It is now widely known that our diet and other lifestyle factors play a central role in our physical health and can prevent the development of many chronic diseases. However, the links between nutrition and mental health have not yet been clearly clarified1, but in recent years the area has increasingly come into focus.
A bidirectional relationship has previously been observed between mental health and a healthy lifestyle. Mental health generally promotes a healthier lifestyle. However, it is negatively influenced by poor lifestyle habits, which in turn contributes to an unhealthier lifestyle.
In general, various clinical studies have so far shown that a healthy diet according to general dietary recommendations as well as traditional diets, especially the Mediterranean diet, have improved depressive symptoms. These findings are also consistent with epidemiological observations on depression and dietary habits. Characteristics of these diets were always high proportions of vegetables, fruits, fish, and whole grains in the diet. Adequate nutrient intake is also important because some micronutrients, such as folic acid, vitamins B6 and B12, zinc, magnesium, and vitamin D, are essential for the development and optimal function of the nervous system. For example, the B vitamins are important for the production of neurotransmitters, which in turn are involved in the regulation of appetite, mood, cognition, and metabolic stress responses. Accordingly, a deficient diet with inadequate nutrient intake is a risk factor for the development of mental disorders. It can be concluded that nutritional and lifestyle measures could be a possible clue for the prevention and treatment of mental disorders.
The SMILES (Supporting the Modification of lifestyle in Lowered Emotional States) study examined the effects of a 3-month dietary adjustment on moderate to severe depression. Subjects in the intervention group followed a modified Mediterranean diet. This is characterized, among other things, by an increased consumption of vegetables, fruits, whole grains, legumes, and nuts. At the same time, processed and sugar-rich foods were to be limited. After 3 months, the authors observed a significant reduction in depression symptoms in about 33% of these subjects.
Carbohydrates, blood sugar control and mental health
It has been observed that people with diabetes mellitus often also experience depression and vice versa. In type 2 diabetics, a correlation was found between greater fluctuations in blood glucose and a lower health-related quality of life, as well as the occurrence of anxiety disorders. However, mental deficits have also been observed in healthy, normal weight individuals with poor glycemic control. These observations further the hypothesis that diet and blood glucose may play a role in the treatment of mental illness.
The influence of the quality of carbohydrates consumed on the prevention and treatment of mental illness has already been investigated in several studies. It was found that mood swings, fatigue and also depressive symptoms were promoted by a higher-glycemic diet. These symptoms occurred less with a low-glycemic diet. Increased consumption of added sugars was even associated with an increased risk of depression, whereas increased fiber intake was associated with a reduced risk. Overall, several studies have provided evidence that the quality of carbohydrates consumed plays a role in our mental health and even influences the risk of mental illness.
Increased consumption of whole grains, vegetables, high-quality proteins and fats, and less-processed foods can help prevent severe blood sugar fluctuations because the sugar from these foods is released more slowly.
The increased amount of dietary fiber in these foods also has a positive effect on the intestinal microbiota. This has often been discussed as an underlying factor in the development of insulin resistance and mental illness. Eating smaller portions at regular intervals and paying attention to one’s own sense of hunger can also help to keep blood sugar as constant as possible.
Overall, the results from the various clinical as well as epidemiological studies that have investigated the associations between blood glucose and mental health are rather heterogeneous. Reasons for this include the complexity of mental illnesses and the lack of objective biomarkers to determine them. The underlying mechanisms of the association have also not been fully elucidated. However, observations suggest that a healthy balanced diet that meets nutrient needs promotes optimal mental health. Moreover, the already known positive effects on our physical health could even extend to the prevention of mental illness. In particular, intakes of free sugars and processed carbohydrates appear to be associated with the incidence of depression, and higher intakes of fiber, fish, and omega-3 fatty acids appear to be protective.
Accordingly, monitoring our individual blood glucose responses through continuous blood glucose monitoring and adjusting our diet with these findings could not only help improve our physical health, but also improve our mental health and reduce the risk of depression or anxiety disorders.
- Kris-Etherton, P. M., Petersen, K. S., Hibbeln, J. R., Hurley, D., Kolick, V., Peoples, S., Rodriguez, N., & Woodward-Lopez, G. (2021). Nutrition and behavioral health disorders: depression and anxiety. Nutrition reviews, 79(3), 247–260. https://doi.org/10.1093/nutrit/nuaa025
- https://www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626 (last opened 21.01.2022)
- Jacka, F. N., O’Neil, A., Opie, R., Itsiopoulos, C., Cotton, S., Mohebbi, M., Castle, D., Dash, S., Mihalopoulos, C., Chatterton, M. L., Brazionis, L., Dean, O. M., Hodge, A. M., & Berk, M. (2017). A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC medicine, 15(1), 23. https://doi.org/10.1186/s12916-017-0791-y
- https://www.nutritionist-resource.org.uk/articles/nutrition-and-mental-health.html#foodandmoodwhatsthelink (last opened 20.01.2022)
- https://www.bda.uk.com/resource/depression-diet.html (last opened19.01.2022 )
- Penckofer, S., Quinn, L., Byrn, M., Ferrans, C., Miller, M., & Strange, P. (2012). Does glycemic variability impact mood and quality of life?. Diabetes technology & therapeutics, 14(4), 303–310. https://doi.org/10.1089/dia.2011.0191
- https://www.levelshealth.com/blog/glucose-mood (last opened 19.01.2022)
- Knüppel, A., Shipley, M.J., Llewellyn, C.H. et al. (2017) Sugar intake from sweet foods and beverages, common mental disorder and depression: prospective findings from the Whitehall II study. Sci Rep 7, 6287. https://doi.org/10.1038/s41598-017-05649-7
- Owen, L. and Corfe, B. orcid.org/0000–0003–0449–2228 (2017) The role of diet and nutrition on mental health and wellbeing. Proceedings of the Nutrition Society, 76 (4). pp. 425–426. ISSN 0029–6651 https://doi.org/10.1017/S0029665117001057
- Breymeyer, K. L., Lampe, J. W., McGregor, B. A., & Neuhouser, M. L. (2016). Subjective mood and energy levels of healthy weight and overweight/obese healthy adults on high-and low-glycemic load experimental diets. Appetite, 107, 253–259. https://doi.org/10.1016/j.appet.2016.08.008
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