COLUMBUS, Ohio—There’s new science supporting the old adage “an apple a day keeps the doctor away." Healthy middle-aged adults who ate one apple a day for four weeks lowered blood levels of oxidized low-density lipoprotein (LDL), which is linked to hardening of the arteries, by 40%, according to a new study published online in the Journal of Functional Foods.
For the study, Ohio State University researchers recruited non-smoking healthy adults between the ages 40-60 who had a history of eating apples less than twice a month and who didn't take supplements containing polyphenols or other plant-based concentrates. In all, 16 participants ate a large Red or Golden Delicious apple for four weeks; 17 took capsules containing 194 milligrams of polyphenols a day for four weeks; and 18 took a placebo containing no polyphenols. The researchers found no effect on oxidized LDLs in those taking the placebo.
When LDL becomes oxidized, it takes on a form that begins atherosclerosis, or hardening of the arteries. Lead researcher Robert DiSilvestro, professor of human nutrition at Ohio State University and a researcher at OSU’s Agricultural Research and Development Center, said they found a tremendous effect against LDL being oxidized with just one apple a day for four weeks. The difference was similar to that found between people with normal coronary arteries versus those with coronary artery disease.
"We think the polyphenols account for a lot of the effect from apples, but we did try to isolate just the polyphenols, using about what you'd get from an apple a day," DiSilvestro said. "We found the polyphenol extract did register a measurable effect, but not as strong as the straight apple. That could either be because there are other things in the apple that could contribute to the effect, or, in some cases, these bioactive compounds seem to get absorbed better when they're consumed in foods."
He described daily apple consumption as significantly more effective at lowering oxidized LDL than other antioxidants he has studied, including the spice-based compound curcumin, green tea and tomato extract. “Not all antioxidants are created equal when it comes to this particular effect," he said.
Learn more about recent research on the health benefits of apples by viewing the “An Apple a Day: The Health Benefits of Apples" slide show on Food Product Design.