Approximately 1 in 5 (or 12.7 million adults) in the UK have longstanding respiratory illnesses, and 6.5 million patients report taking prescription medication to ease the burden. Many patients suffer from lung tissue damage, which impairs adequate blood oxygenation and reduces blood saturations, and causes breathlessness. The current method of treatment is palliative - with the patient breathing supplemental oxygen through an oxygen cylinder and tube. This severely compromises patients' quality of life, as they are tethered to a heavy, unwieldy oxygen cylinder, limiting their ability and willingness to leave home.

Several recent studies in both animals and humans have indicated that orally administered oxygenated nanobubbles is a safe intervention that can improve tissue oxygenation. This randomized, double-blinded, cross-over, placebo-controlled study will evaluate the effect of an oxygen nanobubbles drink on the exercise performance of patients with chronic lung disease, such as pulmonary fibrosis. Patients will conduct the 6 Minute Walk Test (6MWT) twice, once with a placebo drink and once with the oxygen nanobubbles drink, based on a double-blind randomization protocol, and this study will evaluate the distance walked, heart rate, oxygen levels, breathlessness, and time to recovery in both cases. The investigators hypothesize that drinking the oxygen nanobubbles drink will improve the delivery of oxygen to vital organs, improving the distance a patient can cover in the 6 Minute Walk Test by 30m, which is the minimum clinically important difference.

Inclusion Criteria:

• Patient is Male or Female, aged 18 years or above
• Participant is willing and able to give informed consent for participation in the study.
• Patients diagnosed with Pulmonary Fibrosis as per ATS/ERS guidelines, and in whom the lung fibrosis is considered the dominant cause of symptoms (i.e. no severe other disease such as COPD or heart failure)
• The patient must be able to walk independently without a walking stick
• The patient can, in the view of their respiratory clinician, adequately participate in a 6MW test

Exclusion Criteria:

• Pregnant or breast feeding
• History of current neurological condition (e.g., epilepsy)
• Patient has consumed liquorice in the last 24 hours.
• Patients with TLCO <30%
• Patients with known unstable ischaemic heart disease or pulmonary hypertension
• Patients with a history of smoking in the previous 30 days
• Patients that are allergic or intolerant towards: Liquorice, Lecithin derived from soya or sunflower, Citric acid, Glycerol
• Patients with known severe Renal Dysfunction
• Patients with known severe Liver Dysfunction