The Food, Brain, and Mood Connection

Submitted by Keara Lubchenko, Nutrition Practicum Student

Edited by Brooke Bulloch, RD

If you think about it, the brain is always working. Even when we are sleeping, it is functioning to help control things like breathing and heartbeat. This means that our brain requires a constant amount of energy to keep working. This energy comes from the foods we eat which can also affect the structure and function of our brain cells, thus food has a direct relationship to mood. Eating foods with a variety of vitamins, minerals, antioxidants, and carbohydrates nourishes the brain, and may have a positive effect on our day-to-day mood, and mood disorders such as anxiety and depression.

 Here are 4 ways that food, the brain, and mood are connected:

1. The Tryptophan - Brain Connection
The gastrointestinal tract produces 95% of the neurotransmitter (a hormone) called serotonin, which acts as a mood stabilizer/booster. To make serotonin, we need an essential amino acid called tryptophan. Our gut microbes obtain tryptophan from food in order to produce serotonin, and the amount of tryptophan that we eat influences how much serotonin is made by the body.

Studies suggest that lower consumption of tryptophan may be associated with mild to moderate depression in older adults. However, it’s important to note that further research is needed to determine whether dietary supplementation with tryptophan may help to prevent and treat mood disorders (2). Try consuming your tryptophan through foods instead.

Foods That Contain Tryptophan:
Tryptophan can be found in most protein foods such as:

• Nuts and seeds (cashews, pistachios, and almonds contain the highest amounts of tryptophan)
• Tofu
• Cheese
• Meat (turkey, chicken, and pork contain the highest amounts of tryptophan)
• Fish
• Beans (e.g. kidney beans, black beans, or navy beans)
• Lentils

How Much Tryptophan to Consume?
Research suggests that consuming between 250-425mg per day of tryptophan supports adequate serotonin production (1). Aim for a variety of protein sources throughout your day, ideally one at each meal and snack to meet tryptophan needs.

2. The Antioxidant - Brain Connection
Antioxidants protect our cells from damage caused by “waste” produced when the body uses oxygen. This process is known as oxidative stress. Oxidative stress may play a role in the development of some diseases or conditions such as cancer, heart disease, or depression.

The Role of Antioxidants on Neurons:
Brain cells are also prone to oxidative stress and damage, and studies show oxidative stress levels are increased in individuals with depression (3). A diet high in antioxidants protects the cells in our brain from damage, which may reduce the risk of anxiety and depression.

Antioxidants include vitamins and minerals such as vitamin C, vitamin E, beta-carotene, and selenium.

Foods that Contain Antioxidants:

• Vegetables
• Fruit
• Whole grains
• Brazil nuts
• Other nuts and seeds

How Much Antioxidant Foods to Consume?
There is currently no daily recommended intake of antioxidants. As a general guide, aim for 5 servings of vegetables and/or fruit per day, and a variety of other foods listed above each week. Being consistent in consuming antioxidant foods will be beneficial to your mental health.

 

3. Food and the Hypothalamic-Pituitary-Adrenal Axis (HPA) Connection
The HPA axis includes the hypothalamus, pituitary, and adrenal glands. It functions to help manage reactions to stress, and helps regulate mood, emotions, digestion, energy storage, and the immune system. Inflammation can cause increased levels of stress hormones such as cortisol, which is associated with a disruption to the HPA axis. The HPA axis has been linked to anxiety and depressive disorders, and some research suggests more than 60% of people with depression show elevated cortisol levels (4).

How Can Food Help?
Certain nutrients can influence the HPA axis by lowering cortisol levels. Some of these nutrients include:

• Vitamin C
• Omega 3 fatty acids
• Polyphenols

Food Sources of Vitamin C

• Citrus fruits such as oranges, lemon, and grapefruit
• Strawberries
• Kiwi fruit
• Bell peppers
• Tomatoes

Food Sources of Omega-3

• Fish and seafood
• Olive oil
• Flaxseed (oil or ground seeds)
• Chia seeds
• Hemp hearts
• Walnuts
• Soybeans (e.g. edamame beans, tofu, or tempeh)
  

Food Sources of Polyphenols
Polyphenols are non-nutrient compounds found in plants.

• Olive oil
  
• Sesame oil
• Cocoa and dark chocolate
• Soybeans
• Flaxseed
• Mangosteen

 

4. The Carbohydrate - Brain Connection
Carbohydrates support optimal brain function and mood in four ways:

1. Carbohydrates are the preferred source of energy for the brain and help the brain to function optimally. Low carbohydrate intake can contribute to mental fatigue and brain fog because the brain cannot store carbohydrates for future use. Thus, the brain needs a continuous supply throughout the day.
2. Carbohydrates play a role in blood sugar management. When carbohydrate intake falls and blood sugars drop, mood can become more irritable, and anxiety can increase. Fibre-rich carbohydrates provide more sustainable energy by slowing digestion, which prevents drastic spikes and drops in blood sugar (5).
3. Carbohydrates help to lower cortisol (stress-induced hormone). “Studies show that a diet adequate in carbohydrates was shown to reduce cortisol and negative mood after stress (6)”. The same is for when we consume low amounts of carbohydrates, this may lead to stress-inducing effects.
4. Inadequate consumption of carbohydrates can also affect how well we sleep. Many studies have shown that carbohydrate intake can affect sleep initiation, continuation, and prolonged REM (rapid eye movement) compared to low carbohydrate consumption (7). REM is important because it is involved with memory, emotional processing, and healthy brain development. Without the brain getting adequate rest, mood can be negatively affected (8).

Food Sources of Fibre-Rich Carbohydrates:

• Vegetables and fruit
• Whole-grain breads or soft tortilla wraps
  
• Quinoa
• Potatoes with the skin on
  
• Sweet potato
• Gluten-free whole grains like brown rice, millet, and buckwheat
• Beans and lentils

Aim to include a variety of carbohydrate foods throughout the day, choosing fibre-rich sources often. Pair carbohydrate foods with protein for further meal or snack satisfaction.

Evidence suggests eating a variety of foods and nutrients can help fuel our brain and support our mood and mental health through neurons, gut bacteria, the HPA axis, and carbohydrates. While this post shares a number of foods being recommended as part of a strategy to manage mood, they are not recommended as a cure-all for mood disorders. If you’re struggling with mental health, reach out to a health care provider. For more information or support with nutrition planning related to your mental health, meet with a Food to Fit registered dietitian.

References:
(2) Richard, D. M., Dawes, M. A., Mathias, C. W., Acheson, A., Hill-Kapturczak, N., & Dougherty, D. M. (2009). l-tryptophan: Basic metabolic functions, behavioral research and therapeutic indications. International Journal of Tryptophan Research, 2. https://doi.org/10.4137/ijtr.s2129

(3) Chojnacki, C., Popławski, T., Chojnacki, J., Fila, M., Konrad, P., & Blasiak, J. (2020). Tryptophan intake and metabolism in older adults with mood disorders. Nutrients, 12(10), 3183. https://doi.org/10.3390/nu12103183

(4) Black, C. N., Bot, M., Scheffer, P. G., Cuijpers, P., & Penninx, B. W. J. H. (2015). Is depression associated with increased oxidative stress? A systematic review and meta-analysis. Psychoneuroendocrinology, 51, 164–175. https://doi.org/10.1016/j.psyneuen.2014.09.025

(5) Mahoney, S. (2021, April 15). Looking through the lens at how food can improve our mood. Food and Mood Centre. Retrieved April 6, 2022, from https://foodandmoodcentre.com.au/2021/04/looking-through-the-lens-at-how-food-can-improve-our-mood/
(6) Bda. (n.d.). Food and mood. Food and mood | British Dietetic Association (BDA). Retrieved April 7, 2022, from https://www.bda.uk.com/resource/food-facts-food-and-mood.html
(7) Soltani, H., Keim, N. L., & Laugero, K. D. (2019). Increasing dietary carbohydrate as part of a healthy whole food diet intervention dampens eight week changes in salivary cortisol and cortisol responsiveness. Nutrients, 11(11), 2563. https://doi.org/10.3390/nu11112563
(8) Vlahoyiannis, A., Giannaki, C. D., Sakkas, G. K., Aphamis, G., & Andreou, E. (2021). A systematic review, meta-analysis and meta-regression on the effects of carbohydrates on sleep. Nutrients, 13(4), 1283. https://doi.org/10.3390/nu13041283