From the Desk of the School Nurse:

Following are summaries of studies on the health benefits of apples and apple products to date.

Add an Apple a Day at School and at Home

Prostate Cancer: Rochester, Minnesota’s Mayo Clinic researchers reported quercetin, a plant-based nutrient found most abundantly in apples, may provide a new method for preventing or treating prostate cancer. Quercetin inhibited, reduced, or prevented the growth of human prostate cancer cells by blocking activity of androgen hormones in an in vitro (laboratory) study. Previous studies had linked androgens to prostate cancer’s growth and development. This is the first known study to link apples with a major men’s health issue. (Source: Carcinogenesis, 2001, 22: 409-414)

Colon and Liver Cancer: Phytonutrients in apples inhibited the growth of colon cancer and liver cancer cells in vitro, according to researchers at Cornell University. While the beneficial phytonutrients were most strongly concentrated in the apple skin, the apple flesh also contained significant levels of phytonutrients. According to the Cornell researchers, 100 grams of unpeeled fresh apple – about two-thirds of a medium-sized apple – provides the total antioxidant activity of 1,500 milligrams of vitamin C. (Source: Nature, 2000, 405: 903-904)

Lung Cancer: Researchers at the University of Hawaii found increased consumption of quercetin was associated with a reduced risk of lung cancer in this population-based, case-control study involving 600 lung cancer patients and 600 cancer-free persons. Researchers investigating a possible relationship between the consumption of flavonoids and lung cancer risk found a statistically significant inverse association between lung cancer risk and intake of the flavonoid quercetin, found primarily in apples and onions, and the flavonoid naringin, found in white grapefruit. No association was found for important food sources of other flavonoids. This study validated similar findings published in 1997 (see the American Journal of Epidemiology study referenced below). (Source: Journal of the National Cancer Institute, 2000, 92: 154-160)

Cancer and Lung Cancer: Epidemiologists from Finland’s National Public Health Institute reported consumption of a flavonoid-rich diet – and particularly flavonoid-rich apples – was associated with a reduced risk of developing cancer. Their study of 9,959 cancer-free, Finnish men and women, begun in 1965, revealed people who regularly consumed the most flavonoid-rich foods – apples, onions, fruits, juices, vegetables, and jams – during the 24-year study period were about 20 percent less likely to develop cancer. Researchers found lung cancer was 46 percent lower among those whose diets contained the highest amount of flavonoids, particularly from apples. Of the major dietary flavonoid sources, apples showed the greatest inverse association with lung cancer incidence. (Source: American Journal of Epidemiology, 1997, 146: 223-230)

Lung Health

Lung Disease: Researchers from the University of Groningen in the Netherlands reported eating fruits and vegetables, and in particular an apple a day, may reduce smokers’ risk of developing chronic obstructive pulmonary disease (COPD), based on their case-control study of long-term, heavy smokers. This is the first known study to suggest smokers could benefit from increased apple consumption. (Source: American Thoracic Society, unpublished findings presented at the society’s Annual Meeting, May 2001, poster 617)

Lung Function:

• Apple eaters have better lung function and lower risk of respiratory disease such as asthma than non-apple eaters, based on a nine-year population study of 2,633 adults. This study’s findings, compiled by researchers from the University of Nottingham in the United Kingdom, are similar to previous findings (see the Journal of the National Cancer Institute and Thorax studies referenced below). (Source: American Thoracic Society, unpublished findings presented at the society’s Annual Meeting, May 2001, poster 618)

• British researchers reported apple eaters had better lung function than non-apple eaters, as measured by forced expiratory volume. Investigating an hypothesized association between diet and lung function, researchers found a strong positive association between lung function and the number of apples eaten each week after analyzing dietary records and health outcomes of a study group of 2,512 men studied for five years. Although it had been suggested by other researchers that vitamin C from fresh fruit was responsible for improving lung function, this research found the contrary. Researchers postulated the healthful effect may be due to antioxidants in apples (e.g., flavonoids like quercetin). (Source: Thorax, 2000, 55: 102-108)

LDL Oxidation:

• Daily consumption of apples and apple juice may help reduce damage caused by the “bad” type of cholesterol and protect against heart disease, based on the first human study of its kind. Researchers at the University of California-Davis demonstrated apples and apple juice may help to slow the oxidation process involved in the buildup of plaque that leads to heart disease. Clinical study participants added only two apples, or 12 ounces of apple juice, to their diet. This study validated earlier in vitro findings (see the Life Sciences study referenced below). (Source: Journal of Medicinal Food, 2000, 3: 159-165)

• The University of California-Davis reported phytonutrients in apples and apple juice prevent oxidation in vitro of the “bad” (LDL) cholesterol and thus may help protect against cardiovascular disease. University of California-Davis researchers also confirmed important phytonutrients from apples also are found in apple juice. While both foods varied in the levels of phytonutrient concentrations, both inhibited oxidation of LDL cholesterol, which can lead to buildup of harmful plaque in arteries. (Source: Life Sciences, 1999, 64: 1913-1920)

Stroke

Thrombotic Stroke: People who ate the most apples had the lowest risk of thrombotic stroke, possibly due to the phytonutrients found in the apples, according to Finnish researchers. This conclusion was based on evaluation of dietary records and health outcomes of 9,208 men followed for 28 years. Unlike findings from other epidemiological studies, the researchers attributed this positive association to phytonutrients other than quercetin found in apples (e.g., catechins), demonstrating apples’ broad phytonutrient content. (Source: European Journal of Clinical Nutrition, 2000, 54: 415-417)