Seasonal mood and behaviour shifts
Especially in cold and dark winter, for many people including myself, there is a noticeable shift in mood. Some possible explanations that experts have come up with for the melancholy associated with winter time include vitamin D deficiency, seasonal affective disorder, and most recently, gut health disorders.
A 2019 meta review highlighted that the bacteria that reside in our gut have a “bidirectional link” with our body’s systems. (1) Our food choices and stress experiences impact their population and composition, while they can release metabolites and neurohormones to influence our mood and behaviour. (1)
Stress and gut health
In our gut, there are trillions of bacteria fighting for survival resources. Some of them are great for our health, while others are harmful. As long as the dominant bacteria types are the ones that support our wellness, then our bodies remain functional and healthy. However, if our lifestyle factors and choices cause an overgrowth of bad bacteria, then this empowers these harmful strains to wreak havoc on our health, both physical and psychological.
For example, an increase in inflammation as a result of stress and depression associated with winter time can send the body’s immune cell messengers via the blood and bone marrow to the gut to convey signs of stress. (2) This in turn allows bad bacteria to thrive in the gut flora and disrupt the healthy flow of digestion and much more. (2)
Neurotransmitters and hormones production and regulation
The Gastrointestinal Tract, where gut bacteria reside, is the site of production and regulation for important neurotransmitters, such as GABA, dopamine, and serotonin! This means that your gut health is intimately connected to feelings of happiness, pleasure, and calm. (5)
Additionally, research has found that gut bacteria specifically produce chemical molecules that can replace or affect proteins and hormones that regulate appetite in humans. (3) Gut bacteria can even modify neural pathways related to reward using the vagus nerve! (4)
All this to say, depression in the winter can create a cyclical effect where the change in mood, stress levels, and eating habits influence the composition of gut bacteria, and as a result, can further impact appetite, behaviours, and psychology. (1)
To disrupt the cycle, one dietary intervention is to promote the proliferation of good bacteria in 2 steps:
Consume prebiotic-rich foods that feed the existing good bacteria in your gut on a daily basis. These are foods that are high in gut-friendly fibres, such as dandelion greens, bananas, asparagus, barley and apples. R’s KOSO is a traditional Japanese beverage that ferments many prebiotic-rich ingredients for over one year.
Add in daily servings of fermented foods that are high in probiotics, which are good live bacteria that can add to your gut flora to keep it in balance! In addition to R’s KOSO which contains probiotics, you can also try raw kimchi, beet kvass, kefir, or kombucha. Many cultures around the world have their own traditional fermented food!
Keren Chen | CBT Nutritionist
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