You are what you Eat

You are what you eat

I recently read of Professor Jeremy Nicholson's recent research which discovered that children with autism have a different chemical fingerprint in their urine. He notes that people with autism are also known to suffer from gastrointestinal disorders which can be explained by the different makeup of bacteria in their guts from non-autistic people. His fascinating research shows that it is possible to distinguish between autistic and non-autistic children by looking at the by-products of gut bacteria and the body's metabolic processes in the children's urine. Although the exact biological significance of gastrointestinal disorders in the development of autism is still unknown it set me thinking about my own health.

Professor Jeremy Nicholson, at Imperial college, explains that Autism is a condition that affects a person's social skills, so at first it might seem strange that there's a relationship between autism and what's happening in someone's gut. However, your metabolism and the makeup of your gut bacteria reflect all sorts of things, including your lifestyle and your genes. Autism affects many different parts of a person's system and our study shows that you can see how it disrupts their system by looking at their metabolism and their gut bacteria.

I was born with eczema and later developed hay fever and asthma. Like most of my contemporaries I was not breast fed, had a relatively poor standard diet - typical of the sixties, deficient in B vitamins/micro nutrients and containing no omega oils. During my teenage years I suffered from countless infections including pneumonia and pleurisy necessitating antibiotics. I, like many others, foolishly dieted to an excessive degree. I also walked to and from school cutting through fields where organo-phosphates were sprayed. I rarely felt well. Over the years I have had a lot of gut problems and reactions to various foods (both classical NHS diagnosed food allergies and intolerances) leaving me feeling below par much of the time. I am therefore particularly interested by this research and feel that it is potentially relevant for parents who have children on the spectrum or who themselves have gut problems.

Humans, like other animals, are born germ-free. However, once born, we are rapidly colonized with microbial cells .The number of bacteria living within the body of the average healthy adult human are estimated to outnumber human cells 10 to 1. The microbial biodiversity in the human intestine is believed to be upwards of 40,000 bacterial species which comprise the collective gastrointestinal micro biome.

Changes in these microbial communities are believed to be responsible for digestive disorders, skin diseases, gum disease and even obesity. Despite their vital importance in human health and disease, these communities residing within us remain largely unstudied and may account for many people who suffer a general malaise but who appear healthy by conventional tests. This could be the basis of a whole new way of looking at disease. There is clearly a need to increase our understanding of the relationships between humans and our microbiota so that we can learn the risks and benefits of modifying its composition, either deliberately or inadvertently through lifestyle changes. Diverse conditions such as antibiotic-associated diarrhoea, Crohn's disease, ulcerative colitis, obesity, and pouchitis have been correlated with large-scale imbalances in gastrointestinal microbiota, or 'dysbiosis'.

The collective genome (microbiome) of our microbial partners complements and enhances our own genome. We heavily depend on our microbial partners for essential services such harvesting energy from food and its detoxification, supplying vitamins, and protection against harmful invaders of our body surfaces. Although the human genome has been sequenced, characterization of the microbiome is just beginning and I find this extremely exciting.

Researchers, such as Daniel Frank of the University of Colorado, have long suspected and researched the role of beneficial microbial communities within humans. These communities are known collectively as the human micro biome. They play a role in our health and diseases but only recently has molecular technology reached the point where they can truly begin to identify and characterize all the species that make up an individual's microbiome.

Martin Blaser of New York University has been working to identify the numerous bacteria that live on the human skin helping to form a protective barrier on the outside. Before he started his research it was estimated that fewer than 100 different species lived on the skin but through new techniques it is now estimated that the number of different bacteria species living on the skin could be nearer 500.

It is likely that we each have our own unique bacterial signature, much in the same way as we have our own unique DNA. In conditions such as psoriasis, Blaser has found differences in skin bacterial populations between patients who have the disease and those who do not.

Humans have evolved intimate symbiotic relationships with our gut microbes (microbiome) and individual variations in the microbiome influence host health. It is believed that they may actually play a part in causes of disease and affect drug metabolism, toxicity, and efficacy.

It is also believed that selective losses of human-associated microorganisms may be responsible for a wide range of modern ailments. Blaser gives the example of Helicobacter pylori, a bacterium usually associated with stomach ulcers. H. pylori have been disappearing with remarkable speed in developed countries, which would appear to be a good thing, however, this loss is bringing significant gastric secretory, hormonal, and immune changes, including some that harm human health.
Over the long history of its relationship with humans, H. pylori-provoked inflammation which has progressively decreased the numbers of gastric acids secreting glands, with a consequent decline in acid production, Blaser says. This decline is not all bad; it has led to a drop in incidence of illnesses with long latent periods such as gastric cancer. However, the trade off is a rise in gastroesophageal reflux disease for example. The stomach produces the hormones ghrelin and leptin, both of which have multiple roles in energy homeostasis, Blaser says. Children growing up in developed countries have little gastric H. pylori-mediated regulation of these adipokines, which may contribute to our current epidemic of childhood obesity, type 2 diabetes, and related metabolic syndromes.

H. pylori-positive individuals tend to have lower risks of childhood asthma, allergic rhinitis, and skin allergies than do their H. pylori-deficient peers.

Daniel Frank of The university of Colarado has been collecting and comparing microbial communities in samples from people with Crohn's disease, people with ulcerative colitis and healthy volunteers.

Some researchers are looking at the role a specific organism, like E. coli, might play in the development of inflammatory bowel disease. Our task was to look more broadly. What are the microbes we see as a whole in the gut and how might those populations change in relation to disease, says Frank.

Instead of any one particular organism associated with inflammatory bowel diseases, they observed significant shifts in microbial populations between healthy subjects and those with disease, including a loss of normally protective bacterial populations.

It may also be that the bacteria in the digestive tract could play a role in obesity as our gut flora have shifted. Ruth Ley of Washington University in St. Louis is part of a team that has been investigating the relationship between bacteria in the gut and weight. They discovered that obesity appears to be associated with changes in the relative abundance of certain types of bacteria in the digestive tract.

A really surprising discovery is that microbes may be involved in mental health too. Exposure to specific bacteria in the environment are already believed to have antidepressant qualities but could also increase learning behaviour. Mycobacterium vaccae is a natural soil bacterium which people probably ingest or breathe in when they spend time in nature. Matthews and Jenks fed live Mycobacterium vaccae bacteria to mice and assessed their ability to navigate a maze compared to control mice that were not fed the bacteria. We found that mice that were fed live M. vaccae navigated the maze twice as fast and with less demonstrated anxiety behaviors as control mice. This research suggests that M. vaccae may play a beneficial role in lessening anxiety and heightening learning, but continued exposure is necessary.

Where does all this research leave us? Well, we can take up gardening in the hope of befriending M. Vaccae, we can eat a balanced healthy diet with plenty of raw and cooked vegetables/fruits which are believed to help the healthy bacteria thrive in our guts, eat live yoghurt, try making fermented drinks such as Kombucha and kefir. Beyond these simple steps there is not much to be done except to wait patiently for more breakthroughs and for the research knowledge to slowly filter through to medical practice.

It should be noted that it has never been suggested that this research will lead to a direct cure for autism.

Here are a few links for further reading:

Anna van der Post
Jun 2010

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