The relationship between how you feel and what you eat has been observed thousands of years ago by Hippocrates (460 – 370BC):
- “Let your food be your medicine and your medicine be your food”
More than two thousand years later, with the epidemic-level increases in lifestyle-related chronic health diseases, such as type II diabetes, heart failure, stroke, heart disease and emerging evidence that depression itself is a lifestyle-related illness [2,4], this claim is well in need of a full revival in popular culture.
Countries which are experiencing this rapid decline in physical and mental health are also consuming what is known as a “western diet”, which is a diet where a large portion of calories are derived from processed and fast foods, saturated fats, simple carbohydrates and sugars and a lack of fresh fruit and vegetables [1].
How does diet influence the way we feel?
This is an incredibly complicated question where there is no single answer, however the main aspects where your diet can affect the way you feel, or ways it can lead to promoting depression lie in a few main factors.
Inflammation has been linked as a common factor in depression [1,2,5,6], therefore a diet which promotes inflammation is likely to promote depression and its symptoms. Diets high in sugars, high GI foods and saturated fats promote insulin resistance, which reduces the body’s ability to utilise insulin (where insulin is involved in uptake of glucose by cells and neurons, as well as maintaining structure and function). Insulin resistance negatively impacts neurons and their function, leading to a decrease in neural plasticity (which results in impaired cognitive function) and an increase in chronic neuroinflammation, a large contributor to depressive symptoms! [5]
For effective balance of inflammatory activity in the body, humans require an equal, 1:1 balance of omega 6 (pro-inflammatory) to omega 3 (anti-inflammatory) fats [1]. However, in our ‘western diet’ the omega 6:3 ratio is common to sit at 16:1! [4] Shifting your sources of fats away from saturated and omega 6, to more unsaturated and omega 3 will result in a great reduction of inflammatory activity. Supplementing omega 3 in the form of fish oil is a small and simple measure to shift the ratio towards a more anti-inflammatory and thus, anti-depressant level.
Fibre and nutrient quantity is incredibly important in a diet, especially one where prevention or treatment of chronic illnesses and depression is involved. A diet high in fibre is shown to reduce inflammation [1], as well as promote healthy gut function. Nutrients including vitamins, minerals and phytochemicals are important for all bodily functions. Not consuming enough of a certain vitamin or mineral will lead to a deficiency, for example a deficiency of vitamin B1, B6 and E as well as minerals iron and folic acid are closely related to depression [6]. The best way to prevent vitamin and mineral deficiencies is to consume plentiful amounts and range of fresh vegetables and fruit (aim for 5 cups per day).
Finally, some foods we eat are able to positively influence mood through a protein called tryptophan, which is used to make serotonin (low levels of serotonin are associated with depression and other mood disorders). Foods, such as eggs, cheese, salmon, nuts and turkey, are good sources of this protein. Carbohydrates are known to increase tryptophan levels and availability in the blood. This explains how people, while experiencing poor mood, often crave foods high in carbs, as they are known to give you a serotonin boost [3,6].
However, comfort eating is not a good practice to undertake when experiencing low mood, as this can result in a bad relationship with food and weight gain, which is known to be a risk factor for depression [1,2,5,6].
Your diet is one of the primary motivators behind your mood. If feeling good is important to you, then developing healthy diet practices should be at the top of your list of lifestyle changes!
References:
1. Galland, L (2010). Diet and inflammation. Nutrition in Clinical Practice, 25(6). 634-640.
2. Kiecolt-Glaser, J; Derry, H; Fagundes, C (2015). Inflammation: depression fans the flames and feasts on the heat. American Journal of Psychiatry, 172(11). 1075-1091.
3. Silber, B; Schmitt, J (2010). Effects of tryptophan loading on human cognition, mood, and sleep. Neuroscience & Biobehavioral Reviews, 34(3). 387-407.
4. Simopoulos, A (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomedicine & pharmacotherapy, 56(8). 365-379.
5. Slavich, G; Irwin, M (2014). From stress to inflammation and major depressive disorder: a social signal transduction theory of depression. Psychological bulletin, 140(3). 774.
6. Strasser, B; Fuchs, D (2015). Role of physical activity and diet on mood, behavior, and cognition. Neurology, Psychiatry and Brain Research, 21(3). 118-126.
