Depression, diabetes and obesity are all widespread in the modern western world. Contemporary nutritional guidelines call for consuming more low GI (glycemic index) carbohydrates and less high GI foods. This is especially emphasised for those looking to eat healthier and maintaining a healthy weight.
But could those same foods that cause diabetes and obesity also be the cause of our rising rate of ill mental health? Could high GI foods be a factor in depression?
What are High GI Foods?
First, I want to clear up any confusion before we dive into all the sciencey stuff. The glycemic index (GI) is a numeric rating system for individual foods, first developed over 20 years ago. This system was created after the observation that while carbohydrates have 4 calories per gram, the body tends to digest those calories differently, depending on the type of carbohydrate.
Foods rated at a high glycemic value (high GI foods) are broken down quickly; causing blood glucose levels to rise sharply, and prompting the pancreas to produce more insulin which causes a subsequent fall in blood glucose levels.
Remember that rollercoaster analogy about eating sugary foods? That’s exactly what this is describing. Those foods that cause a rapid upswing in glucose levels are now known to be a major risk factor in diabetes and obesity.
On the other hand, foods with a low GI take longer to digest and, subsequently, have a less rollercoaster-esque effect on our blood sugars. So they’re considered ‘healthy’ and less of a risk factor.
But what does all of this glycemic index stuff have to do with depression? I’m glad you asked.
Depression and High GI Foods
Research is revealing that high glycemic index foods could be a contributing factor to our current mental health crisis. Several studies have found that those who consume a diet of high GI, processed foods are at higher risk of developing major depression [1,2].
One study compared those who regularly consumed processed foods – which tend to have added sugars – with those who followed a wholefoods diet. It concluded that “a processed food dietary pattern is a risk factor for CES–D depression 5 years later, whereas a whole food pattern is protective” .
Another study investigating postmenopausal women also found that high-GI diets were likely a risk factor for depression. They even called for trials to determine whether low-gi diets could serve as treatments or preventative measures for those at risk .
Further investigation may be needed, but it’s highly likely that opting for a low-GI diet could be beneficial for you – especially if you’re predisposed to depression or have a family history of diabetes. Another thing to keep in mind is the link between gut health and depression. With the majority of our bodies serotonin being produced in the digestive tract, keeping our intestines happy is vital for maintaining chemical balance.
If you experience any digestive discomfort, you might want to consider intolerance testing to eliminate any problem foods that could be the root cause. Once your gut is healthy, your digestive system can get back to looking after the rest of your body! Of course, you should always consult your family doctor before making any major dietary changes.
 Akbaraly, T.N., Brunner, E.J., Ferrie, J.E., Marmot, M.G., Kivimaki, M. and Singh-Manoux, A. (2009). Dietary pattern and depressive symptoms in middle age. British Journal of Psychiatry, [online] 195(5), pp.408–413. Available at: https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/dietary-pattern-and-depressive-symptoms-in-middle-age/96D634CD33BD7B11F0C731BF73BA9CD3 [Accessed 22 Jul. 2020].
 Gangwisch, J.E., Hale, L., Garcia, L., Malaspina, D., Opler, M.G., Payne, M.E., Rossom, R.C. and Lane, D. (2015). High glycemic index diet as a risk factor for depression: analyses from the Women’s Health Initiative. The American Journal of Clinical Nutrition, [online] 102(2), pp.454–463. Available at: https://academic.oup.com/ajcn/article/102/2/454/4564524 [Accessed 22 Jul. 2020].