"Functional foods," "nutraceuticals," "designer
foods" and "medicinal foods" are terms that describe
foods, and key ingredients isolated from foods, that have non-nutritive
or tertiary functional properties. Researchers, healthcare practitioners,
laypersons, and the popular media use these words interchangeably.
The purpose of this article is to detail valid scientific information
available on the physiologic actions of known constituents and combinations
of constituents, as they naturally occur in apples, highlighting their
medicinal and nutritive mechanisms of action in preventing lung cancer
and optimizing lung capacity.
Whole Foods Bestow Lung Cancer Protection and Improve
Apples contain well-recognized medicinal and nutritive
constituents that offer profound benefit in protecting the health of,
lung function. These constituents include the antioxidants quercetin
and vitamin C, along with other flavonoids and vitamins, pectins, tannins
and fruit acids like malic acid.
Researchers are not entirely clear on why apples offer a scientifically
documented benefit in protecting lung health and improving lung function,
in those individuals suffering from lung cancer and asthma. Most postulate
that antioxidant protection may be a key mechanism of action. It has been proposed
that the antioxidant flavonoid quercetin may play a major role.1,2 Additionally,
pectins and pectin-like rhamnogalacturonans found in apples have pronounced
antimutagenic effects in vitro.3 Pectin
polysaccharides most likely interact directly with cells (Salmonella typhimurium)
to sterically protect them from
As well, apple pectin decreases the incidence and number of dimethylhydrazine-
and azoxymethane-induced colon tumors in rats.4-6 It
is also believed that pectin lowers ß-glucuronidase activity, a key enzymatic
step in carcinogen activation and tumor initiation.
In the intestine, apple pectin is a bulk-forming agent similar to psyllium
and prevents diarrhea and constipation by a similar mechanism. Pectin also
may modify intestinal bacterial enzyme activity in favor of a reduction of
toxic breakdown products in the gut.7 This
may contribute to an overall chemoprotective effect in lung carcinogenesis.
Research on Apples and Lung Cancer
Researchers1 documented a statistically significant inverse relationship between
lung cancer risk and food sources high in the flavonoid quercetin (onions
and apples) after controlling for smoking and intakes of saturated fat and ß-carotene
in a population-based, case-controlled study conducted in Hawaii (Table 1).
This research, published in the Journal of the National
found that increased intake of foods containing flavonoids, like those found
in apples, have the potential to cut the risk of lung cancer in half.
Table 1. Odds
ratio for lung cancer in the highest vs. the lowest quartiles for apple
intake in a Hawaiian population. An odds ratio
of 1.0 indicates no difference (Q1). Parentheses indicate 95% CI. Other
foods high in isoflavones are shown for comparison. Of these, only
apples and onions are high in quercetin. Adapted from Le Marchand et
||Two-sided P for trend
|Red wine (tertiles)
This is the second study to link apple consumption to reduced risk
of lung cancer. While it is well established that consumption of fruits
and vegetables is linked to a reduced risk of lung cancer, this study,
which builds on the results of an earlier study8 published in the American
Journal of Epidemiology, shows that the cancer protective effect largely
stems from the flavonoid quercetin found in apples.
In 1997, researchers8 reported on a 25-year study of 10,000 Finnish men that
found that intake of antioxidant flavonoids, and in particular the consumption
of the flavonoid quercetin (which provided 95% of the total flavonoid intake
in the population studied), reduced the incidence of lung cancer. After adjusting
for other fruits and vegetables in the diet, researchers noted an inverse association
between consumption of apples and lung cancer risk. In fact, the likelihood
of lung cancer among those who ate the most apples fell by 58% relative to
those who ate fewer apples.
Research on Apples and Overall Lung Function
A long-term cross-sectional analysis2 of a cohort of 2512 Welshmen aged 45-59
living in Caerphilly, Wales between 1979 and 1983 found that lung function
was linearly associated with dietary apple intake (Table 2).
Table 2. Cross-sectional
analysis: Differences in forced expiratory volume in one second (FEV1)
in mL associated with increases in the
frequency of apple intake from baseline. Adapted from Butland et al.2
Difference in lung function (95% CI)
|Frequency of apple intake
|(1) Adjusted for age, height
||(2) Adjusted for (1), body mass index, and smoking
||(3) Adjusted for (2), social class, work exercise, and leisure
||(4) Adjusted for (3) and total energy intake
|5 or more
|Test for trend
The researchers found that good lung function was associated with
high intakes of vitamins C, E, and beta-carotene, citrus fruits, apples,
and fruit juices. However, after they took into consideration factors
such as body mass, smoking history and exercise, the only food that
seemed to make a significant difference was apples.
In fact, eating five or more apples a week was linked to slightly better lung
function. The lung capacity in those individuals who ate apples was 138 millilitres
higher, as compared to those who did not eat apples. This study additionally
found that the age-related decline in lung function over five years in these
men was offset by consuming five or more apples per week during the study period.
Researchers from the University of Nottingham in the United Kingdom reported
similar findings. A nine-year population study9 of 2,633 adults found that
apple eaters have better lung function and lower risk of respiratory disease
such as asthma than non-apple eaters.
Research on Apples and Asthma
Apples also appear to play a significant role, along with pears, in offering
protection against asthma. A recent cross-sectional study10 designed to evaluate
the relationship between diet and asthma found that among the wide variety
of fruits and vegetables studied, apples and pears provided superior protection
against asthma. The study, conducted in Australia, involved 1,607 young adults
aged 20-44 and the results were published in the American
Journal of Clinical Nutrition.
An earlier study, completed in 2001, demonstrated similar findings. This
was a population-based case-control study11 of 1,471 adults in the United
conducted by researchers from London's King's College and the
University of Southampton. The study examined the effects of dietary antioxidants
on asthma risk and severity. The researchers discovered that people eating
at least two apples per week resulted in a 22-32% decreased risk of developing
asthma as compared to those that ate less than that. The medicinal properties
inherent in apples also demonstrate benefit in preventing chronic obstructive
pulmonary disease in long-term heavy smokers.
Research on Apples and COPD in Smokers
A preliminary case control study,12 completed by researchers from the University
of Groningen in the Netherlands offers some evidence that apples may also
bestow protection against chronic obstructive pulmonary disease (COPD) in
long-term smokers. These researchers reported that eating fruits and vegetables,
and in particular an apple a day, may reduce smokers' risk of developing
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
Researchers are still not clear on what the entire medicinal profile of an
apple is and exactly how it functions to protect lung tissue and prevent
lung-related health challenges. What we do know is that the fruit offers
a simple and effective means of protecting the health of the lungs. After
reviewing the available research on the conditions that benefit from increased
apple consumption, including chronic obstructive pulmonary disease in heavy
smokers, asthma, a general decline in lung function and lung cancer, the
use of this inexpensive, readily accessible whole food turns out to be an
important primary or complementary therapy for anyone battling the effects
of compromised lung function.
Excerpts reprinted with permission from the book Clinical
Purification: A Complete Treatment and Reference Manual by Dr. Gina L. Nick.
1. Le Marchand, L. et al. 2000. Intake of flavonoids and lung cancer.
J Natl Cancer Inst 92(2): 154-160.
2. Butland, B. K. et al. 2000. Diet, lung function, and lung function
decline in a cohort of 2512 middle aged men. Thorax 55(2): 102-108.
3. Hensel, A. and K. Meier. 1999. Pectins and xyloglucans exhibit antimutagenic
activities against nitroaromatic compounds. Planta
Med 65(5): 395-399.
4. Ohkami, H. et al. 1995. Effects of apple pectin on fecal bacterial
enzymes in azoxymethane-induced rat colon carcinogenesis. Jpn
J Cancer Res 86(6): 523-529.
5. Tazawa, K. et al. 1997. Anticarcinogenic action of apple pectin
on fecal enzyme activities and mucosal or portal prostaglandin E2 levels
in experimental rat colon carcinogenesis. J
Exp Clin Cancer Res 16(1):
6. Tazawa, K. et al. 1999. Dietary fiber inhibits the incidence of
hepatic metastasis with the antioxidant activity and portal scavenging
functions. Hum Cell 12(4): 189-196.
7. Mallett, A.. et al. 1987. Dietary modification of intestinal bacterial
enzyme activities — potential formation of toxic agents in the
gut. Scand J Gastroenterol Suppl 129: 251-257.
8. Knekt, P. et al.1997. Dietary flavonoids and the risk of lung cancer
and other malignant neoplasms. Am J Epidemiol 146(3):223-230.
9. American Thoracic Society, unpublished findings presented at the
society's Annual Meeting, May 2001, poster 618.
10. Woods, R. et al. 2003. Food and nutrient intakes and asthma risk
in young adults. Am J Clin Nutr 78(3):414-421.
11. Shaheen, S. et al. 2001. Dietary antioxidants and asthma in adults:
population-based case-control study. Am J
Respir Crit Care Med 164(10):1823-8.
12. American Thoracic Society, unpublished findings presented at the
society's Annual Meeting, May 2001, poster 617.