The Links Between Blood Sugar Level and Anxiety, Depression, and Other Mood Disorders.

Blog Post by Lucy Collins

Sugar is perhaps the most readily available drug out there right now, with sugary foods being amongst the cheapest and most accessible foods out there, as well as being heaving marketed by the advertising industry. It’s no wonder that the majority of us are over consuming sugar, and feeling the effects; not just from a physical health stand point, but also mental health wise.

According to the British Nutrition Foundation on average in the UK we are consuming between 9% and 12.5% of our calories from free sugars, depending on the age group. The recommended daily sugar intake is 5g on average, so we can see just how much we are overconsuming by.

There have been an increasing number of studies surrounding the relationship between mood stability and blood-sugar, or ‘glycemic, highs and lows’. Symptoms of poor ‘glycemic regulation’ (the process of maintaining blood sugar levels within a normal range) have been shown to lead to symptoms of irritability, anxiety, and worry in individuals.

The brain's main source of energy is glucose, which it uses to support functions like learning, memory, and thinking. Neurons require glucose in the brain to carry messages effectively. If this is inhibited it makes perfect sense that there would be negatives effects from this.

According to a 2017 study (1), it was found that there were positive associations between high sugar consumption and common mental disorders, concluding that sugar intake from sweet foods and beverages has an adverse effect on long-term psychological health. This is not new information, but perhaps it’s time that instead of solely diagnosing mental health disorders and prescribing anti-depressants in a lot of cases in a matter of minutes, we could be looking at lifestyle aspects such as glucose intake as a huge contributing factor, and discussing how to better manage this.

Insulin resistance is expressed throughout the brain’s emotional regulation centres, allowing the cells in those regions to absorb and convert glucose for energy. An overconsumption of sugar over time can lead to insulin resistance, and as insulin resistance develops, it may have similar negative effects on the brain and contribute to mood issues.

Insulin resistance can alter the signalling pathways in the brain that allow for optimal “wiring” of brain cells related to reward and learning behaviours. This impairment in wiring is linked to depressive symptoms and a reduced ability to adapt to stress over time .

Too much sugar in the diet is also a key factor in inducing low-grade chronic inflammation, autoimmune diseases, and even neuroinflammation, leading to many additional complications.

“Autoimmune disease is an abnormal immune response in which the immune system attacks the body’s normal tissues, resulting in the chronic destruction of these tissues and severely reducing the patient’s quality of life. Consumption of glucose-rich foods and beverages is very common in the West and may also be a key cause of the breakdown of metabolic and immune self-tolerance”. (2)

In summary, we are consuming more sugar than ever before, leading to a heightened risk in a range of different physical and mental health symptoms. There are also an increasing number of studies demonstrating how the over consumption of sugar can led to insulin resistance, also increasing the risk of mental health issues such as depression and mood disorders.

1)     Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study.

2)     Sugar-sweetened soda consumption and risk of developing rheumatoid arthritis in women. Am J Clin Nutr (2014)