A new study conducted by researchers at Penn State shows that eating two servings of pistachio nuts a day can lower vascular constriction during stress, thus improving the heart’s ability to function, especially in type 2 diabetics. In fact, results indicated that pistachios effectively increased the activity of the vagus nerve (part of the parasympathetic nervous system that can be damaged with diabetes).
"When arteries are dilated, the load on the heart is reduced. 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." stated Sheila G. West, professor of bio-behavioral health and nutritional sciences, who led the investigation regarding the effects of the nuts had regarding responses to standardized stress tasks in patients who were considered to be healthy despite having (well-controlled) Type 2 diabetes. To do this, West and her team used a randomized, crossover study design in which all meals were provided. Each of the diets contained the same number of calories.
During the first two weeks, participants ate a “typical American diet” containing 36% fat and 12% percent saturated fats. This was followed by four weeks in which participants were fed only food supplied by the study. A physical challenge involved immersing one hand into icy water for 2 minutes was used to test stress levels.
"After the pistachio diet, blood vessels remained more relaxed and open during the stress tests. This cold stressor produces a large vascular constriction response in most people," noted West. "The same pattern was seen when participants engaged in a challenging and confusing mental arithmetic task.”
The researchers also found that “real-world measures of blood pressure (measured by an automated monitor) were significantly lower after the pistachio diet,”.added Katherine A. Sauder, former graduate student in bio-behavioral 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."