Healthy soil and sustainable growing

["TradingPostPaul" <tradingpost@riseup.net>]

(Well, I always said the way to connect with the earth isn't some
airy-fairy seminar but simply getting our hands in the soil)

Health and happiness is all down to a roll in the dirt
April 1, 2007
http://www.timesonline.co.uk/tol/life_and_style/health/article1596735.ece

FORGET the spring-cleaning. A study has found evidence that bacteria common
in soil and dirt could improve people’s spirits.

According to the research, the action of Mycobacterium vaccae (M vaccae) on
the brain is similar to that of some commonly used antidepressants.

The bacterium, which is related to the microbe that causes tuberculosis,
appears to work by stimulating the body’s immune system. This, in turn,
prompts certain cells in the brain to produce more serotonin, a hormone
associated with feelings of wellbeing.

“These studies help us to understand how the body communicates with the
brain and why a healthy immune system is important for maintaining mental
health,” said Dr Chris Lowry, a neuroscientist at Bristol University who
carried out the research.

“They also leave us wondering if we shouldn’t all spend more time
playing in the dirt.”

The finding follows separate research by other scientists into the impact
of bringing children up in “overhygienic” conditions.

They found evidence that exposure to a wide range of common microbes in
early life helped to promote healthy development of the immune system.

Without such exposure, the immune system seems more likely to mistake the
body’s own cells as invaders and launch attacks on them. This could be
one of the mechanisms underlying the surge in conditions such as asthma and
eczema.

The research by Lowry and a team of 12 scientists at Bristol and University
College London (UCL) takes this “hygiene hypothesis” a step further by
linking exposure to the microbes found in dirt with good mental, as well as
physical, health.

Interest in the project arose after human cancer patients being treated
with M vaccae unexpectedly reported increases in their quality of life.

This could have been caused by the microbe having indirectly activated the
brain cells that produce serotonin.

The researchers injected some mice with the bacteria while others were made
to inhale it. They then analysed the blood and brains of the infected mice
to see what effect the microbes might have had on their immune systems and
on serotonin levels.

Details will be published in Neuroscience, an academic journal, this week.

The study is highly unlikely to lead to new therapies for depression in the
near future but it does build on the growing body of research showing the
importance of the human immune system in regulating even the subtlest
aspects of health.

There are a range of studies supporting the hygiene hypothesis and the idea
that exposure to microbes is good for long-term health.

In families with several children, the youngest often has the least
allergies, most likely because it picks up the elder siblings’ infections
so activating the child’s immune system.

Graham Rook, a professor of immunology at UCL who worked with Lowry, has
already published research into the link between exposure to microbes and
subsequent development of allergies.

Rook and two of his co-researchers are also working with S R Pharma, a
company looking into whether M vaccae could become the basis of treatments
for conditions such as asthma.

Rook believes that improved cleanliness may be a contributory factor in
diseases such as asthma, eczema and hay fever, along with autoimmune
diseases such as Type 1 diabetes and inflammatory bowel disorders such as
Crohn’s disease. He said: “We’ve known for a couple of decades now
that a whole group of chronic inflammatory disorders are becoming much
commoner in the rich developed world.”

The body’s response to such inflammatory diseases is regulated by immune
cells which, said Rook, need to encounter harmless bacteria early in life
in order to work out how to respond effectively to real threats.

Without these encounters, he said, the regulatory cells can malfunction,
leading to health problems.

Mark Pepys, professor of medicine at UCL, said that there was “quite a
lot of evidence” to support the hygiene hypothesis but said he would be
cautious about extending the theory to mental wellbeing.