By Lauren Wheeler
The concept of consuming specific foods to boost brain power is not a new one. Nutrients such as omega 3, found in oily fish, were first linked to improvements in cognitive function in the early nineties and we are increasingly being targeted by brands who boast their product’s ability to increase memory and enhance our brain’s performance. Less frequently reported, however, is how the foods we eat affect our mental health and wellbeing. Yet recent findings from the emerging field of nutritional psychiatry, the use of nutritional medicine in the practice of psychiatry, suggest that the quality of our diets directly influences our risk of developing a range of neuropsychiatric disorders and correlate improvements in dietary patterns with positive mental health outcomes (Sarris et al. 2015).
Scientists have postulated that, for the first time in history, the majority of the population is both overfed and undernourished – with increased consumption of energy-dense yet nutrient-poor foods driving caloric intake up and the consumption of key nutrients down (Parker et al., 2014). Most notably the consumption of fruits, vegetables and whole grains is significantly lower than recommended. This is especially worrying considering that these foods are a crucial source of nutrients critical to brain health including B vitamins, zinc and magnesium.
In contrast diets high in these foods, along with sources of healthy fats such as omega 3s, have been linked to improvements in mental health and decreased risk of disorders such as depression and psychosis, as well as lower rates of suicide. Studies comparing the efficacy of nutritional interventions to traditionally used talking therapies have also found them to be equally effective in ameliorating depressive symptoms and reducing anxiety (Jacka, 2017). Furthermore, consumption of the MIND diet, short for Mediterranean-DASH Diet Intervention for Neurodegenerative Delay, which includes ample vegetables, fruits, nuts and plant-derived fats, has been associated with slower rates of cognitive decline and decreased risk of dementia in older age (Morris et al., 2015).
The observation that what we eat can have a profound effect on cognitive function is not particularly surprising, given that the brain’s composition and structure are directly influenced by the availability of specific nutrients. The organ, which has an incredibly high metabolic rate, relies on a constant influx of energy, amino acids, lipids, vitamins and minerals to function optimally. Food intake also affects the integrity of both the antioxidant defence and immune systems whose dysfunction, leading to problems such as increased inflammation, may contribute to the pathophysiology of a range of mental health disorders.
In terms of particular nutrients which have been implicated as critical to brain health, the vitamins B12, thiamine (B1), folic acid (B9) and niacin (B3) appear to be most strongly linked to impairments in cognition (Adan et al., 2019). Vitamin B12 deficiency has been associated with poor memory, lethargy and increased risk of psychosis (Smith et al, 2018), whilst a lack of folic acid during pregnancy may hinder the neurodevelopment of a growing foetus and increase risk of depression in adulthood (Black, 2008). Random controlled trials have further illustrated that diets rich in polyphenols, found in foods such as blueberries, dark leafy green vegetables and extra virgin olive, produce beneficial effects on mental health including reduced neuroinflammation and improvements in mood (Firth et al., 2019).
It should be noted, however, that whilst many associations have been made between certain foods/dietary patterns and mental health, many of the studies linking nutrition to psychiatric outcomes are observational and do not provide information relating to causality or the underlying mechanisms by which these foods may bring about improvements in neuropsychiatric conditions. The limitations of such studies are that they typically assess the effects brought about by a given food holistically, rather than distilling them down to a single nutrient. Also, whilst drugs tend to act on a single target, nutrients and their metabolites act on a range of targets across a variety of organs, being metabolised differently by different individuals, it would be difficult to produce a specific ‘prescription’ which would be effective for any given patient. Finally, whilst altering the diet may be a useful tool for symptomatic improvement in mental health conditions, it is by no means a cure-all and is certainly not a suitable alternative to current pharmaceuticals for people with severe neuropsychiatric disorders.
Nevertheless given that the disease burden attributable to mental illness is set to continue to rise over the coming years, not least due to the psychiatric repercussions brought about by the recent pandemic (Whiteford et al., 2013; Pierce et al, 2020) and that few effective methods for preventing and treating mental health disorders currently exist, the dietary interventions implicated by neuropsychiatric research could prove pertinent as rapid, accessible first-line interventions in mental health care settings. With further research to elucidate the exact mechanisms by which specific nutrients improve or impair cognition at a cellular level, nutrition could prove a powerful lever both in the prevention and amelioration of illnesses which, at present, cause immense suffering in the lives of the people they afflict.
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