Why is it that "an apple a day keeps the doctor away"? Our ancestors believed that old maxim without understanding why it seemed to be true. Modern nutritional scientists are building evidence that confirms just how good apples are for our health.

The big buzzwords in nutrition nowadays are antioxidants (which control substances that can damage cells) and phytonutrients or phytochemicals (compounds found in plants). It turns out apples contain many antioxidant phytochemicals. Apples are also rich in pectins, which are soluble fibers demonstrated to be effective in lowering cholesterol levels.

Apples are nature's gift to help us achieve cardiovascular health. They can be ingested in any form, including juice, to do their good work.

Phenolic Antioxidants

A recent study on cholesterol reduction involved both juice and whole apples. Researchers at the University of California at Davis (UC Davis) found that phenolic compounds (phytochemicals) in apples acted as antioxidants against LDL (low-density lipoproteins), the damaging portion of cholesterol in the blood stream. The research results were published in the April 16, 1999, issue of Life Sciences.

Research leaders emphasized a positive message for children. Since kids like to drink pure apple juice, they should be encouraged to keep the habit through a lifetime. Too many people, they pointed out, start worrying about heart disease after many years of ignoring good nutrition. Establish good food habits early and maintain them, they recommend. That means plenty of apple juice and plenty of apples.

Dr. Eric Gershwin, a co-author of the research study and chief of the Division of Rheumatology, Allergy and Clinical Immunology at the UC Davis School of Medicine and Medical Center, cited the "significant" amounts and activity of apple antioxidants. He suggested that if people have to overdo on fatty foods, such as in fast-food restaurants, they wash them down with apple juice or other phytonutrient-rich beverages rather than the usual drinks. Doing that, he believes, could help nullify the potential damage of the fat.

Flavonoids

Another class of antioxidant phytochemicals is the flavonoids group. Apple are rich in flavonoids, especially one member called quercetin. European researchers have been investigating the relationship between flavonoid intake and reduced incidence of heart disease and cancer.

A Finnish study published in 1996 in the British Medical Journal followed more than 5,000 Finnish men and women aged 30-69 years for about a quarter of a century to try to establish links between mortality causes and flavonoids in their diets. Among the approximately one-quarter of the participants who died during the study, flavonoid intakes were lower than among those still living in 1992, the conclusion of the study period. The researchers found that "there was an inverse gradient between flavonoid intake and total mortality" and added that "the consumption of apples and onions was inversely associated with total and coronary mortality." They stated, "In summary, the results of the present study suggest that people with very low dietary intakes of flavonoids have increased risks of coronary heart disease."

Two "key messages" that come out of the research, they observed, are that "the incidence of coronary mortality is higher among populations with low dietary intake of flavonoids" and that "the protective effect of flavonoids was associated with a diet high in intake of apples."

The research conclusions are in line with those of an earlier study on a population of elderly men in the Netherlands. The Dutch researchers wrote that "flavonoid intake…was significantly inversely associated with mortality from coronary heart disease" and that "the habitual intake of flavonoids…may protect against stroke." The men in the studied group received their flavonoids primarily from black tea and apples--more evidence that apples appear to have a protective effect against cardiovascular disease.

Dutch researchers also tested various fruits and vegetables for quercetin content. Apples were the fruit richest in this antioxidant phytonutrient, and the Jonagold variety was the particular leader.

Pectin

Ingestion of pectin, a soluble fiber present in most fruits and vegetables, has been shown in many research studies to lower blood cholesterol levels. Apples are an excellent source, providing .78 grams of pectin per 100 grams of edible fruit.

The link between pectin and cholesterol reduction was first discovered in the early 1960s. European scientists soon began testing human subjects to determine the cholesterol-lowering potential of apple-rich diets. The conclusions from the studies all indicated that apples have a positive effect. Persons with high cholesterol levels can benefit the most from eating more apples, according to a French study.

French researchers working with cholesterol-prone hamsters found that feeding the animals plenty of apples not only lowered the total cholesterol reading but improved the ratio of beneficial HDL (high-density lipoproteins) to the harmful LDL. They also hypothesize that apples contain some beneficial ingredient besides pectin because the cholesterol reduction from apple diets exceeds what would be expected simply from the pectin content of apples. Jean Carper in her book Food--Your Miracle Medicine cites the same phenomenon. She quotes Dr. David Kritchevsky, a noted cardiovascular researcher at the Wistar Institute in Philadelphia, Pa., who said that apple intake "lowers cholesterol more than its pectin content predicts. Something else is at work also."

D-glucaric Acid

Perhaps the mysterious ingredient in apples is D-glucaric acid. Preliminary research, according to a study published in Nutrition Research, indicates that it and a related compound may be natural regulators of cholesterogenesis. Laboratory rats fed the substances showed markedly reduced blood cholesterol levels. The results point to the need for further studies to identify the mechanism by which this effect is achieved, the researchers stated.

They also did an analysis of many fruits and vegetables to determine their D-glucaric acid content. Apples had higher readings than all other types of fruit except grapefruit.

A bonus that D-glucaric acid appears to offer, based on the early research, is that the form of cholesterol that it lowers is the damaging LDL type. Reductions of up to 35 percent were found in the laboratory studies. The "good" type of cholesterol, the HDL that should have a relatively high ratio to LDL in an ideal blood cholesterol profile was not affected. The research adds to the case that apples are a real health food.

Vitamin C

Vitamin C, or ascorbic acid, has antioxidant properties and therefore also has positive effects on the cardiovascular system. One medium apple provides 8 percent of the daily requirement of humans based on a 2,000-calorie-per-day diet.

French research on hamsters and guinea pigs indicated that apples make vitamin C more available in blood and organs to do its good work, helping to make a given amount--from whatever source--go a long way. Thus apples and oranges form a good dietary combination because the apples would make the rich amounts of vitamin C in oranges even more helpful than from oranges alone.