Several studies have previously reported the relationships between lifestyle factors
and asthma incidence [1
]. However, few reports have focused on the relationships
between asthma control and lifestyle factors. A total of 437 asthmatic patients were
interviewed in our outpatient clinic, and the relationships between asthma control
and several lifestyle factors were investigated. The relationships of smoking or
alcohol drinking with asthma have already been reported in several articles. Radon
and colleagues reported that passive smoking was a risk factor for asthma occurrence
], while Bakirtas reported that passive
smoking and low income were risk factors for asthma incidence [4
]. Similar results were observed in the present study; patients
who were exposed to passive smoking or who could not pay any medical expenses for
asthma treatment, had a tendency to poor asthma control (data partly shown).
Regarding lifestyle-related factors, González reported that alcohol drinking did not
affect asthma control [12
]. Similar results
were obtained in the present study.
Lucas and colleagues insisted on the importance of physical activity on decreases in
asthma prevalence [14
]. On the other hand,
Westermann found that there was no relationship between asthma control and periodic
]. However, moderate exercise
(> 80 min/week) was found to be associated with good asthma control in the
present study. The Japanese government has recommended that 4 METs-h/week exercise
is required for the prevention of lifestyle-related diseases. In the present study,
patients with more than 3 METs-h/week exercise had good asthma control.
Comparisons of median ACT scores by various vegetable and fruit
intakes stratified by age groups.
Several empirical studies have investigated the effects of dietary intakes on asthma.
Frode reported that daily intakes of fresh fruit or vegetables in infancy decreased
the risk of asthma in school-age children [5
Rodriguez found that increased intakes of saturated fatty acids, myristic and
palmitic acids, and butter appeared to be related to the risk of current asthma in
]. Other reports mentioned that
intakes of α-linolenic acid and a low ratio of n-6:n-3 PUFA were associated with
decreased exhaled NO and improved asthma control [8
]. Nagel reported that more frequent consumption of fruit, vegetables,
and fish was associated with a lower lifetime prevalence of asthma, whereas high
burger consumption was associated with higher lifetime asthma prevalence [9
]. On the other hand, other investigators
reported that there were no clear relationships between dietary patterns and asthma
These previous reports focused on the relationships between asthma incidence and
diet, while the present study examined the relationships between asthma control and
diet. Particularly fresh vegetable, but not heated vegetable, intakes were
associated with good asthma control in the present study. The possible explanations
for this relationship remain to be investigated. In general, flavonoids and related
polyphenolic compounds in vegetables are lost with heating. There is a report that
flavonoids and related polyphenolic compounds had significant anti-inflammatory
]. Recently, Wood reported the
importance of intakes of antioxidants in vegetables for asthma [16
]. Further studies are required to elucidate
the relationship between flavonoids or antioxidants and asthma control.
In general, citrus fruits contain more amount of vitamin C than other fruits.
Previous reports indicated the relationship between consumption of citrus fruits and
incidence of asthma [17
]. Furthermore, citrus fruits contain anti-inflammatory
]. However, we could not find the
relation between the consumption of citrus fruits and asthma control in our study.
Although citrus fruits are also included in fruit mixed juice and 100% fruit juice,
the relation between asthma control and fruit mixed juice or 100% fruit juice was
not observed. One of the possible reasons is the genotype of the patient because
citrus fruits may influence the sensitivity of the treatment of asthma [20
Findings from this study are strengthened by the use of reliable and standardized
questionnaire to measure asthma control levels. Diez reported the relationships
between asthma control and several risk factors, including sex, race, BMI, smoking,
level of education, and habitual activity, in Spanish asthmatic patients [21
]. They used the asthma control questionnaire
(ACQ) to evaluate asthma control. This questionnaire reflected asthma control for
the most recent week. In the present study, we used the ACT questionnaire, which
reflects longer term (recent one month) of asthma control than the ACQ. For this
reason, we believe that the ACT is better than the ACQ for evaluation of asthma
control when comparing lifestyle factors.
The statistical significance of the relation between asthma control and exercise or
raw vegetable diet intake was observed in our multiple linear regression analysis.
However, the adjusted R squared was 0.049, indicating that the correlation
coefficient was relatively weak. Interpretation of the results of our study should
be made with caution. Since this study was conducted by only one institution,
further multicenter studies are required for universalization of our results.
In conclusion, periodical exercise and raw vegetable intakes are associated with good
asthma control in Japanese patients.