Our brains are the most powerful, metabolically active organs in our bodies as they use an astonishing 20% of our overall daily energy produced by the body (1) . However, it isn’t always a common thought to think to ourselves about how best we can look after and provide high quality and nutritious foods to our brains in order to optimise our brain health.
Here we will uncover the research behind nutrition, diet and brain health as well as the role food can have on our mood and mental health.
Omega 3 and 6 fatty acids
Previous research has shown that a range of specific nutrients can have an influence on our brain function and health. When breaking down the brain into its nutritional parts, fats also known as lipids form a large proportion (nearly 60%) of the brain and they determine the brains function and performance (3).
Both Omega 3 and 6 fatty acids are essential in the body ie our bodies cannot make them and therefore they must be obtain from foods.
Omega 3 fatty acids are crucial to the development and maintenance of cell membranes in the brain. In particular, DHA is an omega 3 fatty acid that is essential for the growth and functional development of the brain in infants and it is also required for the maintenance of normal brain function in adults (4). The strongest evidence for the role of specific nutrients on brain health is with omega 3 fatty acids. They have been shown to be associated with the prevention of degenerative brain conditions and cognitive decline including dementia and Alzheimer’s disease due to their role in reducing low-grade inflammation in the early stages of neurodegenerative disease (5).
Sources of omega 3 fatty acidsconsisting of EPA and DHA include
- Nuts and seeds including walnuts, chia seeds, flaxseeds,
- Oily fish including salmon, mackerel, herring, sardines, kippers and trout
- Plant oils including flaxseeds oil, soybean oil and canola oil
In addition to the beneficial fats for our health, long-term consumption of other types of fat including saturated and trans fats may compromise and have detrimental impacts on our brain health (6).
A variety of micronutrients have been shown to support brain function and cognition (7). Anti-oxidants found in a range of fruits, vegetables, nuts, seeds and legumes can strengthen our brains to fight off free radicals which are molecules produced when your body breaks down food or when you have been exposed to tobacco smoke or radiation. These free radicals can cause oxidative damage ie destroy brain cells. However, antioxidants have been shown to delay or reduce age-related cognitive decline caused by free radicals, prolonging our brains health and longevity (7).
Antioxidant rich sources of foods include:
- Oranges, kiwis, strawberries, lemons, peppers which are rich in vitamin C and flavonoids and raspberries and blueberries
- Artichokes and coloured vegetables including red peppers, red cabbage, spinach, beetroot, kale containing lutein
- Nuts, seeds and legumes including pecans, pumpkin seeds and beans
B-vitamins consist of eight essential dietary micronutrients that work closely together and form an essential component of brain function (8).
It is interesting to note that a dietary deficiency of B-vitamins during critical periods of development can result in permanent changes to the brain (9), highlighting the importance of B-vitamins for brain function.
Without these vital micronutrients including vitamins B6, B12 and folic acid, our brains are more susceptible to brain disease and mental decline (8).
Dietary sources of folate include:
- Leafy green vegetables, fruit, legumes, fortified cereals
Dietary sources of B-vitamins B1, B3 & B12 include:
- Wholegrains, meat, fish, eggs and dairy.
Trace amounts of minerals and vitamins including iron, copper, zinc and selenium, iodine, vitamin A and choline are also fundamental to brain health and early cognitive development (10).
Dietary Patterns of the Mediterranean Diet and Mental Health
However, single nutrient trials and their effects can often be limited as we consume wholefoods and not single nutrients.
Recent and emerging evidence has delved into the impact of dietary patterns on our mental health and has found strong evidence for a potential benefit of a Mediterranean style diet in the aid of treatment for depression.
This ‘low MED diet’ included the consumption of wholegrain, vegetables, fruit, legumes, low fat dairy, fish, chicken and olive oil and emphasised reducing sweets, refined cereals, fast/fried food and sugary drinks. Results of this study demonstrate that the dietary intervention group consuming a Mediterranean style diet showed significantly greater improvements in symptoms of depression after 12 weeks when compared with the social support group (11).
In regards to Omega-3 fatty acids and our mental health, patients with depression and mental health disorders have been found to have low-levels of Omega-3 fatty acids in their blood and omega-3 fatty acids have been previously used as the basis for treatment in patients with mood disorders (12)(13). Therefore, another study has shown that healthy dietary changes through Mediterranean style diet supplemented with fish oil can improve mental health in people with depression (14).
It must be noted that depression is a mental health disorder that can be caused by various factors. However, this research does provide the first sign of evidence that improving our diets and nutrition can provide an effective treatment option alongside current treatments for depression including medications and psychotherapy.
Food and Mood
The common term ‘Food and Mood’ evolved from the idea that food can affect our brains emotional and mental state.
Mental health is defined by the World Health Organization (WHO,2014) as a ‘state of well-being in which every individual realizes his or her own potential, can cope with normal stresses of life, can work productively and is able to make a contribution to her or his community’ (15). Essentially, mental health disorders are experienced as problems with emotions, behaviours, thoughts or perceptions. Anything that affects how your body functions will affect how your brain functions. The foods that we eat can impact on the way we feel. Drinking a cup of coffee or glass of wine can make us feel good, sleepy or drowsy, providing a clear example as to how particular compounds and combinations of compounds in foods can impact our brain and mood.
When looking at how certain nutrients can have an impact on our mood however, the process is usually slower and occurs gradually.
In particular, protein and amino acids have been associated with our mood and behaviour. Amino acids which are the building blocks of protein can directly impact the conversion of neurotransmitters which are chemical messengers in the brain that can influence brain function and mood(16).
The complex combination of nutrients in foods that we consume can stimulate our brain cells to release mood altering norepinephrine, dopamine and serotonin hormones. Therefore having a diverse, nutrient dense diet could provide beneficial effects to our mood and emotions.
The main source of energy for the brain is glucose which is required to fuel physiological brain function, generation of neurotransmitters and the maintenance of brain cells (17). High quality carbohydrates including wholegrain sources and low glycaemic index (GI) foods can reduce a spike in blood sugar levels and thus changes in mood.
- Wholegrains, beans, legumes and plant-based foods to provide enough fibre to your gut microbiome.
Lastly, it is not only nutrition which has been shown to be strongly linked with our brain health, other lifestyle factors are also highly involved too.
The role of the gut-microbiota and immune system has been linked to mental health also. IBS is a disorder of the gut-brain axis. Stress is one of the diagnostic criteria for IBS which can increase stress hormones, impact gut microbiome, increase the speed at which food moves through your gut and an individual’s perception of pain in the gut. Therefore, psychological stress can have physiological effects on the body. Addressing stressful stimuli could help improve IBS symptoms.
- Raichle ME, Gusnard DA. Appraising the brain’s energy budget. Proc Natl Acad Sci U S A. 2002 Aug 6;99(16):10237–9.
- Raichle ME. Two views of brain function. Trends in Cognitive Sciences. 2010 Apr 1;14(4):180–90.
- Chang C-Y, Ke D-S, Chen J-Y. Essential fatty acids and human brain. Acta Neurol Taiwan. 2009 Dec;18(4):231–41.
- Horrocks LA, Yeo YK. Health benefits of docosahexaenoic acid (DHA). Pharmacol Res. 1999 Sep;40(3):211–25.
- Thomas J, Thomas CJ, Radcliffe J, Itsiopoulos C. Omega-3 Fatty Acids in Early Prevention of Inflammatory Neurodegenerative Disease: A Focus on Alzheimer’s Disease. Biomed Res Int [Internet]. 2015 [cited 2021 Feb 14];2015. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4537710/
- Impact of fatty acids on brain circulation, structure and function | Elsevier Enhanced Reader [Internet]. [cited 2021 Feb 14]. Available from: https://reader.elsevier.com/reader/sd/pii/S0952327814000052?token=B2976F92968EC9ACAA380EEE5F7D9B5934A43A8CCD267C9926EE7F9F2E04411B625B15CCC27F923B46017EB168C3866C
- Packer L, Sies H, Eggersdorfer M, Cadenas E. Micronutrients and Brain Health. CRC Press; 2009. 444 p.
- Kennedy DO. B Vitamins and the Brain: Mechanisms, Dose and Efficacy—A Review. Nutrients [Internet]. 2016 Jan 28 [cited 2021 Feb 14];8(2). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772032/
- Anjos T, Altmäe S, Emmett P, Tiemeier H, Closa-Monasterolo R, Luque V, et al. Nutrition and neurodevelopment in children: focus on NUTRIMENTHE project. Eur J Nutr. 2013 Dec;52(8):1825–42.
- Georgieff MK. Nutrition and the developing brain: nutrient priorities and measurement. The American Journal of Clinical Nutrition. 2007 Feb 1;85(2):614S-620S.
- Jacka FN, O’Neil A, Opie R, Itsiopoulos C, Cotton S, Mohebbi M, et al. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med. 2017 Dec;15(1):23.
- Sinn N, Milte C, Howe PRC. Oiling the Brain: A Review of Randomized Controlled Trials of Omega-3 Fatty Acids in Psychopathology across the Lifespan. Nutrients. 2010 Feb 9;2(2):128–70.
- Freeman MP, Hibbeln JR, Wisner KL, Davis JM, Mischoulon D, Peet M, et al. Omega-3 fatty acids: evidence basis for treatment and future research in psychiatry. J Clin Psychiatry. 2006 Dec;67(12):1954–67.
- Parletta N, Zarnowiecki D, Cho J, Wilson A, Bogomolova S, Villani A, et al. A Mediterranean-style dietary intervention supplemented with fish oil improves diet quality and mental health in people with depression: A randomized controlled trial (HELFIMED). Nutritional Neuroscience. 2019 Jul 3;22(7):474–87.
- Mental health: strengthening our response [Internet]. [cited 2021 Feb 23]. Available from: https://www.who.int/news-room/fact-sheets/detail/mental-health-strengthening-our-response
- Research I of M (US) C on MN. Amino Acid and Protein Requirements: Cognitive Performance, Stress, and Brain Function [Internet]. The Role of Protein and Amino Acids in Sustaining and Enhancing Performance. National Academies Press (US); 1999 [cited 2021 Feb 14]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK224629/
- Mergenthaler P, Lindauer U, Dienel GA, Meisel A. Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends Neurosci. 2013 Oct;36(10):587–97.
Contribution from Emily Stynes Nutritionist