Brain fatty acid levels linked to depression

A group of Israel researchers has discovered that rats with increased levels of the omega-6 fatty acid, arachidonic acid, show signs of depression.  There is also evidence that  a dietary deficiency in omega-3 fatty acids may be associated with depression.  The  ”phospholipid hypothesis” postulates decreased omega-3 fatty acid intake could be responsible for some types of depression.

The details of their findings appear in the Journal of Lipid Research  showing that omega-3 fatty acid concentration in the blood of depressed patients is lower than that in control patients.  Dr. Green in collaboration with Dr Gal Yadid of Bar-Ilan University, Ramat Gan used the Flinders Sensitive Line rats to investigate the link between omega-3 fatty acids and depression. They examined the brains of the depressed rats and compared them with brains from normal rats. Surprisingly, they found that the main difference between the two types of rats was in omega-6 fatty acid levels and not omega-3 fatty acid levels. Specifically, they discovered that brains from rats with depression had higher concentrations of arachidonic acid, a long-chain unsaturated metabolite of omega-6 fatty acid.

Arachidonic acid is found throughout the body and is essential for the proper functioning of almost every body organ, including the brain. It serves a wide variety of purposes, from being a purely structural element in phospholipids to being involved in signal transduction and being a substrate for a host of derivatives involved in second messenger function.

“The finding that in the depressive rats the omega-3 fatty acid levels were not decreased, but arachidonic acid was substantially increased as compared to controls is somewhat unexpected,” admits Dr. Green. “But the finding lends itself nicely to the theory that increased omega-3 fatty acid intake may shift the balance between the two fatty acid families in the brain, since it has been demonstrated in animal studies that increased omega-3 fatty acid intake may result in decreased brain arachidonic acid.”

Although far less attention has been paid to dietary requirements for omega-6 fatty acids, which can be found in most edible oils and meat, perhaps in the future depression may be controlled by increasing omega-3 fatty acid intake and decreasing omega-6 fatty acid intake.

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Article adapted by MD Only from original press release.
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Contact: Nicole Kresge
American Society for Biochemistry and Molecular Biology 
The American Society for Biochemistry and Molecular Biology (ASBMB) is a nonprofit scientific and educational organization with over 11,000 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions, and industry.

The manuscript for the Journal of Lipid Research paper can be downloaded from clicking Here

CLA found to successfully treat diabetes in mice

Fatty acids commonly found in dairy products have successfully treated diabetes in mice, according to a researcher at Penn State. The compounds, known as conjugated linoleic acids (CLA), have also shown promising results in human trials, signaling a new way of potentially treating the disease without synthetic drugs.

“The compounds are predominantly found in dairy products such as milk, cheese and meat, and are formed by bacteria in ruminants that take linoleic acids – fatty acids from plants – and convert them into conjugated linoleic acids, or CLA,” says Jack Vanden Heuvel, professor of molecular toxicology in Penn State’s College of Agricultural Sciences and co-director of Penn State’s Center of Excellence in Nutrigenomics.

Researchers first became interested in CLA when it was shown to inhibit a variety of cancers such as breast, skin and colon in mice, and further research showed effects on circulating cholesterol and inflammation. These effects are the same as the newest generation of synthetic drugs used to treat diabetes in humans.

These synthetic drugs act by triggering a set of nuclear receptors called PPAR. In addition to being targets for a variety of clinically effective drugs, PPARs belong to a large family of proteins, and their biological purpose is to sense fatty acids and fatty acid metabolites within the cell, says Vanden Heuvel.

When the synthetic drugs interact with these protein receptors, it turns the receptor “on,” making it an active form of the protein, which then interacts with DNA and regulates gene expression. This increases the enzymes that process fatty acids and also increases the tissues’ sensitivity to insulin.

“We wondered if CLA was using the same mechanism, in which case it could be used as an anti-diabetes drug,” Vanden Heuvel says.

To test the idea, he used CLA on mice prone to adult onset (Type-2) diabetes. Results indicated that the mice had an improvement in insulin action, and a decrease in circulating glucose. Also, the mechanism was indeed similar to that of the drugs.

“Anti-diabetes drugs act the same way. They mimic the natural activators of the receptors by getting into the cell and interacting with the PPARs to regulate glucose and fat metabolism,” says Vanden Heuvel.

Early human trials indicate that when administered for longer than 8 weeks, CLA improves the body’s misregulation of insulin and lowers the level of glucose in the blood in patients with adult onset, or Type-2 diabetes, the most common form of this disease.

However, Vanden Heuvel cautions that while having a diet that is high in dairy and meat products, and thereby CLA, might have a health benefit, one must also be aware of other lipids present in these products, such as trans fatty acids. Instead, he suggests that in addition to a well-balanced diet, it is advantageous to incorporate CLA as a dietary supplement, or to seek out new products that enrich foods such as butter, margarine and ice cream with CLA.

“Adult-onset diabetes is fast becoming an epidemic and is largely associated with poor diet and nutrition and other lifestyle issues,” Vanden Heuvel says. The reason for the increase in diabetes may have to do with the ratio of so-called “good” and “bad” fats, with the average American diet containing too much of the “bad” fats. CLA, whose effect is very similar to fish oil, a source of “good” fat, could prove beneficial against Type-2 diabetes.

“And compared to the synthetic drugs used to treated this disease, CLA does not cause weight gain and may in fact decrease overall body fat,” says Vanden Heuvel, who has been granted a patent on the new method of treating diabetes with CLA.

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Article adapted by MD Only Weblog from original press release.
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Contact: Amitabh Avasthi
Penn State

CLA reduces weight, blood sugar and leptin levels

Supplementing the diet with a certain fatty acid may lead to better weight control and disease management in diabetics, a new study suggests.Diabetics who added an essential fatty acid called conjugated linoleic acid (CLA) to their diets had lower body mass as well as lower blood sugar levels by the end of the eight-week study. Hyperglycemia, or high blood sugar, is a hallmark of diabetes.

Researchers also found that higher levels of this fatty acid in the bloodstream meant lower levels of leptin, a hormone thought to regulate fat levels. Scientists think that high leptin levels may play a role in obesity, one of the biggest risk factors for adult-onset diabetes.

“In previous work, we found that CLA delayed the onset of diabetes in rats,” said Martha Belury, the senior author of the study and an associate professor of human nutrition at Ohio State University. “In this study, we found that it also helped improve the management of adult-onset diabetes in humans.”

CLA is made up of various fatty acid isomers – compounds that share the same chemical formula but differ in chemical structure. Related isomers can have very different effects.

In the current study, the researchers found that one particular CLA isomer, t10c12-CLA, helped control both body weight and leptin levels. Nutritionists sometimes call this isomer the 10-12, isomer.

The research appears in the January issue of the Journal of Nutrition. Belury conducted the study while with the department of foods and nutrition at Purdue University. She is continuing the research at Ohio State.

The researchers asked 21 people with adult-onset diabetes to take either a supplement containing a mix of rumenic acid and 10-12 isomer or a safflower oil supplement as a control. The group was divided roughly in half. Rumenic acid is the predominant isomer in foods that contain CLA, while the 10-12 isomer is less abundant.

Participants were instructed to take their respective supplements every day for eight weeks.

“The amount of CLA, how long it’s taken and the type taken all impact the fatty acid’s ability to affect obesity in humans, and therefore help manage diabetes.”

While CLA supplements are available to consumers, Belury encourages diabetics to get their CLA from food sources – primarily beef, lamb and dairy products.

“Not only does it taste better, it’s also safer and more beneficial to get the nutrients from food,” she said. “Besides, we don’t yet know the long-term effects of taking CLA in supplement form.”

At the end of the trial, the researchers took blood samples from each participant to check CLA levels. By then, fasting blood glucose levels had decreased in nine of the 11 people taking the CLA supplement, but only in two of the 10 taking safflower supplements, meaning that CLA was helping to control certain symptoms of diabetes.

Fasting blood glucose levels decreased nearly five-fold in patients taking CLA, compared to patients taking the safflower oil.

The researchers also studied the impact each isomer had on changes in body weight and levels of the hormone leptin.

It was the 10-12 isomer, and not rumenic acid, that was linked to a reduction in body weight and leptin levels. While the average weight loss among patients taking CLA supplements was small (about 3.5 pounds), they had been asked to not change their normal caloric intake during the study. The group taking safflower supplements neither lost nor gained weight. Leptin levels decreased in the CLA group, and rose slightly in the safflower group.

“The effect of the 10-12 isomer on reducing body mass and leptin levels was key,” Belury said, adding that other researchers have shown the 10-12 isomer to be helpful in reducing body mass in animals.

“The amount of CLA, how long it’s taken and the type taken all impact the fatty acid’s ability to affect obesity in humans, and therefore help manage diabetes,” Belury said.

A 2002 study conducted by the Diabetes Prevention Program Research Group found that a modest reduction in body weight resulted in a 58 percent reduction in the incidence of diabetes in a group of people at high risk for developing the disease.

Belury conducted the study with Annie Mahon of the department of foods and nutrition at Purdue University and Sebastiano Banni of the department of experimental biology at the University of Cagliari, Italy.

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Article adapted by MD Only Weblog from original press release.
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Contact: Martha A. Belury
Ohio State University