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The strong link between obesity and your 'carb breakdown' gene

A new study finds strong link between obesity and 'carb breakdown' gene. Researchers at King's College London and Imperial College London have discovered that people with fewer copies of a gene coding for a carb-digesting enzyme may be at higher risk of obesity. The findings, published in Nature Genetics, suggest that dietary advice may need to be more tailored to an individual's digestive system, based on whether they have the genetic predisposition and necessary enzymes to digest different foods. You also may wish to check out the site, "Risk of obesity from regular consumption of fried foods may depend on genetic makeup." Or see another article, "Grass-Fed Animal Foods and Diseases of Civilization: Cardiovascular Disease in Ancient Civilizations."

 The strong link between obesity and your 'carb breakdown' gene.
Anne Hart, photography, Academy of Science pendulum exhibit, San Francisco 2009.

Salivary amylase plays a significant role in breaking down carbohydrates in the mouth at the start of the digestion process. The new study suggests that people with fewer copies of the AMY1 gene have lower levels of this enzyme and therefore will have more difficulty breaking down carbohydrates than those with more copies. You may also wish to see the article, "Why We Got Fatter During The Fat-Free Food Boom."

Previous research has found a genetic link between obesity and food behaviors and appetite, but the new discovery highlights a novel genetic link between metabolism and obesity. It suggests that people's bodies may react differently to the same type and amount of food, leading to weight gain in some and not in others. The effect of the genetic difference found in the latest study appears much stronger link than any of those found before. You also may wish to check out the site, "Enzyme in saliva helps regulate blood glucose."

Researchers first measured gene expression patterns in 149 Swedish families with differences in the levels of obesity and found unusual patterns around two amylase genes (AMY1 and AMY2), which code for salivary and pancreatic amylase. This was suggestive of a variation in copy numbers relating directly to obesity. You also may wish to check out the site, "Underweight people at as high risk of dying as obese people, new study finds."

The finding was replicated strongly in 972 twins from TwinsUK, the biggest UK adult twin registry, which found a similar pattern of expression. The researchers then estimated the precise copy numbers of the amylase gene in the DNA of a further 481 Swedish subjects, 1,479 subjects from TwinsUK and 2,137 subjects from the DESIR project.

The collaborative team found that the number of copies of the AMY1 gene (salivary amylase) was consistently linked to obesity. Further replication in French and Chinese patients with and without obesity showed the same patterns

A lower estimated AMY1 copy-number showed a significantly increased risk of obesity in all samples and this translated to an approximate eight-fold difference in the risk of obesity between those subjects with the highest number of copies of the gene and those with the lowest.

Standard Genome wide mapping methods (GWAS) had missed this strong association as the area is technically hard to map. This variation in copy numbers, also known as 'copy number variants' (CNV) has been underestimated as a genetic cause of disease, but the link between CNV in the amylase gene and obesity provides an indication that other major diseases may be influenced by similar mechanisms.

Professor Tim Spector, Head of the Department of Twin Research and Genetic Epidemiology at King's College London and joint lead investigator said, according to the March 30, 2014 news release, New study finds strong link between obesity and 'carb breakdown' gene,
"These findings are very exciting. While studies to date have mainly found small effect genes that alter eating behavior, we discovered how the digestive 'tools' in your metabolism vary between people – and the genes coding for these – can have a large influence on your weight.

"The next step is to find out more about the activity of this digestive enzyme, and whether this might prove a useful biomarker or target for the treatment of obesity. In the future, a simple blood or saliva test might be used to measure levels of key enzymes such as amylase in the body and therefore shape dietary advice for both overweight and underweight people. Treatments are a long way away but this is an important step in realizing that all of us digest and metabolize food differently – and we can move away from 'one-size fits all diets' to more personalized approaches."

Researchers in another study now have a new guide for measuring food consumption

Scientists have to make conclusions about total caloric intake over days or longer when doing research. So now Scripps Florida scientists offer a new 'best practices' nutrition measurement for researchers, says a new study, "Quantifying Drosophila Food Intake: Comparative Analysis of Current Methodology," published online ahead of print on March 30, 2014 by the journal Nature Methods. Authors include Angela M Phillips, Sany Hoxha and Keith J Lizotte of the Scripps Research Institute (TSRI).

At first glance, measuring what the common fruit fly eats might seem like a trivial matter, but it is absolutely critical when it comes to conducting studies of aging, health, metabolism and disease. How researchers measure consumption can make all the difference in the accuracy of a study's conclusions. You also may wish to check out the site, "Researchers reverse a liver disorder in mice by correcting a mutated gene." Or check out a September 9, 2013 Life Extension magazine article, "Myths of Paleo, Part Three: The Amylase Gene."

Measuring food consumption

Scientists from the Florida campus of The Scripps Research Institute (TSRI) have developed what amounts to a best practices guide to the most accurate way of measuring fruit fly food consumption that could lead to more informed research and better decisions about directions in further studies.

"While our study isn't the final technical reference on measuring fly food consumption, it will help guide researchers to think more carefully about nutrition and nutrient intake in their own studies," said TSRI Assistant Professor William Ja, who led the study, according to the March 30, 2014 news release, "Scripps Florida scientists offer 'best practices' nutrition measurement for researchers.."

Researchers, Ja said, generally haven't given sufficient thought to feeding and nutrient intake when it comes to measuring fruit fly behavior, metabolism and health

"If you're making a huge effort to change an animal's diet and trying to draw conclusions about what nutrition and nutrients do to animal health and lifespan," he said, according to the news release, "then one of the most fundamental parameters is accurately measuring food intake."

TSRI Research Associate Sonali Deshpande, a first author of the study with graduate student Ariadna Amador and former TSRI Research Associate Gil Carvalho, underlined the importance of using the best measurement methods. "Drug studies, in particular, where compounds are added to fly food, are difficult to interpret without proper measurement of food and drug intake," she said.

Separate food and drug intake need to be measured, even when both are compounded together

In the study, the team determined that radioisotope labeling food is the most sensitive and consistently accurate feeding method now available—levels of accumulated isotope are later measured in the animals. This method's main limitation appears to be underestimation of consumption due to excretion.

For the most accurate measurement, the study suggested pairing radioisotope labeling with a more low-tech approach, such as the capillary feeder (CAFE). The CAFE assay, introduced by Ja in 2007, is similar to a water dispenser used for pet hamsters, but on a smaller scale.

"In a significant number of studies, we found that researchers appeared indifferent to the impact feeding might have on the experiment," Ja said, according to the news release. "This doesn't seem like good science to me. Can you imagine doing a mouse experiment, saying that you watched mice for four hours and saw no difference in feeding, then make conclusions about total caloric intake over days or longer?" The funders supporting the study are the National Institutes of Health (grants R00AG030493 and R21DK092735), the Ellison Medical Foundation, and the Glenn Foundation for Medical Research.

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