Getting Forgetful? Then Blueberries May Hold The Key

ScienceDaily (Apr. 12, 2008) If you are getting forgetful as you get older, then a research team from the University of Reading and the Peninsula Medical School in the Southwest of England may have good news for you

They have found that phytochemical-rich foods, such as blueberries, are effective at reversing age-related deficits in memory, according to a study soon to be published in the science journal Free Radical Biology and Medicine. The researchers working at the Schools of Food Biosciences and Psychology in Reading and the Institute of Biomedical and Clinical Sciences at the Peninsula Medical School in Exeter supplemented a regular diet with blueberries over a 12-week period, and found that improvements in spatial working memory tasks emerged within three weeks and continued throughout the period of the study.

Blueberries are a major source of flavonoids, in particular anthocyanins and flavanols. Although the precise mechanisms by which these plant-derived molecules affect the brain are unknown, they have been shown to cross the blood brain barrier after dietary intake. It is believed that they exert their effects on learning and memory by enhancing existing neuronal (brain cell) connections, improving cellular communications and stimulating neuronal regeneration.

The enhancement of both short-term and long-term memory is controlled at the molecular level in neurons. The research team was able to show that the ability of flavonoids to induce memory improvements are mediated by the activation of signalling proteins via a specific pathway in the hippocampus, the part of the brain that controls learning and memory.

This innovative research was conducted by a multidisciplinary research team led by Dr. Jeremy Spencer, a lecturer in Molecular Nutrition at the University of Reading and included Dr. Claire Williams, a Psychologist also from Reading and Dr. Matt Whiteman, a Principal Investigator at the Institute of Biomedical and Clinical Science, Peninsula Medical School. Dr Spencer commented: "Impaired or failing memory as we get older is one of life's major inconveniences. Scientists have known of the potential health benefits of diets rich in fresh fruits for a long time. Our previous work had suggested that flavonoid compounds had some kind of effect on memory, but until now we had not known the potential mechanisms to account for this".

Dr. Whiteman added "This study not only adds science to the claim that eating blueberries are good for you, it also provides support to a diet-based approach that could potentially be used to increase memory capacity and performance in the future. Indeed, Dr. Spencer's research team plan on extending these findings further by investigating the effects of diets rich in flavonoids on individuals suffering from cognitive impairment and Alzheimer's disease."

Adapted from materials provided by The Peninsula College of Medicine and Dentistry


Natural Purple Pigments In Fruits, Vegetables And Berries, Such As Blueberries, May Help Prevent Obesity

Here's to purple power: Colorful pigments found in the skin of blueberries, strawberries and other fruits and vegetables may help prevent obesity, according to recent animal studies. (Courtesy of USDA Agricultural Research Service)

ScienceDaily (Feb. 14, 2008) Scientists in Arkansas are reporting new evidence that natural pigments responsible for the beautiful blue/purple/reddish color of certain fruits and vegetables may help prevent obesity. Their animal study however, reports that eating the whole fruit containing these pigments seems to be less effective than eating an extract of the berry.

Ronald L. Prior and colleagues, who did the new study, note that past research has shown that the pigments -- called anthocyanins -- prevent obesity in laboratory mice fed a high-fat diet. Anthocyanins are found in grape skins, blueberries, blackberries, purple corn, and other foods. The mice also had other healthful changes in disease-related substances found in the blood.

In the new study, researchers found that mice fed a high-fat diet for 8 weeks plus drinking water with purified anthocyanins from blueberries and strawberries gained less weight and had lower body fat levels than a control group. "Anthocyanins fed as the whole blueberry did not prevent and may have actually increased obesity," the study reported. "However, feeding purified anthocyanins from blueberries or strawberries reduced obesity."

The article "Whole Berries versus Berry Anthocyanins: Interactions with Dietary Fat Levels in the C57BL/6J Mouse Model of Obesity" is scheduled for the Feb. 13 issue of ACS' Journal of Agricultural and Food Chemistry.

Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.


Wild Blueberries May Help Protect Arteries, Reduce Risks From Cardiovascular Disease

ScienceDaily (Nov. 3, 2003) ORONO, Maine -- A University of Maine nutritionist has found evidence that consumption of wild blueberries can help arteries relax and reduce risks associated with cardiovascular disease. The project is the first using rats fed blueberry diets to demonstrate a relationship between consumption of whole wild blueberries and processes that can lead to high blood pressure.

The study was published earlier this year in the FASEB Journal, published by the American Societies for Experimental Biology.

Cardiovascular disease is the leading cause of death in the United States. Previous studies with cell cultures have shown that antioxidants such as anthocyanines contained in wild blueberries may help protect cells. Wild blueberry consumption in laboratory rats has also been linked to improvements in memory and motor skills.

At UMaine, Dorothy Klimis-Zacas, professor in the Dept. of Food Science and Human Nutrition, led a team of graduate and undergraduate students in a two-year research project that was supported by the Maine Agriculture and Forestry Experiment Station, the Maine Wild Blueberry Commission, the U.S. Dept. of Agriculture and the Wild Blueberry Association of North America. "Our experiments focused on the effect of whole wild blueberries on the biomechanical properties of arteries as related to cardiovascular disease," says Klimis-Zacas. "This is the first in-vivo study to examine this relationship."

Students working on the project included Cynthia Norton and Anastasia Kalea, master's and Ph.D. candidates respectively in the department.

Researchers found that arteries of Sprague-Dawley laboratory rats fed a diet enriched with wild blueberries generated less force in response to phenylephrine, a stress hormone, than did arteries in rats fed the same diet without blueberries. "Those arteries (in rats fed the blueberry enriched diet) were more relaxed. When they were challenged with the stress hormone, they didn't develop as much force. We know now that blueberries affect the contractile machinery of the artery," says Klimis-Zacas.

The finding is important because the force with which an artery responds to stress can directly affect blood pressure. Norton and Klimis-Zacas presented the results of the study at the 2003 annual conference of the Federation of American Societies for Experimental Biology in San Diego, California and to the Wild Blueberry Association of North America in Bar Harbor, Maine.

The apparent benefit of the blueberry enriched diet carried over to older rats which received blueberries later in the study. The implication is that the addition of wild blueberries to the diet later in life may still have a protective effect on arteries.

The study has not been replicated in humans, and the researchers did not identify the compounds in wild blueberries that affect arteries. However, it is likely that high concentrations of antioxidants and trace minerals such as manganese which are high in blueberries could explain the beneficial effect, says Klimis-Zacas.

During the project, three groups of rats containing ten animals per group were fed the same diets with the exception of ground, whole wild blueberries. One group received the blueberry addition for the entire time, while another group had the same diet without blueberries. To test the addition of blueberries to the diet later in life, the third group received a diet without blueberries for 14 weeks followed by a blueberry enriched diet for eight weeks.

The amount of blueberries given to the rats per day corresponds to between one and two cups of blueberries per day for humans.

Researchers then surgically removed the aortas from each rat. They cut four ring sections from each aorta and tested the force generated by each section in response to the presence of hormones that stimulate arteries to relax or contract. During the tests, the arterial ring sections were hung in a tissue bath under conditions that mimicked the body's internal chemical environment.

In a second round of experiments, researchers wanted to find out what layers in the artery are affected by blueberries. They focused on the inside surface of the artery, a layer of cells known as the endothelium.

"Increasing vascular resistance may lead to an elevation of blood pressure which may in turn damage the delicate endothelial layer," says Klimis-Zacas. "This layer is affected by many things in the blood. By removing the endothelium, we are left with the smooth muscle layer of the artery, and we can localize the effect of wild blueberries in response to stress hormones. "

In these tests, researchers purposely damaged a portion of the endothelium and then exposed the arteries to the hormones. "We found that when we remove the endothelium, the artery cannot relax. And the contractile force it exerts in response to the stress hormone is about three times what it was with the intact arterial rings," says Klimis-Zacas.

The endothelial layer is known to be an important source of nitric oxide that helps to relax the arteries. "You can imagine what happens with atherosclerosis. Your endothelium gets damaged. There are many different relaxation factors in the endothelium, but nitric oxide is a major one. We think that blueberries may function by preserving the bioavailability of nitric oxide," says Klimis-Zacas.

"We know that nitric oxide concentration decreases at the onset of cardiovascular disease. By preserving nitric oxide bioavailabilty, blueberries may aid in maintaining arterial relaxation and thus prevent elevation of blood pressure that damages the endothelium and contributes to cardiovascular disease," says Klimis-Zacas.

Future research is planned with rats that have high blood pressure, she says, to see if blueberries will lower blood pressure. A key will be the role of antioxidants in endothelium function.

Adapted from materials provided by University Of Maine.