Medical Studies


Latest News

Cornell University

Breast Cancer
Colon Cancer
Fat Loss
Hair Growth
Heart Disease
Lung Cancer
Prostate Cancer
Skin Cancer
Apple Polyphenols and Asthma  
  • Large scale human studies repeatedly confirm benefits of apples and apple phytochemicals in improvement of asthma, lung function and overall lung health.

  • The clearest effect was seen in individuals with the highest consumption of apples.

  • Researchers consistently express high confidence that apples and apple polyphenols improve lung function in humans with asthma.

Apple phytochemicals and their health benefits, Nutr J. 2004
Flavonoid intake and risk of chronic diseases, American Journal of Clinical Nutrition 2002
Dietary antioxidants and asthma in adults: population-based case-control study, Am J Respir Crit Care Med. Nov 2001
Diet, lung function, and lung function decline in a cohort of 2512 middle aged men, Thorax 2000
Chronic Obstructive Pulmonary Disease and Intake of Catechins, Flavonols, and Flavones - The MORGEN Study, Am. J. Respir. Crit. Care Med., July 2001
Food and nutrient intakes and asthma risk in young adults, Am J Clin Nutr. 2003


Nutr J. 2004
Apple Phytochemicals and their health benefits.

Free full text of this journal article is available here.


Asthma and pulmonary function

Apple consumption has been inversely linked with asthma and has also been positively associated with general pulmonary health. In a recent study involving 1600 adults in Australia, apple and pear intake was associated with a decreased risk of asthma and a decrease in bronchial hypersensitivity, but total fruit and vegetable intake was not associated with asthma risk or severity. Specific antioxidants, such as vitamin E, vitamin C, retinol, and β-carotene, were not associated with asthma or bronchial hypersensitivity. Previously it had been found that apple intake, as well as selenium intake, was associated with less asthma in adults in the United Kingdom. This study surveyed nearly 600 individuals with asthma and 900 individuals without asthma about their diet and lifestyle. Total fruit and vegetable intake was weakly associated with asthma, and apple intake showed a stronger inverse relationship with asthma. This latter effect was most clear in subjects who consumed at least two apples per week. Onion, tea, and red wine consumption were not related to asthma incidence, suggesting an especially beneficial effect of apple flavonoids. Vitamin C and vitamin E were not correlated with asthma incidence, and carotene intake was weakly, but positively, associated with asthma. Apple intake and orange intake were both associated with a reduced incidence of asthma in the Finnish study involving 10, 000 men and women. Flavonoid intake in general was associated with a lower risk of asthma, and the association was attributed mainly to quercetin, hesperitin, and naringenin. Other fruits and vegetables, such as onions, grapefruit, white cabbage, and juices, were not associated with a decreased risk in asthma.

In a study of over 13,000 adults in the Netherlands, it was found that apples might beneficially affect lung function. Apple and pear intake was positively associated with pulmonary function and negatively associated with chronic obstructive pulmonary disease. Catechin intake was also associated with pulmonary function and negatively associated with chronic obstructive pulmonary disease, but there was no association between tea, the main source of catechins, and chronic obstructive pulmonary disease. A study of approximately 2500 middle aged (45–59 yrs) Welsh men also demonstrated a beneficial effect of apple consumption on lung function. Lung function was measured as forced expiratory volume (FEV) in one second, and was positively correlated with citrus fruit, fruit juice/squash, and apple consumption. However, the association with citrus fruit and fruit juice/squash lost significance after adjustment for smoking. Apple consumption remained positively correlated with lung function after taking into account possible confounders such as smoking, body mass index, social class, and exercise. Participants who consumed five or more apples per week had a significantly greater FEV of 138 mL when compared to those who did not consume apples.


American Journal of Clinical Nutrition, Vol. 76, No. 3, 560-568, September 2002

© 2002 American Society for Clinical Nutrition

Original Research Communication

Flavonoid intake and risk of chronic diseases1,2

Paul Knekt, Jorma Kumpulainen, Ritva Järvinen, Harri Rissanen, Markku Heliövaara, Antti Reunanen, Timo Hakulinen and Arpo Aromaa

[Reprint (PDF) Version of full study available here]

Background: Flavonoids are effective antioxidants and may protect against several chronic diseases.

Objective: The association between flavonoid intake and risk of several chronic diseases was studied.

Design: The total dietary intakes of 10 054 men and women during the year preceding the baseline examination were determined with a dietary history method. Flavonoid intakes were estimated, mainly on the basis of the flavonoid concentrations in Finnish foods. The incident cases of the diseases considered were identified from different national public health registers.

Results: Persons with higher quercetin intakes had lower mortality from ischemic heart disease. The relative risk (RR) between the highest and lowest quartiles was 0.79 (95% CI: 0.63, 0.99: P for trend = 0.02). The incidence of cerebrovascular disease was lower at higher kaempferol (0.70; 0.56, 0.86; P = 0.003), naringenin (0.79; 0.64, 0.98; P = 0.06), and hesperetin (0.80; 0.64, 0.99; P = 0.008) intakes. Men with higher quercetin intakes had a lower lung cancer incidence (0.42; 0.25, 0.72; P = 0.001), and men with higher myricetin intakes had a lower prostate cancer risk (0.43; 0.22, 0.86; P = 0.002). Asthma incidence was lower at higher quercetin (0.76; 0.56, 1.01; P = 0.005), naringenin (0.69; 0.50, 0.94; P = 0.06), and hesperetin (0.64; 0.46, 0.88; P = 0.03) intakes. A trend toward a reduction in risk of type 2 diabetes was associated with higher quercetin (0.81; 0.64, 1.02; P = 0.07) and myricetin (0.79; 0.62, 1.00; P = 0.07) intakes.

Conclusion: The risk of some chronic diseases may be lower at higher dietary flavonoid intakes.

Key Words: Chronic disease • diet • flavonoids • flavonols • flavanones • flavones • prospective study • free radicals

Excerpts: "The incidence of asthma was lower at higher total flavonoid intakes (RR: 065; 95% CI: 0.47, 0.90; P = 0.04). This association was due to quercetin (0.76; 0.56, 1.01; P = 0.05), hesperetin (0.64; 0.46, 0.88; P = 0.03), and naringenin (0.69; 0.50, 0.94; P = 0.06)."

"The strongest associations were noted for apple (0.55; 0.40, 0.76; P = 0.001) and orange (0.71; 0.52, 0.98; P = 0.09) intakes."

"Of the main flavonoid sources, apple intake was associated with almost all of the chronic diseases considered. Apple intake was, after adjustment for intake of vegetables and fruit other than apples, inversely associated with occurrence of all cancers combined, lung cancer, asthma, type 2 diabetes, thrombotic stroke, total mortality and ischemic heart disease mortality."

Am J Respir Crit Care Med. 2001 Nov 15;164(10 Pt 1):1823-8.
Dietary antioxidants and asthma in adults: population-based case-control study.

Shaheen SO, Sterne JA, Thompson RL, Songhurst CE, Margetts BM, Burney PG.

Department of Public Health Sciences, King's College, Capital House, London, United Kingdom.

A protective role for dietary antioxidants in asthma has been proposed. However, epidemiological evidence to implicate antioxidant vitamins is weak, and data on the role of flavonoid-rich foods and antioxidant trace elements are lacking. We carried out a population-based case-control study in South London, UK, to investigate whether asthma is less common and less severe in adults who consume more dietary antioxidants. Participants were aged 16-50 yr and registered with 40 general practices. Asthma was defined by positive responses to a standard screening questionnaire in 1996, and complete information about usual diet was obtained by food frequency questionnaire from 607 cases and 864 controls in 1997. After controlling for potential confounding factors and total energy intake, apple consumption was negatively associated with asthma (odds ratio [OR] per increase in frequency group 0.89 [95% confidence interval [CI]: 0.82 to 0.97]; p = 0.006). Intake of selenium was also negatively associated with asthma (OR per quintile increase 0.84 [0.75 to 0.94]; p = 0.002). Red wine intake was negatively associated with asthma severity. The associations between apple and red wine consumption and asthma may indicate a protective effect of flavonoids. The findings for dietary selenium could have implications for health policy in Britain where intake has been declining.

Excerpts: "The clearest effect was seen in individuals who ate apples twice a week or more."

"Intakes of other fruits (citrus, pears, bananas) were not related to asthma after controlling for intake of apples and selenium."

"In this population-based study, we have found that asthma was less common in adults who consumed more apples and who had a higher intake of selenium."

PMID: 11734430 [PubMed - indexed for MEDLINE]


Thorax 2000;55:102-108 ( February )

Diet, lung function, and lung function decline in a cohort of 2512 middle aged men

Free full text of this journal article is available here.

Barbara K Butlanda, Ann M Fehilyb, Peter C Elwoodc

a Department of Public Health Sciences, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK, b H J Heinz Company Ltd, Kitt Green, Wigan, Lancashire WN5 0JL, UK, c MRC Epidemiology Unit (South Wales), Llandough Hospital, Penarth, South Glamorgan CF64 2XW, UK

Correspondence to: Ms B K Butland

Received 2 June 1999; Returned to authors 4 August 1999; Revised version received 22 October 1999; Accepted for publication 5 November 1999

BACKGROUND---A prospective cohort study of 2512 Welshmen aged 45-59 living in Caerphilly in 1979-1983 was used to investigate associations between diet and lung function.
METHODS---At baseline (phase I) and at five year follow up (phase II), forced expiratory volume in one second (FEV1) was measured using a McDermott spirometer and dietary data were obtained using a semi-quantitative food frequency questionnaire.
RESULTS---Good lung function, indicated by high maximum FEV1 given age and height, was associated with high intakes of vitamin C, vitamin E, beta -carotene, citrus fruit, apples, and the frequent consumption of fruit juices/squashes. Lung function was inversely associated with magnesium intake but there was no evidence of an association with fatty fish. Following adjustment for confounders including body mass index, smoking history, social class, exercise, and total energy intake, only the associations with vitamin E and apples persisted, with lung function estimated to be 39 ml (95% confidence interval (CI) 9 to 69) higher for vitamin E intakes one standard deviation (SD) apart and 138 ml higher (95% CI 58 to 218) for those eating five or more apples per week compared with non-consumers. Decline in lung function between phases was not significantly associated with the changing intakes of apples or vitamin E. An association between high average apple consumption and slow decline in lung function lost significance after adjustment for confounders.
CONCLUSIONS---A strong positive association is seen between lung function and the number of apples eaten per week cross sectionally, consistent with a protective effect of hard fruit rather than soft/citrus fruit. The recent suggestion that such effects are reversible was not supported by our longitudinal analysis.

We have demonstrated a positive cross sectional association between lung function and the number of apples eaten per week in a cohort of middle aged Welshmen. This association appeared to be independent of vitamin E and vitamin C intakes and may therefore be explained by other antioxidant constituents of apples such as flavonoids (e.g. quercetin).


Am. J. Respir. Crit. Care Med., Volume 164, Number 1, July 2001, 61-64
Chronic Obstructive Pulmonary Disease and Intake of Catechins, Flavonols, and Flavones
The MORGEN Study

Free full text of this journal article is available here.


Department of Chronic Disease Epidemiology and Division of Public Health Research, National Institute of Public Health and the Environment, Bilthoven; the Institute for Risk Assessment Sciences, Division Environmental and Occupational Health, University Utrecht, Utrecht; and Wageningen Research Centre, State Institute for Quality Control of Agricultural Products (RIKILT), Wageningen, The Netherlands

Flavonoids have been suggested to protect against chronic lung disease. We studied intake of catechins, flavonols, and flavones in relation to pulmonary function and COPD symptoms in 13,651 adults from three Dutch cities examined from 1994 to 1997. Dietary intake was estimated using a food frequency questionnaire, and flavonoid intake was calculated using specific food composition tables. Pulmonary function (FEV1) was determined by spirometry and COPD symptoms by questionnaire. Associations were presented for the fifth versus the first quintile of intake (Q5-Q1), adjusted for age, height (for FEV1 only), sex, smoking, BMI, and energy intake. Smoking was strongly associated with COPD, independent of dietary effects. Average catechin, flavonol, and flavone intake was 58 mg/d (SD = 46) with tea and apples as main sources. Total catechin, flavonol, and flavone intake was positively associated with FEV1 (beta Q5-Q1 = 44 ml, 95% CI = 18-69) and inversely associated with chronic cough (ORQ5-Q1 = 0.80, 95% CI = 0.66-0.97) and breathlessness (ORQ5-Q1 = 0.74, 95% CI = 0.58- 0.94), but not chronic phlegm. Catechin intake was independently associated with FEV1 (beta Q5-Q1 = 130 ml, 95% CI = 101-159) and all three COPD symptoms (ORQ5-Q1 = 0.60-0.72, p < 0.001). Flavonol and flavone intake was independently associated with chronic cough only. Solid fruit, but not tea, intake was beneficially associated with COPD. Our results suggest a beneficial effect of a high intake of catechins and solid fruits against COPD.

Excerpts: "A protective effect of flavonoids against chronic lung disease has been hypothesized by Miedema and colleagues (5). They suggested that the stronger association with 25-yr incidence of asthma and COPD observed for solid fruits (apples, pears) than for other types of fruits, may be due to the high level of flavonoids in apples."


Am J Clin Nutr. 2003 Sep;78(3):414-21.
Food and nutrient intakes and asthma risk in young adults.

Woods RK, Walters EH, Raven JM, Wolfe R, Ireland PD, Thien FC, Abramson MJ.

Department of Epidemiology & Preventive Medicine, Central and Eastern Clinical School, Monash University, and The Alfred Hospital, Melbourne, Victoria, Australia.

BACKGROUND: Some aspects of diet are relatively newly recognized potential risk factors for asthma, but the evidence to date is conflicting. OBJECTIVE: The goal was to determine whether the food and nutrient intakes of adults with asthma differ from those of adults without asthma. DESIGN: This was a community-based, cross-sectional study of 1601 young adults ( +/- SD age: 34.6 +/- 7.1 y) who were initially recruited by random selection from the federal electoral rolls in Melbourne in 1999. Subjects completed a detailed respiratory questionnaire, a validated semiquantitative food-frequency questionnaire, skin-prick testing, and lung function tests, including a methacholine challenge test for bronchial hyperreactivity (BHR). A total of 25 nutrients and 47 food groups were analyzed by using multiple logistic regression with alternate definitions of asthma and atopy as the outcomes. RESULTS: Whole milk appeared to protect against current asthma (odds ratio: 0.66; 95% CI: 0.46, 0.97), doctor-diagnosed asthma (0.73; 0.54, 0.99), BHR (0.68; 0.48, 0.92), and atopy (0.71; 0.54, 0.94). Conversely, soy beverage was associated with an increased risk of current asthma (2.05; 1.19, 3.53), doctor-diagnosed asthma (1.69; 1.04, 2.77), and BHR (1.65; 1.00, 2.71). Apples and pears appeared to protect against current asthma (0.83; 0.71, 0.98), asthma (0.88; 0.78, 1.00), and BHR (0.88; 0.77, 1.00). CONCLUSIONS: The consumption of dairy products, soy beverages, and apples and pears, but not of nutrients per se, was associated with a range of asthma definitions. Dietary modification after diagnosis is one possible explanation for this finding. Intervention studies using whole foods are required to ascertain whether such modifications of food intake could be beneficial in the prevention or amelioration of asthma.

Excerpt: "... given that the associations between dairy products, soy beverage, and apples and pears were reasonably consistent across all the outcome measures, we are confident that these represent real underlying patterns of association."

PMID: 12936923 [PubMed - indexed for MEDLINE]

(more research)
Can I just eat apples? Read the frequently asked questions here
What concentrated products are available? Check the Suppliers page here


Sign up FREE to get the latest news on apple polyphenols:

Your First Name:

Your email:

Be the first to know about new studies, reports and products.