The field of Nutritional Psychiatry is relatively new, however there are observational data regarding the association between diet quality and mental health across countries, cultures and age groups – depression in particular.
Brain is the most active organ in human body, i.e. requires most energy in order to function properly. It is ”responsible” for the entire body: thoughts, movements, breathing and heartbeat, as well as senses- it works 24/7, even while you’re asleep. This means your brain requires a constant supply of energy. Energy comes from the foods you eat, and what’s in the food makes a lot of difference. Simply said, what you eat directly affects the structure and function of your brain and, ultimately, your mood.
Eating high-quality foods that contain lots of vitamins, minerals, and antioxidants nourishes the brain and protects it from oxidative stress, i.e. free radicals produced when the body uses oxygen, which can damage cells.
Your brain can be damaged if you take in anything other than high quality foods. If substances from poor quality food (such as processed or refined foods) get to the brain, it has little ability to get rid of them. Diets high in refined sugars are harmful to the brain. In addition to worsening your body’s regulation of insulin, they also promote inflammation and oxidative stress. Multiple studies have found a correlation between a diet high in refined sugars and impaired brain function — and even a worsening of symptoms of mood disorders, such as depression.
It can be easily explained: if your brain is deprived of good-quality nutrition, or if free radicals or damaging inflammatory cells are circulating within the brain’s enclosed space, further contributing to brain tissue injury, consequences are to be expected.
For many years, the medical field did not fully acknowledge the connection between mood and food. Today, fortunately, the growing field of nutritional psychiatry is finding there are many consequences and correlations between not only what you eat, how you feel, and how you ultimately behave, but also the kinds of bacteria that live in your gut.
How the food you consume affects how you feel
Serotonin is a neurotransmitter that helps regulate sleep and appetite, mediate moods, and prevent or alleviate pain. Since about 95% of serotonin is produced in gastrointestinal tract, and gastrointestinal tract is lined with a hundred million nerve cells, or neurons, it makes sense that the inner workings of the digestive system don’t just help you digest food, but also guide human emotions. The function of these neurons — and the production of neurotransmitters like serotonin — is highly influenced by the billions of “good” bacteria that make up your intestinal micro biome. These bacteria play an essential role in human’s health. They protect the lining of your intestines and ensure they provide a strong barrier against toxins and “bad” bacteria; they limit inflammation; they improve how well you absorb nutrients from your food; and they activate neural pathways that travel directly between the gut and the brain.
Studies have shown that when people take probiotics (supplements containing the good bacteria), their anxiety and stress levels are reduced, compared with people who did not take probiotics. Other studies have compared “traditional” diets, like the Mediterranean diet and the traditional Japanese diet, to a typical “Western” diet and have shown that the risk of depression is 25% to 35% lower in those who eat a traditional diet. Scientists account for this difference because these traditional diets tend to be high in vegetables, fruits, unprocessed grains, and fish and seafood, and to contain only modest amounts of lean meats and dairy. They are also void of processed and refined foods and sugars, which are so present in everyday “Western” diet. Many of these unprocessed foods are fermented, and therefore act as natural probiotics. Fermentation uses bacteria and yeast to convert sugar in food to carbon dioxide, alcohol, and lactic acid. It is used to protect food from spoiling and can add a pleasant taste and texture.
Good bacteria not only influence what your gut digests and absorbs, but that they also affect the degree of inflammation throughout your body.
What can you do?
Start paying attention to how eating different foods makes you feel — not just in the moment, but the next day. Try eating a “clean” diet for two to three weeks, i.e. cutting out all processed foods and sugar. Add fermented foods like kimchi, miso, sauerkraut, pickles, or kombucha. Try going dairy-free. Some people even feel that they feel better when their diets are grain-free. See how you feel. Then slowly introduce foods back into your diet, one by one, and see how you feel.
For more information on this topic, please see: Nutritional medicine as mainstream in psychiatry, Sarris J, et al. Lancet Psychiatry. 2015
(source: Harvard Health Publications, Eva Selhub MD)