UC Davis Study Finds Heart Benefits From Apples & Juice

The study shows that compounds in apples and apple juice act in much the same way that red wine and tea do to slow one of the processes that lead to heart disease. These compounds act as antioxidants to delay the break down of LDL or "bad" cholesterol. When LDL oxidizes, or deteriorates in the blood, plaque accumulates along the walls of the coronary artery and causes atherosclerosis.

"Previous studies have shown that eating fruits and vegetables is associated with a reduced risk of coronary artery disease," says Dianne Hyson, a registered dietitian and lead researcher of the study. "But this is the first clinical study to show the potential benefits of active compounds in apple juice and apples."

Hyson and her colleagues previously conducted an in vitro, or lab study, to show that apples and their juice contain beneficial phytonutrients, or plant compounds, that function as potent antioxidants. Their next step was to conduct an in vivo, or human trial, to determine whether the compounds actually protect the heart by slowing the process of LDL oxidation.

Although Hyson expected to see positive results from drinking apple juice and eating apples, she was surprised to find beneficial effects after only six weeks.

"A very moderate intake of apple juice or apples has the potential to reduce risk factors for heart disease in a fairly short period of time," she says. "These small diet changes might play an important role in a heart healthy diet."

During the 12-week clinical study, 25 healthy adult men and women added either 12 ounces of 100 percent apple juice or two apples into their daily diet without changing anything else. Half of the participants drank 100 percent apple juice daily for six weeks while the other half ate apples including the peel. The varieties of apples the group consumed included Fuji, Golden Delicious, Granny Smith and Red Delicious. After six weeks, the subjects switched groups.

Each participant kept a detailed five-day food record every two weeks, and researchers monitored the subjects' body weight throughout the 12-week study period. There were no significant differences in the intake of dietary fat, cholesterol, total carbohydrate, sugar or calories.

Researchers measured levels of LDL oxidation lag time before the study and at each six-week interval. Lag time measurements are commonly used to determine how long it takes for cholesterol to oxidize or break down when exposed to certain chemicals. A longer lag time indicates a greater delay in the start of oxidation, which is associated with a reduced risk of heart disease.

Study results were more dramatic in subjects drinking apple juice, showing a 20 percent increase in lag time after six weeks, but eating apples also showed potential health benefits, including reduced oxidation markers and a 22 percent increase in dietary fiber.

Jack Farrell, a UC registrar on the Davis campus, says he didn't give the study much thought while he was involved, but when the results came in six months later, he was struck by the marked decrease of LDL in his blood. Cholesterol levels that had been borderline were now within the healthy range. The father of two young children, Farrell decided apple juice wasn't just for their lunch box, but for his as well.

"If I can get this result from just drinking 12 ounces of apple juice a day, it's definitely worth making part of my daily routine," he says.

The study was funded with an unrestricted grant from the United States Apple Association and Processed Apple Institute. The two industry funders had no input regarding the design of the study, its execution, interpretation, analysis of the data, writing of the manuscript, or approval of the manuscript text prior to submission to the journal.