Daily Intake of Pistachios Lowers Vascular Response to Stress in Type-2 Diabetics

People with type-2 diabetes can lower body's response to stress of everyday life by consuming pistachios on a daily basis.

In a new study, led by Penn State researchers, effect of pistachios on the responses to standardized stress tasks were investigated in patients with well-controlled type-2 diabetes who were otherwise healthy.

They used randomized cross-over study design in which all meals were provided. Each diet had the same number of calories. They noticed that adults with diabetes can lower the vascular constriction during stress by consuming two servings of pistachios per day. Apart from this, the neural control of the heart also improved.

"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."

Pistachio (pistachio vera) nuts have been known as a symbol of wellness and robust health.  They have healthy and heart-protective unsaturated fats that offer vital vitamins and minerals. This study highlights the benefits that type-2 diabetes people receive.

The participants were initially given two weeks of typical American diet, containing 36 percent fat and 12 percent saturated fats. They were further randomized to one of the two tests diets. During the four-week test diet, the participants ate only what was supplied by the study.

The test diet included a standard healthy diet i.e. 27 percent fat and 7 percent saturated fat - along with two servings per day of pistachios i.e. 3 ounces or 20 percent of calories from pistachio nuts. The participants had 150 pistachio nuts per day. The pistachio diet had 33 percent fat, 7 percent saturated fat. 

Half of the nuts taken each day were salted and the other half unsalted. At the end of the four-week diet period, the participant's blood pressure and total peripheral vascular resistance at rest and also during stress tests. The stress test included a cold water challenge and a confusing mental arithmetic test.

The researchers noticed that on consuming pistachio diet, the blood vessels remained relaxed and open during the stress tests. The lab measurements were not affected by pistachio intake. It was noticed that the blood pressure levels were lower after following a pistachio diet.

"We found that systolic blood pressure during sleep was particularly affected by pistachios," said Katherine A. Sauder, former graduate student in bio-behavioral health, who conducted these measurements. "Average sleep blood pressure was reduced by about 4 points and this would be expected to lower workload on the heart. 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."

A large vascular constriction response was produced by cold stressor in most people. A pistachio diet blunted the vascular response to stress. They noticed a similar pattern when the patients underwent challenging and confusing mental arithmetic tasks.

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 study was documented in the Journal of the American Heart Association.