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Food and Mood: How what you eat can influence your mental health after cancer

The mental and emotional impacts of living with or beyond cancer can be every bit as difficult as the physical impacts. Of course, it’s important for anybody struggling to tell their medical team about their difficulties, as there are a number of sources of support that can make a difference.


Would you be surprised to learn that what you eat can affect your mood and even your mental health? It’s only one part of a much bigger picture, but paying attention to your nutrition could be an important part of your mental health toolkit.


It’s not uncommon to become interested in nutrition after a cancer diagnosis, as the knowledge that you are nourishing yourself with every meal can feel empowering. This in itself is a mood boosting advantage of good nutrition! However, the benefits of food for our mood go well beyond any placebo effect, and we are understanding more and more of the reasons why as the science develops. Let’s explore a few of them.


The Gut-Brain Axis

The gut and the brain are in constant, close communication. Whereas perhaps we once thought that the brain was the control centre, telling the rest of the body what to do, we now know that the flow of information goes in both directions. Our language suggests that we have always known this intuitively, at least on some level. Think of sayings such as “I have a gut feeling about it”, “butterflies in my stomach”, and “go with your gut”. They all suggest that our gut is sending strong signals to our brain, not the other way around! Communication between the gut and the brain happens via the nervous system, hormones, and the immune system.


Animal studies show that changes to the gut microbiome affect mood. It is more difficult to show causation in humans, but multiple studies show that there is a difference in the gut microbiome of depressed people compared to that of healthy controls(1). An imbalance in the gut microbiome (called “dysbiosis”) can result in inflammation. The nervous system sends messages about inflammation to the brain, and then mood is affected. Beneficial gut bacteria produce metabolites called short chain fatty acids, which reduce inflammation, including neuroinflammation. By contrast, opportunistic or pathogenic gut bacteria release inflammatory molecules.


The gut affects mood, but stress can also adversely affect the gut microbiome. Stress compromises digestion, which can create an inflammatory state in the gut and encourage the growth of opportunistic bacteria. We can end up in a vicious cycle in which stress causes dysbiosis, and dysbiosis exaggerates our stress response and can make us feel more anxious or depressed(2). How – where - can we intervene in this vicious circle? With food!


Best nutrition practices to nurture your gut microbiome, and in turn nurture your mood, include:

  • Do your best to get into the relaxation response before you eat. Take a few deep diaphragmatic breaths, focusing on the exhalation, or practise alternate nostril breathing for a couple of minutes. Sit upright, chew your food well and avoid scrolling through your emails while you eat!

  • Eat small amounts of fermented foods daily.  Enjoy sauerkraut, kimchi, kefir, probiotic yoghurt, miso.

  • See if you can eat at least 30 different plant foods every week. This is easier than it sounds, as vegetables, fruit, herbs, spices, nuts, seeds, legumes and whole grains all count. Plant diversity = gut microbiome diversity.

  • If you find it difficult to tolerate too much fibre, focus on herbs, spices and berries. These contain compounds called polyphenols, which also feed beneficial gut bacteria.


Inflammation and your Brain

We have previously talked about the fact that chronic inflammation is a driver of many diseases, including cancer, cardiovascular diseases, diabetes and autoimmune conditions. Perhaps it won’t come as too much of a surprise to learn that inflammation is also associated with depression and anxiety(3). Despite the fact that the blood-brain barrier should keep the brain protected from the rest of the body, systemic inflammation does correlate with neuroinflammation. This may be another effect of gut dysbiosis. Certain opportunistic bacteria in the gut can produce metabolites which weaken the blood-brain barrier, so that if there is inflammation in the body it can also be present in the brain.


As well as depending on the health of the gut microbiome, chronic inflammation can be caused by infections (either acute or low-grade and chronic), autoimmunity, poor sleep, chronic stress and dietary factors.


Nutrition can be very powerful at reducing inflammation. Eating an anti-inflammatory diet to reduce inflammation could not only benefit your mood, but it can reduce your risk of developing many chronic health conditions, and recent evidence also shows that it can reduce recurrence risk in a range of cancer types(4), (5), (6). If you haven’t considered this before, then I recommend having a read of an earlier blog post, Why an Anti-Inflammatory Diet is Beneficial after a Cancer Diagnosis. Key components of an anti-inflammatory diet include:


  • A wide variety of vegetables of all colours, especially deep colours

  • Liberal use of herbs and spices, such as turmeric, garlic, ginger and rosemary

  • Fruit, especially berries

  • Oily fish: salmon, mackerel, anchovies, sardines and herring

  • Green and black tea (as well as herbal teas)

  • Healthy fats such as extra virgin olive oil, avocados, nuts and seeds

  • Whole grains and pulses

  • Appropriate amounts of lean animal protein


Conversely, inflammation is increased by eating too much of the following: refined carbohydrates, saturated fats, omega 6 fats, alcohol and ultra-processed foods (UPFs).


Brain Plasticity

We used to think that it was impossible to generate new brain cells (neurons) after a certain age. However, we now know that new brain cells can be formed in certain areas of the adult brain, and new neural connections can also be made. This is referred to as neuroplasticity, and the ability to make new neurons is called neurogenesis.


Although still somewhat controversial, there is a theory that decreased neurogenesis is linked to depression and anxiety. It doesn’t seem to be so much the case that decreased neurogenesis causes mood disorders, but more that neurogenesis increases mental resilience(7).


If we consider the lifestyle factors that have been found to promote neurogenesis, this theory seems to make sense, as they are things that tend to help us to cope: exercise, learning new things, music, dance, singing, yoga, social connection.  From a nutrition perspective, foods that support neurogenesis include:


  • Polyphenols, such as those in extra virgin olive oil, berries, pomegranates, herbs and spices

  • Flavonoids in parsley, citrus fruits, apples and buckwheat

  • Omega 3 fats in oily fish, flaxseeds and chia seeds

  • Zinc, in shellfish, pumpkin seeds, cashew nuts, ginger

  • Magnesium in green leafy vegetables, legumes, nuts

  • Coffee – although there is a balance as too much can activate the stress response!


Neurogenesis is inhibited by gut microbiome dysbiosis (there it is again!), chronic stress, UPFs, trauma and a sedentary lifestyle.


Our brain accounts for only 2% of our weight, but takes approximately 20% of our energy. In order to function well and keep our mood stable, it needs a steady supply of that energy. This does not mean that we should be eating all the time, though! An excess of energy to the brain can lead to toxicity that eventually leads to the death of neurons(8). This is another reason to avoid energy dense UPFs, as well as too many foods high in sugar and refined carbohydrates.


Nutrient Requirements

We know that a deficiency of certain nutrients is associated with depressive symptoms. A 2018 study listed these as folate, iron, the omega 3 fatty acids EPA and DHA, magnesium, potassium, selenium, vitamin B1, vitamin A, vitamin B6, vitamin B12, vitamin C, and zinc(9). The foods that are highest in these nutrients are vegetables (specifically leafy green vegetables, lettuces, peppers and cruciferous vegetables), organ meats (such as liver), fruit and seafood (especially oysters / mussels and oily fish). Selected animal foods are included in this list because they can be more concentrated and bioavailable sources of some of these key nutrients, such as B12, EPA and DHA and zinc.


Overall Dietary Patterns

Thinking about all the ways in which specific foods and nutrients can affect mood is interesting (well, it is to me, anyway!), but what does it mean in terms of what we should actually eat on a day-to-day basis to support our mood and mental wellbeing?


The SMILES (Supporting the Modification of Lifestyle in Lowered Emotional States) trial in 2017(10) was seen as a landmark because it was the first randomised controlled trial to show that diet could have an impact in major depressive disorder. Participants with moderate to severe depression were randomised either to eat a modified Mediterranean Diet or to receive social support. The composition of the diet was described as follows:


“12 key food groups (recommended servings in brackets): whole grains (5–8 servings per day); vegetables (6 per day); fruit (3 per day), legumes (3–4 per week); low-fat and unsweetened dairy foods (2–3 per day); raw and unsalted nuts (1 per day); fish (at least 2 per week); lean red meats (3–4 per week), chicken (2–3 per week); eggs (up to 6 per week); and olive oil (3 tablespoons per day), whilst reducing intake of ‘extras’ foods, such as sweets, refined cereals, fried food, fast-food, processed meats and sugary drinks (no more than 3 per week). Red or white wine consumption beyond 2 standard drinks per day and all other alcohol (e.g. spirits, beer) were included within the ‘extras’ food group. Individuals were advised to select red wine preferably and only drink with meals.”


Notice that this describes an anti-inflammatory diet which could also be expected to have anticancer benefits – a win-win.


At the end of 12 weeks, 31% of the subjects in the diet group met the criteria for remission of depression compared to 8% in the social support group. That’s quite an impressive result! The study authors theorised that the Mediterranean Diet works on mood via the mechanisms we have discussed her: the gut microbiome, brain plasticity, and inflammatory and oxidative stress pathways.


By way of contrast, a prospective study of over 26,000 people in France found that for every 10% increase in the amount of UPFs in the diet, the risk of depressive symptoms increased by 21%(11). Some of this effect may be due to the fact that diets that are higher in UPFs also tend to have higher amounts of inflammatory ingredients (such as red meat and refined grains) and lower amounts of vegetables, fruits and dietary fibre. However, there are also additives in UPFs which can have negative effects on the gut microbiome. With what you now know, it shouldn’t come as a surprise that these might adversely affect mood.


There have been some interesting studies trying to tease out the best approaches to take to improve mood via improving gut health. One of these, the small “Gut Feelings” trial, found that switching to a diet high in prebiotic fibre for 8 weeks improved anxiety, stress and sleep in moderately depressed adults who did not previously eat a diet high in prebiotic fibre. Some of the prebiotic foods included in this diet were asparagus, garlic, onion, oats, whole wheat, chickpeas, and watermelon(12).


Conclusions

For each of the ways above in which food links to mood, I have listed particular foods that can be good choices. However, your overall dietary pattern is always more important than any single food, and this is very much the case when it comes to foods for your mood. Eating an anti-inflammatory, Mediterranean-style diet that is rich in vegetables, berries, extra virgin olive oil, herbs and spices, nuts and seed, legumes, whole grains and some seafood is a great place to start. Avoid overeating and minimise ultra-processed foods, refined grains, alcohol, deep fried foods and sugar. Aim to keep your blood sugar levels stable to avoid energy (and mood) crashes.


There is one final study that I would like to leave any chocolate lovers with. A small Korean study(13) randomised healthy adults to eat either 30g of 85% dark chocolate, 30g of 70% dark chocolate, or no chocolate daily for 3 weeks. Daily consumption of 85% dark chocolate significantly reduced “negative effect” and this was associated with improvements in gut microbial diversity. Enjoy a little bit of good quality dark chocolate for your mood – but make sure that it’s at least 85% cocoa!

 

Food and mental health after cancer

Nutrition and mental health after cancer


References

(1)   Lu, L., Wang, H., Chen, X. et al. (2023). ‘Gut microbiota and its metabolites in depression: from pathogenesis to treatment’, eBioMedicine, 90: 104527. Available at https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(23)00092-0/fulltext (Accessed 24 June 2024).

(2)   Bear, T., Dalziel, J., Coad, J. et al. (2021). ‘The Microbiome-Gut-Brain Axis and Resilience to Developing Anxiety or Depression under Stress’, Microorganisms, 9(4), 723. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065970/ (Accessed 24 June 2024).

(3)   Milaneschi, Y., Kappelmann, N., Ye, Z. et al. (2021). ‘Association of inflammation with depression and anxiety: evidence for symptom-specificity and potential causality from UK Biobank and NESDA cohorts’, Molecular Psychiatry, 26(12), 7393-7402. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8873022/ (Accessed 24 June 2024).

(4)   Fowler, M.E. and Akinyemiju, T.F. (2017). ‘Meta-analysis of the association between dietary inflammatory index (DII) and cancer outcomes’, International Journal of Cancer, 141(11), pp2215-2227. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056732/ (Accessed 24 June 2024).

(5)   Wang, K., Sun, J.-Z., Wu, Q.-X. et al. (2020). ‘Long-term anti-inflammatory diet in relation to improved breast cancer prognosis: a prospective cohort study’, NPJ Breast Cancer, 6: 36.  Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7426822/ (Accessed 24 June 2024).

(6)   Sasamoto, N., Wang, T., Townsend, M.K. et al. (2022). ‘Pre-diagnosis and post-diagnosis dietary patterns and survival in women with ovarian cancer’, British Journal of Cancer, 127(6), pp1097-1105. Available at https://pubmed.ncbi.nlm.nih.gov/35760897/ (Accessed 24 June 2024).

(7)   Tartt, A., N., Mariani, M.B., Hen, R. et al. (2022). ‘Dysregulation of adult hippocampal neuroplasticity in major depression: pathogenesis and therapeutic implications’, Molecular Psychiatry, 27(6), 2689-2699. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9167750/ (Accessed 24 June 2024).

(8)   Yang, Z., Zhang, W., Lu, H. et al. (2022). ‘Methylglyoxal in the Brain: From Glycolytic Metabolite to Signalling Molecule’, Molecules, 27(22), 7905. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9696358/ (Accessed 24 June 2024).

(9)   LaChance, L.R. and Ramsey, D. (2018). ‘Antidepressant foods: An evidence-based nutrient profiling system for depression’, World Journal of Psychiatry, 8(3), 97-104. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6147775/ (Accessed 25 June 2024).

(10)Jacka, F.N, O’Neill, A., Opie, R. et al. (2017). ‘A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial)’, BMC Medicine, 15(1), 23. Available at https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-017-0791-y (Accessed 25 June 2024).

(11)Adjibade, M., Julia, C., Allèè. B et al. (2019). ‘Prospective association between ultra-processed food consumption and incident depressive symptoms in the French NutriNet-Santé cohort’, BMC Medicine, 17(1), 78. Available at https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-019-1312-y (Accessed 25 June 2024).

(12)Freijy, T.M., Cribb, L., Oliver, G. et al. (2022). ‘Effects of a high-prebiotic diet versus probiotic supplements versus synbiotics on adult mental health: The “Gut Feelings” randomised controlled trial’, Frontiers in Neuroscience, 16: 1097278. Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9940791/ (Accessed 25 June 2024).

(13)Shin, J.-H., Kim, C.-S., Cha, L. et al. (2022). ‘Consumption of 85% cocoa dark chocolate improves mood in association with gut microbial changes in healthy adults: a randomized controlled trial’, The Journal of Nutritional Biochemistry, 99:108854. Available at https://www.sciencedirect.com/science/article/pii/S0955286321002746 (Accessed 25 June 2024).

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