Sugar Intake, Inflammation, & Mental Health

Another reason to avoid sugar….Inflammation is on the forefront of brain and mental health research, and dietary sugar intake may be a significant contributor to the inflammatory processes that contribute to conditions such as depression. As a naturopath, nutrition is a fundamental component of mental health treatment.

Sugar has many names: sucrose, dextrose, maltose, high fructose corn syrup (you can learn them all here), and these added sugars are found everywhere nowadays. Protecting our brains is one more (pretty important) reason to be conscious of the amount of sugar we consume. We know intuitively that sugar affects brain activity. The first thing that comes to my mind is my hyper-active nephew trying his first bites of chocolate birthday cake. But the long term effects of sugar on mental health are becoming better understood as the research continues to dig into the connection between digestive health and brain health, also known as the Gut-Brain Axis. Sugar may contribute to this link by altering the bacteria found in our gut and contributing to intestinal inflammation.


The bacteria found in the digestive system are impacted by our diets since they eat whatever we eat. When these bacteria fall out of balance (higher amounts of ‘bad’ bacteria and decreased ‘good’ bacteria), this results in dysbiosis. Two of the more prominent types of bacteria often found in probiotic supplements are Bifidobacterium and Lactobacillus. A combination of the specific species Bifidobacterium longum and Lactobacillus helveticus have been found to decrease feelings of anxiety and depression in healthy individuals (1).

High dietary sugar intake may reduce levels of Lactobacilli as shown in animal studies (2). Furthermore, refined sugar intake has also been shown to increase the intestinal growth of unwanted bacteria such as Clostridium species (3). One theory on how these bacteria impact mental health, is that they contribute to intestinal inflammation by producing inflammatory substances, which are then relayed through the immune system and nervous systems to alter brain activity.


Inflammation appears to be one of the main links between sugar intake, gut health, and brain function. As outlined above, sugar alters gut microbiota, which in turn may contribute to inflammation. Sugar consumption also contributes to the production of an inflammatory substance called CRP (4), and elevations in CRP have been associated with mental health conditions such as depression (5). Additionally, weight gain related to sugar intake results in formation of fat tissue, which produces various other inflammatory substances.

How much sugar should I be eating?

When it comes to refined, processed sugars, the lower the better. The World Health Organization recommends limiting free sugar intake to less than 10% of total energy intake, but notes that for additional health benefits it should be reduced to less than 5%.

What about sugar substitutes?

Although they don’t have the calories associated with them, artificial sweeteners may have negative effects of their own. Specifically, they have been shown to alter the intestinal microbiota in ways that result in glucose intolerance (6). This means the body is unable to handle glucose appropriately, and can lead to weight gain, which as we saw above can contribute to inflammation in itself. Furthermore, some of the bacterial changes that occur with artificial sweetener consumption have been associated with type 2 diabetes in humans (6).

What about fruit?

If you have a sweet tooth, fruit is a good way to ‘healthify’ the situation. Although some fruits are fairly high in sugar, they also contain nutritious vitamins and minerals that the body needs. Choosing fruits that are high in fibre will decrease some of the effects of sugar content by preventing spikes in blood sugar. Fruits high in fibre often contain seeds or are eaten with the skin on such as strawberries, blueberries, blackberries, apples, pears, passionfruit, guava, and oranges.

Nutrition plays a vital role when it comes to mental health. Naturopathic medicine emphasizes foundations of health such as nutrition and involves individualized treatment approaches. To learn more about a naturopathic approach to anxiety, depression, and other mental health concern come see me at Juniper Family Health (778-265-8340) in Victoria, BC.


1. Messaoudi, M., Lalonde, R., Violle, N., Javelot, H., Desor, D., Nejdi, A…Cazaubiel, J. (2011). Assessment of psychotropic-like properties of a probiotic formulation (Lactobacillus helveticus R0052 and Bifidobacterium longum R0175) in rats and human subjects. British Journal of Nutrition, 105, 755-764 doi:10.1017/S0007114510004319

2. Noble, E., Hsu, T., Kanoski, S. (2017). Gut to brain dysbiosis: mechanisms linking western diet consumption, the microbiome, and cognitive impairment. Frontiers in Behavioural Neuroscience, doi:10.3389/fnbeh.2017.00009

3. Brown, K., DeCoffe, D., Molcan, E., Gibson, D. (2012). Diet-induced dysbiosis of the intestinal microbiota and the effects on immunity and disease. Nutrients, 4, 1095-1119 doi:10.3390/nu4081095

4. Corte, K., Perrar, I., Penczynski, K., Schwingshackl, L., Herder, C., Buyken, A. (2018). Effect of dietary sugar intake on biomarkers of subclinical inflammation: a systematic review and meta-analysis of intervention studies. Nutrients, 10, 606 doi:10.3390/nu10050606

5. Pasco, J., Nicholson, G., Williams, L., Jacka, F., Henry, M., Kotowicz, M… Berk, M. (2010). Association of high-sensitivity C-reactive protein with de novo major depression. British Journal of Psychiatry, 197(5), 372-377 doi:10.1192/bpj.bp.109.076430

6. Suez, J., Korem, T., Zeevi, D., Zilberman-Schapira, G., Thaiss, C., Maza, O… Elinav, E. (2014). Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature, doi:10.1038/nature13793