adherence to traditional dietary patterns with lowered risk
of anxiety or depression [15-20]. Among the more convincing
of these studies are the recent prospective investigations
showing that stronger adherence to traditional
healthy dietary patterns is associated with a 25 to 30%
lower risk of depression [16,17]. Traditional Japanese
dietary practices, where fermented soy products are specifically
linked to adherence, have also been associated
with lower rates of depressive symptoms [21,22]. Alcohol
has deservedly received much attention in the link
between problematic consumption and a higher risk
of depression. However, when consumed in modest
amounts (5 to 15 g per day) as part of traditional dietary
practices, alcohol (red wine in particular) has been
associated with a lower risk of depression [23]. Indeed,
light to moderate alcohol consumption has been associated
with lower systemic inflammation, a finding not
evident in those with depression [24].
Epidemiological studies show that there exists an elevated
risk of depressive symptoms in healthy adults with
blood chemistry indicative of insulin resistance [25].
Depressive symptoms correlate with higher fasting and
stimulated glucose levels, even in the absence of an association
with adiposity in adolescents at risk of type II diabetes
[26]. This is of relevance when viewed along with a rapidly
growing body of research highlighting the type-II-diabetes
protective properties of traditional dietary practices [27]. As
we will discuss, the intestinal microbiota, via a number of
mechanisms, may play a role in mediating the glycemic and
mood related effects of the Western dietary pattern [28].