Bacteria Linked Also With Heart Disease

Background

It was found that the association between eating a lot of red meat and the risk of heart disease could not be entirely explained by the cholesterol and saturated fat content of meat.  So researchers began to look for other factors in meat which might be responsible.

Trimethylamine-N-oxide and heart disease

Trimethylamine-N-oxide (TMAO) is produced by the metabolism in the body of two dietary constituents of red meat.  The significance of this is that TMAO has been linked not only with cardiovascular (heart) disease but also with sudden events such as heart attack, stroke and death. 

The two compounds found in red meat are L-carnitine and choline, both of which are present in other protein foods.  Some people take L-carnitine supplements to promote muscle enlargement. 

 The researchers found that even people not considered not to be at high risk for sudden cardiovascular events had a significantly increased chance of having such an event after three years, if they had high levels in the blood of TMAO.  In other words TMAO production appears to be a highly significant factor for the development of heart disease and risk of serious events, and bacteria seem to play an integral part in this.

Dr Stanley L Hazen of the Cleveland Clinic, Ohio, who is one of the researchers, said that this story is not about L-carnitine and choline, but about the gut bacteria and the part played by TMAO in heart disease.

Where will this research lead?

Although this all sounds rather scary, the scientists say the good news is that their findings indicate what they call modifiable risk factors for heart disease.  In other words there are things which can be done to reduce the risk associated with bacterial production of TMAO. 

One option of course is modifying the diet to keep the precursor compounds – choline and L-carnitine – to a minimum. 

Drugs may also be developed which will block the production of TMAO in the gut.

A final solution is to eradicate the bacteria in the gut responsible for producing TMAO.  

Whether this strategy would represent a long-term solution is another matter.

Should we be worried about this research?

No. It is all part of the unfolding mystery about the complex causes of heart disease and stroke.  A lot more work still needs to be done before the medical profession will be in a position to offer advice on lowering risk associated with these findings. The main value of it may be in its predictive value – of detecting people at high risk and therefore in need of interventions.

 So it may be a good idea to follow existing advice about reducing consumption of red meat by obtaining protein from other foods such as dairy produce or vegetable sources such as beans and tofu.