KATHMANDU — Excess fat in the heart — a common feature in diabetes and obesity — may contribute to the two to five fold increased risk of heart failure in people with diabetes, a study by University of Iowa has found.
The heart is the most energy-hungry organ in the body. Just like a combustion engine burning fuel to power the pistons, healthy heart cells consume fuel molecules to create the necessary energy to keep the heart pumping.This essential energy production takes place inside mitochondria, the self-contained ‘powerplant’ organelles inside cells.
Although mitochondria in a healthy heart primarily use fatty acids as fuel, they can easily adapt to use other fuel molecules as needed, including glucose, lactate, and ketone bodies.
Diabetes, however, reduces the heart muscle’s metabolic adaptability and causes heart cells to overuse fat as a metabolic fuel.
“Diabetes, which affects almost 30 million Americans, significantly increases the risk of heart failure, and one of the cardinal manifestations of the hearts of people with diabetes is the tendency to overuse fat as a metabolic fuel, which ultimately leads to mitochondrial and cardiac damage,” said E Dale Abel, from the University of Iowa in the US.
The study, published in the journal Circulation Research, found this cardiac lipid overload leads to numerous small, misshapen mitochondria that don’t produce energy as efficiently as normal mitochondria.
“We have demonstrated and detected how increasing the amount of fat (lipid) that the heart consumes leads to dramatic changes in the structure and function of the mitochondria in the heart,” Abel said.
To investigate the consequences of cardiac lipid overload on mitochondria, the team used genetically modified mice that mimic the increased fatty acid uptake (lipid overload) that characterises diabetes.
“These studies provide a new window into how these changes to mitochondria could occur in the lipid-overloaded heart,” he added.
In the mouse model, lipid uptake to heart is doubled. This modest increase resulted in mitochondria that became thinner and more twisted than mitochondria in healthy heart cells.
These structural changes (almost like a noodle snaking through the heart) lead to an appearance of mitochondrial fragmentation when imaged by conventional electron microscopy.
The study also revealed the molecular cause of the change in mitochondrial structure. Prolonged lipid overload leads to increased levels of damaging substances called reactive oxygen species (ROS).
The findings further suggest that cardiac lipid overload disrupts normal mitochondrial structure, which may impair energy production and compromise heart function.
With Agency InputsFollow @gorkhapost
Drinking 3 cups of coffee or tea daily may keep stroke risk at bay
KATHMANDU — There have been several conflicting studies on the health benefits of drinking coffee and tea and their various varieties. But drinking up to three cups of coffee or tea in a day is safe because it reduces irregular heartbeat and stroke risk, according to a new study published in the journal JACC: Clinical Electrophysiology.
Coffee has previously been believed to worsen abnormal heart rhythms, as doctors generally discourage patients suffering from the condition. However, the results of this particular study say that a daily consumption of upto 300 mg of caffeine may be safe for arrhythmic patients.
This is because the caffeine acts as a stimulant to the central nervous system and blocks the effect of adenosine. Adenosine is a chemical which causes Atrial Fibrillation (AFib).
A single cup of coffee contains about 95 mg of caffeine. It acts as a stimulant to the central nervous system and works to block the effects of adenosine — a chemical that causes AFib.
AFib is the most common heart rhythm disorder, causes the heart to beat rapidly and skip beats, and if left untreated, can cause strokes.
“There is a public perception, often based on anecdotal experience, that caffeine is a common acute trigger for heart rhythm problems,” said lead author Peter Kistler, Director at Melbourne’s Alfred Hospital.
But, “caffeinated beverages such as coffee and tea have long-term anti-arrhythmic properties mediated by antioxidant effects and antagonism of adenosine,” he added.
A meta-analysis of 228,465 participants showed that AFib frequency decreasing by 6 per cent in regular coffee drinkers, and an analysis of 115,993 patients showed a 13 per cent reduced risk.
Another study of 103 post-heart attack patients who received an average of 353 mg of caffeine a day showed improvement in heart rate and no significant arrhythmias — or abnormal heart rhythms, that cause the heart to beat too fast, slow or unevenly.
However, in two studies, where patients drank at least 10 cups and nine cups of coffee per day, showed an increased risk for ventricular arrhythmias (VAs) – a condition in which the lower chambers of the heart (ventricles) beat very quickly.
On the other hand, patients with pre-existing heart conditions who consumed two or more energy drinks — that contains concentrated caffeine — per day reported palpitations within 24 hours.
With Agency InputsFollow @gorkhapost