Sugar has well and truly inveigled itself into the modern diet. You will find it in many processed and pre-packaged foods, bakery items, takeaways, desserts and sweet beverages. In fact, unless you are diligently checking ingredients lists, chances are you are consuming more than you realise.
While sugar may provide a temporary feeling of pleasure and satisfaction, most people recognise that its overconsumption can have negative effects on our physical health. Yet what is often overlooked or under-appreciated is the link between sugar and our mental health.
The relationship between food and mood works both ways – our mood affects what we eat, and what we eat affects our mood. This is particularly true for sugar. Research shows a link between sugar intake and feelings of depression and anxiety. A study published in the British Journal of Psychiatry found that those who consumed more than 67g of sugar a day had a higher risk of developing depression than those who consumed less than 40g a day.
One possible explanation for this link is the effect of sugar on our brain chemistry. When we eat sugar it stimulates the release of dopamine in our brain, which makes us feel pleasure. The brain recognises and likes this feeling and begins to crave more, as dopamine is one of the neurotransmitters involved in reward-seeking behaviour. Yet this surge of dopamine is only temporary and can lead to a sugar crash when blood sugar levels drop, leaving us feeling tired and moody. And over time, it’s possible dopamine becomes depleted.
In addition to affecting brain chemistry, overconsumption of sugar can lead to inflammation, which has been linked to depressed mood and anxiety. It can also disrupt the balance of gut bacteria, which can contribute to inflammation and also affect our mental health. Research suggests that our gut bacteria may be able to influence the messages our gut sends to the brain, and certain bacteria that live in the gut have also been shown to produce some of our feel-good neurotransmitters.
Neurotransmitters are chemicals that transmit messages in our brain, and many of these are made in the gut. In fact, 80 percent of the body’s serotonin – a happy, calm, content hormone – is made in the gut. Poor serotonin metabolism has been linked to anxiety and depression.
High sugar intake has also been associated with insulin resistance, which can increase the risk of developing type 2 diabetes. Studies show a link between type 2 diabetes and depression, and some research suggests that the inflammation associated with type 2 diabetes may contribute to these mood disorders.
Another challenge with sugar is that it doesn’t readily activate satiety centres in our body until we have had too much. This is why once we start eating it can feel tricky to stop at times. For some people, this can lead to a push/pull relationship with food where they internally berate themselves for not having enough willpower or self-control, affecting how they feel about themselves every day.
It is important to note that sugar is not the sole cause of a low mood or anxious feelings. However, reducing sugar intake can be a highly effective step towards feeling happier and healthier. Cutting back on sugar can help regulate blood sugar levels, reduce inflammation and improve gut health.
Well-regulated blood glucose levels are critical to an even mood. These are helped by including proteins, fats and/or fibre with meals and snacks to ensure glucose from carbohydrate-rich foods –whether they are sugary or starchy – is released slowly into the blood.
Most importantly though, don’t rely on fats, proteins and fibre to do this – avoid overconsuming sugars and starches in the first place. If you know you are going to want something sweet mid-afternoon, keep a nourishing choice on hand, like some homemade bliss balls, a more nourishing option that will provide you with longer-lasting energy.
Nutritional biochemist Dr Libby Weaver (PhD) is a 13-times bestselling author, speaker and founder of Bio Blends, the plant-based nutritional supplement range.