I was interested to read this short review article, “A healthy gastrointestinal microbiome is dependent on dietary diversity”, by Mark L. Heiman and Frank L. Greenway, published in Molecular Metabolism as an open access article in March 2016. I immediately noticed that both authors disclose a potential conflict of
interest relative to their relationship to a company known as Microbiome Therapeutics, which is developing microbiome modulators as a class of therapeuticagents, and you should be aware of their disclosure, especially because their last sentence makes a reference to these substances as new avenues for drug discovery. However, the focus of this well referenced 2 page article is the effect of diet on microbiome diversity, and salient points about our industrialized food complex and our dietary patterns over the past 50 years are well made and worth your attention.
The authors note that during the past 50 years, the prevalence of obesity, type 2 diabetes, and inflammatory bowel diseases have sharply increased, while a shared finding for each condition seems to be a reduction of GI microbiome diversity. They add that the more diverse the diet is, the more diverse the microbiome will be, which makes the host more adaptable to perturbations. They explain that richness of microbiome diversity correlates well with health.
Adults have lower microbiome diversity than children. By adulthood, diets have been established, based on lifestyle, palate and unwillingness to explore new foods. Furthermore, our industrialized food complex has not only normalized highly processed foods, which of course can be causative factors in the development of these chronic conditions, but has dramatically reduced dietary diversity. In a nutshell, they tell us:
“Unfortunately, dietary diversity has been lost during the past 50 years because of economic pressures for greater food production to support a growing world population. This decreased agrobiodiversity, or the decline in rearing varied edible plant varieties and animal breeds, is occurring at an incredible rate. According to the Food and Agricultural Organization of the United Nations, 75 percent of plant genetic diversity has been lost, as farmers worldwide have left their multiple local varieties for genetically uniform, high-yielding varieties. Of the 250,000 to 300,000 known edible plant species, humans use only 150 to 200. Six livestock breeds are lost each month in favor of high production practices. Today, 75 percent of the world’s food is generated from only 12 plants and five animal species.”
Wow (I say that a lot, don’t I? But this work constantly fascinates me). We’ve learned so much over the past few decades about how our genes haven’t changed since we were hunter gatherers, but our environments have changed dramatically, and are responsible for the host of common conditions for which we treat our patients every day. The authors paint a very clear picture of how some of these environmental changes have occurred in such a short time. They also mention that the problem is heightened by the routine use of antibiotics, growth promotors and pesticides in our food supply. Taken one step further in context, it is also deeply troubling that our pollinators are at high risk of extinction, presumably from neonicotinoid pesticides, which could only reduce food diversity more.
Remember a couple of years ago when we talked about TMAO (trimethylamine-N-oxide) as an atherogenic microbial metabolic product that can be formed after ingesting carnitine or red meat? That story is still unfolding, but the authors explain here that dietary foods common to Mediterranean diets such as balsamic vinegar, red wine, cold-pressed extra virgin olive oil or grapeseed oil contain an inhibitor of TMA (TMAO’s precursor) production.
Jeff Bland, PhD, FACN, CNS, recently spoke at the Natural Supplements conference. He gave a great lecture about phytonutrients, reminding us that for all of the oxidative stress we experience as part of life, nature has really provided everything we need to keep ourselves healthy and in balance, including a natural abundance of antioxidants in the plants we are meant to be consuming. There are over 10,000 phytonutrients in our food supply, and by consuming a diversity of plant based foods within a balanced diet, we really can mitigate our risk of chronic disease.
Heiman and Greenway end by stating that weight loss therapy may begin with a specific dietary plan to broaden an individual’s microbiome as a prelude to obesity treatments to maintain a weight loss over a long period, as is the case for preadolescent children with obesity and obesity surgery. Furthermore, they state that short-term personalized dietary interventions based on a personalized GI microbiome, can improve postprandial glucose regulation in pre-diabetics and type two diabetes.
It is clear that the microbiome is a critical factor in health. And over and over, we go back to the basic truth that if we begin with diet, eating as we are ‘designed’ to eat, and if we tend to our planet as if a patient, there is hope for a healthier future.
Blessings on your journey,
Mimi Guarneri, MD, FACC, ABIHM