Food for Mood?

Kashish Janiani

Most of us are well aware of the correlation between diet and physical health. However, we fail to realise how nutrition affects our mental health. We fail to recognise that our eating habits are part of the jigsaw in prevention of poor mental health. Based on investigations between nutrition and brain functions related to mental health, from the 1970s, alternative medicine and nutritionists have long accepted the relation between mood and food (Zepf, 2015, p. 19). However, it seems that the field of nutritional psychology - one that acknowledges the mind-body connect, is finally gaining traction. (Seligman 2018) 

To begin with, it is important to understand what consists of a ‘good’ versus a ‘bad’ diet. A ‘good,’ healthy diet consists of loads of fresh vegetables, fruits, wholegrains, nuts and limited processed foods. In contrast, a ‘bad,’ unhealthy diet is high in saturated fats, sugar and processed foods (Marx, 2016, p. 428). A study of over 12,000 Australians found a significant correlation between consumption of fruits and vegetables with self-reported happiness and life satisfaction. (Mujcic and Oswald 2016, 1505) Another study that coached participants to follow a Mediterannean diet - rich in whole grains, legumes and seafood for 12 weeks reported improvement in moods and lower levels of anxiety (Jacka et al., 2017, p. 10). This study indicates dietary changes’ contribution to the development, prevention and management of mental health problems. 

When researchers began exploring specific nutritional aspects, related brain functions and associated neurochemical properties, their key findings were related to deficiencies of neurotransmitters in the central nervous system. The availability of the amino acid tryptophan (precursor to serotonin) in the body, controls the levels of serotonin in the brain. (Fadda 2000) So, after consuming tryptophan-rich foods such as soy, serotonin levels increase. Likewise, they decrease with low-intake of tryptophan. Most importantly, serotonin is linked to improved moods and feelings of well being. This research lead to the contemporary serotonin-deficit hypothesis of depression which has become foundational to pharmacological treatments of depression. However, current research, is fueling a new perspective - one that attempts to overcome this deficit not through drugs, but dietary changes. 

Depression is an illness that affects over 322 million people worldwide and is only becoming more prevalent despite the increased use of psychotropics and availability of psychotherapy (WHO, 2017, p. 8) With this, we are forced to look at operative environmental risk factors for depression. A deteriorating diet seems to be one. As mentioned earlier, tryptophan is a precursor to serotonin - the neurotransmitter whose low levels are linked to depression. Therefore, increased consumption of tryptophan means higher levels of serotonin and better well-being. Not surprisingly, there are complexities to this link. When compared to antidepressants, tryptophan was only equally effective or inferior. However, studies comparing a combination of antidepressants and a tryptophan-rich diet to just antidepressants, found the addition of tryptophan to be most effective in treating depression. These complexities also arise in interactions with other amino acids. Tryptophan crosses the blood-brain barrier by a special transport system it shares with other large amino acids like phenylalanine. In order to ensure increased absorption of tryptophan in the brain, consumption of phenylalanine - a competing amino acid, could be reduced. Moreover, a different number of enzymes, minerals and vitamins are essential in the process of converting tryptophan to serotonin. If any of these are insufficient, no amount of tryptophan will be enough. (Mental Health Foundation 2006) 

In a case study, after months of ineffective pharmacotherapy, supplementing the patient’s diet with omega-3 fat - an Essential Fatty Acid (EFA) as an additional treatment alleviated all depressive symptoms. This case study has been corroborated with controlled trials indicating a significant relation between intake of EFAs (typically high in traditional diets, but low in modern ones)  and depression. (Lakhan and Vieria 2008).  

The link between nutrition and mental health is not limited to depression, but extends to illnesses like bipolar disorder, ADHD and schizophrenia. There is a need for more controlled trials - ones that account for confounding variables like socioeconomic status that have not been controlled for in previous research. 

Although still in its nascent stages, nutrition-based therapy for mental illness is exciting. The question of the extent to which diet affects our mental health becomes important for several reasons. First, we seem to be moving away from traditional diets (which have been linked to better mental health) towards a diet of convenience filled with processed foods and refined carbs. It also allows us to bring into question our reliance on pharmacotherapy. Most medication has undesired side-effects that could possibly be limited by complementing drug therapy with nutritional supplements. (Young, 2002, p. 206)

Since food is inherently sociocultural - part of our external environment, we will have to engage with the social and cultural for future research and treatment. A risk that also comes with nutritional psychology is -  in place of empowering people to find non-pharmaceutical treatments, it may enable people to blame those who do not have the choice of good nutrition, for their mental illnesses. 

References: 

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Seligman, R. (2018). Can What You Eat Affect Your Mood?. [online] Scientific American Blog Network. Available at: https://blogs.scientificamerican.com/observations/can-what-you-eat-affect-your-mood/ [Accessed 26 Oct. 2019].

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