AGEs in Alzheimer's disease. We found
that mice kept on a diet high in AGEs, similar to
Western diet, had high levels of AGEs in their
brains together with deposits of amyloid-?, a
component of the plaques characteristic of
Alzheimer's disease, while at the same time
developed declines in cognitive and motor abilities.
The mice fed a low AGE diet remained free of
these conditions. In addition, clinical studies have
shown that subjects with higher blood AGE levels,
in turn resulting from high AGE diets, are more
likely to develop cognitive decline on follow up.
The findings point to an easily achievable goal that
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