Written by Diana Gnat, DC.
Cardiovascular disease causes more deaths in Americans than any other disease. (1) Medical expenses and lost productivity in the US due to this condition are expected to cost $449 billion in 2008. Treatment costs for Cardiovascular disease are expected to rise from 64% to 84% by 2025. (2) Previous studies have indicated that nut consumption lowers Cardiovascular disease risk factors. “Pistachios have a unique nutrient and fatty acid profile.” (3) They are a source of “good” unsaturated fat, as well as numerous antioxidants, such as beta carotene, lutein, gamma-tocopherol, amino acids, selenium, flavonoids, and phytoestrogens.
Now a new study has shown that adding pistachios to a lower-fat diet may help heart health. Pistachio intake was calculated as 10% of total calories (2100) for 1PD (one dose of pistachios) and the dose ranged from 1.1 to 2.2 oz per day. The 2PD (two doses of pistachios) intake was calculated as 20% of total calories and the dose ranged from 2.2 to 4.8 oz day, depending on the assigned amount of calories.
The researchers studied twenty-eight men and women with elevated LDL cholesterol (> 2.86 mmol/L). Inclusion criteria were as follows: triacyglycerols < 3.94 mmol/L, blood pressure < 160/90 mmHg, body mass index (BMI) between 21 and 35, and fasting blood glucose < 6.93 mmol/L. All participants were otherwise in good health and nonsmokers.
This study used a two-week run-in period*** before the first test diet to establish a baseline. Participants were then randomly assigned to the following diets for four weeks each.
- Control diet (no pistachios)
- One dose of pistachios, equal to 10% of total calories
- Two doses of pistachios, equal to 20% of total calories
The total calories in each type of diet was constant and all diets were rich in fruit, vegetables, lean meats, and whole grains. The pistachio diets were higher in protein and unsaturated fats and lower in carbohydrates. However, the control diet and pistachio diets contained the same Saturated Fatty Acids (SFA’s) and cholesterol. All meals and snacks were prepared at the Metabolic Diet Study Center and one meal per day Monday-Friday was eaten at the center, while the rest of the meals were prepared and packed for off-site eating. Blood was drawn on two consecutive days at the end of each four-week diet period. (3)
By the end of the study, the diet containing one dose of pistachios decreased LDL cholesterol by 9% and 12% for the diet containing two doses of pistachios. One significant difference between this study and previous studies was that it exchanged a fixed percentage of total calories (10% and 20% of total calories) for pistachios, while keeping SFAs, cholesterol, energy and body weight constant.
“The LDL cholesterol reduction that we observed was seven times that expected on the basis of fatty acid composition alone. This suggests that the lipid-lowering effects in this study not only reflect the fatty acid profile of the diet, but also are the result of other bioactive components in pistachios, such as phytosterols and fiber.” (3) A larger study is recommended to confirm and expand other mechanisms in pistachios that may lower Cardiovascular disease risk factors.
*Apolipoproteins are proteins that bind to fats and transport dietary fats through the body. There are six types of classes of apolipoproteins. This research article refers to variations of A (A-1) and B. (4)
*”Stearoyl-CoA desaturase (SCD) is the rate-limiting enzyme that catalyzes the syntheses of monounsaturated fatty acids from saturated fatty acids and plays an important role in cholesterol, triaclglycerol, and lipoprotein metabolism” (3).
***The run-in diet was a typical American Diet every study subject consumed for two weeks to establish lab results for a typical American diet before being randomly assigned to the other treatment diets.
Source: Gebauer, Sarah K., Sheila G. West, Colin D. Kay, Petar Alaupovic, Deborah Bagshaw, and Penny M. Kris-Etherton. “Effects of pistachios on cardiovascular disease risk factors and potential mechanisms of action: a dose-response study.” The American journal of clinical nutrition 88, no. 3 (2008): 651-659.
© 2008 American Society for Clinical Nutrition
Posted January 13, 2009.
References:
- National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP), 2002.
- Circulation. 2008;117:e25-e146.
- Gebauer S. et al. Effects of pistachios on cardiovascular disease risk factors and potential mechanisms of action: a dose-response study.Am J Clinic Nutr. 2008;88: 651-9.
- Wikipedia, The Free Encyclopedia.
