The relationship between food and your mood

To coincide with National Nutrition Week (11^th-17^th Oct) and Mental Health Month, let’s shine a light on the role nutrition plays in reducing the risk of and managing mental health conditions.

Diet quality really matters in terms of prevention

Research is consistently finding associations between the quality of a person’s diet and their risk of depression.

Traditional dietary patterns that are higher in whole foods and minimal processed foods are consistently linked to reduced risk of depression. One meta-analysis from 2017 reported 30% reduced risk of depression in those with the highest adherence to a healthful dietary pattern.¹

Young people whose diets are highest in junk and processed foods are 80% more likely to have depression

This association is strong in adolescence, research finding the quality of young people’s diet is intrinsically linked to mental health which is critical as half of all mental disorders start before the age of 14 years. These findings are independent of various family factors, various socio-economic factors and independent of body weight.^{4, 5}

Looking to pregnancy, studies have revealed that mothers whose diets had higher levels of processed, fried and sugary foods during pregnancy, independent of a whole range of other factors, offspring had higher levels of emotional dysregulation during the first five years of life. Similarly, children who consume higher levels of discretionary foods or those who eat minimal amounts of healthful foods, studies are finding they too have higher levels of emotional problems.^{2, 3}

Dietary change can improve depressive symptoms

One study to prove dietary changes can improve depressive symptoms is The SMILES trial (2012-2015).  This ground-breaking Australian trial was the first study in the world to show that dietary changes can in fact improve symptoms in those with clinically diagnosed depression. Participants were allocated to either receive seven individual counselling sessions with an Accredited Practising Dietitian or to receive social support to the same visit schedule and length.

A whopping 32% or 1/3 of participants allocated to receive Dietitian counselling saw significantly greater improvements to mood after 12 weeks.  After six months, 33% met criteria for remission of major depression, compared to 8% of those in the social support group.⁶

So what did participants eat that significantly reduced depressive symptoms?

The SMILES trial intervention participants followed a modified Mediterranean Dietary pattern, which combines recommendations from Greece with our Australian Guide to Healthy Eating.  There is a large focus on plant-based foods such as wholegrains, vegetables, fruit, olive oil, legumes, nuts and seeds, while dairy, meats, poultry, fish and eggs were consumed in smaller portions and less often.⁸

Healthy isn't expensive

The SMILES Trial undertook cost modelling and disproved the myth that healthy is more expensive. Participants who followed a Mediterranean-style dietary pattern reduced their individual weekly food bill from $138 per week on average to $112.90!⁷

The how? High fibre, anti-inflammatory, antioxidant rich

A Mediterranean Dietary pattern focuses around whole plant foods so this pattern of eating is especially rich in antioxidants, exceptionally high in fibre and contains many compounds that are anti-inflammatory such as Omega-3s and polyphenols.

Research is finding that silent chronic inflammation is linked to brain function and mood and people with higher blood levels of inflammatory markers are more likely to develop depression. Dietary patterns that favour a high consumption of processed food contribute to this inflammation. One mechanism is by a weakening of the gut lining so food particles leak into the bloodstream where they do not belong, so off go alarm bells (inflammatory response). On the contrary, a whole plant food dietary pattern rich in fibre and anti-inflammatory nutrients will boost the health of our gut microbiome and strengthens the gut lining.

This connection between what we eat and how the gut functions is emerging. Similarly Nutritional Psychiatry, whilst is a new area, has incredible potential for our future in terms of prevention and treatment of mental illness.

Want to improve your mood? Here's how - A day on a plate

• Breakfast might be sourdough with ½ avocado, leafy greens and a poached egg, dressed with extra virgin olive oil. Or perhaps wholegrain cereal, sprinkled with nuts and topped with Greek yoghurt.
• Lunch might be chickpea and brown rice salad with feta, extra virgin olive oil dressing and a piece of fruit. Or perhaps wholegrain sandwich or crackers with canned salmon and salad.
• Dinner might be a piece of fish with veggies, cooked and dressed in extra virgin olive oil. Or pasta, tomato garlic chili sauce, sprinkle parmesan, served with green leafy salad and olive oil balsamic dressing.
• Daily snacks include Greek yoghurt, nuts, fruits, goats cheese or feta on wholegrain crispbread.
• Looking for a post dinner treat? Treat yourself to a couple of squares of dark chocolate.

1. Dietary patterns and depression risk: A meta-analysis
   Li, Y., et al.
   Psychiatry Research
   Volume 253, July 2017, Pages 373-382
2. Maternal and Early Postnatal Nutrition and Mental Health of Offspring by Age 5 Years: A Prospective Cohort Study
   Jacka FN., et al
   Journal of the American Academy of Child & Adolescent Psychiatry
   Volume 52, Issue 10, October 2013, Pages 1038-1047
3. Maternal depression symptoms, unhealthy diet and child emotional–behavioural dysregulation
   Pina-Camacho L., et al
   Psychological Medicine
   Volume 45, Issue 9, July 2015, pp. 1851-1860

4. A prospective study of diet quality and mental health in adolescents.
   Jacka FN, et al.
   PLoS One. 2011;6(9);e24805.
5. Associations between diet quality and depressed mood in adolescents: results from the Australian Healthy Neighbourhoods Study.
   Jacka FN, et al.
   Aust N Z J Psychiatry.  2010;44(5):435-42.
6. A Randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial).
   Jacka FN, et al.
   BMC Medicine 15(1):23.
7. Assessing Healthy Diet Affordability in a Cohort with Mayor Depressive Disorder.
   Opie RS, et al.
   Journal of Public Health and Epidemiology. 2015;7(5):159-69.
8. A modified Mediterranean dietary intervention for adults with major depression: Dietary protocol and feasibility data from the SMILES trial.
   Opie RS, et al.
   Nutr Neurosci. 2017:1-15.

Written by Hunter Primary Care Dietitian, Kate Wood