(Independently of the experimental evidence that shows flavonoids
improve cognitive performance, there is emerging evidence that
flavonoids may also support mental health and well-being)
Effects of Acute Blueberry Flavonoids on Mood in Children and Young
Major depressive disorder is the leading
international cause of disability and is estimated to affect 350 million
people worldwide. It is the second most common cause of death in 15–29
years old, via suicide.
Current treatments for depression include
psychological therapies and a range of pharmacological agents. The
treatment options recommended for children and adolescents are limited,
with only one recommended pharmacological treatment, fluoxetine, in
addition to psychotherapy.
These treatment options are further
constrained because of concerns about the use of anti-depressant
medication with young people and because most young people do not have
easy access to psychological therapies.
Therefore, there is a
pressing need for alternative interventions, especially those that offer
a cost-effective and practical means of preventing, or alleviating,
depression in this population.
A common symptom of depression is
impaired cognitive functioning, with significant deficits in executive
functioning (EF). EF is an umbrella term, describing cognitive processes
such as working memory, planning, problem-solving, cognitive
flexibility, inhibitory control, directing attention, thoughts and,
Impaired EF is believed to maintain
depressive symptoms, such as negative self-perception and low mood, via
perseveration and rumination. Importantly, EF is associated with the
development of the frontal area of the brain, an area that continues to
mature and develop throughout adolescence and into early adulthood.
Thus, any disturbance to the development of the frontal region during
this critical period (for example because of an episode of depression)
can have a long-lasting impact and may explain why depression that
occurs during adolescence and early adulthood is associated with
long-term impairments into adult life.
Flavonoids are a class of
polyphenols (micronutrients) found naturally in fruits, vegetables, tea,
coffee and cocoa. Flavonoid consumption has been associated with both
vascular and cognitive benefits across the lifespan.
flavonoid interventions have produced improvements in attention,
inhibition, visuospatial memory and executive function between 2–6 h
post-consumption, whilst supplementation of flavonoids for 1.5–8 weeks
has been associated with improved visuospatial memory and improved
Numerous mechanisms of action have been
investigated to explain the beneficial effects of flavonoids on
cognition. These include increases in cerebral blood flow, protecting
against neuronal stress via anti-inflammatory and anti-oxidative effects
and positively stimulating neural signaling pathways, such as
Extracellular Signal-Regulated Kinase (ERK), Serine/Threonine-specific
Protein Kinase (Akt) and Brain-Derived Neurotrophic Factor (BDNF),
leading to improved neural signaling.
Independently of the
experimental evidence that shows flavonoids improve cognitive
performance, there is emerging evidence that flavonoids may also support
mental health and well-being.
Epidemiological data shows that
lifetime consumption of fruit and vegetables (and therefore higher
flavonoid consumption) predicts a lower incidence of depression in later
life. The benefits are also seen earlier in life; a recent systematic
review concluded that whilst the quality of evidence was weak, there was
a consistent body of research reporting cross-sectional and longitudinal
associations between nutrition and mental health in children and young
Similar findings have been shown by other authors.
However, there is an absence of studies exploring the effects of
flavonoid-rich interventions on mood.
Given the well-documented
links between flavonoid consumption and cognition, and between cognition
and depression, the studies reported in this paper assess the acute
effects of flavonoid-rich wild blueberries (WBB) on mood two hours
post-consumption. This two-hour interval coincides with the time-frame
for the peak absorption and metabolism of the anthocyanins present in
In addition, it is important to establish whether
acute effects on mood are observable prior to considering a chronic
flavonoid-based intervention for mood outcomes.
groups, healthy children and young adults, were recruited. These groups
represent individuals who are at crucial stages of mental and cognitive
development and thus plausible points at which prevention and public
health interventions may be particularly powerful.
This study demonstrated acute effects of
blueberry flavonoid consumption on Positive Affect and no effect on
Negative Affect in healthy children and young adults.
interventions could play a key role in promoting positive mood and are a
possible way to prevent dysphoria and depression.
potential implications of these findings for preventing depression, a
disabling and common mental health problem in adolescents and adults, it
is important to replicate the study and assess the potential to
translate these findings to practical, cost-effective and acceptable
are grateful to the Wild Blueberry Association of North America who
provided the freeze-dried wild blueberry powder used for this study.