Tuesday, June 20, 2017

The Microbiome and Your Health - a few examples

Understanding how our microbiome impacts our health is one of the biggest advances in staying healthy in the last several decades. 

In a prior post, I promised examples to illustrate the significance of the connection between microbiome and overall health.  Those described below suggest that we can begin to use rational nutritional choices to modify the microbiome and provide new approaches to both avoid and treat chronic diseases. 

Weight Management - It looks as if our microbiome is involved in the current obesity epidemic by modifying how efficiently we use our daily calories, and may also help explain why some of us can eat anything we want and not gain weight. 

In one study bacteria from the large intestine (colon) of two twins, one lean and one overweight, were injected into the colon of genetically identical mice that had been raised in a germ free environment. They were then placed on an identical diet and after just two weeks the mouse that received bacteria from the heavier twin had 17% more body fat. It appears that the microbiome from an overweight person can signal the body to change how our cells use sugar for energy and store the rest as fat. 

 Have you changed to diet soda to lose a few pounds?  Studies in mice compared artificial sweeteners (aspartame, sucralose or saccharin ) and natural sugars ( glucose and sucrose). The mice given the artificial sweeteners experienced a documented change in the bacterial composition of their microbiome, and that change caused them to extract more energy from their food as well as storing more of that energy as fat. The result was the paradoxical effect of taking in fewer daily calories but not losing weight. 

Diabetes - Along with obesity, we are experiencing a diabetes epidemic in this country. The microbiome may be playing a role here as well. Mice given artificial sweeteners developed glucose intolerance (an abnormal glucose metabolism often referred to as pre-diabetes) compared to mice given the natural sugar glucose. When their feces were transplanted into germ free mice, these mice also developed glucose intolerance. Treating the newly prediabetic mice with antibiotics eliminated the glucose intolerance as the microbiome was altered. 

This experiment was duplicated in human subjects. Seven healthy volunteers were given artificial sweeteners for a week and four of them also developed glucose intolerance which, just as in the mouse model, could be transmitted to germ free mice with a fecal transplant. 

Not only is it possible that the microbiome is linked to the diabetes epidemic, it also offers us the possibility of a novel dietary treatment option. In a study of large populations, it was noticed that those that ate beans regularly had a lower incidence of diabetes. On further investigation it was found that the poorly absorbed carbohydrates in legumes are metabolized by colon bacteria into proprionate, a molecule which slowed stomach emptying and the rate at which dietary sugar is absorbed. Proprionate, given as a  rectal suppository, produced the same effect. 

But eating a half cup of beans a day and letting your colon bacteria do the work is more acceptable to most people. 

Heart Disease - Bacteria in the colon modify a protein in red meat (L-carnitine) into trimethylamine oxide (TMAO) which rapidly accelerates atherosclerosis in mice. TMAO can be measured in the blood, and the more red meat one eats per meal, the higher the TMAO blood levels. Thus it may be TMAO, not cholesterol or fat, that is the smoking gun that explains the association (in large groups) of a high red meat diet with a higher rate of heart disease. 

Interestingly TMAO is also formed from the metabolism of the amino acid choline. Choline is found in significant amounts in eggs and thus TMAO, not cholesterol, may also explain the link between egg consumption and heart disease. 

What can you do to maintain a healthy microbiome? 

  • Avoiding unnecessary antibiotics for “possible” infections is important. 
  • It is harder to avoid second hand exposure to the antibiotics in meat from animals raised on antibiotics as a growth strategy (yes, via their effect on the animals microbiome). 
  • Most experts agree that increasing fiber in our diet is the most important, and relatively easy, step we can take. 
  • Your regular diet has such a pronounced effect on your microbiome that there is little impact from adding daily probiotics. 

My suggestions: 

  • Eat an extra serving of vegetables with dinner. 
  • Decrease the amount of red meat in your diet (try to incorporate a meatless dinner once a week) 
  • Add beans to your diet as often as seems reasonable for your personal tastes Take your daily flax meal. 

Each of these will add their little bit to keeping your microbiome diverse and healthy.

Friday, June 2, 2017

The Microbome and Your Health

What we eat has a big impact on how healthy we will be.

It is generally assumed that it is the breakdown products of digestion (fats, sugars, and proteins) that are absorbed provide the energy for our cells and the raw materials for repair of injured tissues. But we are now finding that some of what we eat makes it to the colon where it is modified by bacteria before being absorbed. And those products of bacterial metabolism are also a key part of keeping us healthy.

Microbiome--a word most of us could not have defined 10 years ago--is now encountered daily on television, in newspaper articles and in advertisements for probiotic containing yogurts.

So, what is this mysterious microbiome? It is the collection of organisms (really an interactive community) that live on and in our bodies and includes all the bacteria, viruses and fungi that live on our skin, in our nose, our mouths and in our digestive tract. It is a diverse community calculated to consist of more than 10,000 unique microbial species.

Investigation of the microbiome has made huge strides using the same genetic techniques that have sequenced the human genome. PCR (polymerase chain reaction) is a tool that can rapidly identify and catalogue the entire collection of organisms that is unique to each of us.

How big is the microbiome? It has been estimated that 9 out of 10 of the cells in our body are microbiome organisms while just 1 of 10 are truly “us,” the cells whose DNA we inherited directly from our parents. But because bacteria are small compared to human cells, these organisms comprise only 3 percent of a body's total weight (2 to 6 pounds in a 200-pound adult).

The types and numbers means that microbiome organisms vary from person to person, and can change quite quickly depending on our diet and any medications we might be prescribed.

One study on the effect of diet on the microbiome compared the bacterial balance in the large intestine (colon) in three discrete groups - one on a full vegetarian diet, another on an unlimited animal product diet, and a third group that ate meat just once a week. The colon bacteria ratio in all three groups remained stable over time with the ratio of bacteria in the “meat once a week” group intermediate between the two extremes.

A recent study demonstrated how quickly a change can happen. Researchers looked at two groups: 1) Those on a plant-based diet rich in grains, beans, fruits and vegetables and 2) A second group on an animal-based diet of meats, eggs and cheeses.

Researchers again found a stable (and similar) bacterial population in each group, but in addition demonstrated that when a traditional vegetarian was changed to an animal-based diet, the ratio of bacteria could in just four days.

The bacteria, fungi and viruses that make up our microbiome can impact our health in two ways.

First, this stable community of thousands of organisms can help prevent infection with disease causing bacteria. It is thought that the microbiome controls the real estate, so to speak, and thus “crowds out” undesirable bacteria. When you take antibiotics, this balance can be upset, a niche for new bacteria opens up the chances of developing a colon infection with a new bacteria (C. Difficile Colitis is one example) increases.

The treatment? A targeted antibiotic specific for C Difficile which allows the normal microbiome to reestablish itself. With sensitive genetic testing, the C Difficile can still be detected in small numbers in some patients, but they are now held in check by the “good” bacteria.

The moral to this story is that you want to minimize antibiotic (and other unneeded medication) use as much as possible.

A second--and until recently less appreciated--health benefit results from our body absorbing and then utilizing the products of microbiome metabolism.

The food we eat is never completely absorbed in the upper digestive tract, and fiber (which is not easily digested) as well as a small amount of the proteins, fats and carbohydrates make their way to the colon where they are used as nutrition by the colon bacteria. It is these final products of their energy metabolism that are absorbed by the colon.

These “leftover” molecules that are absorbed through our skin or lining of the digestive tract provide their health benefits via their influence our daily metabolism or by modifying the effectiveness of medications we might be taking.

I suspect you have heard the phrase “we are what we eat.” That would assume that our health and our diet are interrelated. But now we have learned that it is more complex than just the direct effects of proteins, sugars and fats that are used by our bodies for energy and healing. Our health is also impacted by molecules produced by our microbiome.

We will review a few specific examples of how the microbiome can impact our health in my next column.