Why Do Humans Continue to Eat Meat When It Is Not Good for Us

Why Do Humans Continue to Eat Meat When It Is Not Good for Us By Emeran A. Mayer, MD Personal and environmental health are closely interconnected. Increasing evidence suggests that diets inextricably links human health and environmental sustainability as recently described in great detail in the Eat-Lancet Commission report.1 The authors of the report state that “unhealthy diets are the largest global burden of disease and pose a greater risk to morbidity and mortality than does unsafe sex, alcohol, drug and tobacco combined.” The report goes on to propose a dramatic shift from the current lose-lose diets to worldwide acceptance of “win-win” diets which are both healthy and environmentally sustainable. What are these unhealthy lose-lose diets? The term is generally used to refer to the modern Western diet, a dietary pattern with high consumption of red meat (including beef, lamb and pork), ultra-processed foods and sugar, as well as low consumption of fruits, vegetables, legumes and fish, which are typically consumed by people who are overweight or obese, and who have growing rates of chronic metabolic diseases. So even if people claim to feel better, have less “brain fog”, lower rates of obesity and metabolic disease on diets predominantly based on animal products, such as the ketogenic diet, the environmental impact of such diets are shocking. To use a quote from a conversation I recently had with Dr. Walter Willett, Professor of Epidemiology and Nutrition and chairman of the Department of Nutrition at the Harvard School of Public Health, and the first author of the Eat Lancet Commission report:”… what kind of world population could our earth support if everyone adopted …. the animal based keto diet. And the response I got was about 200 million people, which means that about 7.2 billion people need to find another planet. If we can only support 200 million people with this almost completely animal source kind of diet, it's just not realistic for the world.” So why is it that so many Americans cling so desperately to their Western diet and their meat-eating habits despite a growing body of research that eating a lot of meat is not only bad for our bodies, but for the environment? One answer to this question has to do with the image that society, with the help of the advertisement industry, has attached to eating a meat based, protein rich diet as masculine, while eating a…

A Personal Experience from 2 Months of Time-Restricted Eating

A Personal Experience from 2 Months of Time-Restricted Eating By E. Dylan Mayer with Emeran Mayer, MD The Science You may have heard the terms intermittent fasting and time-restricted eating being used interchangeably; however, there is an important difference between the two. By definition, intermittent fasting is an energy restriction on 2-3 days per week, or alternate days, while time-restricted eating is compressing the daily period of food intake to 10 hours or less on most days of the week, without restricting calorie intake.1 Two studies , I came across from the Salk Institute for Biological Studies in La Jolla, CA reported several amazing effects of time-restricted feeding on metabolism, systemic inflammation and on the gut microbiome. In these animal studies, the time restriction was from 9-15 hours per day while the animals had unrestricted access to food the remainder of the 24 hours. In one study,2, 3 led by Amandine Chaix, the researchers showed that the effects of time restricted feeding were proportional to the fasting duration with few benefits being observed with less than 12 hours of fasting. However, the positive effects of the time restricted feeding paradigm included a protective effect against excessive body weight gain when the mice were put on a “Western” diet high in fat and sugar and remarkably this effect was seen without a change in 24-hour caloric intake. In other words, the mice could enjoy their high fat high sugar diet, as long as they consumed their unhealthy diet in a window of less than 12 hours a day. The investigators also found a reduction in whole body fat accumulation and associated inflammation, an improvement in glucose tolerance and a reduction in insulin resistance in the time restricted diet group. In a second study, led by Amir Zarrinpar, the group showed that the normal diurnal fluctuations in the gut microbiome were abolished when animals were put on a “Western” diet, high in fat and sugar, and that the rhythmic 24 hour oscillations were restored when these mice were put on a time restricted feeding schedule. Consistent with this healthy system behavior, these microbial oscillations were accompanied by a greater diversity of the gut microbes, and by changes in the relative abundance of microbes known to be involved in obesity. What is most remarkable about these experiments is the fact that they didn’t really involve any fasting, e.g. reduction in calorie intake, but…

Treating Chronic Gastrointestinal Symptoms with Digital Therapeutics

Treating Chronic Gastrointestinal Symptoms with Digital Therapeutics By E. Dylan Mayer and Emeran Mayer, MD Chronic disorders of the intestinal tract, such as inflammatory bowel diseases (IBD) and irritable bowel syndrome (IBS) are common, affect both children and adults, greatly impact patients’ quality of life and contribute significantly to the economic healthcare burden. About 1.6 million Americans suffer from IBD and the prevalence of these disorders has increased by 200,000 since 2011. Ten to fifteen percent of the US population meet the symptom criteria for IBS. Despite their different disease mechanisms, scientific and clinical evidence point towards alterations in the bidirectional interactions between the brain and the gut, and the important role of the brain in influencing symptom severity.1, 2 The great majority of patients are treated symptomatically with medications which do not always provide satisfactory symptom relief or are limited by side effects. It has been more than 7 years since our group published the results from a small clinical trial on the effectiveness of a psychoeducational treatment program for IBS patients which showed significant clinical benefits.3 A plan to move this treatment program to an online format did not materialize as not enough patients regularly used the internet at the time. A recent large clinical trial from Dr. Jeffrey Lackner’s group at the University of Buffalo show a persistent clinical benefit of a patient-centered cognitive behavior therapy (CBT) approach in IBS patients.4 And our two groups showed in a recent study that CBT not only improves symptoms in IBS, but that this clinical benefit is associated by changes in the brain and the gut microbiome, a finding that qualifies CBT as a biological therapy.5 Even though CBT has been shown to be one of the most effective treatments for IBS patients, the widespread application of CBT in gastrointestinal (GI) disorders is greatly limited by two major factors. Even though it is not a new treatment, there are still a very limited number of CBT therapists with expertise in GI disorders, in particular in non-metropolitan areas. The other issue is that when you do find someone, the duration and cost of traditional face to face CBT has prevented this therapy from being adopted widely. Welcome to 2020 and the age of digital therapeutics. Digital therapeutics or prescription digital therapeutics (PDTs) are clinically validated software treatments prescribed by a doctor and have the potential to greatly improve life outcomes for…

Are Probiotics Good for You?

Are Probiotics Good for You? By Emeran Mayer, MD A recently published report by the American Gastroenterological Association (AGA) on Clinical Practice Guidelines for the role of probiotics in the management of gastrointestinal disorders, based on an in depth Technical Review of the published literature concludes that probiotics have little if any evidence based value in treating digestive diseases (including irritable bowel syndrome [IBS] and inflammatory bowel diseases),1 a statement that is not surprising to somebody who has long followed the scientific debate about probiotics and who gets the question from nearly all of my patients which probiotic is best to take. The only disease populations that the report exempts from their negative assessment were children and adults on antibiotic treatment, preterm infants with low birthweight and patients with pouchitis, a postoperative complication in patients following a colectomy. According to the World Health Organization, “Probiotics are live microorganisms which when administered in an adequate dose confer a health benefit on the host.” This is an ambiguous definition, as it includes both the possible benefits of ingested microbes on gut and overall health in individuals without any specific gastrointestinal (GI) disorder (probably the majority of people who take probiotics), as well as the possible benefits in treating or preventing a specific disease (a small fraction of the overall market). Even though there are a number of clinical trials which have aimed to demonstrate an effect on GI disorders (most of which according to the report have not been conclusive, were of low quality or have been negative), there is a small number of studies which have shown that certain probiotics are effective in reducing common digestive symptoms such as rumbling and abdominal discomfort in otherwise healthy people.2 Unfortunately, for most probiotics such well designed and controlled studies do not exist. Even though I generally agree with the conclusions of the AGA guidelines, there are several important points to consider before we close the curtain on the benefits of probiotics: The same microbes may not be effective in everybody, and based on current knowledge, the effectiveness of a particular microbe is likely to depend on the unique composition and function of the gut microbiome of a particular individual. Until we are able to design custom cocktails of probiotic strains which match an individual’s microbiome, and evaluate the effectiveness in such selected populations it may be impossible to demonstrate significant benefits in clinical…

The Magic Weight Loss Diet Does Not Exist

The Magic Weight Loss Diet Does Not Exist By Juliette Frank and Emeran Mayer, MD Currently, one in three Americans of all ages – over 100 million people – are obese.1 As obesity rates hit peak levels, causing a major public health crisis, many Americans are looking to popular diet programs for a simple solution. There are countless diet recommendations for losing weight and reducing cardiovascular risk factors associated with being overweight such as heart disease, metabolic syndrome, high blood pressure, high cholesterol, and C reactive protein (inflammation in the body). Many popular diets have even been branded and named, promoting theirs to be the “magic key” for a healthy life and perfect body. The great majority of the promoted diets aim to either restrict or reduce the energy-providing macronutrients, e.g. fat, protein and carbohydrates without much consideration of the downstream effect of such diets on the gut’s microbial ecosystem. With one third of Americans dieting, there is high demand for evidence-based studies reporting which popular diet programs are most effective.2 In February of this year thee British Medical Journal (BMJ) released a study with 21 eligible trials with 21,942 patients comparing 14 of the most popular diet programs. Their network meta-analysis quantifies the comparative effectiveness of three dietary macronutrient patterns based on 14 popular diet programs for both weight loss and related cardiovascular risk factors at six and 12 months using the GRADE approach. The BMJ categorized each of the 14 popular diet programs into three dietary macronutrient patterns:3 Low Fat: approximately 60, Fat, % kcal = approximately 10-15, Fat, % kcal = <20 (Ornish, Rosemary Conley) Low Carbohydrate: Carbs, % kcal = <40, Fat, % kcal = approximately 30, Fat, % kcal = 30-55 (Atkins, South Beach, Zone) Moderate Macronutrients: Carbs, % kcal = approximately 55-60, Fat, % kcal = approx 15, Fat, % kcal = 21-<30 (Biggest Loser, DASH, Jenny Craig, Mediterranean, Portfolio, Slimming World, Weight Watchers, Volumetrics) The study measured the effectiveness of each dietary macronutrient pattern to a “usual diet” by comparing its effects on: change in body weight, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, systolic blood pressure, diastolic blood pressure, and C reactive protein at the six and 12 month follow-up. At the six month mark they found that low carbohydrate diets, compared to the normal diet, had median difference in weight loss of 4.63 kg or ~10 lbs, a…