An interesting study describing the development and testing of a molecule first identified in obese laboratory animals and humans, which appears to play a role in modulating the brain-gut axis in a way to prevent further weight gain. The scientists at the pharmaceutical company Amgen modified the molecule so it stays in the circulation longer and demonstrated in mice that it results in a decrease in the drive for high density foods, slowing of the emptying of the stomach, and significant weight loss.
Interestingly, the observed effects were similar to what is observed after so-called bariatric surgeries, which is currently the only effective, long lasting therapy for morbid obesity. In their studies, the investigator demonstrated effects of the molecule on brain regions involved in the processing of gut signals, such as the site in the brain where the vagus nerve ends. Should these initial findings observed in laboratory mice be confirmed in human studies, it would be a major step forward in the development of effective treatments for obesity.
But we must not forget that the human brain is a very different “animal” than the tiny mouse brain. The dopamine driven reward system that drives our food intake is an incredibly powerful system which might override any attempts to curb its appetite!
The NIH held a workshop on the topic “Sex as a Biological Variable” recently. Women make up half of the world’s population, but the great majority of medical research studies have been performed in males. It has erroneously been assumed that the results and recommendations from these male only studies equally apply to women.
In order to change this situation, the NIH’s Office of Research on Women’s Health over the past 2 decades has led the effort to change this situation and this workshop has been an excellent demonstration of the progress that has been made. Sex-related differences are now being revealed in every organ system, including the brain, from clinical studies all the way to individual cells. It is remarkable that even though men’s and women’s biology is so different at every level, both sexes are able to perform at the same level in society.
Do men and women achieve this remarkable accomplishment by employing different biological mechanisms?
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!