Does our Microbiome Affect our Mood?

Microbes are hot on the scientific agenda. In May, the US government launched a National Microbiome Initiative with an overall budget of half a billion dollars, while the EU is funding more than 300 projects related to the microbiome.  MyNewGut is the largest EU program, with 30 partners in 15 countries.  The director is Yolanda Sanz at the Spanish National Research Council in Valencia.  Much of this article is based on her perspectives.

“Our intestine hosts a complex ecosystem of bacteria; we call it the gut microbiota, which includes at least 1000 difference species. We get most of our gut microbes soon after birth, although there is evidence of colonization even during prenatal life.

Over the first 2-3 years of life, the microbiota is very unstable in its composition. This condition overlaps with a period in which the immune system is still immature. At this stage, the microbiota is greatly influenced by diet, for example whether you are breastfed or not.  When an adult diet takes over, the composition of the gut microbiota becomes more stable and a microbiotic profile emerges. This usually prevails until old age when the diet goes back to being less diverse and more unstable, such as in babies. In some way, the evolution of microbiota reflects our growth and senescence.”  My comment here – keep your diet diverse, in terms of vegetables, fruits, nuts and whole grains as you age.  If you are eating less, make every bite count.

“Each person has a different proportion of bacterial species and strains in his or her gut. If I had to put a figure on it, I would say that about a quarter of the microbiota is unique to each individual, but it's difficult to give a precise estimate. Also, we know that our genome influences our gut flora. We don't know how it works, but at least some features of our microbiota are associated with our DNA.

If you alter your diet dramatically, for instance by changing the proportion of fibres, proteins or fats, you will see relatively quick changes in your microbiota. About 30-40 percent of the bacterial strains will vary in their abundance. Drugs can also alter the microbiota. Recent studies point to antibiotics, of course, but also to proton pump inhibitors, anti-inflammatory drugs and other classes of medications that do not interact directly with bacteria.

There is growing evidence of a microbial gut-brain axis in which bacteria can influence the brain, and vice versa. We know that some strains of intestinal bacteria produce compounds that have an effect on the nervous system: neurotransmitters, for example, or metabolites that alter the blood-brain barrier (a barrier which filters the molecules passing from the body to the brain circulation). We don't yet know the precise mechanisms, but it's quite clear that the gut microbes can influence mood and the behavioural patterns. Most of the information comes from animal studies, but some data in humans are quite conclusive. People with primary depression, for example, show alterations in the microbiota. Transplanting the microbiota of depressed patients into mice can replicate the pathology in the animals.

There have been a few trials where patients with depression have been given probiotic treatments. The results are encouraging, but they are small studies, and there are many steps before we can say whether or not these interventions actually work.

To date, we found many correlations between the gut microbiota and pathologies: to move towards therapy we need to establish a causal relationship, and look closely at the mechanisms by which bacteria interact with the nervous system.”

While waiting for further data and advice from researchers, it’s a good idea to turn to a diet that helps the healthy bacteria in your gut, and see whether your mood can be affected positively.  Remember, your gut bacteria thrive on the fiber from vegetables and fruit, and a diet high in sugars and refined flour cause them to eat the mucus layer lining your intestinal tract, leading to a ‘leaky gut’ and inflammation.  Use your brain to help your gut – it can go both ways!

Researchers at the University of Melbourne published on Omega 3 fish oil in The American Journal of Psychiatry in 2016:  "The strongest finding from our review was that Omega 3 fish oil -- in combination with antidepressants -- had a statistically significant effect over a placebo. Many studies have shown Omega 3s are very good for general brain health and improving mood, but this is the first analysis of studies that looks at using them in combination with antidepressant medication. The difference for patients taking both antidepressants and Omega 3, compared to a placebo, was highly significant. This is an exciting finding because here we have a safe, evidence-based approach that could be considered a mainstream treatment."

Sadja Greenwood, MD, MPH 

Happy New Year, 2017 

Quoting Ananda’s song: May you never, never, never be blue

I know – the country is in for hard times.  Stay strong and resist. s

The Microbiome in Your Gut & The 12 hour Fast

 Here are some take-home messages for human health from the recent Commonweal symposium on the microbiome – the trillions of bacteria, viruses and fungi that live on and in our bodies.

*the good ones can be our friends – they want us to survive (from an

evolutionary standpoint) so they can survive.  We can work with them.  We want them to outnumber the bad bacteria that promote disease.

*good microbes in our guts eat fiber – from vegetables and fruits.  If we don’t give them plenty of fiber, they start eating the mucus lining of our intestines.  This promotes a ‘leaky gut’, allowing bacteria to enter our bloodstream.  This promotes inflammation and human disease. Eat plenty of fiber – meaning vegetables and fruits.  They have many other benefits in terms of vitamins and related nutrients. Avoid refined flours and sugars, which lack fiber and promote obesity.

*Good bacteria are found in probiotic foods, especially fermented foods, such as yogurt, kefir, kimchi, sauerkraut, miso, and also in probiotic supplements.  Have a probiotic food daily, including when you take antibiotics. Take a probiotic supplement if you don't eat these foods daily.

*Vegetables and fruits grown organically in healthy soil will be good for the earth and for you – you will benefit from their good bacteria.

More on the 12 Hour fast

Researchers from UC San Diego and the Salk Institute have done extensive work with mice  - showing that restricting food intake to an 8 to 12 hour time is beneficial.  Mice fed ad lib throughout 24 hours become obese and diabetic, whereas mice eating the same calories in an 8 to 12 hour window stay at normal weight and do not develop diabetes.

These researchers have not yet done human studies, as funding is scarce.  However, many previous studies done in mice been shown to be helpful in humans, as we share a similar metabolism.  Here is a quote from the Salk Institute – “The daily feeding-fasting cycle activates liver enzymes that breakdown cholesterol into bile acids, spurring the metabolism of brown fat -- a type of "good fat" in our body that converts extra calories to heat. Thus the body literally burns fat during fasting. The liver also shuts down glucose production for several hours, which helps lower blood glucose. The extra glucose that would have ended up in the blood -- high blood sugar is a hallmark of diabetes -- is instead used to build molecules that repair damaged cells and make new DNA. This helps prevent chronic inflammation, which has been implicated in the development of a number of diseases, including heart disease, cancer, stroke and Alzheimer's. Under the time-restricted feeding schedule studied by Panda's lab, such low-grade inflammation was also reduced.”

It’s easy and beneficial to do a 12 hour fast.  (It’s safe for most people – consult your doctor if you are taking meds for diabetes, have type 1 diabetes, or any other questions.)  Eat enough healthy food during the day, and see if it works for you.

Sadja Greenwood, MD, MPH  back issues on this blog.  Leave me a message, and I'll answer you.