19 August 2010

What can beetles tell us about slowing aging? Answers are in the mitochondria

Mitochondrial genes influence life expectancy in beetles, a new study reports.
Genetic research into aging and longevity revolves mainly around the nuclear genome, which encodes most of our multicellular bodies, but a new Monash University study performed on beetles suggests shifting focus to the mitochondrial genome.  

The mitochondria—kidney-shaped organelles often referred to as the cell's powerhouses—each contain their own set of DNA, passed on from mother to offspring, and according to the study, it's these strands that may hold key genes that determine one's life expectancy, at least in bugs.  

The study, published in the August issue of The American Naturalist, found evidence that particular combinations of genes (haplotypes) in the mitochondrial genome influenced lifespan in a species of seed beetles (Callosobruchus maculates).  

As a result, the research supports growing evidence that particular mitochondrial gene combinations could also play a major role in accelerating the aging process in humans because they could cause mitochondria to produce greater amounts of toxic molecules called free radicals causing oxidative damage to cells, cellular proteins and DNA.  

Evolutionary biologist Damian Dowling of Melbourne, who conducted the study, hopes his research will help medical scientists identify which gene combinations accelerate aging, as well as develop gene therapies that alter the combinations, or develop antioxidant therapies that neutralize free radicals and protect cells from oxidative damage. Do mothers show favoritism toward daughters?  

Although Dowling found his discovery interesting, he said it was not the original intent of his research; in fact, he was testing a debated theory that mitochondrial genes make an impact on the tug-of-war between the sexes in the beetles. Previous research in beetles and fruit flies has explored a ubiquitous phenomenon in insects commonly called the "cost of mating"—that is, that the simple act of sexual reproduction can take a toll on mothers, and sometimes fathers, by reducing their life expectancy.  

Dowling’s wanted to find out if mitochondria bestowed any reward to female beetles. He explained to me: "Because the mitochondrial genome is maternally inherited it has been hypothesized that it will take the female's best interests at heart." 

But, he adds, "Our study was the first experimental test of this idea, and we didn't support the controversial idea." However, what Dowling did find was something more exciting—that different mitochondrial gene combinations, sourced from different geographic locations from around the globe, produced large differences in life spans in the beetles.  

“Beetles that harbored certain mitochondrial DNA sequences could live up to 30 percent longer,” he told me. Thirty percent longer is about 20 more days for the life of a beetle, which is nothing short of a leap for the crawling critters—when scaled up to human years, it amounts to adding about 23 more years.

17 August 2010

How to win her heart? Moderate amounts of dark chocolate

They say chocolate is the way to a woman's heart, and they could be right – eating one or two servings of dark chocolate weekly is good for the hearts of middle-aged or elderly women.
A nine-year observational study followed 31,823 healthy Swedish women ages 48 to 82 and found that those who ate moderate amounts of high-quality chocolate had healthier hearts.

The women who gained the most heart-health benefits had eaten one or two servings of the dark chocolate weekly, followed by those who ate one to three servings monthly. Each serving of chocolate was typically between 19 and 30 grams.

On the other hand, the women who ate one or more servings per day received no benefit, which the researchers suggest was result of replacing other nutritious foods with the chocolate. So, enjoy dark chocolate, but in moderation and as part of a nutritious diet.

Men, take note – the quality of the chocolate matters.

Finding the right chocolate for a woman’s heart health, while avoiding the pitfalls of eating other chocolates high in fat and sugar, depends on content and value of its cocoa.

The chocolate the Swedish women ate contained higher amounts of cocoa than milk chocolate and was not as highly processed as most dark chocolate found typically in North America.

When choosing dark chocolate, seek out versions that are minimally processed and high in cocoa flavonoids for greatest antioxidant strength. Cocoa is naturally one of the world's richest sources of antioxidant flavonoids, which are also found in various fruits and vegetables, tea and red wine.

Previous studies have explored dark chocolate as a delicious and convenient way to gain sufficient antioxidants to support cell health, cardiovascular and heart health.

Source: Mostofsky E., Levitan E.B., Wolk A. et al. Journal of the American Heart Association.

Note: This original post was written to be published here.

11 August 2010

Resveratrol-Rich Plant Extract Stifles Inflammation in Humans

Resveratrol’s antioxidant and anti-inflammation actions shown previously only in vitro and in laboratory animals have now been observed in a small human study.

State University of Buffalo New York and Kaleida Health researchers found that supplementation with a plant extract containing resveratrol suppressed generation of free radicals called reactive oxygen species (ROS) and reduced expression of two major proinflammatory pathways.

Writing in their study, published in Journal of Clinical Endocrinology and Metabolism, the researchers state that they have demonstrated for the first time in humans “comprehensive effects on ROS generation and inflammation” and the “antiaging action of resveratrol.”

In the trial, two groups of 10 healthy adults were randomized to receive placebo or 200 milligrams of Japanese knotweed extract (Polygonum cuspidatum) supplying 40 milligrams of resveratrol daily. Fasting blood samples were collected before, during and after six weeks of supplementation. Subjects chosen were not on any antiinflammatory drugs.

The researchers’ data showed clear suppression of ROS generation and reduced expression of TNF-alpha and IL-6, which are regulated by NFkB, that led to falling levels of C-reactive protein, which are all involved with inflammatory response.

In parallel, the extract reduced expression of two major proinflammatory enzymes, JNK-1 and IKK-beta.

Resveratrol’s effects on reducing oxidative stress and inflammation are thought to take place because it activates production of SIRT1, one of a family of proteins that is positively associated with influencing fat metabolism, slowing aging, and extending lifespan in response to calorie restriction and fasting in yeast and animals.

Chronic oxidative stress and inflammation are implicated as factors that accelerate aging because of damage caused to cellular components including membranes, mitochondria and DNA.

Source: Ghanim H, Sia CL, Abuaysheh S, Korzeniewski K, Patnaik P, Marumganti A, Chaudhuri A, Dandona P. An Antiinflammatory and Reactive oxygen Species Suprressive Effects of an Extract of Polygonum Cuspidatum Containing Resveratrol. J Clin Endocrin Metab. 2010; 10:12.