The study is also interesting because it helps explain human studies showing that people who incorporate medium chain ‘fatty acids’, such as those found in coconut oil, into their diets can lose body fat.

Dr Nigel Turner and Associate Professor Jiming Ye, from Sydney’s Garvan Institute of Medical Research, compared fat metabolism and insulin resistance in mice fed coconut oil and lard based diets. Their findings are now published online in the international journal Diabetes.

“The medium chain fatty acids, like those found in coconut oil, are interesting to us because they behave very differently to the fats normally found in our diets,” said study leader Nigel Turner.

“Unlike the long chain fatty acids contained in animal fats, medium chain fatty acids are small enough to enter mitochondria – the cells’ energy burning powerhouses – directly, where they can then be converted to energy.”

“Unfortunately the downside to eating medium chain fatty acids is that they can lead to fat build up in the liver, an important fact to be taken into consideration by anyone considering using them as a weight loss therapy.”

Fat storage is determined by the balance between how much fat is taken in by cells and how much of this fat is burned for energy. When people eat a high fat diet, their bodies attempt to compensate by increasing their capacity to oxidise fat. The medium chain fatty acid (coconut oil) diet was more effective at increasing the oxidative capacity of muscle than the long chain fatty acid (lard) diet leading to less fat storage in muscle and better insulin action.

According to Turner, the lard-based diet used in this research is similar to the diet eaten by people in the Western world. “Its fatty acid composition is about 40% saturated fats, 40% monounsaturated fats and 20% polyunsaturated fats, of which the vast proportion is omega-6, rather than omega-3,” he said.

“Obese humans usually eat 40-50% of their calories as fat. Our mice were fed 45% of their calories as fat.”

“No high fat diet is good, and the normal dietary combination of long chain fats leads to an overload that our bodies can’t cope with. Therefore high consumption of common dietary fats is contributing directly towards the global escalation of obesity and Type 2 diabetes.”

“If someone is trying to prevent weight gain, we can see they may benefit from substituting oils containing medium chain fatty acids for other oils in their diet, as long as consideration is given to the potential problem of excess fat in the liver. Other natural dietary alternatives, such as fish oil, might be helpful because the fatty acids in fish oil are thought to exert a lot of their beneficial effects through improving fat oxidation in the liver.”

Source
Garvan Institute of Medical Research

More importantly, according to two new studies led by a University of Utah human geneticist, fruit flies use the same molecular mechanisms as humans to help maintain proper balances of cholesterol and a key form of stored fat that contributes to obesity. The findings mean that as researchers try to learn more about the genetic and biological processes through which people regulate cholesterol and fat metabolism, the humble fruit fly, also called Drosophila, can teach humans much about themselves.

“Not a lot is known about these regulatory mechanisms in people,” says Carl S. Thummel, Ph.D., professor of human genetics at the U of U School of Medicine and senior author on the two studies. “But we can learn a lot by studying metabolic control in fruit flies and apply what we learn to humans.”

High cholesterol and obesity, which affects an estimated 25 percent to 30 percent of the U.S. population, are linked to heart disease, diabetes, and other diseases that take huge tolls on health and add billions of dollars to the nation’s medical bills. Understanding the processes that regulate cholesterol and fat in humans could be critical for addressing those health risks in people, Thummel believes.

The two studies identify a nuclear receptor, DHR96, which plays a critical role in regulating the balance or homeostasis of cholesterol and another fat molecule called triacylglycerol (TAG). Nuclear receptors are proteins that sense the presence of chemical compounds within cells. DHR96 corresponds closely to a nuclear receptor in humans, called LXR, that is known to regulate cholesterol levels.

In a study published Dec. 2 in Genes & Development, Thummel and colleagues at the U of U and two Canadian universities show that DHR96 helps regulate cholesterol in fruit flies by binding with this compound. When this binding occurs, it allows DNA to be read, which switches genes on and off that help maintain proper levels of cholesterol, according to Thummel, who also holds an H.A. and Edna Benning Presidential Endowed Chair in Human Genetics.

The researchers used a technique developed by University of Utah biologist Kent Golic, Ph.D., in which they silenced or disabled the DHR96 protein so it couldn’t function in fruit flies. They then grew flies in which DHR96 was silenced. Depending on what the fruit flies were fed, lean or fat diets, they had either too little or too much cholesterol. Flies fed too little cholesterol died, while those with too much developed hypercholesterolemia or chronically excessive cholesterol levels. At the same time, flies in which DHR96 functioned normally maintained a proper level of cholesterol.

“When they lacked the DHR96 receptor, the flies were unable to maintain cholesterol homeostasis,” Thummel says. “This is similar to what happens in humans who have high cholesterol levels.”

Fruit flies are good for such research insights in large part because of the insects’ short life span – about 30 days – meaning their development and biological processes are more easily observed than in other, longer-lived models, such as mice. Fruit flies also are easy to manipulate genetically and are less expensive to study compared to mice or other models, according to Thummel. In addition, the mechanisms by which metabolism is controlled in fruit flies are very similar to those in mice or humans.

“We can do a lot more mechanistic studies in a fly than are possible in a mouse,” he says. “We can study metabolic pathways faster and more in-depth.”

Along with its important role in helping to maintain proper levels of cholesterol, DHR96 also plays an integral part in regulating dietary fat metabolism, Thummel and another U of U researcher report in a Dec. 2 study in Cell Metabolism.

In flies in which DHR96 was silenced, TAG levels were markedly reduced in the intestine, making the insects resistant to diet-induced obesity. But when DHR96 was overexpressed, meaning there were higher levels of the protein, it led to increased TAG levels and made the flies more prone to being overweight. These findings show that DHR96 is required for breaking down dietary fat in the intestine of fruit flies and provide insight into how dietary fat metabolism is regulated in Drosophila.

“This nuclear receptor plays a major role in sensing and regulating cholesterol and TAG uptake in the intestine in fruit flies,” Thummel says. “It functions similarly to the way LXR functions in humans, although we have a relatively poor understanding about how LXR controls these pathways.”

In his future studies, Thummel intends to learn more about how DHR96 regulates metabolism by studying the functions of the genes that it controls.

Source: Phil Sahm
University of Utah Health Sciences

Results of this paper, co-authored by Beatrice Golomb, MD, PhD, associate professor of medicine at UCSD School of Medicine, will appear in the April 26 issue of Archives of Internal Medicine.

“Our study confirms long-held suspicions that eating chocolate is something that people do when they are feeling down,” said Dr. Golomb. “Because it was a cross sectional study, meaning a slice in time, it did not tell us whether the chocolate decreased or intensified the depression.”

Golomb and her colleagues examined the relationship of chocolate consumption to mood in an adult study sample of about 1,000 subjects who were not on antidepressant medications and did not have any known cardiovascular disease or diabetes. Participants were asked questions regarding how many servings of chocolate they ate in a week, and were screened using the Center for Epidemiologic Studies Depression Scale (CES-D) to measure mood.

The researchers found that both men and women who had higher depression scores consumed almost 12 servings of chocolate per month, those with lesser depression scores ate about eight servings of chocolate per month, and those with no depression had five servings per month. No differentiation was made between dark and milk chocolate; a medium serving of chocolate was one ounce, which is slightly less than an average chocolate candy bar.

“The findings did not appear to be explained by a general increase in caffeine, fat, carbohydrate or energy intake, suggesting that our findings are specific to chocolate,” said Golomb. There was also no difference in the consumption of other antioxidant-rich foods, such as fish, coffee, fruits and vegetables between those with depression and those without.

Golomb added that future studies will be required to determine the basis of this association, as well as the role of chocolate in depression, as cause or cure.

Additional contributors are Sabrina Koperski, University of California, San Diego, Department of Medicine, and Natalie Rose, University of California, Davis, Department of Obstetrics and Gynecology.

This study was funded by grants from the National Heart, Lung, and Blood Institute and the UCSD General Clinical Research Center.

Source: University of California San Diego Health Sciences

Dr. Jay Udani, M.D. from Medicus Research, California, worked with a team of researchers to carry out a randomized, double-blind placebo controlled trial. He said, “For people drinking over half a liter of mangosteen juice a day, the degree of reduction in CRP levels was statistically significant – a reduction of 1.33mg/L compared to an increase of 0.9mg/L in the placebo group”.

Inflammation, as measured here by CRP, is a predictor of cardiovascular disease and a precursor of metabolic syndrome. Reducing inflammation in obese people is a treatment goal, and a natural treatment may be preferable to other treatments which may carry the risk of side effect. According to Udani, “Further studies with a larger population are required to confirm and further define the benefits of this juice, which was safe at all dosages tested”.

Notes:
Evaluation of Mangosteen juice blend on biomarkers of inflammation in obese subjects: a pilot, dose finding study.
Jay K Udani, Betsy B Singh, Marilyn L Barrett and Vijay J Singh
Nutrition Journal (in press)
http://www.nutritionj.com/

Source:
Charlotte Webber
BioMed Central

The analysis of this large Atherosclerosis Risk in Communities (ARIC) Study, which appears in the August issue of Journal of Lipid Research, was carried out by Keri Monda and colleagues at North Carolina and Baylor. They found that over a 12 year period, all individuals who increased their exercise by about 180 metabolic units per week (equivalent to an additional hour of mild or 30 minutes of moderate activity per week) displayed decreased levels of triglycerides and increased levels of the “good” HDL cholesterol. However, statistically significant decreases in the “bad” LDL cholesterol were only observed in women, with particularly strong effects in menopausal women and African-American women. And total cholesterol levels were only significantly decreased in African-American women.

The authors speculate that these novel differences may arise from hormonal differences between the sexes, especially considering the extra effects seen post-menopause. The racial differences observed may stem from genetic variations that require further exploration.

The authors do also note that their exercise data was assessed by questionnaire and this was non-scientific, though the particular methodology used has been extremely reliable in other studies. They also note that all evaluated participants were healthy, so these results cannot be generalized to individuals with diabetes or those on cholesterol-lowering medications.

From the article: Longitudinal impact of physical activity on lipid profiles in middle-aged adults: the Atherosclerosis Risk in Communities Study, by Keri L. Monda, Christie M. Ballantyne and Kari North

Source:
Nick Zagorski
American Society for Biochemistry and Molecular Biology

The research team studied a group of 13,475 women from the Nurses’ Health Study II. During 10 years of follow-up, 860 incident GDM cases were identified. After adjustment for known risk factors for GDM including age, family history of diabetes, parity, physical activity, smoking status, sugar-sweetened beverage intake, alcohol intake, prepregnancy BMI, and Western dietary pattern, intake of sugar-sweetened cola was positively associated with the risk of GDM. No significant association was found for other sugar-sweetened beverages or diet beverages.

“Compared with women who consumed less than 1 serving per month, those who consumed more than 5 servings per week of sugar-sweetened cola had a 22% greater GDM risk,” notes Dr. Chen.

Gestational diabetes mellitus (GDM), defined as glucose intolerance beginning during pregnancy, is one of the most common pregnancy complications. Women with GDM are at increased risk for complications and illness during pregnancy and delivery, as well as post-pregnancy type 2 diabetes. Children of mothers with GDM are at increased risk for obesity, glucose intolerance, and early onset diabetes.

Although the underlying mechanism remains unclear, available evidence suggests that the main defect in the development of GDM is relatively diminished insulin secretion coupled with pregnancy-induced insulin resistance. The researchers discuss a number of explanations of their findings. Consuming a large amount of sugar-sweetened beverages could contribute to a high glycemic load (GL) by providing a large amount of rapidly absorbable sugars. High-GL foods induce a greater plasma glucose response after eating which can result in insulin resistance and impaired beta cell function. (Pancreatic beta cells make insulin.) In addition, higher sugar intake itself may lead to impaired pancreatic cell function.

“We don’t know why significant association was only found in sugar-sweetened cola, but not other types of sugar-sweetened beverages – fruit drinks, other soft drinks, etc.,” says Dr. Chen. “One of the explanations could be the tremendous popularity of cola in the US.”

Previous studies in children and adults have shown that regular consumption of sugary drinks is associated with excess caloric intake, greater weight gain, and increased risk of obesity. Sugary drinks have also been linked to type 2 diabetes and other metabolic disorders.

“This is the first study on the impact of sugar-sweetened beverages on GDM risk,” notes Dr. Chen. “This finding is important because sugar-sweetened beverages are the leading source of added sugars in the American diet, particularly in the age group most likely to conceive. Cutting down sugary drinks is clearly an important way to reduce this common pregnancy complication.”

According to the National Health and Nutrition Examination Survey 1999-2001, from 1977 to 2001, soft drink intake increased from 4.1% to 9.8% for 19- to 39-year-olds. In percentage terms, soft drink intake was highest among this age group in comparison to other ages.

This study was supported by the National Institutes of Health and part of the work was done when Dr. Chen received an Intramural Research Training Award Fellowship under Dr. Cuilin Zhang (senior author) at the Division of Epidemiology, Statistics, and Prevention Research at the NICHD.

Source:
Leslie Capo
Louisiana State University Health Sciences Center