Called HPMC (hydroxypropylmethylcellulose), the cellulose-derivative has been used for half-a-century as an additive in many foods and drugs, mostly to provide texture, but the researchers believe this is the first study to demonstrate its potential as a functional food ingredient. HPMC, which is tasteless and odorless, could one day be added to hamburgers, pizza, hot dogs and other high-fat foods as a novel line of defense against diabetes, which is on the rise in this country, the researchers say.
If the findings prove true in human studies, it could benefit young people, who tend to be frequent consumers of high-fat fast-foods. Although HPMC isn't likely to prevent obesity, the compound may reduce the chances that obese people will develop diabetes and its deadly complications, particularly heart disease, the researchers note. This study was funded by the USDA.
"Obviously, the less fat you eat, the better off you are. But if you're going to eat high fat foods, then adding HPMC to it might help limit the damage," says Wallace H. Yokoyama, Ph.D., a research chemist with USDA's Agricultural Research Service in Albany, Calif. "In our studies with hamsters, adding HPMC to the animals' high-fat diet prevented development of insulin resistance."
The compound could actually make its way into food products as a functional food additive within one to two years, he estimates. Human studies are anticipated.
Over a four-week period, Yokoyama's research team fed a group of hamsters a high-fat diet -- about 38 percent of calories derived from fat -- similar to the fat content of typical American fast-food diets. Results were then compared to a group of animals that were fed a low-fat (11 percent fat-derived calories) diet. As expected, the animals fed the high-fat diets developed insulin resistance, but the animals fed the low-fat diet did not. But when soluble cellulose in the form of HPMC was substituted for the insoluble fiber normally found in the high-fat diets and then fed to another group of test animals over the same period, it prevented insulin resistance, according to the researchers.
Using special analytical techniques, the investigative team also studied metabolic changes in the test animals at the genetic level. They found significant differences in gene expression, as measured by messenger RNA changes, between animals that became insulin resistant and those that did not, they say.
Although the exact mechanism by which HPMC works is unclear, Yokoyama believes that it acts as a fat regulator. The compound appears to slow down the absorption of fats -- either in the stomach, small intestine, or both -- preventing high fat levels from overwhelming the digestive system, he says. The compound also seems to facilitate the normal transport of fat into the adipose tissue, where it is normally stored, he adds.
By contrast, fats that are taken into the body too quickly, as during a fast-food binge, tend to be rapidly shunted to non-adipose tissues such as the liver, heart and pancreas, where they can do extensive damage to cells. Pancreatic damage can lead to diabetes.
HPMC, which is manufactured by Dow Chemical Company, is used in many common food products such as fillings, sauces and glazes, where it usually functions as a texture modifier. Although it constitutes from 0.5 to 1.5 percent of the total ingredients found in individual servings of most of these food products, the researchers say that it will likely be added in higher proportions if used in food as a diabetes-fighter.
Already proven to be safe at lower amounts, the researchers do not anticipate that HPMC will cause any adverse effects at higher amounts. Based on animal studies, the researcher estimates that only a few grams (approximately 5 grams) would be needed to have a positive impact on health. But further studies are needed to determine effective doses, Yokoyama says.
In addition to Yokoyama, other researchers in this study include Qiming Shao and Gerard R. Lazo, also of the Agricultural Research Service; Wei-Shou Hu and Katie Wlaschin, of the University of Minnesota; and Peter M. Nissom and Miranda G.S. Yap, of the Bioprocessing Technology Institute in Singapore.
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The paper on this research, AGFD 103, will be presented at 1:35 p.m., Tuesday, March 15, at the Horton Grand, Regal B, during the "Dietary Supplements" symposium.
Wally Yokoyama, Ph.D., is a research chemist with the U.S. Department of Agriculture's Agricultural Research Service, Western Regional Research Center, in Albany, Calif.
AGFD 103 Hydroxypropylmethylcellulose (HPMC) prevents insulin resistance in hamsters fed high saturated fat diets through regulation of metabolic genes
Qiming Shao1, Katie Wlaschin2, Wallace H. Yokoyama1, Peter M. Nissom3, Miranda G.S. Yap3, Wei-Shou Hu2, and Gerald Lazo1. (1) Western Regional Research Center, USDA-ARS, 800 Buchanan St., Albany, CA 94710-1105, Fax: 510-559-5777, firstname.lastname@example.org, Phone: 510-559-5695, (2) Department of Chemical Engineering and Materials Science, University of Minnesota, (3) Bioprocessing Technology Institute
Syrian hamsters fed a high fat (HF) diet similar in fat content to the American diet become insulin resistant (IR). We have shown earlier that replacing cellulose in this HF diet with hydroxypropylmethylcellulose (HPMC) significantly decreases the incidence of IR. HPMC significantly reduced the glucose infusion rate, fasting plasma insulin, plasma lipids, overall fat distribution in non-adipose tissues, and the cell size of adipose tissues. The underlying mechanisms of these beneficial physiological effects are unknown. A cDNA microarray, constructed from Chinese hamster ovary cells, was used to analyze gene expression in liver tissues from hamsters fed the HF or the HF with HPMC diets. Genes related to fat metabolism, glucose metabolism, insulin metabolism, inflammation, and glucose transport, were differentially expressed between the two groups. These results indicate that HPMC may prevent the cellular oxidative damage leading to diabetes by normalizing fat metabolism.