Heart failure is the leading
cause of death in the aged. With more than 970 million hypertensive people
worldwide, and more than double the number of people at risk for heart failure,
scientists are now intensively looking for solutions.
Untreated chronic high blood
pressure leads to heart failure where the heart muscles become stiff and
and are not able to fill up with blood. This results
in diastolic heart failure.
Studies have shown that oxidative
stress plays an important role in causing heart failure. Oxidative stress
occurs when there is an excess production of reactive oxygen species (ROS)
relative to levels of antioxidants. This imbalance is called impaired
antioxidant defense. It's seen that reduced levels of antioxidants such as
glutathione can increase ROS levels.
Therefore, levels of antioxidants
in the heart need to be increased through intake of antioxidant rich diet to
reduce ROS levels and increase antioxidant defense.
Although it is known that
phytochemicals in plants can alter gene activity related to antioxidant
defense, scientists were not sure if dietary
of these phytochemicals brings about the chemical changes and
whether it can reduce the chances of hypertension-associated heart failure.
Grapes are a natural source of antioxidants and other
polyphenols that are highly beneficial for heart health and general well being.
So, to study the mechanism of
effect, E. Mitchell Seymour at University of Michigan
Center and his colleagues used whole grapes as a model of a phytochemical-rich
(antioxidants and other polyphenols) food and tested them on hypertensive heart
failure-prone rats for 18 weeks.
'Our hypothesis is that whole grapes will be superior to any
individual grape component, in each of the areas being investigated,'
Seymour. 'The whole fruit contains hundreds of individual components, which we
suspect likely work together to provide a synergistic beneficial effect'.
They found that grape intake reduced cardiac hypertrophy
(thickening of heart muscle) and fibrosis, and also improved diastolic
function. They also found that grape intake significantly increased gene
activity related to antioxidant defense.
"The insights gained from our NIH
study, including the ability of grapes to influence several genetic pathways
related to antioxidant defense, provide further evidence that grapes work on
multiple levels to deliver their beneficial effects," said Seymour.
"Concentrated antioxidant nutrient trials have failed
to affect heart failure. However, this study demonstrates that diet-relevant
intake of antioxidants significantly reduces heart failure progression,"
concluded the researchers. "Therefore, this study
suggests that higher intake of phytochemical-containing foods may achieve
cardiac benefits that isolated antioxidant supplements may not".