Backed by studies that sought to establish the link between gastrointestinal health with neurological disorders, the association appears to be gathering pace, as nutritional psychiatrists are adamant the “gut-brain” pathway is the key to managing anxiety and depression.

Dr Alex Richardson, visiting senior research fellow, department of physiology, anatomy and genetics at the University of Oxford, initially sees its promise in a supportive, rather than a main therapeutic approach.

“In my view, nutritional approaches should always be integrated with – and complementary to - standard treatments, rather than being seen as ‘alternative’,” s​he said.

“There’s good evidence that the provision of some essential nutrients via diet or supplements may help to prevent or treat many mental (as well as physical) health conditions.”​

Research looking into this link is not short in number with a recent review​​ for example suggesting a benefit of omega-3 oils as well as probiotics and prebiotics in improving anxiety, stress and depressive symptoms.

Compelling evidence​​ exists to back supplementation with L-theanine, beta-alanine, and theacrine to help users increase brain alertness, according to Hofstra University in New York.

Equally, the evidence is offset by research​​ that concludes dietary supplementation with the omega-3 fatty acid DHA has no impact on reading, working memory or behaviour of under-performing UK schoolchildren.

Nutrient-profile scale​

Expectations are high in anticipation of the publication entitled “Antidepressant Foods: An Evidence-based Nutrient Profiling System for Depression,​” in next month’s World Journal of Psychiatry.​

The publication, written by Dr Drew Ramsey, assistant clinical professor of psychiatry at Columbia University, and Dr Laura LaChance of the Centre for Addiction and Mental Health in Toronto, outlines a nutrient-profile scale, which lists the most nutrient-dense foods that aid “the prevention and treatment of depressive disorders”.​

The research also identifies folate (vitamin B9), iron, long-chain omega-3 fatty acids, magnesium, selenium, thiamine (vitamin B1), vitamin A, vitamin B6, vitamin B12 and vitamin C amongst others as key nutrients in addressing depression and anxiety.

Supplemental strategies are complimented by the use of probiotics and prebiotics as another example of a nutrient-dense food approach.

Researchers are particularly encouraged by fermented foods’ ability to get at the underlying mechanism of a disorder.

“Increasing evidence for the importance of the gut-brain axis indicates that the use of probiotics and/or prebiotics to improve some mental health conditions is a very promising area,” ​said Dr Richardson, who is also founder director of Food and Behaviour (FAB) Research​​, based in the UK.

“But more human research studies are still needed and individual differences present both serious challenges to this and significant opportunities for ‘personalisation.’”​

‘Ethical and practical obstacles’​

Dr Richardson points to additional challenges as to why nutritional approaches to psychiatry have not been widely adopted within mainstream health policy and practice.

This is despite the library of evidence in many areas that this would help improve both patient outcomes and cost-efficiency.

“Mainstream acceptance of nutritional interventions at the level of public health recommendations relies heavily on evidence from randomised, controlled clinical trials – but the provision of this kind of evidence for nutritional interventions is seriously limited for many reasons,”​ she said.

“The essentiality of nutrition (in contrast to pharmaceutical or other interventions) creates many ethical and practical obstacles; and the effects of nutrition on health are also both long-term and synergistic. ​

“For these reasons, acceptance at the level of clinical practice is likely to come first, and we can already see that happening in the private sector.”​

Nutrition industry activity​

Professor Felice Jacka, director of the Food and Mood Centre and founder and president of the International Society for Nutritional Psychiatry Research (ISNPR) is an advocate of using dietary and nutritional strategies to tackling mental health problems.

She identifies the food and nutrition industry’s role in the field as her research​​ identifies ‘western’ diets as being “more homogeneous in their composition due to their common source (i.e. industry).”​

This is despite noting that ‘healthy’ diets in Spain, Norway, Japan, Australia, China and the UK, have at their core, higher intakes of nutrient-dense plant based foods and quality sources of protein, in spite of the difference in culturally specific foods.

The industry’s efforts in producing foods with more health-conscious ingredients has in part been overshadowed by the continuing increase in obesity and deaths related to obesity over the last few decades.

Nevertheless, the shift towards a healthy eating approach and active lifestyle has gathered momentum as food firms increasingly recognise the enormous therapeutic potential inherent in the field as well as the long-term possibilities.

“Mental health is an area in which the unmet needs of consumers are huge, and increasing – because in terms of the relative lack of effective diagnoses and treatments, psychiatry currently lags well behind many other areas of medicine,” ​said Dr Richardson.

“In my view, nutritional psychiatry has a key role to play in helping to meet some of those needs – but better education, information and training on the fundamental importance of nutrition for health is also needed much more generally, at both the public and professional level. ​

“Challenges to this include both commercial vested interests and the difficulties of providing the kind of research evidence demanded by our current public health systems.”​