Posts Tagged ‘Note Materials’

Zebrafish Research Shows How Dietary Fat Regulates Cholesterol …

ScienceDaily (June 23, 2012) — Buttery shrimp. Fried eggs. Burgers and fries. New research suggests there may be a biological reason why fatty and cholesterol-rich foods are so appealing together.

It has been known for more than 40 years that dietary fat promotes cholesterol uptake, but fundamental aspects of that process remain poorly understood. James Walters, Ph.D., and his colleagues at the Carnegie Institution for Science are using zebrafish to better understand the cellular mechanisms of cholesterol processing and have discovered a surprising link between dietary fat and cholesterol absorption.

“One reason these questions remain unknown is because of the difficulty of studying such a complex biological system as the intestine,” which in addition to multiple cell types also includes a diverse array of enzymes, mucus, and symbiotic bacteria, he said in a June 20 presentation at the ongoing 2012 International Zebrafish Development and Genetics Conference in Madison, Wisconsin.

As a postdoctoral fellow in Dr. Steven Farber’s lab at the Carnegie Institution for Science, in Baltimore, Maryland, Dr. Walters turned to young zebrafish, which provide a biologically complete and scientifically accessible system for studying the workings of the gut.

“Because the larval zebrafish are optically clear, we can visualize fat transport and processing by looking right through their body wall into the intestine where the action is,” Dr. Walters said.

He developed a way to feed zebrafish a diet high in lipids (e.g., fat and cholesterol) or high in protein and low in lipids. He accomplished this by turning to the chicken egg, whipping fish water with the yolk for a high-lipid diet and the egg white as a high-protein diet. Before feeding these diets, fluorescently tagged cholesterol or fatty acid was added, enabling the microscopic viewing of how lipids are absorbed and processed by the intestinal cells.

Dr. Walters found that cholesterol was only absorbed when the fish ate a high-fat diet, not a low-fat diet. The fats and cholesterol were packaged into separate and clearly visible compartments within the cells. “You can tell which larvae had eggs for breakfast,” he said.

The researchers also found that some long-chain fatty acids, particularly a common one called oleic acid, were especially effective for promoting cholesterol uptake. They provided evidence that oleic acid acts to drive a cholesterol transport protein from within the intestinal cell to the cell surface, where it can interact with cholesterol passing through the gut and pull it into the cell.

Their findings suggest a tightly regulated system in which cholesterol is only taken up by the intestine in the presence of fats. One reason such regulation is important, Dr. Walters said, is that unprocessed cholesterol can be toxic to cells and requires fatty acid-mediated modification to render it safe in a process called esterification.

“In nature, cholesterol and fatty acids go hand in hand. It makes sense that you could use dietary fatty acids as a cue for the transport protein to translocate to the cell surface and that dietary cholesterol may be available for absorption,” he said. “The protein isn’t displayed on the cell surface unless its preferred substrate for making cholesterol less toxic is also there.”

Dr. Walters and his colleagues are now exploring the system’s potential for studying and testing compounds that can block the absorption of dietary cholesterol, including one drug already on the market.

“Diet is a huge modulator of human disease,” says Dr. Walters. “Our work demonstrates the power of the zebrafish larval system to provide fresh insights into the process of intestinal cholesterol absorption. It gives us a way to look at these processes for the first time in the context of a whole organism.”

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The above story is reprinted from materials provided by Genetics Society of America, via Newswise.

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Article source: http://www.sciencedaily.com/releases/2012/06/120623094417.htm

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Can our genes be making us fat?

ScienceDaily (Mar. 22, 2012) — While high-fat foods are thought to be of universal appeal, there is actually a lot of variation in the extent to which people like and consume fat. A new study in the March issue of the Journal of Food Science, published by the Institute of Food Technologists, reported that two specific genes (TAS2R38-a bitter taste receptor and CD36-a possible fat receptor), may play a role in some people’s ability to taste and enjoy dietary fat. By understanding the role of these two genes, food scientists may be able to help people who have trouble controlling how much fat they eat.

Most food scientists acknowledge the texture of fat plays a big role in how fat is perceived in the mouth. For example, ice cream is typically “rich, smooth and creamy.” And certain fats, scientists have determined, can be detected by smell. Only recently have food scientists explored that most fats have a taste too. Researchers are now investigating the gene (CD360) that is responsible for detecting the taste of fats (fatty acids) in the mouth.

In the recent Journal of Food Science study, investigators focused on one ethnic group to limit genetic variation that could reduce the ability to detect associations with the gene of interest. They determined the fat preferences and CD36 status of more than 300 African-American adults. The investigators from the New York Obesity Research Center identified a genetic variant present in 21 percent of the African-Americans that was associated with higher preferences for added fats and oils (e.g. salad dressings, cooking oils, etc). They also found study participants with this genetic variance ranked Italian salad dressings creamier than those who have other genotypes.

The other gene explored by these investigators, TAS2R38, is the receptor for bitter taste compounds. About 70 percent of U.S. adults and children are “tasters” of these compounds, while the remaining 30 percent are “nontasters.” Results indicate that nontasters of these compounds tend to be poor at discriminating fat in foods; therefore individuals who can’t detect fat’s presence may consume higher fat foods to compensate. This is in part due to the fact that nontasters have fewer taste buds than tasters. While researchers recognize that the cause of obesity is multifaceted, they continue to examine the role of these genotypes in weight management.

Genetic testing within the food industry may not be too far off. Once studies like these are more fully developed, there may be a role for genotyping study participants when it comes to testing a new product. For example, a company wanting to test out a dressing may include people with different genes relating to fat perception in order to get a more accurate opinion. In addition, the food industry will be able to create different kinds of foods for certain populations.

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The above story is reprinted from materials provided by Institute of Food Technologists (IFT), via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2012/03/120322162042.htm

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Can Our Genes Be Making Us Fat?

ScienceDaily (Mar. 22, 2012) — While high-fat foods are thought to be of universal appeal, there is actually a lot of variation in the extent to which people like and consume fat. A new study in the March issue of the Journal of Food Science, published by the Institute of Food Technologists, reported that two specific genes (TAS2R38-a bitter taste receptor and CD36-a possible fat receptor), may play a role in some people’s ability to taste and enjoy dietary fat. By understanding the role of these two genes, food scientists may be able to help people who have trouble controlling how much fat they eat.

Most food scientists acknowledge the texture of fat plays a big role in how fat is perceived in the mouth. For example, ice cream is typically “rich, smooth and creamy.” And certain fats, scientists have determined, can be detected by smell. Only recently have food scientists explored that most fats have a taste too. Researchers are now investigating the gene (CD360) that is responsible for detecting the taste of fats (fatty acids) in the mouth.

In the recent Journal of Food Science study, investigators focused on one ethnic group to limit genetic variation that could reduce the ability to detect associations with the gene of interest. They determined the fat preferences and CD36 status of more than 300 African-American adults. The investigators from the New York Obesity Research Center identified a genetic variant present in 21 percent of the African-Americans that was associated with higher preferences for added fats and oils (e.g. salad dressings, cooking oils, etc). They also found study participants with this genetic variance ranked Italian salad dressings creamier than those who have other genotypes.

The other gene explored by these investigators, TAS2R38, is the receptor for bitter taste compounds. About 70 percent of U.S. adults and children are “tasters” of these compounds, while the remaining 30 percent are “nontasters.” Results indicate that nontasters of these compounds tend to be poor at discriminating fat in foods; therefore individuals who can’t detect fat’s presence may consume higher fat foods to compensate. This is in part due to the fact that nontasters have fewer taste buds than tasters. While researchers recognize that the cause of obesity is multifaceted, they continue to examine the role of these genotypes in weight management.

Genetic testing within the food industry may not be too far off. Once studies like these are more fully developed, there may be a role for genotyping study participants when it comes to testing a new product. For example, a company wanting to test out a dressing may include people with different genes relating to fat perception in order to get a more accurate opinion. In addition, the food industry will be able to create different kinds of foods for certain populations.

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Story Source:

The above story is reprinted from materials provided by Institute of Food Technologists (IFT), via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2012/03/120322162042.htm

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Losing belly fat, whether from a low-carb or a low-fat diet, helps improve blood vessel function

ScienceDaily (Mar. 13, 2012) — Overweight people who shed pounds, especially belly fat, can improve the function of their blood vessels no matter whether they are on a low-carb or a low-fat diet, according to a study being presented by Johns Hopkins researchers at an American Heart Association scientific meeting in San Diego on March 13 that is focused on cardiovascular disease prevention.

In the six-month weight-loss study, Hopkins researchers found that the more belly fat the participants lost, the better their arteries were able to expand when needed, allowing more blood to flow more freely. The researchers also found that participants in the study who were on a low-carb diet lost about ten pounds more, on average, than those who were on a low-fat diet. Being overweight increases the risk of cardiovascular disease, especially if the fat is accumulated in the belly above the waist.

“After six months, those who were on the low-carb diet lost an average of 28.9 pounds versus 18.7 pounds among those on the low-fat diet,” says lead investigator Kerry J. Stewart, Ed.D., a professor of medicine at the Johns Hopkins University School of Medicine and director of clinical and research exercise physiology at the Johns Hopkins Heart and Vascular Institute.

Stewart and his colleagues studied 60 men and women who weighed an average of 215 pounds at the start of the program. Half of the participants went on a low-carb diet while the others followed a low-fat diet. All took part in moderate exercise and their diets provided a similar amount of calories each day.

In order to evaluate the health of the participants’ blood vessels before and after the weight loss program, the researchers conducted a blood flow test by constricting circulation in the upper arm for five minutes with a blood pressure cuff. With this type of test, when the cuff is released, a healthier artery will expand more, allowing more blood to flow through the artery. The researchers measured how much blood reached the fingertips before, during, and after the constriction of the artery. Stewart says this test can give an indication of the overall health of the vascular system throughout the body. The researchers found that the more belly fat a person had lost, the greater the blood flow to the finger, signaling better the function of the artery.

“Our study demonstrated that the amount of improvement in the vessels was directly linked to how much central, or belly fat, the individuals lost, regardless of which diet they were on,” says Stewart. “This is important since there have been concerns that a low-carb diet, which means eating more fat, may have a harmful effect on cardiovascular health. These results showed no harmful effects from the low-carb diet.”

In the low-carb diet used in the study, up to 30 percent of calories came from carbs such as bread, pasta and certain fruits, while 40 percent was from fat consumed from meat, dairy products and nuts. In contrast, the low-fat diet consisted of no more than 30 percent of calories from fat and 55 percent from carbs.

Stewart notes that participants on the low-carb diet lost more weight and at a faster pace, on average, which has also been seen in several other studies. He says eating higher amounts of carbohydrates can slow down the rate of body fat loss while on a weight reduction diet.

The findings were consistent with early results presented by Stewart in June 2011 at the annual meeting of the American College of Sports Medicine in Denver. That initial report was based on results after participants in the study had lost their first 10 pounds. These longer-term results show that weight loss, along with exercise, is important for improving vascular health, and suggests following a low-carb diet rather than the conventionally recommended low-fat diet for weight loss is not a concern in terms of vascular health.

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The above story is reprinted from materials provided by Johns Hopkins Medicine, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2012/03/120313230314.htm

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