April 22/New Orleans/PRNewswire -- Pistachios may do more for the heart, blood sugar and waistline than many other snack food choices, according to research presented t Experimental Biology 2009 in New Orleans. Researchers from UCLA and the University of Toronto presented, for the first time, their findings from human clinical trials showing major health benefits from eating pistachios.
Several studies have previously shown that pistachios -- and tree nuts in general -- do not contribute to overweight or obesity, when consumed in moderation. In fact, more recent studies suggest that nut consumption is linked to a lower body mass index, and pistachios are thought to provide a high satiety value that may help curb appetite, making adherence to a calorie-reduced diet easier. The UCLA researchers set out to determine if equal amounts of calories from either pistachios or pretzels would result in any metabolic or anthropometric differences, when given as part of a calorie-controlled, three-month weight loss diet.
The researchers randomly assigned overweight adults to follow a diet that cut calories by 500 per day from usual calorie intake. The new diet added in either an afternoon snack of 2oz of unsalted pretzels (220 calories) or 3oz of in-shell pistachios (240 calories). The subjects following the pistachio intervention lost a statistically significant amount of weight, enough to reduce BMI from 30.88 at the onset of the study to 28.84. This is equivalent to about a 10-12 pound weight loss for most adults of average height. At the mid-point (six weeks) of the study, pistachio eaters had significantly lower triglycerides (a form of fat present in the bloodstream that is linked to diet and lifestyle factors) compared to pretzel eaters. Subjects who ate pistachios had an average triglyceride level of 90 mg/dl versus 132 mg/dl for the pretzel eaters. Triglycerides of 150 mg/dl or higher are associated with an increased risk for heart disease, metabolic syndrome and type II diabetes.
"Our results are promising because they show that pistachios can be part of a successful weight loss program, and they provide the added benefits of helping to control blood lipids, like triglycerides and LDL cholesterol," said Dr. Heber, M.D., Ph.D., director of the UCLA Center for Human Nutrition.
Pistachios Blunt Blood Sugar
Researchers from the University of Toronto and St. Michel's Hospital in Toronto presented results for their study evaluating the ability of pistachios to help control blood sugar levels and enhance satiety of meals and snacks. Fifteen subjects ate three nutritionally equivalent test meals on three separate occasions: 1) white bread alone; 2) white bread plus 2oz pistachios; or 3) white bread with butter and cheese. The researchers measured blood sugar and gut hormone responses to each of the test meals over a three-hour period. Their results showed that, compared to the white bread alone, pistachios blunt the blood sugar response, delay gastric emptying and increase levels of the satiety hormone, ghrelin. The results show the power of pistachios in helping to control glycemic response and appetite.
The same researchers presented their findings from the largest human clinical trial to evaluate the effects of nut consumption on individuals with Type II diabetes. The three-month study included 117 subjects (mean age 62) who were randomly assigned to receive one of three diet interventions: 1) 2.5oz or .5-cup of mixed nuts (including pistachios); 2) 1.33 ounces or .25-cup of mixed nuts and half portion of muffin; or 3) full portion of muffin. Each snack accounted for 450 calories, and all the overall diets were matched for caloric intake.
While on each diet intervention, researchers measured the subjects' HbA1c (a marker of blood sugar control over the previous three months) as well as blood lipid markers associated with heart heath. The findings revealed that the full dose nut group had significantly reduced LDL and total cholesterol levels compared to the full dose muffin group, as well as a significant reduction in HbA1c from baseline in the full dose nuts compared to the other two diets.
"Type II diabetes, heart disease and overweight are all related conditions, and a healthy diet -- one that includes pistachios -- may have a positive impact on these widespread public health conditions," said registered dietitian Kelly Plowe, MS, RD., nutrition communications manager at Paramount Farms.
From the April 27, 2009, Prepared Foods E-dition