Observational study into the Relationship between Asthma and Nutrition in asthma sub-Groups including clinical, functional and inflammatory Endpoints

Asthma is an increasing problem in the western industrialized countries, which
has been suggested to be related to environmental exposures and lifestyle
changes, particularly diet. Asthma is a heterogeneous condition with many
clinical and inflammatory subgroups. In particular for late-onset eosinophilic
asthma, exogenous trigger factors, other than allergens, have been suggested to
induce the highly inflammatory status, including dietary factors.
The Western diet has been thought to promote a pro-inflammatory environment,
due to factors such as lack of antioxidants and abundance of saturated fatty
acids. Dietary antioxidants (e.g. vitamin A, C, E, and selenium) might protect
lung tissue against oxidative damage, in response to exposures such as air
pollution and airway inflammatory cell responses. On the other hand, excess fat
intake may induce activation of the innate immune system and inflammatory
pathways. By contrast, the Mediterranean diet, which is deemed more
anti-inflammatory, has been associated with fewer asthma symptoms and improved
asthma control.
Furthermore, poor nutritional status, weight loss and muscle wasting have been
associated with lower quality of life, lower physical exercise performance and
higher risk of exacerbation in patients with chronic obstructive pulmonary
disease, a closely linked inflammatory airway disease. Likewise, the existence
of both airway and systemic inflammation in severe asthma patients may also
lead to loss of muscle mass and subsequently declined nutritional status.
However, no studies have examined the role of nutritional status on clinical,
functional and inflammatory asthma outcomes yet.
Although the role of diet in asthma has gained interest in literature, the
evidence is inconclusive. It remains unclear whether nutritional factors are
related to the different types of inflammation in asthma, and the various
asthma subgroups. The capacity of nutritional intake and status to alter
disease outcome (e.g. on asthma control, lung function, quality of life)
remains underexplored.

Primary objective
1. To assess differences in nutritional intake and status, by asthma subgroups
(e.g. early vs late onset; allergic vs non-allergic; eosinophilic vs
non-eosinophilic; obese vs non-obese; moderate vs severe)

Secondary objective
2. To explore associations of nutritional intake and status, with clinical,
functional and inflammatory characteristics of asthma
a. To assess differences in these associations between asthma subgroups

This study is a cross-sectional study and will be performed in two clinical
settings at the MCL Pulmonary Department: 1) the 1-day visiting programme of
the Severe Asthma Centre (tertiary referral for difficult-to-control/severe
asthma) and 2) the general Asthma Outpatient Clinic (moderate to severe
asthma).

The burden associated with this study includes two times of extra assessments
added to regular visits to the pulmonary department. For a subset of patients
only one assessment can be combined with regular care and therefore an extra
visit is requested of them. Each assessment will last approximately 45-60
minutes. The first visit will include anthropometric measurements, a
bio-electrical impedance analysis and a handgrip strength test. Patients of
Asthma Outpatient Clinic will also perform the 6-minute walking test as part of
research. This walking test is already part of regular care for patients of the
Severe Asthma Centre. Furthermore, in addition to regular blood testing 40 ml
extra blood will be drawn, of which 10 ml will be stored for potential future
research. Prior to the second visit, all patients will complete the dietary
assessment (two questionnaires and a 3-day food record), a physical activity
questionnaire and collect a 24-hour urine sample at home. The dietary
assessment will be discussed during the second visit.
The risks and disadvantages of this study are small. Participants may
experience discomfort from collecting a 24-hour urine sample. Blood withdrawal
may also cause discomfort and pain, but this is combined with blood collection
in regular care and will therefore not cause extra discomfort.
The results of this study may be important for asthmatic patients, as it may
identify differences in nutritional intake and status in subgroups of asthma
patients. Furthermore, this study may help to understand the relation between
nutritional intake and status and clinical, functional and inflammatory
characteristics of asthma. However, there are no personal direct benefits for
the participants. We think the potentially obtainable knowledge outweigh the
risks and discomfort of this study.