While debate continues and more rigorous scientific evidence is needed as to how to best feed the population as a whole, connections continue to strengthen between certain foods and certain health conditions.
One of these being too much sugar and mood.
Diet, depression, insulin resistance and inflammation
Diet plays an important role in mental health.
High consumption of foods typical of the Western diet, particularly added sugar and refined starches, has been associated with increased incidence of depression. And a diet comprising mostly of these foods can also lead insulin resistance,1 encouraging systemic inflammation – and inflammation is seen in both depression and insulin resistance.
The body produces an inflammatory response as a protective mechanism. When injured or infected, the body sends chemical messengers to the ‘war zone’ – be it a wound or to kill off pathogens, where they also clear out cellular debris and create protection to enable healing.
Now, whilst it isn’t the only factor, what we eat can enable this reaction. And on the flipside, what we eat can support anti-inflammatory mechanisms.
When we eat too much pro-inflammatory stuff we are a-buzz with pro-inflammatory chemical messengers (a.k.a. cytokines) – this includes too much added sugar, which spikes insulin and in turn triggers an inflammatory response.2
And excessive inflammation can overwhelm the antioxidant defence forces of the body, damaging cells and hindering their function. This can impact our joints, heart, and a myriad of other parts of our body, including the brain.
Depression, inflammation and the gut
It is now recognised that elevated inflammation in mental health conditions like depression isn’t simply a consequence of emotional disorder, but inflammation and oxidative stress are also a causal factor, creating a vicious cycle influencing mood.3
This may explain why there are thoughts in the scientific community that anti-depressants may actually act as anti-inflammatory agents in certain populations to exert their positive effects.4-6
And while the link between higher levels of inflammation and depression is well documented,7 increasingly so is their connection with what is going on with our gut bugs.
Chronic and systemic inflammation often starts in the gut. This is where a huge portion of our immune system lies, contending with all the stuff that enters through our mouths.
The diversity and balance of good and not-so-good gut bugs of the intestinal microbiome can affect the capacity for the gut to be an effective immune-acting barricade. When that barricade is compromised, an inflammatory response ensues when perceived pathogens enter the gut space and into the bloodstream through the ‘leaky’ intestinal barrier.
And guess what? High consumption of foods typical of the Western diet, particularly added sugar and refined starches, ain’t providing your good gut bugs with the food they need (like fibre from real whole plant foods) to create a protective intestinal barrier.
Add to that the influence that specific gut bacteria appear to have on levels of mood modulating neurotransmitters, such as dopamine, GABA, histamine, acetylcholine and serotonin, and we’ve a multi-pronged hit encouraging mental health disorder.8
If you are experiencing persistent low mood, we encourage that you chat with your trusted healthcare practitioner who can refer you to a registered psychologist. You can also touch base with any of the amazing support services out there, such as Lifeline and Beyond Blue in Australia.
In the meantime, there are a couple of things you can do to help lower inflammation – through what you eat and managing stress.
Limit the heavily processed stuff, especially added sugars and refined carbohydrates, as well as trans-fat laden foods.
Choose instead real whole foods that won’t encourage excessive inflammation and will support the health and function of the intestinal microbiome, whilst providing nutrients for proper brain function.
This includes colourful non-starchy veg, low-GI fruit, leafy greens, nuts, seeds, grass-fed meat, organic free-range eggs, and sustainably caught oily fish like sardines. Fermented foods and fibre are also great for your gut bugs.
Traumatic or stressful events, acute or on-going, encourage higher levels of inflammation.
And elevated levels of systemic pro-inflammatory cytokines activate the HPA axis (which is a complicated set of relationships and signals between the hypothalamus, pituitary gland and adrenals), which leads to cortisol release from the adrenal glands. Cortisol, a major stress hormone, can be anti-inflammatory in the short-term, but on-going it negatively affects many human organs, including the brain.9
Find ways to manage stress, either through regularly participating in activities you love, meditation, tai chi or yoga, or speaking to a mental health specialist.
By Angela Johnson (BHSc Nut. Med.)
- Gangwisch, JE, Hale, L, Garcia, L, Malaspina, D, Opler, MG, Payne, ME, Rossom, RC, & 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, vol. 102, no. 2, pp. 454-463.
- Wieser, V, Moschen, AR, & Tilg, H 2013, ‘Inflammation, cytokines and insulin resistance: a clinical perspective’, Archivum Immunologiae Et Therapiae Experimentalis, vol. 61, no. 2, pp. 119-125.
- Selhub, EM, Logan, AC, & Bested, AC 2014, ‘Fermented foods, microbiota, and mental health: ancient practice meets nutritional psychiatry’, Journal of Physiological Anthropology, vol. 33, no. 1, p.2.
- Cattaneo, A, Ferrari, C, Uher, R, Bocchio-Chiavetto, L, Riva, MA, & Pariante, CM 2016, ‘Absolute Measurements of Macrophage Migration Inhibitory Factor and Interleukin-1-β mRNA Levels Accurately Predict Treatment Response in Depressed Patients’, The International Journal Of Neuropsychopharmacology.
- Hayley, S, Audet, M, & Anisman, H 2016, ‘Inflammation and the microbiome: implications for depressive disorders’, Current Opinion in Pharmacology, vol. 29, no. Cancer * Immunomodulation, pp. 42-46
- Miller, AH, & Raison, CL 2016, ‘The role of inflammation in depression: from evolutionary imperative to modern treatment target’, Nature Reviews Immunology, no. 1, p. 22.
- Jokela, M, Virtanen, M, Batty, GD, & Kivimäki, M 2016, ‘Inflammation and Specific Symptoms of Depression’, JAMA Psychiatry, vol. 73, no. 1, pp. 87-88.
- Rogers, GB, Keating, DJ, Young, RL, Wong, M, Licinio, J, & Wesselingh, S 2016, ‘From gut dysbiosis to altered brain function and mental illness: mechanisms and pathways’, Molecular Psychiatry, vol. 21, no. 6, pp. 738-748.
- Carabotti, M Scirocco, A Maselli, MA & Severi, C 2015, ‘The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems’, Annals of Gastroenterology : Quarterly Publication of the Hellenic Society of Gastroenterology, vol. 28, no. 2, pp. 203–209.