How food can affect your mood: a study review

Thursday, March 2, 2017. Author Nathan West

It’s not news that the food we eat has a significant impact on our training performance, body composition and physiological and metabolic health, but did you know that food may also affect our mood and mental well-being?

Having processed and/or fast food every day isn’t a good idea for your long-term health. These types of food can be extremely calorie dense and severely lack micronutrients. Fruits, vegetables, and legumes are much more beneficial for our bodies; they are less calorie dense and plentiful in micronutrients & minerals. The physical and physiological effects of our diets on our bodies is widely acknowledged and reported on in the media, but what about the psychological effects of food?

Scientific study on how food can affect mood

In a recently published study1, the effect of diet in the treatment of moderate to severe depression was investigated. In a randomized controlled trial, people with moderate to severe depression were allocated to receive either a nutritional intervention or to serve as a control group. The 31 people in the nutritional intervention group attended 7 nutritional consulting sessions with a clinical dietician. The 25 controls followed a befriending protocol of the same schedule and duration as the nutritional intervention group.

The diet intervention consisted of personalized dietary and nutritional counseling support to help them adjust their eating patterns and help them adhere to the new diet. Since the study did not have a weight-loss focus, the participants were not given a calorie limit and could eat as much as they wanted to. The prescribed diet was based on a Mediterranean style diet and consisted of increasing the intake of the following key food groups:

Vegetables (6 servings per day)
Fruits (3 per day)
Legumes (3-4 per week)
Whole grains (5-8 per day)
Raw & unsalted nuts (1 per day)
Fish (at least twice per week)
Lean red meats (3-4 per week)
Chicken (2-3 per week)
Eggs (up to 6 per week)
Low-fat & unsweetened dairy foods (2-3 per day)
Olive oil (3 tablespoons per day)

The following was aimed to be reduced/removed:

Sugary drinks
Processed meats
Fried food
Fast food
Refined cereals
Sweets/candy/desserts
Opt for wine over beer or spirits, and max of 2 standard drinks per day

The macronutrient ratio (also included in your personalized FitnessGenes’ nutritional advice) for this diet worked out to be roughly 18% of calories from protein, 40% fat and 37% carbohydrates (with fiber (3%) and alcohol (2%) making up the remainder).

What did they find?

At the end of the 12-week trial, the diet group had significantly greater reductions in their depressive symptoms than the control group independent of any changes in weight, BMI and/or physical activity.

Previous studies had already suggested that a healthy diet may have a positive impact on anxiety and signs of depression and other mental health issues2–4, but this is one of the first randomized controlled trials to show a healthy diet may help in treating moderate to severe depression. Higher intakes of processed food, refined carbohydrates and saturated fats have been also associated with poorer mental health5.

How does this work?

The mechanism of how someone’s diet impacts mental well-being is not fully understood but there are several overlapping hypotheses. To begin with, a balanced diet of vegetables, fruits, legumes, whole grains, nuts and lean meat (basically all the good stuff) provides plentiful nutrition at both the macro and micro levels. Diets that lack those foods, and that are mostly composed of refined carbs and processed meats/foods is less well balanced and unhealthier. Unfortunately, the latter is a typical Western diet – especially in the US and UK, and is deficient in some important micronutrients.

Secondly, it is also known that an unhealthy diet can be more inflammatory6, increase oxidative stress7 in a negative way, reduce brain plasticity8 and can negatively impact your gut microbiota9. Together, this may impair cellular functioning and health, consequently reducing energy levels and motivation to exercise, pulling someone into a vicious negative circle.

Physical activity is known to have mood enhancing effects (it is also recommended as part of an overall treatment package for people suffering from depressive symptoms) and lacking the energy or motivation to exercise could have further negative impacts on someone's mood.

How must we interpret these findings?

Of course, depression isn't treated through a healthy diet alone. In the study1 discussed here, the diet intervention group still needed psycho- and/or pharmaco-therapy. It is also not true that a poor diet will definitely lead to a low mood or depressive symptoms. But it highlights again that a healthy balanced diet, along with regular exercise, can help you to get into a positive, motivated, and healthier rhythm where energy levels, motivation and mood all positively feedback on each other, helping you to reach your health and fitness goals.

Whether it be building muscle, losing fat, hitting sporting PB's or just improving our lifestyles, long-term consistency is the key, and having the energy, motivation and having the right mind frame can be essential for success.

Take home message

The next time you hear someone preaching the benefits of eating a healthy, fresh, whole foods, well-balanced diet, remember it doesn’t only improve physiological and metabolic health, but also potentially mental health and mood, all of which can contribute to making sustainable long-term improvements in your lifestyle.

If you enjoyed this article, please read my other blog posts on:

What type of body fat do you carry?

Smart goal setting

Saturated fat and genetics

7 rules for sustainable weight loss

The quantified self

 

References

  1. Jacka FN, O’Neil A, Opie R, et al. A randomised controlled trial of dietary improvement for adults with major depression (the “SMILES” trial). BMC Med. 2017;15(1):23. doi:10.1186/s12916-017-0791-y.
  2. Lai JS, Hiles S, Bisquera A, Hure AJ, McEvoy M, Attia J. A systematic review and meta-analysis of dietary patterns and depression in community-dwelling adults. Am J Clin Nutr. 2014;99(1):181-197. doi:10.3945/ajcn.113.069880.
  3. Jacka FN, Pasco JA, Mykletun A, et al. Association of Western and Traditional Diets With Depression and Anxiety in Women. Am J Psychiatry. 2010;167(3):305-311. doi:10.1176/appi.ajp.2009.09060881.
  4. Akbaraly TN, Brunner EJ, Ferrie JE, Marmot MG, Kivimaki M, Singh-Manoux A. Dietary pattern and depressive symptoms in middle age. Br J Psychiatry. 2009;195(5).
  5. O’Neil A, Quirk SE, Housden S, et al. Relationship Between Diet and Mental Health in Children and Adolescents: A Systematic Review. Am J Public Health. 2014;104(10):e31-e42. doi:10.2105/AJPH.2014.302110.
  6. Berk M, Williams LJ, Jacka FN, et al. So depression is an inflammatory disease, but where does the inflammation come from? BMC Med. 2013;11(1):200. doi:10.1186/1741-7015-11-200.
  7. Moylan S, Berk M, Dean OM, et al. Oxidative & nitrosative stress in depression: Why so much stress? Neurosci Biobehav Rev. 2014;45:46-62. doi:10.1016/j.neubiorev.2014.05.007.
  8. Jacka FN, Cherbuin N, Anstey KJ, Sachdev P, Butterworth P. Western diet is associated with a smaller hippocampus: a longitudinal investigation. BMC Med. 2015;13(1):215. doi:10.1186/s12916-015-0461-x.
  9. Dash S, Clarke G, Berk M, Jacka FN. The gut microbiome and diet in psychiatry. Curr Opin Psychiatry. 2015;28(1):1-6. doi:10.1097/YCO.0000000000000117.

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