Category Archives: Transhuman News

TUESDAY, Sept. 30, 2014 (HealthDay News) -- There's no genetic evidence that high levels of vitamin D can prevent type 2 diabetes, a new study says.

Some previous research had suggested that elevated levels of vitamin D might protect people against type 2 diabetes, raising the possibility of a link between vitamin D deficiency and the blood sugar disease.

In this study, British researchers investigated the association between diabetes risk and vitamin D by focusing on genes that control blood levels of vitamin D. They found no connection between different variants of these genes and the risk of developing type 2 diabetes.

The results were published Sept. 30 in The Lancet Diabetes & Endocrinology.

"Our findings suggest that interventions to reduce the risk of type 2 diabetes by increasing concentrations of vitamin D are not currently justified. Observational studies that show a strong and consistent higher risk of type 2 diabetes with lower levels of vitamin D may do so because they have thus far not been able to adequately control for distorting or confounding factors, such as physical activity levels," study author Dr. Nita Forouhi, of the University of Cambridge's School of Clinical Medicine, said in a journal news release.

The findings add to evidence showing that taking vitamin D supplements does not prevent diabetes. The only proven ways to prevent type 2 diabetes are diet and exercise, Forouhi said.

One expert noted that long-term trials that are still looking at any possible connection should be weighed in the final analysis.

The results "need careful interpretation, and long-term randomized trials of vitamin D supplementation, which are underway, remain important," Dr. Brian Buijsse, from the German Institute of Human Nutrition Potsdam-Rehbruecke in Germany, wrote in an accompanying commentary in the journal.

"The results of an [analysis] of 35 short-term trials, however, do not offer much hope that vitamin D supplementation can be used to prevent type 2 diabetes. The sky is becoming rather clouded for vitamin D in the context of preventing type 2 diabetes," he said.

-- Robert Preidt

Original post:
Gene Study Finds No Proof Vitamin D Guards Against Type 2 Diabetes

PUBLIC RELEASE DATE:

2-Oct-2014

Contact: Katherine Unger Baillie kbaillie@upenn.edu 215-898-9194 University of Pennsylvania @Penn

It's an early lesson in genetics: we get half our DNA from Mom, half from Dad.

But that straightforward explanation does not account for a process that sometimes occurs when cells divide. Called gene conversion, the copy of a gene from Mom can replace the one from Dad, or vice versa, making the two copies identical.

In a new study published in the American Journal of Human Genetics, University of Pennsylvania researchers Joseph Lachance and Sarah A. Tishkoff investigated this process in the context of the evolution of human populations. They found that a bias toward certain types of DNA sequences during gene conversion may be an important factor in why certain heritable diseases persist in populations around the world.

Lachance is a postdoctoral fellow at Penn in Tishkoff's lab and will be starting his own lab at Georgia Tech in January. Tishkoff is a Penn Integrates Knowledge Professor with appointments in the Perelman School of Medicine's Department of Genetics and the School of Arts & Sciences' Department of Biology.

The study pins on the question of why humans have a genetic predilection for certain diseases. Some reasons have become clear to scientists. The Amish, for example, have a higher risk of several genetic diseases due in part to a phenomenon called founder effects, whereby certain genes rise to prevalence in populations that originated with a relatively small number of individuals.

Other genetic diseases can become relatively common if some aspect about them is advantageous.

"The classic example is sickle-cell anemia," Lachance said. "It's an evolutionary trade-off because people with one copy of a sickle-cell mutation are highly protected from malaria."

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DNA 'bias' may keep some diseases in circulation, Penn biologists show