Recently, Zinöcker and Lindseth7 looked at the western diet, the microbiome-host interaction, and its role in metabolic disease. They report that the gut environment (or microbiome) is changed by what we eat and is affected by the western diet that contains ultra-processed foods. The change that occurs leads to inflammation in the gut, and consequently symptoms of disorders. While we know that processed foods are poor nutritional substitutes for whole foods such as fruits and vegetables—the authors delve further into the impact that these food additives have on inflammation in the body and possibly contribute to diseases.
Many studies have outlined the connection between processed foods and obesity, diabetes and heart disease. This study looked at the additional possibility that food processing affects inflammatory processes in the body (and thereby diseases) via diet-microbiome-host interactions. The food industry has continually increased the number of food additives without testing their impact in the microbiome. The findings from this study suggest that reducing processed foods from our diets would help reduce the likelihood of diseases related to inflammation.
A study at the University of Michigan evaluated withdrawal symptoms that people experience when they stop eating processed foods.8 The study looked at data that food addiction (eg, eating highly processed foods) may trigger addictive like symptoms in some people, including withdrawal symptoms. The Highly Processed Food Withdrawal Scale (ProWS) was adapted from self-report measures of drug withdrawal symptoms. The researchers feel that this scale may be a psychometrically sound tool for future research investigating highly processed food withdrawal in humans. The data can inform us of how patients may experience withdrawal-like symptoms when they suddenly stop eating highly processed foods.
Prebiotics and probiotics
Some ways in which we can protect our microbiome balance is to include both prebiotic and probiotic foods in our diets. A prebiotic is a soluble fiber that helps feed the good organisms (probiotics) in our gut. Probiotics already live inside the large intestine. The more prebiotics that the probiotics have to eat, the more efficiently they will work. Examples of prebiotic foods include onions, leeks, asparagus, bananas, Jerusalem artichokes, chicory root, garlic, dandelion greens.
Probiotic foods that supply these bacteria include fermented foods such as sauerkraut, yogurt with active cultures, pickles, kefir, kimchi, kombucha, miso. Have your patients read labels carefully, try to avoid extra sugar/preservatives—pickles and yogurt may have added sugar or food coloring. Select plain yogurt or kefir—adding berries and cinnamon instead of sugar are healthier options.
A recent study suggests that eating a healthy balanced diet such as the Mediterranean diet and avoiding inflammation-producing foods may be protective against depression.4 The most compelling evidence was seen with the Mediterranean Diet, which focuses on eating whole grains, seafood and poultry at least twice a week; consuming beans, legumes, fresh fruit, and leafy greens (spinach, kale, arugula, romaine), nuts (almonds, walnuts), cruciferous vegetables (cauliflower, broccoli), healthy fats (olive and canola oil), and less red meat.
Helping our patients understand what they can do
Traditionally, doctors are not well equipped after medical school to discuss nutrition, and most patients do not seek nutritional advice from their doctors. However, given the link between the gut and brain it may be clinically useful for mental health clinicians to have a basic working knowledge of nutrition and tips to share with their patients.
• Eat whole foods and avoid packaged or processed foods
• Think of eating an orange rather than drinking orange juice to avoid added sugars
• Instead of a vegetable juice, consider increasing your daily servings of fruits and vegetables
• Include probiotic-rich foods such as yogurt (avoid fruit-based yogurt, which is high in unwanted sugars)
• Eat foods rich in fiber
• Replace sugary desserts with a serving of fresh fruit and dark chocolate
• Avoid processed and packaged foods that are high in food additives that disrupt the healthy bacteria in the gut
Dr Naidoo is Director of Nutritional and Lifestyle Psychiatry at the Massachusetts General Hospital (MGH) and Director of Nutritional Psychiatry, MGH Psychiatry Academy, Boston, MA. She is also a Professional Chef, Culinary Instructor, and has studied Nutritional Science.
Dr Naidoo reports no conflicts of interest concerning the subject matter of this article.
1. Sarris J, Logan AC, Akbaraly TN, et al. Nutritional medicine as mainstream in psychiatry. Lancet Psychiatry. 2015;2:271-274.
2. Marx W, Moseley G, Berk M, Jacka F. Nutritional psychiatry: the present state of the evidence. Proc Nutr Soc. 2017;76:427-436.
3. Jacka F, O’Neil A, Opie R, et al. A randomized controlled trial of dietary improvement for adults with major depression. BMC Med. 2017;15:23.
4. Lassale C, Batty GD, Baghdadli A, et al. Healthy dietary indices and risk of depression outcomes; a systematic review and meta-analysis of observational studies. Mol Psychiatry. September 26, 2018; E-pub ahead of print.
5. LaChance LR, Ramsey D. Antidepressant foods: an evidence-based nutrient rofiling system for depression. World J Psychiatry. 2018;8:97-104.
6. International Society for Nutritional Psychiatry Research. http://www.isnpr.org/. Accessed December 7, 2018.
7. Zinöcker MK, Lindseth IA. The Western diet-microbiome-host interaction and its role in metabolic disease. Nutrients. 2018;10:pii:E365.
8. Schulte EM, Smeal JK, Lewis J, Gearhardt AN. Development of the highly processed food withdrawal scale. Appetite. 2018;131:148-154.