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Sugar and Mood
By now we’ve all heard that sugar is bad and has been associated with physical health issues such as obesity, diabetes, and other diseases. The most recent condemnation of sugar comes from a study (Knuppel, Shipley, Llewellyn, and Brunner, 2017) that links sugar and mental health (more specifically depression). There are four possible explanations of this link between sugar and depression: 1. Sugar could influence the levels of a chemical in the brain called “brain derived neurotropic factor” which has been associated with high-sugar diets and is believed to have a link with depression; 2. Sugar has been linked to increased inflammation in the body (i.e. inflammatory markers), which could also depress mood; 3. Regularly eating a lot of sugar could cause the body to respond with an “exaggerated insulin response” which can then influence hormone levels and mood; and 4. Dopamine (the happy brain chemical) is released when eating sugar. Over time, the repeated release of high amounts of dopamine can lead to both an addiction to sugar and eventually depression.
This study tracked 8,087 people over 22 years (part of a larger study called the Whitehall Study II) and asked them questions about their diet, physical activity, sleep, physical health, mental health, and some demographic questions. From the study, Knuppel et al. (2017), concluded:
“We found an adverse effect of higher sugar intake on mental health cross-sectionally and 5 years later in a study based on 23,245 repeated measures in men and women aged between 39 and 83. Further, we found an increased likelihood for incident Common Mood Disorders (CMD) in men and some evidence of recurrent depression in both sexes with higher intakes of sugar from sweet food/beverages. These associations with incident CMD could not be explained by socio-demo graphic factors, other diet-related factors, adiposity and other diseases although the association with recurrent depression was explained by other diet-related factors.”
From this specific type of study, we can’t necessarily say this relationship is causal or that sugar causes depression. However, taking repeated measurements with the same participants over the course of 22 years offers a strong enough link to raise real concerns about the consumption of sugar. The researchers also explored the possibility of mood influencing the level of sugar consumption. Over the course of the 22-year study, the authors "found no evidence for a potential reverse effect: participants did not change their sugar intake after suffering from common mood disorders."
Be aware, this one study does not prove that over-consumption of sugar causes depression. The takeaway from this blog post and study should be that eating a lot of sugar could contribute to a decrease in mood. Needless to say, more rigorous research is needed to explore this link, but at present we have more than enough evidence say it is important to be vigilant about how much sugar we consume and know that it does have some type of impact on our overall health.
(based on the article from: https://www.forbes.com/sites/daviddisalvo/2017/07/31/the-link-between-sugar-and-depression-what-you-should-know/#55c933645bbf)
Knuppel, A., Shipley, M. J., Llewellyn, C. H., & Brunner, E. J. (2017). Sugar intake from sweet food and beverages, common mental disorders and depression: Prospective findings from the Whitehall II study. Nature Scientific Reports, 7 (6287). Open online.