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Joanne Pizzino, MD, MPH is board-certified in Preventive Medicine, and Diplomate-certified in Integrative Medicine. Dr. Pizzino is part of the Parsley Health team (https:// Feel free to refer your friends and family. She is licensed to treat patients in 17 states. To see videos about Functional Medicine and brain function, type “Whole Health Solutions Cary” into your YouTube search engine

Can Food Affect Your Mood and Memory?

By Joanne Pizzino, MD, MPH
Medical Editor of Health&Healing

Dr. Pizzino

Evidence continues to grow about a two-way relationship between the gut and the brain, called the gut-brain axis. Of course, we understand that the brain has direct control over digestive organs via a very long wandering nerve called the vagus nerve. This direct outgrowth of the brain also controls, heart rate, blood pressure, and other aspects of the parasympathetic nervous system (PNS). As opposed to the “fight-or-flight” sympathetic nervous system (SNS), the PNS is all about “rest-digest-and-repair.” And, we now know that the digestive tract has even more nerve fibers going from your gut to your brain than from the top down. This puts food squarely in this feedback loop that affects neurotransmitters such as serotonin, as well as immune system and hormonal effects on thinking and mood.

There are five ways that what you eat determines how well you can use your brain:

Blood Glucose Levels. When most people first think about food and the brain, they may jump to the idea that food sensitivities are the culprit. We will talk about that more as we discuss immune effects of the gut on the brain, but even more important to the foundation of controlling conditions such as anxiety, depression, concentration issues, and poor memory is the role of blood glucose. Foods that turn into glucose (sugar) in the body quickly are called high glycemic index foods. This includes sweet things such as donuts and pineapple, but also starchy foods, such as bread, pasta, chips, rice, root veggies, etc.

With 60 percent of calories in the SAD (Standard American Diet) coming from only three high glycemic index foods—wheat, corn, and potatoes—most of us are eating way more sugar-forming foods than we may suspect. This is essentially flooding the engine with too much fuel. The brain, like Goldilocks, is very sensitive to blood glucose levels; it needs not-too-much, not-too-little, but just the right amount to work well. We know about getting “hangry” from too-low blood glucose, like running out of gasoline, but what about when you fall asleep after a big lunch? This is the engine flooding. This high-carb way of eating often causes us to rapidly swing from low to high and back to low all day long. It even interrupts sleep. Choosing a diet that is more balanced with higher fiber, more whole vegetables, lean proteins, and plant-based fats helps the brain achieve a more balanced fuel level all day, greatly aiding its ability to produce neurotransmitters, store memories, and help us control the hormones related to stress management to reduce anxiety, etc.

Nutrient Assimilation. Of course, the gut is all about processing our food to extract all the building blocks we need. But, even if you are eating perfect, organic locally grown food, if you are not able to break this down to assimilate the needed nutrients, it won’t do you any good. Many people lack the correct acids and enzymes to break down food, especially as we age. And this assumes that they are eating the highest nutrition food sources to begin with. And what if you have “leaky gut”? This is a condition that compromises the ability of the gut lining to determine what comes into the blood stream and what stays out. We now have ways to measure and treat leaky gut, which is often the real source of food sensitivities.

Immune Control of the Brain. Two-thirds of the immune system is located in the gut, therefore, what goes on with the very large number of critters (bacteria, protozoa, yeasts, viruses, parasites, etc.) who live there makes a huge difference to everything from brain inflammation to hormone metabolism to whether you are more susceptible to the latest strain of pandemic virus.

Do you suffer from “brain fog”? This is often the result of a “brain on fire,” whether inflamed directly by a pathogen, or as the result of waste products created in the immune system’s attempt to fight the invader. Changes in the balance of flora, known as the microbiome, determine how you react to various foods, whether leaky gut happens, even how much weight you gain or lose. I find detailed stool testing to assess all these digestive factors invaluable when assisting patients with any brain-related conditions, including mood disorders, Alzheimer’s dementia, MS, ADD, etc. This testing is useful whether or not you have any digestive issues along with thinking/mood disorders. Avoiding inflamogens such as gluten, dairy and refined sugar is vital to preserving the brain’s immune system.

Production of Neurotransmitters. Did you know that the gut makes more serotonin, our “contentment chemical”, than the brain? In fact, 90 percent of serotonin is produced in the gut where it contributes to things such as peristalsis, that is the actual movement of the intestines. The microbiome also controls which brain receptors react to GABA, another neurotransmitter related to calmness and ability to sleep. Specific foods (think avocados and chocolate!) and herbs (chamomile or valerian) can help us balance these neurotransmitters. Specific vitamin co-factors such as B6, magnesium, and zinc are crucial to making these neurotransmitters. Having your nutrient levels checked can give us information on the foundations of what you specifically lack, which may be necessary to turn on your brain function.

Toxin Elimination. While we often think of taking things in through the gut, we often forget that it is also our largest elimination pathway. If we think of our classic “intoxication” with alcohol, we can see why the brain is very sensitive to toxins. And if our main elimination route is not functioning, going either too fast or too slow, toxins can build up, causing significant effects on the brain. It has recently been shown that the autoimmune disease called ulcerative colitis hastens the onset of Alzheimer’s dementia. If leaky gut is involved, this can allow waste products to circulate up to the nervous system, and literally “intoxicate” us. Many of the colored components of food are actually powerful phytochemical detoxifiers. This is the place to start while you work with a skilled Functional Medicine physician to identify the best detoxification process for your particular needs.

Feeding the brain to address all these factors is not complex. Start with eating more whole, less-processed foods, with at least five servings of fruits and veggies daily for those colorful phytonutrients. Minimize high carbs, particularly cutting back on gluten, which has known toxic effects on the brain. Use specialized testing to determine how to improve the communication bandwidth between your gut and your brain to put yourself back in control of mood and memory.