Pistachios lower cholesterol, provide antioxidants

Apr 30, 2007

A handful of pistachios may lower cholesterol and provide the antioxidants usually found in leafy green vegetables and brightly colored fruit, according to a team of researchers.

"Pistachio amounts of 1.5 ounces and 3 ounces – one to two handfuls – reduced risk for cardiovascular disease by significantly reducing LDL cholesterol levels and the higher dose significantly reduced lipoprotein ratios," says Sarah K. Gebauer, graduate student in integrative biosciences, Penn State, to attendees at the Experimental Biology meeting today (April 30) in Washington, D.C.

The researchers conducted a randomized, crossover design, controlled feeding experiment to test the effects of pistachios added to a heart healthy moderate-fat diet on cardiovascular disease risk factors. Controlled feeding experiments provide all the food eaten by study subjects for the duration of the study segment.

Participants began the study by eating an Average American Diet consisting of 35 percent total fat and 11 percent saturated fat for two weeks. They then tested three diets for four weeks each with a two-week break between each diet.

All three diets were variations on the Step I Diet, a cholesterol-lowering diet in general use. The diets included a Step I Diet without pistachios which had 25 percent total fat and 8 percent saturated fat; a Step I Diet including 1.5 ounces of pistachios per day which had 30 percent total fat and 8 percent saturated fat, and a Step I Diet including three ounces of pistachios per day which had 34 percent total fat and 8 percent saturated fat. The researchers added pistachios into the diets by including about half the amount of pistachios as a snack and by incorporating the rest into such foods as pistachio muffins, granola and pistachio pesto.

"We had really good compliance and participants were generally pleased with the diets," says Gebauer.

Standard blood tests determined the various cholesterol levels in the participant’s blood after each diet. Researchers found that 3 ounces of pistachios reduced the amounts of total cholesterol in the blood by 8.4 percent and low-density lipoprotein (LDL), the so-called bad cholesterol, by 11.6 percent. The study also found that non-high density lipoproteins (non-HDL) decreased by 11.2 percent. Non-HDL levels are considered reliable predictors of cardiovascular disease risk.

The three-ounce pistachio diet also decreased the ratios of total cholesterol to HDL, LDL to HDL and non-HDL to HDL and apolipoprotein B, which are all measures of cardiovascular disease risk. "We were pleased to see a difference between the two doses of pistachios for the lipoprotein ratios because it would appear that pistachios are causing the effect and that they act in a dose dependent way," says Gebauer.

In addition, during this study researchers, researchers looked at the effects of these diets on oxidized LDL and on antioxidants in the blood.

"We were trying to see if the increased levels of antioxidants provided by pistachios could reduce inflammation and oxidation," says Gebauer. Pistachios contain more lutein, – normally found in dark leafy vegetables -- beta carotene – a precursor to vitamin A – and gamma tocopherol – the major form of vitamin E – than other nuts. It is oxidized LDL and other lipproteins that contribute to plaque formation in arteries.

The researchers reported that both the 1.5 and 3 ounce pistachio diets reduced oxidized LDL compared with the baseline diet. Pistachio-enriched diets also resulted in significantly higher levels of lutein in the blood. The increased lutein from the 3-ounce pistachio diet correlated with a reduction in oxidized LDL which may indicate that the lutein in pistachio nuts improves the risk of cardiovascular disease by reducing serum oxidized LDL.

"Our study has shown that pistachios, eaten with a heart healthy diet, may decrease a person's CVD risk profile," says Dr. Penny Kris-Etherton, distinguished professor of nutrition and primary investigator of the study.

Source: Penn State

Explore further: Porches an overlooked lead hazard

add to favorites email to friend print save as pdf

Related Stories

Study uncovers secrets of a clump-dissolving protein

37 minutes ago

Workhorse molecules called heat-shock proteins contribute to refolding proteins that were once misfolded and clumped, causing such disorders as Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's ...

Using viruses to find the cellular Achilles heel

37 minutes ago

Back-to-back studies from researchers at the Gladstone Institutes have exposed new battle tactics employed by two deadly viruses: hepatitis C (HCV) and the Kaposi's sarcoma-associated herpesvirus (KSHV). Published in the ...

These jellyfish aren't just drifters

37 minutes ago

Jellyfish might look like mere drifters, but some of them have a remarkable ability to detect the direction of ocean currents and to swim strongly against them, according to new evidence in free-ranging barrel-jellyfish ...

Recommended for you

Porches an overlooked lead hazard

2 hours ago

A new study in the journal Environmental Health indicates that porches in older homes can be a significant source of lead dust and that housing regulations – which have been instrumental in lower rates ...

Child maltreatment not a clear path to adult crime

2 hours ago

Research has found a significant link between childhood abuse and neglect and crime in adulthood. But a recent University of Washington study finds that link all but disappears when accounting for other life factors.

Canada's Winnipeg still under boil-water advisory

5 hours ago

Residents of Canada's sixth-largest city were advised to keep boiling tap water before using it late Wednesday, even though latest tests showed no traces of harmful bacteria, officials said.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.