Dr Keith Souter writes: Many studies have demonstrated that they have a beneficial effect in patients suffering from conditions including depression, high blood pressure, diabetes and arthritis. They can even help during cancer treatment.
It is not just that they help the person to feel relaxed, but because they cause the release of various chemicals and hormones in the body.
Several studies have shown that yoga causes the release of a particular neurotransmitter called GABA, or gamma-aminobutyric acid, one of the so-called feel-good brain chemicals. People with depression and anxiety often have low levels of it, hence yoga is a natural antidepressant.
A lot of scientific interest has turned to the new science of epigenetics.
This literally means ‘above genetics,’ and is the study of the way that environmental factors like diet, mental attitude, exercise and life habits, like yoga and tai chi can modify the way that genes are expressed.
Within each cell of the body there is six feet of DNA, which is wrapped round little protein spindles called histones.
If it is tightly wrapped, like a ball of string, then some genes may not be expressed.
There are several epigenetic mechanisms that affect this wrapping, one of the main ones being DNA methylation.
A study from Australia demonstrated that yoga actually affects DNA methylation.
Another review of 18 studies of yoga, meditation and tai chi, involving almost 850 people looked at how these mind-body interventions affect gene intervention.
The overall conclusion was that these activities potentially reverse molecular reactions in DNA that cause poor health and depression.
It is also known that a molecule known as NF-kB controls many genes involved in the production of proteins called cytokines
These proteins produce cellular level inflammation, which is the root of many chronic conditions.
Yoga seems to inhibit the NF-kB signalling, reducing cytokines, and thereby enhancing the immune system.
It seems that mind-body interventions effectively cause the brain to steer the DNA processes along a path, which improves well-being.