The health benefits of garlic have been touted for centuries, from its anti-bacterial and antifungal properties, to its positive effects on the cardiovascular system.
Now US researchers say they have figured out precisely why the
pungent clove makes such a valuable health tonic: it boosts the body's
own production of a compound that relaxes blood vessels, increases
blood flow, and prevents blood clots and oxidative damage.
"This will help us standardise over the counter garlic supplements,
and ensure they have the ingredients that produce the key compound,"
said David Kraus, a physiologist in the department of environmental
health sciences at the University of Alabama at Birmingham.
Much of the research into the pharmacological benefits of garlic has
focused on the organic polysulphides that the clove is rich in - the
best known of which is Allicin.
Only a piece of the puzzle
But the new research suggests that Allicin and similar biologically
active compounds are only a piece of the puzzle, and that it's the
chemical messenger that is produced when these compounds are
metabolised that is important.
In laboratory tests, the researchers at the University of Alabama
found that it was this chemical messenger - hydrogen sulphide (H2S) -
which is essential at low levels for cellular signalling, that appears
to relax blood vessels, enhancing blood flow.
The team conducted a series of experiments, first extracting juice
from supermarket garlic and adding minute amounts to red blood cells.
The cells immediately began emitting hydrogen sulphide.
Further experiments showed that the key chemical reaction took place
mainly at the membrane of the red blood cells, although a fraction of
H2S was also produced inside the cells.
Further, when the team added a section of rat aorta, a heart blood
vessel, to a solution containing organic polysulphides, it began to
relax as it produced H2S.
The finding may explain why some studies showed there were no
cardiovascular benefits to be gained from taking garlic supplements
while many others showed that such supplements could halt the progress
of cardiovascular disease, the authors said.
"In addition, our results suggest that the capacity to produce H2S can be used to standardise garlic dietary supplements," the authors wrote.
The study appears in the Proceedings of the National Academy of Sciences. – (Sapa-AFP)
Garlic claims crushed