Among people with type 2 diabetes, eating pistachios may reduce the body's response to the stresses of everyday life, according to Penn State researchers.
"In adults with diabetes, two servings of pistachios per day lowered vascular constriction during stress and improved neural control of the heart," said Sheila G. West, professor of biobehavioral health and nutritional sciences. "Although nuts are high in fat, they contain good fats, fiber, potassium and antioxidants. Given the high risk of heart disease in people with diabetes, nuts are an important component of a heart healthy diet in this population."
West and her colleagues investigated the effects of pistachios on responses to standardized stress tasks in patients with well-controlled Type 2 diabetes who were otherwise healthy. They used a randomized, crossover study design in which all meals were provided. Each of the diets contained the same number of calories.
After two weeks on the typical American diet -- containing 36 percent fat and 12 percent saturated fats -- participants were randomized to one of two test diets. During the four-week test diets, participants ate only food supplied by the study. The researchers reported the results of this study in a recent issue of the Journal of the American Heart Association.
Test diets included a standard heart-healthy diet -- 27 percent fat and 7 percent saturated fat -- and a diet containing two servings per day of pistachios -- about 3 ounces or 20 percent of calories from pistachio nuts. The typical research participant consumed about 150 pistachio nuts per day.
The pistachio diet contained 33 percent fat and 7 percent saturated fat. Half of the nuts consumed each day were salted and half were unsalted. At the end of each four-week diet period, the researchers measured blood pressure and total peripheral vascular resistance at rest and during two stress tests -- a cold water challenge and a confusing mental arithmetic test.
"After the pistachio diet, blood vessels remained more relaxed and open during the stress tests," West said.
Although laboratory measurements of blood pressure were not affected by pistachios, real-world measures of blood pressure (measured by an automated monitor) were significantly lower after the pistachio diet. Katherine A. Sauder, former graduate student in biobehavioral health, conducted these measurements.
"We found that systolic blood pressure during sleep was particularly affected by pistachios," she said. "Average sleep blood pressure was reduced by about 4 points and this would be expected to lower workload on the heart."
The researchers found that the pistachio diet lowered vascular constriction during stress. When arteries are dilated, the load on the heart is reduced. The physical challenge involved immersing one hand into icy water for two minutes.
"This cold stressor produces a large vascular constriction response in most people," said West. "In comparison with a low fat diet, the pistachio diet blunted that vascular response to stress."
The same pattern was seen when participants engaged in a challenging and confusing mental arithmetic task.
"Our participants still felt frustrated and angry during the math test," West noted. "The pistachio diet reduced their bodies' responses to stress, but nuts are not a cure for the emotional distress that we feel in our daily lives."
Sauder added: "As in our last study of pistachios, we did not see lower blood pressure in the laboratory setting with this dose of nuts. However, we were surprised and pleased to see that 24-hour ambulatory blood pressure was lower after the pistachio diet."
The researchers also recorded improvements in heart rate variability, a measure of how well the nervous system controls heart function. These data indicate that pistachios increased the activity of the vagus nerve, an important part of the parasympathetic nervous system that can be damaged with diabetes.
"If sustained with longer term treatment, these improvements in sleep blood pressure, vascular response to stress and vagal control of the heart could reduce risk of heart disease in this high risk group," West said.
Other researchers on this study included Cindy E. McCrea, graduate student in biobehavioral health; Jan S. Ulbrecht, endocrinologist and professor of biobehavioral health and medicine; and Penny M. Kris-Etherton, Distinguished Professor of Nutritional Sciences.
The American Pistachio Growers, formerly the Western Pistachio Association, supported this study. Partial support also came from the NIH-supported Clinical Research Center at Penn State.
A'ndrea Elyse Messer | Eurek Alert!
New evidence: How amino acid cysteine combats Huntington's disease
27.07.2016 | Johns Hopkins Medicine
Cord blood outperforms matched, unrelated donor in bone marrow transplant
27.07.2016 | University of Colorado Anschutz Medical Campus
Transparent electronics devices are present in today’s thin film displays, solar cells, and touchscreens. The future will bring flexible versions of such devices. Their production requires printable materials that are transparent and remain highly conductive even when deformed. Researchers at INM – Leibniz Institute for New Materials have combined a new self-assembling nano ink with an imprint process to create flexible conductive grids with a resolution below one micrometer.
To print the grids, an ink of gold nanowires is applied to a substrate. A structured stamp is pressed on the substrate and forces the ink into a pattern. “The...
A new Fraunhofer MEVIS method conveys medical interrelationships quickly and intuitively with innovative visualization technology
On the monitor, a brain spins slowly and can be examined from every angle. Suddenly, some sections start glowing, first on the side and then the entire back of...
Researchers at the U.S. Department of Energy's (DOE) Ames Laboratory have discovered an unusual property of purple bronze that may point to new ways to achieve high temperature superconductivity.
While studying purple bronze, a molybdenum oxide, researchers discovered an unconventional charge density wave on its surface.
Munich Physicists have developed a novel electron microscope that can visualize electromagnetic fields oscillating at frequencies of billions of cycles per second.
Temporally varying electromagnetic fields are the driving force behind the whole of electronics. Their polarities can change at mind-bogglingly fast rates, and...
Breakup of continents with two speed: Continents initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. The final speed can be up to 20 times faster than in the first, slow extension phase.phases
Present-day continents were shaped hundreds of millions of years ago as the supercontinent Pangaea broke apart. Derived from Pangaea’s main fragments Gondwana...
15.07.2016 | Event News
15.07.2016 | Event News
11.07.2016 | Event News
28.07.2016 | Information Technology
28.07.2016 | Materials Sciences
28.07.2016 | Earth Sciences