We all know that what we put into our bodies can have a major impact on our physical health. But did you know that the food you eat can also affect your mental health and gut health?
Recent studies have shown that there is a strong connection between diet and depression and that changing your diet may help to treat depression. If you’re looking for additional ways to improve your mental health, check out these tips to nourish your brain!
Table of Contents
- How Depression Affects the Brain and Body
- What Are Polyphenols?
- Foods Higher in Polyphenols and Flavonoids
- 7 Easy Tips To Improve Mental Health and Gut Health
- Caution: The Research Still Needs Improvement
Depression is a significant problem that affects many people all over the world. An estimated 3% of the population or ~264 million people, are affected by it. The cause of depression is not fully known, but it is likely due to a combination of genetic and environmental factors. This blog article summarizes a new meta-analysis study that examines the available research to determine whether nutrition therapy can be used to treat depression (1).
How Depression Affects the Brain and Body
Depression changes the way the brain forms new connections (aka neuroplasticity), how things are organized, and causes problems with mood-regulating chemicals (neurotransmitters such as serotonin).
Inflammation and Depression
There is some evidence that suggests higher inflammation levels can influence different functions related to depression. Additionally, high levels of oxidative stress markers have been associated with increased levels of depression.
Gut Microbiome and Depression
The gut microbiome has been linked to depression. This may be due in part to a release of inflammatory cytokines and other metabolic products such as TNF-a and MCP (monocyte chemoattractant protein) by the microbiota (2). These molecules can travel throughout the body when intestinal permeability increases. When there are high levels of cytokines in the blood, it makes the blood-brain barrier more permeable, which allows rogue molecules from the gut to enter the brain and affect its function (anxiety, depressive symptoms, memory etc). It is not clear how TNF, cytokines, and the gut microbiome are related to the development of mental health disorders. This is an area that needs a lot more research!
For more gut health and nutrition tips, read my other blogs:
- Food Sensitivity Tests are B.S.
- 1 Way to Improve Gut Health You May Be Overlooking
- 12 Reasons Why Bloating is Normal
Cortisol and Depression
Depression is a condition that can lead to high levels of cortisol production.
Cortisol messes with the balance of other hormones in your body and makes it hard for you to deal with stress (that fight or flight system in your brain can get thrown off).
Another effect is a decrease in brain-derived neurotrophic factor (BDNF) levels. BDNF is essential for the growth, development, and maintenance of neurons (remember the term neuroplasticity?).
When cortisol levels increase, it can lead to a decrease in the production of ATP, which is what our cells need to produce energy. A lack of ATP production has been linked with depression. This can lead to a decrease in the number of new neurons being produced and an inability of the brain to form new connections and pathways.
How Does Nutrition Improve Symptoms of Depression?
I just explained how depression could increase inflammation, cortisol levels, and inflammatory metabolites from your gut, but how does that relate to treating depression with nutrition?
This could mean an anti-inflammatory diet may help lower oxidative stress levels in addition to reducing systemic inflammation, which leads us to lower levels of depressive symptoms! Studies have found that diets rich in vitamins, polyphenol compounds, and omega-3 fatty acids support these physiological pathways and functions.
The current review found some evidence that suggests whole diet and whole food interventions may help improve depression symptoms. When we eat foods with more polyphenols, they can help reduce symptoms of depression because these healthy compounds act as antioxidants. Polyphenols stop harmful chemicals from damaging cells and they reduce our risk for cancer or other chronic illnesses. Polyphenols and other antioxidants can even decrease inflammation in the body which is thought to be the root cause of many health problems!
What Are Polyphenols?
Polyphenols are a type of compound that exists naturally in some plant-based foods. Scientists have identified more than 8,000 types of polyphenols!
4 Main Groups of Polyphenols
- Phenolic acids
- Polyphenolic amides
- Other polyphenols
The research article only specified polyphenols & flavonoids for their positive impact on depression symptoms.
Foods Higher in Polyphenols and Flavonoids
Note that the amount and type of polyphenols in we eat depends on the type of food, where it is grown, how it was farmed, its ripeness, how it was transported, and how it was processed.
- Spices & Herbs
- The highest sources are cloves, star anise, Mexican oregano, thyme, rosemary, sage, basil, curry, ginger, cumin and turmeric.
- The highest sources are artichokes, red onions, spinach, broccoli, asparagus and potatoes.
- The highest sources are black currant, sweet cherry, plum, berries, prunes, black grapes, apples, peaches, apricots and citrus.
- Nuts & Seeds
- The highest sources are ground flaxseed, chestnut, hazelnut, pecan, almonds and walnuts.
- Such as roasted soybeans, edamame beans, tofu, tempeh, miso and natto.
- Capers, Olives & Olive Oil
- Green Tea & Coffee
- Beans & Legumes
- The highest sources are black beans and white beans.
- Whole Grains
- The highest sources are whole wheat, maize flour, whole rye and oats.
- Cocoa Powder & Dark Chocolate
What I love about these findings is that many traditional & cultural diets around the world include foods high in polyphenols such as:
- East Asian dishes with star anise, ginger, soy products, tea, and cruciferous vegetables like broccoli.
- Latin American diets with Mexican oregano, cumin, cocoa powder, red onions, limes, black beans, coffee, and maize.
- Indian dishes with high in star anise, ginger, turmeric, curry, cumin, beans & lentils, tea, and spinach.
- Mediterranean diets with dishes that include olives, thyme, basil, red onions, spinach, beans & lentils, and whole grains.
- Northern European diets traditionally use more thyme, basil, potatoes, onions, cloves, and sage.
You can get more polyphenols without sacrificing your favorite cultural foods or eating boring salads for the rest of your life!
7 Easy Tips To Improve Mental Health and Gut Health
1. Use Cocoa Powder For More Than Just Baking
2 tablespoons has ~372 mg of polyphenols.
- Add to your smoothie, overnight oats, Greek yogurt (it makes a great dip), dessert hummus, peanut butter, chili (trust me), and even a rub for meat!
- This is my favourite chili recipe that uses both cocoa powder and coffee.
2. Use Red Onions More Often
1 medium red onion has 235 mg of polyphenols whereas 1 medium yellow onion only has 74 mg.
- Try this recipe for Quick Pickled Onions to use as a topping for tacos, nachos, or burritos. They taste amazing with pork or fish tacos!
3. Get Familiar With Ground Flaxseed
2 tablespoons has 214 mg of polyphenols.
- Add to your smoothies, oatmeal, or yogurt!
4. Don’t Throw Away Your Citrus Peels!
Citrus peels contain more polyphenols than the fruit itself!
- Zest your citrus with a microplane and store in the freezer.
- You can use this in vinaigrettes, sauces, salsa, marinades, rubs & brines, mayo or aioli, baking, pasta, and you can even add it to smoothies (lemon strawberry smoothie, anyone?).
- If you don’t like hot drinks in the summer, start to make your own cold-brew or iced green tea at home!
5. Add More Green Tea to Your Life
I love to brew green tea & put it in an infuser jug in the summer. This way you can add more polyphenols with fruit such as berries and mint leaves or citrus slices (with the peel of course) and peaches.
6. Audit Your Spice Cabinet!
- Dried herbs may last for 1-2 years and ground spices have a shelf life of 2-3 years. So if you got your spices as a wedding present 5 years ago, they may not be as potent in flavour and polyphenols.
- Also, if you store your herbs & spices near or above the stove, they may go bad even quicker due to the repetitive exposure to heat.
7. Bonus Tip: Eat Artichoke Heads More Often
~1 cup has 260 mg, the highest of any vegetable.
- Make your own artichoke spinach dip at home or add it to a creamy pasta.
- Try this dip recipe made with Greek yogurt.
Caution: The Research Still Needs Improvement
The studies available on mental health and gut health are limited in terms of how long they lasted and how many people were studied. They are also inconsistent in their design. Despite this, all the studies showed a reduction in scores assessing depression symptoms. This suggests that more research is needed to figure out how long the benefits of whole food and whole diet interventions last and what mechanisms are involved.
Before we can say for sure that nutrition can help treat depression, we need more high-quality studies with a wider variety of people, better control of confounding variables (some factors that also affect depression include gender, race, physical activity, sleep, alcohol, and smoking), longer duration (at least 3 months long), and better control on assessing nutrition intake during the study (which is notoriously difficult in research). If we want to study depression accurately, we need to take these into account). We also need to be careful about which depression scales are used to measure the outcomes.
We also cannot neglect other important factors of the accessibility for many people to eat or prepare these foods on a regular basis. These factors could include low income, food insecurity, limited cooking or food preservation skills, limited time, geographic location such as living in a food desert or in Canada’s north, language barriers, and social isolation during mealtimes. For some people, it is not the lack of “willpower”. There are very real barriers from an environmental and societal level that can make these changes very difficult to achieve. It is important to remember that supporting our public services in Canada directly improves people’s ability to nourish themselves and their families.
The evidence is currently limited but it does appear that eating more plants and whole foods can reduce depression symptoms; however, I would caution anyone to interpret this article as a replacement for therapy or medication. At best, nutrition changes might be used as an adjunct treatment (in addition to meds & therapy) for those struggling with depressive disorders!
Polyphenols are a type of phytonutrient found in plant-based foods that have been linked to reducing symptoms of depression and may even be used as an adjunct treatment for depressive disorders. While more research is needed, it’s exciting to think about the potential these nutrients have to improve our mental health.
Get the Most Polyphenols in Your Diet With These 3 Steps
- First, use whole foods more often.
- Secondly, cook at home using spices or herbs whenever possible — not only will this help protect against inflammation but also increase flavor!
- Lastly don’t forget about eating many plants, volume & variety! Read more tips on how to get more plants here.
What’s your favourite way to get polyphenols? Mine is coffee! Let me know in the comments!
- O’Neill, S., Minehan, M., Knight-Agarwal, C. R., & Turner, M. (2022). Depression, Is It Treatable in Adults Utilising Dietary Interventions? A Systematic Review of Randomised Controlled Trials. Nutrients, 14(7), 1398. MDPI AG. Retrieved from https://dx.doi.org/10.3390/nu14071398
- Clapp, M., Aurora, N., Herrera, L., Bhatia, M., Wilen, E., & Wakefield, S. (2017). Gut microbiota’s effect on mental health: The gut-brain axis. Clinics and practice, 7(4), 987. https://doi.org/10.4081/cp.2017.987