Dr Bradley McEwen PhD, MHSc (Hum Nutr) discusses the health benefits of consuming blueberries, in particular, their potential of improving mood and decreasing the risk of developing depression.
Depression is a major contributor to the global burden of disease (Chang et al., 2016) with more than 300 million people affected (World Health Organization, 2017). Depression is the leading international cause of disability (Khalid et al., 2017). The burden of depression and other mental health conditions are globally rising (World Health Organization, 2017). A person with depression experiences depressed mood, loss of interest and enjoyment, and reduced energy leading to diminished activity for at least two weeks.
Many people with depression also suffer from anxiety symptoms, disturbed sleep and appetite and may have feelings of guilt or low self-worth, poor concentration and even medically unexplained symptoms (WHO, 2017). Depression results from a complex interaction of social, psychological and biological factors. People who have gone through adverse life events are more likely to develop depression. Depression can lead to more stress and dysfunction and worsen the affected person’s life situation and depression itself (WHO, 2017). A low positive affect is more highly linked to depression and sustained periods of low mood (dysphoria) is a strong predictor of major depressive disorder (Khalid et al., 2017).
Diet and nutrition play a major role in chronic disease (McEwen, 2014). Blueberries containing flavonoids should be consumed regularly as fresh or frozen whole fruits, freeze-dried, puree, and as a juice (Stull, 2016).
Mechanistic studies have found that blueberries have the following properties:
- antihypertensive antihyperlipidemic properties (Basu et al., 2010).
In addition, flavonoids have numerous properties, including:
- enhancing cognitive functioning (Vauzour et al., 2010)
- anti-inflammatory (Vauzour et al., 2010)
- enhanced blood flow (Chang et al., 2016)
- antioxidant (Vauzour et al., 2010)
- cellular signalling, cell functioning (Vauzour et al., 2010)
- alter lipid metabolism, inhibit low-density lipoprotein (LDL) oxidation, reduce atherosclerotic lesion formation, inhibit platelet aggregation, decrease vascular cell adhesion molecule expression, improved endothelial function (Vauzour et al., 2010)
Flavonoid consumption has been associated with the improvement of depression (Chang et al., 2016), chronic disease, cardiovascular disease (Vauzour et al., 2010), vascular health (Chang et al., 2016) neurodegenerative disorders (Vauzour et al., 2010). Flavonoids have cognitive benefits across the lifespan (Khalid et al., 2017).
Epidemiological evidence suggests that consumption of flavonoids is associated with decreased risk of developing depression. A common symptom of depression is impaired cognitive functioning (Khalid et al., 2017). Increased consumption of berries has been shown to improve cognitive function (Stull, Cash, Johnson, Champagne, & Cefalu, 2010).
Single-dose flavonoid interventions have produced improvements in attention, inhibition, visuospatial memory, and executive function between 2–6 hours post-consumption, while supplementation of flavonoids for 1.5–8 weeks has been associated with improved visuospatial memory and improved long-term memory (Khalid et al., 2017). Compared to placebo, consuming a smoothie supplemented with blueberries for six weeks had a greater increase in insulin sensitivity in obese and insulin-resistant adults (Stull et al., 2010).
A double-blind placebo-controlled study found increased positive affect in both young adults and children 2 hours after consumption of the blueberry drink. Whereas there was no effect on negative affect. The effect of blueberries on mood was consistent across young adults and children, at two different time points (morning and afternoon) (Khalid et al., 2017).
It is suggested that if acute consumption of blueberries improves positive affect, sustained consumption of flavonoids may help to prevent dysphoria, and thus, major depression (Khalid et al., 2017).
- Basu, A., Du, M., Leyva, M. J., Sanchez, K., Betts, N. M., Wu, M., . . . Lyons, T. J. (2010). Blueberries decrease cardiovascular risk factors in obese men and women with metabolic syndrome. J Nutr, 140(9), 1582-1587. doi:10.3945/jn.110.124701
- Chang, S. C., Cassidy, A., Willett, W. C., Rimm, E. B., O'Reilly, E. J., & Okereke, O. I. (2016). Dietary flavonoid intake and risk of incident depression in midlife and older women. Am J Clin Nutr, 104(3), 704-714. doi:10.3945/ajcn.115.124545
- Khalid, S., Barfoot, K. L., May, G., Lamport, D. J., Reynolds, S. A., & Williams, C. M. (2017). Effects of Acute Blueberry Flavonoids on Mood in Children and Young Adults. Nutrients, 9(2). doi:10.3390/nu9020158
- McEwen, B. J. (2014). The influence of diet and nutrients on platelet function. Semin Thromb Hemost, 40(2), 214-226. doi:10.1055/s-0034-1365839
- Stull, A. J. (2016). Blueberries' Impact on Insulin Resistance and Glucose Intolerance. Antioxidants (Basel), 5(4). doi:10.3390/antiox5040044
- Stull, A. J., Cash, K. C., Johnson, W. D., Champagne, C. M., & Cefalu, W. T. (2010). Bioactives in blueberries improve insulin sensitivity in obese, insulin-resistant men and women. J Nutr, 140(10), 1764-1768. doi:10.3945/jn.110.125336
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