As health-conscious consumers, we are constantly concerned about finding the healthiest foods in the market. We perform calorie counts of our meals and worry that we may not get enough protein, vitamins, calcium or other minerals. Millions of people with a syndrome called non-celiac gluten sensitivity spend a lot of their attention and money on gluten-free foods. A similar number of individuals suffering from symptoms of irritable bowel syndrome struggle to adhere to a diet called the Low FODMAP diet, which relieves their symptoms temporarily, yet is unhealthy and cannot be adhered to for long.
What many (not all!) of these individuals have in common is the fact that they are part of what has been called a National Eating Disorder. Just like the eating disorders anorexia nervosa and bulimia, anxiety is one of the major risk factors for this phenomenon. People are probably more worried about what they eat and shouldn’t eat today than at any other time in modern history. This anxiety often leads to the ritual of restricted diets and avoidance of certain food items, which come in ever new variations. Reflecting this situation are the labels on many processed foods, which seem to list more items that are NOT contained in a particular food (sugar free, gluten free, fat free, GMO free, etc.) than the healthy ingredients that should be in it (antioxidants, polyphenols, fiber). Furthermore, there are hundreds of dietary supplements, including different mixtures of probiotics, that promise wellness and miraculous improvement of all kinds of common symptoms.
Speaking with many of my patients, I have learned that sticking to some of these popular recommendations actually does make people feel better: less bloating, more energy, less brain fog, better concentration, better sleep, less worry about their food (at least temporarily). Interestingly, the same individuals still come to see me in my clinic for their persistent symptoms!
So here is the big question: do these symptom improvements have anything to with the postulated and heavily advertised beneficial effects on our digestive system, gut health, gut permeability, or gut microbes? Or, could there be some powerful underlying mechanism that most people either ignore or vehemently reject, like the powerful mechanisms of the mind called nocebo and placebo effects?
If you believe something will harm you, your brain will make predictions about a high likelihood of this harm to occur in the future. For example, if you are convinced that eating grains will make your headache and stomach symptoms worse, your mind will translate this belief into a prediction that these bad things will happen to you. On the other hand, if you believe something will be good for you, your brain will make a prediction about a high likelihood of you feeling better. In the first case, your worry and anxiety will go up, while in the second case, it will decrease or disappear, at least temporarily. These changes in your anxiety level are associated with corresponding changes in the activity of your gut and likely the behavior of your gut microbes.
When you eat something while stressed out about its likely bad effects, it will be processed by your digestive system in a different way than when you are relaxed. The stress may even make your gut more permeable or “leaky.” This chronic anxiety will, in many people, cause symptoms of indigestion, fullness, bloating, and brain fog. On the other hand, if someone puts you on a strict diet or makes you avoid certain food items with the assurance of you feeling better, your anxiety will go down. Adhering to any ritual has this beneficial effect on one’s anxiety level. Then, the signals that your reassured mind sends to the gut will indeed be good for your gut functioning, the wellbeing of your gut microbes, and yourself.
While these powerful mechanisms of the mind almost certainly contribute to our current eating disorder epidemic, the increasing prevalence of true food allergies and sensitivities are likely to play a role as well. The problem is that with our current diagnostic tools, we have not been able to find an objective and biological measure that underlies these non-allergic food sensitivities. One such mechanism could be through the systems within our brain that regulate our sensitivity to multiple sensory stimuli. Individuals with a generalized hypersensitivity are sometimes even overly sensitive to the tiniest dose of medication entering their system. And there is no reason to believe why such individuals may not be sensitive to a variety of food items that interact with nerve endings in the gut which then signal to the brain.
So if you do feel better, does it matter if it is due to some advertised effect on your gut health, or if it is due to the power of your mind, the placebo effect? As a physician who takes advantage of the powerful placebo effect all the time, my answer is no, it doesn’t make a difference. However, regarding the nocebo effect, my recommendation is: spend less time worrying about the food and harmful components, read less about the hidden dangers of our food and indulge in the evidence-based dietary recommendations of a balanced, largely plant based (e.g. high fiber), low fat, low sugar diet for optimal health and prevention of disease. By working closely together, your mind and gut will figure out the rest!