Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fat in the liver -- not the belly -- is a better marker for disease risk

26.08.2009
New findings from nutrition researchers at Washington University School of Medicine in St. Louis suggest that it's not whether body fat is stored in the belly that affects metabolic risk factors for diabetes, high blood triglycerides and cardiovascular disease, but whether it collects in the liver.

Having too much liver fat is known as nonalcoholic fatty liver disease. The researchers report online in the journal PNAS Early Edition that when fat collects in the liver, people experience serious metabolic problems such as insulin resistance, which affects the body's ability to metabolize sugar.

They also have increases in production of fat particles in the liver that are secreted into the bloodstream and increase the level of triglycerides.

For years, scientists have noted that where individuals carried body fat influences their metabolic and cardiovascular risk. Increased fat inside the belly, known as visceral fat, is associated with an increased risk of diabetes and heart disease.

"Data from a large number of studies shows that visceral fat is associated with metabolic risk, which has led to the belief that visceral fat might even cause metabolic dysfunction," says senior investigator Samuel Klein, M.D. "However, visceral fat tracks closely with liver fat. We have found that excess fat in the liver, not visceral fat, is a key marker of metabolic dysfunction. Visceral fat might simply be an innocent bystander that is associated with liver fat."

Klein, the Danforth Professor of Medicine and Nutritional Science, directs the Division of Geriatrics and Nutritional Science and the Center for Applied Research Studies, as well as Washington University's Center for Human Nutrition. He says most of our body fat, called subcutaneous fat, is located under our skin, but about 10 percent is present inside the belly, while much smaller amounts are found inside organs such as the liver and muscle.

This study compared obese people with elevated and normal amounts of liver fat. All subjects were matched by age, sex, body mass index, percent body fat and degree of obesity. Through careful evaluations of obese people with different amounts of visceral fat or liver fat, Klein's team determined that excess fat inside the liver identifies those individuals who are at risk for metabolic problems.

"We don't know exactly why some fats, particularly triglycerides, will accumulate inside the liver and muscle in some people but not in others," says first author Elisa Fabbrini, M.D., Ph.D., assistant professor of medicine. "But our data suggest that a protein called CD36, which controls the transport of fatty acids from the bloodstream into different tissues, is involved."

Fatty acids are the building blocks for making fats, known as triglycerides. Klein, Fabbrini and their colleagues found that CD36 levels were lower in fat tissue and higher in muscle tissue among people with elevated liver fat.

Fabbrini and Klein say changes in CD36 activity could be responsible for diverting circulating fatty acids away from fat tissue and into liver and muscle tissue, where they are converted to triglyceride. Increased tissue uptake of fatty acids could be responsible for metabolic dysfunction.

Klein says those who are obese but don't have high levels of fat in the liver should be encouraged to lose weight, but those with elevated liver fat are at particularly high risk for heart disease and diabetes. He says they need to be treated aggressively to help them lose weight because dropping pounds can make a big difference.

"Fatty liver disease is completely reversible," he says. "If you lose a small amount of weight, you can markedly reduce the fat content in your liver. In fact, even two days of calorie restriction can cause a large reduction in liver fat and improvement in liver insulin sensitivity."

Fabbrini E, Magkos F, Mohammed S, Pietka T, Abumrad NA, Patterson BW, Okunade A, Klein S. Intrahepatic fat, not visceral fat, is linked with metabolic complications of obesity. PNAS Early Edition (2009), published online Aug. 24, 2009. www.pnas.org/cgi/doi/10.1073/pnas.0904944106

(related papers)

Deivanayagam S, Mohammed BS, Vitola BE, Naguib GH, Keshen TH, Kirk EP, Klein S. Nonalcoholic fatty liver disease is associated with hepatic and skeletal muscle insulin resistance in overweight adolescents. American Journal of Clinical Nutrition, 88(2) pp. 257-262, Aug. 2008.

Korenblat K, Fabbrini E, Mohammed BS, Klein S. Liver, muscle and adipose tissue insulin resistance is directly related to intrahepatic triglyceride content in obese subjects. Gastroenterology 134: 1369-1375, 2008.

Kirk E, Reeds DN, Finck BN, Mayurranjan MS, Klein S. Effects of acute and chronic calorie restriction on insulin action in obese men and women. Gastroenterology 136: 1552-1560, 2009.

This research was supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Center for Research Resources of the National Institutes of Health.

Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.

Jim Dryden | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Health and Medicine:

nachricht New antibody analysis accelerates rational vaccine design
09.08.2018 | Scripps Research Institute

nachricht Distrust of power influences choice of medical procedures
01.08.2018 | Johannes Gutenberg-Universität Mainz

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

'Building up' stretchable electronics to be as multipurpose as your smartphone

14.08.2018 | Information Technology

During HIV infection, antibody can block B cells from fighting pathogens

14.08.2018 | Life Sciences

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>