So how can food affect mood? A number of ways. At the most basic, cellular level, food provides glucose, which is used as energy for all of your cells, from your skin to your blood to your bones. The brain cells use this energy to function happily and normally. No glucose means you can get tired and fatigued, which leads to angst, anger, and even anxiety. Your gut, which starts with the esophagus and ends with the colon, may send signals to the brain to ask for more food (hunger) or to stop eating (fullness). Because your gut has this direct connection to delivering energy and information, it has evolved to become quite sensitive to what you put in it.
In Chinese medicine, the balance of food that enters the gut is can have heating or cooling effect, a moistening or dampening effect, or more broadly, affect your yin and yang energies. The types of energies are split into five tastes: sweet, bitter, spicy, sour, and salty, which correspond to needs of a balanced Qi.
In Western science, the microflora of the gut has similar demands for balance. Microflora are the bacteria and other microbes that naturally live in your GI from the moment you are born. Recently, scientists are able to estimate that there are more bacteria that live in your body than your own cells with your own DNA. So, these guys are really the ones in charge. Depending on what you eat, whether it is a balance of the five tastes, dampness and dryness, or hot and cold, the digestion of the food itself provides a response back up to the brain. Serotonin, a neurotransmitter involved in mood, is increased with the use of antidepressant or other mood-elevating drugs known as selective serotonin re-uptake inhibitors (SSRIs). However, many of these drugs lead to stomach and digestion issues, such as nausea, constipation, irritable bowel syndrome (IBS), and others, as the gut releases 95% of the body’s serotonin. This unintentional side effect comes from the lack of understanding of how the mind is connected to the body—in this case the GI tract.
In a recent study at Vanderbilt University, chronic stomachaches through childhood indicate a later predisposition to anxiety and depression in adolescence into adulthood. The imbalance of the stomach and subsequent chronic pain is linked to anxiety and depression. Regardless of yin/yang balance, the chronic pain in the gut seems to be a precursor to more defined mental imbalances.
A remedy to microflora imbalances is supplementing your diet with probiotic bacteria. These can be found in pill form, or naturally in cultured yogurt and fermented foods. The most common supplementary bacteria is Lactobacillus acidophilus, commonly referred to as just lactobacillus or just acidophilus. A study on mice reveals that mice fed with L. rhamnosus demonstrated lower effects of stress and anxiety, which was measured by lower levels of corticosterone, a hormone related to stress and weight gain. The absence of bacteria led to increased stress in the mice. In another study, “daring” and more adventurous mice had their microflora swapped with shy and timid mice, changing each group of mice from daring to anxious and shy to bold. This provides evidence that what happens in your gut directly affects your psychological state. Conversely, altering your mood can help reduce inflammation in the gut, providing a feedback loop to better overall wellness.
Like in all things in life, what you eat and how you feel depend mostly on balance. Whether you need to relax more or eat more, what you put in your body needs to be in balance with your mental state.