Dietary fat, airway inflammation and bronchodilator response in asthma - Study 2

Participants will attend four visits. At each visit, participants will consume a study meal at 0 hours and a study meal or water at 2 hours. The order in which these meals will be consumed will be randomly allocated. There will be a washout period of at least 1 week between visits. The four study groups are as follows: 1. Control Group 0 hours - 200g plain mashed potato (720kJ, 0.2g fat, 40g carbohydrate) 2 hours - 250mL plain water (0kJ) 2. Carbohydrate Group 0 hours - 200g plain mashed potato (720kJ, 0.2g fat, 40g carbohydrate) 2 hours - Participants can choose their preference of either: marshmallows (138g) (1918kJ, 0g fat, 109g carbohydrate) OR white jelly beans (114g) (1858kJ, <1g fat, 109g carbohydrate) OR marshmallows (69g) and white jelly beans (57g) (1888kJ, <1g fat, 109g carbohydrate). 3. Saturated Fat Group: 0 hours - 200g mashed potato (720kJ, 0.2g fat, 40g carbohydrate) mixed with 75g double cream and 14g unsalted butter (1940kJ, 50g fat, 3.4g carbohydrate) 2 hours - 250mL plain water (0kJ) 4. Omega-6 Fat Group: 0 hours - 200g mashed potato (720kJ, 0.2g fat, 40g carbohydrate) mixed with 50g sunflower oil (1850kJ, 50g fat, 0g carbohydrate 2 hours - 250mL plain water (0kJ) Participants will be asked to consume each meal within a 15 minute timeframe. On arrival, participants will undergo exhaled nitric oxide (eNO) measurement, blood pressure/pulse wave velocity measurement, and a fasting venous blood sample will be collected. Baseline lung function will be measured. A hypertonic saline challenge/sputum induction will be performed for a standardised 15.5 minutes nebuliser time. All participants will be administered with a short acting B2-agonist (salbutamol 200ug, inhaled via a spacer) either when they exhibit airway hyperresponsiveness during the saline challenge (>=15% drop in FEV1) or after the completion of 15.5 minutes nebuliser time. The participant will then consume the allocated study meal. At 2 hours, a venous blood sample will be collected and lung function measured. Immediately following these measurements, the allocated study meal or water will be consumed. At 3 hours, a venous blood sample and spirometry will be performed. At 4 hours, participants will again undergo exhaled nitric oxide (eNO) measurement, blood pressure/pulse wave velocity measurement, and a venous blood sample will be collected. Lung functionwill be measured. A hypertonic saline sputum induction will be performed for a standardised 15.5 mins nebuliser time. Participants will be administered with a short acting B2-agonist (salbutamol 200ug, inhaled via a spacer) if they exhibit a >=15% drop in FEV1 during the sputum induction, or if at the completion of 15.5 minutes nebuliser time their FEV1 is >=10% below baseline, or at the patients request. At visit 1 a skin prick allergy test will be completed, and height and weight measured. Standardised questionnaires will be completed at: * Visit 1 only: Asthma history, medications, GINA pattern, Juniper asthma quality of life questionnaire. * All visits: Asthma stability, Juniper asthma control quesitonnaire, 24-hour food recall diary.