This large and well designed clinical study performed in men confirms results previously reported from surveys in women by showing that people who identify themselves as vegetarians or vegans are more likely to be depressed. Previous studies had shown that such an increased risk also applies to anxiety disorders.
Like all published studies, the current report doesn’t address the question of causation: Are individuals with increased depression or anxiety more likely to chose a vegetarian diet, or do the nutritional deficiencies associated with a strict vegetarian diet increase the risk to develop mental disorders. Not knowing the scientific answer to this question, I personally favor the former hypothesis.
There is no question that largely plant based diets have significant and well documented health benefits for a wide range of disorders, including mental disorders (https://www.amazon.com/Mind-Gut-Connection-Conversation-Impacts-Choices/dp/0062376551/). However, such diets as the traditional Asian diets, the Mediterranean diet all have a component of meat consumption, even though it comes predominantly from fish and poultry sources.
Thus, if you chose the vegetarian diet exclusively for health reasons, and possibly environmental reasons, you may want to consider switching to one of the predominantly plant based diet with a small component of fish and possibly poultry. if you made the decision primarily based on ethical consideration, you should pay close attention to supplement your diet with essential nutrients.
Even though they represent different races, live in very different parts of the world with different climates and plants, the few remaining hunter gatherer tribes in the world – including the Hazdas in Tanzania, the Yanomamis in Venezuela and the Asmat people in Irian Jaya – they have one important thing in common: their gut microbiomes are the most diverse and abundant ecosystems of any humans in the world, and they have this uniquely diverse microbiome from infancy on.
In contrast to these last descendants of our ancestors, we Westerners have a 40% reduction in the diversity of our gut microbiome, presumably a consequence of several changes associated with our modern lifestyles: excessive hygiene, excessive use of antibiotics and dramatic dietary changes, in particular the change from a largely plant based diet with high fiber content to our high sugar, high fat and high animal product diet. We only have to look at the average fiber consumption of about 15g per day and compare it with the 100 g of fiber the hunter gatherers consume! There is reason to worry that these changes in our gut microbiome play an important role in the rise of many chronic Western diseases, including obesity, type II diabetes, autoimmune diseases, allergies and even different types of cancer.
The recent study by Justin Sonnenburg’s team in Stanford published in Science now shows that the Hazda’s microbiome significantly changes depending on the season: While it looks very similar to our own microbiome during the dry season, when the Hazda’s consume primarily animal based foods, their their gut microbial profile returns to their original diversity when the rainy season returns, and they switch to a predominantly plant based dietary regimen.
Here is the most important question: is our own loss of diversity reversible (with the benefit on our health) if we reverse to a plant based diet, or is the loss of diversity irreversible? The answer to this question will have fundamental consequences for our food choices and for our health.
Read full article from npr.org: www.npr.org/sections/goatsandsoda/2017/08/24/545631521/is-the-secret-to-a-healthier-microbiome-hidden-in-the-hadza-diet
Photo credit: Matthieu Paley/National Geographic
There is an impressive assembly of the leading microbiome scientists attending the conference “The Human Microbiome: Emerging Themes at the Horizon of the 21st Century” which has been going on at the Natcher Conference Center on the National Institutes of Health (NIH) campus.
The presentations about the latest analytical and computational techniques makes it clear that we are only at the very beginning to sort out the complex interactions between bacteria, viruses and fungi living in our gut, and how they interact with our body. The field will have to move from studying associations between gut microbial composition and disease to identifying the causal role of microbes and their metabolites in influencing the host in health and disease.
One important topic of the conference was the role of food in influencing the gut microbiome. As pointed out by J. Lampe, food is a complex mixture of up to 1000 compounds, many of which are influencing gut microbial populations in our gut. J. Sonnenburg presented data showing the decreased abundance of microbial abundance and diversity in Western countries, compared to individuals living in different tribal societies, including the Hazda. One of the major factors in this difference is the amount of plant derived fibers these societies consume. Such diets are high in complex carbohydrates resulting in an abundance of mucus stimulating microbial species. The greater thickness and quality of the mucus layer, separating the gut microbes from our immune system prevents the low grade immune activation which has been implicated in many chronic Western diseases, including inflammatory bowel disease, metabolic syndrome and even degenerative brain disorders. One more reason to eat a predominantly plant based diet!
People love the concept of “detox” and a lot of different strategies such as juicing and fasting, and “cleansing” have been proposed to achieve this goal. Even though the concept goes back thousands of years, most are based on unsubstantiated pseudoscientific concepts that “cleansing” your digestive tract has health benefits over and beyond a general feeling of wellbeing. For example, converting fruits and vegetables into tasty juices deprives your gut microbes of their natural food (undigestible fibers) and results in rapid sugar absorption and subsequent insulin spikes. On the other hand, short term intermittent fasting has little to do with “detox” but may improve your gut microbial composition in a way that is good for your health.
However, the term detoxification borrowed from the substance abuse field is quite appropriate for the treatment of the clinical syndrome “food addiction”. The prevalence and underlying biological mechanisms of this syndrome are well documented in numerous scientific studies. Genetically predisposed individuals can develop such uncontrolled eating behavior when exposed to unlimited amounts of salt, sugar, or fat. Such hedonic eating behavior is associated with a remodeling of the brain-gut-microbiome axis, including a disinhibition of brain reward system, similar to the brain changes in individuals with substance abuse. As pointed out in Michael Moss’s excellent book Salt, Sugar, Fat, marketing experts in some major US food companies are well aware of this target population and have designed their products (high in sugar, fat and salt) to get young people “hooked” on their brands. Not all food companies are to blame, however, and some have undertaken unprecedented efforts to reverse this trend.
The recommendations detailed in Brooke Alpert’s book are a practical, short term approach to detox kids with sugar addiction, but are no substitute for a fundamental switch to a healthy
Mediterranean style diet, high in plant based foods, and with minimal sugar and animal fat, regular exercise, and regular stress management.
I was invited to speak at the Annual Meeting of the American Psychiatric Association (APA) recently in a debate addressing the question: Can Gut Microbiota Affect Mental Illness? The event was organized by Erika Nurmi, MD from the Semel Institute at UCLA and had a prestigious panel of discussants including James McCracken, MD (UCLA), Chadi Calarge, MD (Baylor) and Michele Pato, MD (Suny Downstate). The debate attracted an audience of some 700 attendees, reflecting the considerable interest of the topic to psychiatrists. I emphasized the growing evidence from human studies supporting a role of the gut microbiome in mental health, in particular in depression, as well as the growing evidence for a role of a healthy, “non-inflammatory” diet as an adjuvant therapy. However, I cautioned about the premature acceptance of pro- and prebiotics as effective therapies for depression (“psychobiotics”) and of stool testing for dysbiosis in the clinic.
Also, at the end of the session I was interviewed by David Careon and Jessi Gold from Stanford for the podcast Psyched.