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Department of Agriculture - Latest Research in Nutrition

ARS is the U.S. Department of Agriculture's chief scientific research agency.

Dietary Copper May Ease an Ailing Heart.

By Rosalie Marion Bliss, March 22, 2007

Copper is an essential trace element that acts as a cofactor for the physiological function of many proteins. Tiny amounts are contained in hundreds of copper-dependent proteins that perform essential biological functions in animals and humans.

Hypertrophy is an increase in the size of a tissue or organ. For the study, the researchers challenged two groups of mice for two months, resulting in cardiac hypertrophy - a condition in which the heart becomes bigger followed by disease. Enlarged hearts often occur in response to elevated blood pressure.

Both groups were fed the equivalent of the recommended dietary amount of copper for adults for the entire two months. But after the first month, the test group's diet was increased to contain the equivalent of three times the human recommended amount of dietary copper - an amount that was still just one-third of the equivalent safe upper limit for humans.

By four weeks, heart disease developed in all the mice, and by eight weeks, heart failure developed in the control mice. But the hearts of the mice receiving the extra copper returned to normal size and function, despite the fact that the cardiac challenge continued throughout the eight-week period.

In human hypertrophic heart disease, enlarged heart muscle leads to shortness of breath during exertion, discomfort caused by reduced blood supply to the heart muscle and/or abnormal heart rhythms.

Confirmational, controlled human research studies are needed in which volunteers with hypertrophic heart disease consume copper-rich diets. But this mouse study suggests that consuming more copper in the diet may help people with hypertrophic, or thickened, heart muscle conditions.

For a list of foods that are good sources of copper, go to the USDA site by clicking here, and click on "copper", to see the presence of this element in a number of foods. The list will sort foods in descending order by copper content in terms of common household measures.

New Findings about Dairy Consumption and Body Composition.

By Alfredo Flores, April 10, 2007

Obesity is one of the most prevalent public health problems in the United States, with nearly two-thirds of the adult population-roughly 97 million Americans over the age of 20-considered overweight or obese. This study provided an opportunity for researchers to follow a well-defined biracial (whites and blacks) population representative of the total community to further investigate associations between calcium intake, dairy product consumption and overweight.

Participants included 1,306 young adults ranging from 19 to 38 years old from Bogalusa, LA, and surrounding areas. Of these, 31 percent of black males were considered overweight, compared to 30 percent of white males, while 48 percent of black females were overweight, compared to 29 percent of white females.

Two measures were used to determine who was obese. The first was the body mass index, a measure that correlates height with body fat. The second was waist-to-hip ratio (WHR), which shows how fat is distributed around the torso.

A 0.7 WHR for women and 0.9 for men have been shown to correlate strongly with good general health. Women within the 0.7 WHR range are less susceptible to major diseases such as diabetes, cardiovascular disorders and ovarian cancers. Men with WHRs around 0.9 have also been shown to be healthier, with less prostate or testicular cancer.

No significant association was found between dairy product consumption, calcium intake and overweight, as defined by body mass index or waist circumference. But white males in the study who ate more calcium and low-fat dairy products benefitted by having a reduction in their WHR.

Beneficial Bacteria Boost Intestinal Health

By Rosalie Marioin Bliss, November 17, 2006

Healthy animals and humans benefit every day from trillions of natural intestinal bacteria. These friendly bacteria help keep "bad" bacteria from gaining a foothold that could lead to illness or disease. In the first study, the common probiotic strain Bb 12 was fed to three pregnant sows, while a placebo treatment was fed to three pregnant control sows. The scientists then fed the same Bb 12 treatment to half of each sow's litters, resulting in four experimental groups.

Solano-Aguilar studied gene expression patterns in tissue taken from each animal's lymph nodes, liver, spleen and intestine. She also studied the animals' intestinal contents. The team then compared the gene expression patterns in the pigs from all four groups. The probiotic was found to induce innate immune activity in the colon where the probiotic was in highest concentration.

In a separate study, half of a group of test pigs were treated with the Bb 12 probiotic before all of the test pigs were exposed to a worm infection. The researchers then compared the response to infection of the group of pigs that received the probiotic treatment with the response of those that did not receive the treatment. Preliminary results show better response to the infection-and improved nutrient absorption-in the group of pigs that were supplemented with the probiotic treatment prior to the infection.

Can Fish Intake Predict Chances of Developing Dementia?

By Rosalie Marion Bliss, November 14, 2006

People who ate the most fish on a weekly basis-putting them in the top quarter of a study population-were nearly 50 percent less likely to develop the mental deterioration known as dementia over time than participants in any of the other three quarters.

The observational study was led by Ernst J. Schaefer, an Agricultural Research Service-funded scientist. ARS is the U.S. Department of Agriculture's chief scientific research agency. Schaefer is a physician specializing in nutrition and health with the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Mass.

He and co-authors were looking for a relationship between blood levels of the fatty acid DHA and the risk of developing dementia. DHA is short for docosahexaenoic acid, a so-called "heart-healthy" omega-3 fatty acid. Several different studies have linked either low DHA, or low fish intake levels, with the incidence of dementia.

The study was published in the November 13 issue of the Archives of Neurology. Schaefer and colleagues analyzed available dietary questionnaires and blood levels of DHA of nearly 900 men and women, aged 55 to 88, who participated in the longitudinal Framingham (Mass.) Heart Study.

At the beginning of a nine-year period, all of the participants were found to be free of dementia. Using proportional regression analysis, the researchers determined the relative impact not only of blood levels of DHA, but also of potential "confounding" variables such as age, gender, homocysteine and apolipoprotein-E levels, genotype and education.

They found that the participants who reported consuming an average of about three servings of oily fish a week-equivalent to blood levels of DHA at 180 milligrams daily-were associated with a significantly reduced risk of developing dementia of all types, including Alzheimer's disease. No other fatty acid blood level was independently linked to the risk of dementia.

The study suggests that relatively higher fish consumption over time correlates with a lower incidence of dementia in the over-55 set.

Weight Loss Study Focuses on Dairy Foods

By Marcia Wood, April 27, 2007

Determined northern California dieters are helping Agricultural Research Service (ARS) nutrition researchers learn more about the role that low-fat, calcium-rich dairy foods play in healthful weight-loss regimens. The volunteers: men and women aged 22 to 45 who are nonsmokers and are 45 to 100 pounds overweight, are completing 15-week stints in which they eat varying amounts of dairy foods as part of their everyday meals and snacks.

Earlier studies, conducted elsewhere, suggest that calcium from low-fat dairy foods enhances loss of unwanted pounds and fat. The California study, led by ARS research physiologist Marta D. Van Loan, focuses on the number of servings of dairy foods eaten per day and, as such, may shed new light on previous findings.

For example, for three weeks of the study, volunteers will eat "low-dairy" meals and snacks as is typical of their normal diets, eating only one serving of dairy foods a day, according to Van Loan. For another 12 weeks of the study, they will be assigned to either a high-dairy diet with three servings of dairy foods (milk, yogurt and cheese) or stay with the low-dairy plan of one daily serving.

One serving of dairy equals either one glass of milk, two ounces of cheese or one cup of yogurt, for example.

Van Loan is based at the agency's Western Human Nutrition Research Center, Davis, Calif. She's doing the work with ARS physiologist Sean H. Adams and chemist Nancy L. Keim, both of the nutrition center, and with co-investigators at the University of California-Davis, UC Davis Medical Center, and Iowa State University at Ames.

This ARS study is being supported in part by the National Dairy Council of Rosemont, Ill., and the Dairy Council of California, in Sacramento. Van Loan expects to have preliminary results by early 2008. The findings may help combat America's obesity epidemic. An estimated 97 million adults in this country are overweight or obese.

Sources: National Agricultural Library, Agricultural Research Service, U. S. Department of Agriculture.

Adapted by Editorial Staff, October 2007
Last update, August 2008


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