Most people know that what we eat can have an impact on our physical health. But did you know it can also impact your mental health? Nutritional psychiatry is a relatively new field of research that explores this connection.

Some studies show that individuals who follow a Mediterranean diet are at lower risk of developing depression. The Mediterranean diet includes a wide variety of vegetables, fruit, whole grains, beans, nuts and seeds, fish and extra-virgin olive oil; followers eat chicken, eggs and dairy in moderation, and limit red meat to two small servings per week or less.

In 2017 a research group in Australia recruited individuals who had been diagnosed with depression and enrolled them in a randomized, controlled trial (a well-designed study) to see if switching to this diet would improve their depression. The researchers assigned participants to follow a modified Mediterranean diet for 12 weeks or to attend a social support group for 12 weeks.

At the end of the 12 weeks, 32% of people in the diet group recovered from their depression compared to 8% in the social support group. One surprising finding was that the people who changed to a Mediterranean diet also spent less money on groceries compared to the people who did not change their diet.

Since 2017, two more randomized, controlled studies have shown similar results: adopting a Mediterranean diet can improve symptoms of depression. Likewise, approximately 30% of the patients who participated in the Food as Medicine program at the Mood Disorders Association of BC reported a clinically significant reduction in symptoms of depression after just eight weeks of making meaningful changes to their diet.

One of the mechanisms by which a Mediterranean diet may help depression is by reducing inflammation. Unfortunately, chronic inflammation has become common in our society. Most of us are familiar with acute inflammation, when your immune system gets activated in response to an injury or virus. Inflammatory compounds are released and you may notice pain, redness, fever or fatigue as a result. Inflammation resolves once the virus has been eliminated or the injury has healed.

Chronic inflammation is different. Our immune cells release compounds that continue to circulate in the body, which can cause damage over time. Chronic inflammation can contribute to a wide range of diseases, including depression.

In contrast to the Mediterranean diet, dietary patterns that have a lot of processed food, fast food, sugar and saturated fats can lead to chronic inflammation and have a negative impact on many aspects of our health, including brain health.

The good news is that you can fight inflammation—and, thereby, depression—by following an anti- inflammatory diet. The Mediterranean diet is one example of an anti-inflammatory diet, which can be applied to many cooking styles and cuisines. It is nutrient dense and rich in plant-based foods. Some basic aspects of the diet include:
• eating a wide variety of vegetables and fruit daily, including every colour from the rainbow
• choosing less processed carbohydrates (i.e., beans or whole grains, like brown rice, barley, quinoa or steel cut oats; whole grain bread; winter squash and root vegetables)
• eating fish rich in omega-3 fatty acids (i.e., salmon, sardines, mackerel, herring)
• using extra-virgin olive oil rather than vegetable oils and butter
• including one handful of raw, unsalted nuts or seeds daily (walnuts, almonds, flax, chia or hemp are preferred)
• limiting red meat; eating chicken, eggs and low-fat dairy in moderation
Another important aspect of our dietary choices is the impact they have on the bacteria that live in our gut; these make up what’s called the microbiome. By increasing plant-based foods we increase the amount of fibre in our diet. Many of the “good” bacteria feed on fibre and create compounds that contribute to our health and reduce inflammation. By eating high-fibre foods, such as in the Mediterranean diet, we are feeding these good bacteria. Eating fermented foods like yogurt, kefir (milk fermented with a specific strain of bacteria) or kimchi (Korean salted and fermented vegetables) also contributes to a healthy microbiome.

Research has also focused on specific nutrients in the diet that can help improve depression and identified 12 key nutrients that play a role in preventing and treating depression, and the foods that have the highest density of these nutrients. These foods include:
• seafood and bivalves (mollusks with two-halved shells), such as oysters, clams and mussels
• organ meats (liver, heart, kidney) and poultry giblets
• leafy greens (watercress; spinach; mustard, turnip or beet greens; lettuces; chard; cilantro; basil; parsley; chicory greens; kale or collards; dandelion greens)
• cruciferous vegetables (cauliflower, kohlrabi, red cabbage, broccoli, Brussel sprouts)
• peppers (bell, serrano, jalapeño)
Steps toward a depression-fighting diet

Changing your diet can feel overwhelming—you’ve heard it all before. Yet, making just a few changes can make a huge difference to how you feel. Here are some tips for how to start.
• Add leafy greens to your diet. These can be added to almost any meal—a sandwich, stir-fry, soup, stew or salad. An easy way to get leafy greens is to make a green smoothie for breakfast; you can use fresh or frozen spinach or kale, along with fruit and yogurt or protein powder.
• Snack on vegetables and fruit. Try carrots, celery, cucumber or red peppers with hummus or fresh fruit with nut butter or a handful of nuts.
• Include vegetables with your meals. Frozen vegetables (and fruit) are just as good as fresh.
• Add beans and whole grains to your diet. Breakfast ideas include rolled or steel-cut oats soaked in yogurt or nut milk with berries, or cooked with apples and cinnamon; avocado toast with beans on whole grain bread. Try grain bowls (i.e., brown rice or quinoa) loaded with veggies, or grain and bean salads.
• Eat fish or seafood 2–3 times a week. Remember, canned or frozen are as good as fresh.
• Drink water or other unsweetened drinks. Try carbonated water instead of pop. Add lemon, lime or other flavours to make it interesting.

There are many factors that lead to depression, and not every depression is the same. Many people report better energy, mood and brain fog after switching to a nutrient-dense, anti-inflammatory diet. The key to success is making one change at a time and finding new foods and recipes that you enjoy and look forward to eating.