SupplementsEvidence ReviewAug 2026

Lung Detox Supplements: What the Evidence Says About Cleansing Your Lungs

A lung detox capsule is sold on a picture: black tar sitting in a pink bag, and a pill that rinses it out. That picture is wrong about how lungs work, and no product in this category turns up in the literature having been tested for the thing it promises. Some of the individual ingredients have been through very large trials, and those trials are worth knowing about, because two of them found more lung cancer in smokers rather than less.

1.28

Lung cancer risk ratio on beta carotene plus vitamin A (CARET)

0.58

Lung cancer hazard ratio, complete quitters against continuous smokers, Korean cohort

11 of 11

Vietnamese provinces studied by Nhung and colleagues over the WHO fine-particle guideline

This page is educational and not medical advice. It reports what specific human studies measured and what their authors concluded. It does not tell you to take anything, to stop anything, or what amount to use. Trial amounts appear only to describe what was tested. Anything about your own lungs belongs with a doctor or a pharmacist who can examine you.

Can A Capsule Clean A Lung

The word detox does a lot of work on a label and almost none in a lab. Klein and Kiat reviewed the whole detox category for the Journal of Human Nutrition and Dietetics in 2015 and found the industry booming while the clinical evidence stayed thin. A handful of clinical studies had suggested commercial detox diets enhance liver detoxification and eliminate persistent organic pollutants from the body, although the authors were clear that those studies were hampered by flawed methodologies and small sample sizes. They also noted preliminary evidence that foods such as coriander, nori and olestra have detoxification properties, although the majority of that work had been done in animals rather than people. Their bottom line: to the best of their knowledge, no randomised controlled trial had assessed the effectiveness of a commercial detox programme in humans.

That review covered detox diets rather than lung capsules, and the lung version of the category has even less behind it. Searching PubMed through the NCBI E-utilities interface in August 2026 for lung detox supplement returns a single record. PubMed does not read that as a phrase, it translates the query into lung AND detox AND dietary supplements, and one paper satisfies all three: a 2014 article in Human and Experimental Toxicology built around patented carnosine and carcinine formulations, with cell culture as its investigative tool. That is a laboratory and concept paper, not a trial in people.

Drop the supplement term and the query widens to 11 records, and reading all 11 is the interesting part. Two are laboratory and computational work on a Chinese herbal preparation tested against respiratory viruses, one is a cardamom chemistry paper, one is a report on acupuncture services at a university, one is a non-English paper on a drug used in acute destructive lung disease, one is the carnosine paper above, and the remaining five are melanoma and vaccine studies that matched because DETOX and Detox-PC are names of immunological adjuvants, which is also why PubMed reaches for a supplementary concept called detox adjuvant when it translates the query. Not one of the 11 is a randomised human trial of a lung detox product. A search returning little is not proof that nothing exists anywhere, but when a category this heavily marketed leaves a footprint this small, that gap is the finding.

The category and the ingredients are two different questions. Nobody has tested a lung detox product. Several of the molecules that end up inside one have been tested, sometimes in thousands of people. Keeping those two questions apart is the whole job of reading a label in this aisle.

What Clears Your Lungs Already

Your lungs are not a sealed container that collects sediment. Hill, Button, Rubinstein and Boucher open their 2022 review in Physiological Reviews by describing mucus clearance as the main mechanical defence system the human lung has. Mucus is moved out by cilia and by airflow, including cough-dependent mechanisms, and how fast it moves depends heavily on how concentrated the mucus is. In muco-obstructive diseases such as COPD and cystic fibrosis, mucus becomes hyperconcentrated and sticks, which is where clearance fails. Worth knowing when reading that paper: its declared conflicts of interest state that one author is chairman of the board of a pharmaceutical company, sits on two scientific advisory boards and consults for a fourth firm, and the review goes on to argue for hydrating and mucolytic drugs.

Smoking does not fill that system with a removable substance. It damages the lining that does the clearing and the air sacs where gas exchange happens, and that damage is structural. A Danish study of 62 healthy adults aged 18 to 84 measured clearance with a radioaerosol and found it was faster when the aerosol landed in the central airways than in the peripheral ones, and faster in the 53 lifelong non-smokers than in the 9 ex-smokers, with no influence of age. Nine ex-smokers is a very small group and the study was designed to set reference values rather than to answer this question, so treat it as a hint rather than a verdict.

This is why the marketing image fails. There is no reservoir to flush. There is a moving belt of mucus that either works or does not, and there is tissue that either healed or did not.

NAC And The Big Trials

N-acetylcysteine, usually written NAC, is the ingredient on these labels that has been through large randomised trials. It is a mucolytic, meaning it thins mucus so it is easier to cough up, and it is also a precursor the body uses to make glutathione. Two big trials tested it in COPD and reached different answers, and both answers are real.

Trial	Who and what	Result
BRONCUS (2005)	523 patients with moderate to severe COPD at 50 centres in Europe, 600 mg daily or placebo, 3 years	No difference in yearly FEV1 decline (54 vs 47 mL) and no difference in exacerbations (1.25 vs 1.29 per year, hazard ratio 0.99)
PANTHEON (2014)	1,006 randomised at 34 hospitals in China, 504 to NAC and 502 to placebo, aged 40 to 80 with moderate to severe COPD, 600 mg twice daily, 1 year	1.16 vs 1.49 exacerbations per patient-year, risk ratio 0.78 (95% CI 0.67 to 0.90, p = 0.0011). Funded by Hainan Zambon Pharmaceutical
PANTHER-IPF (2014)	133 on acetylcysteine and 131 on placebo, idiopathic pulmonary fibrosis with mild to moderate impairment, 60 weeks	No significant difference in forced vital capacity change (-0.18 vs -0.19 litres, p = 0.77), and no significant difference in death or acute exacerbation

BRONCUS did report one hedge worth carrying: a subgroup analysis suggested exacerbations might be reduced in the patients who were not taking inhaled corticosteroids, and a secondary analysis was suggestive of an effect on hyperinflation. The authors still concluded NAC was ineffective for preventing deterioration in lung function or exacerbations in COPD. Subgroup findings are hypotheses, not results.

Pooling the class, the 2019 Cochrane review by Poole, Sathananthan and Fortescue covered 38 trials and 10,377 participants, all adults with chronic bronchitis or COPD, testing N-acetylcysteine, carbocysteine, erdosteine and ambroxol against placebo. People on mucolytics were more likely to stay exacerbation-free (Peto odds ratio 1.73, 95 percent CI 1.56 to 1.91), with about eight people needing treatment for an average of nine months to keep one extra person exacerbation-free. The reviewers rated that moderate certainty and immediately qualified it: more recent studies showed less benefit than earlier ones, heterogeneity was high, and their confidence was reduced by possible selection or publication bias in the older trials. They also found limited impact on lung function or health-related quality of life.

The population gap that sells the product. Every trial above enrolled people with a diagnosis: COPD, chronic bronchitis or pulmonary fibrosis. None of them enrolled a healthy smoker, an ex-smoker with normal spirometry, or someone worried about traffic fumes. The outcomes measured were exacerbation counts and lung function, never tar removed. A bottle sold to a healthy person on the strength of a COPD exacerbation result is borrowing a finding from a population that is not you.

One regulatory detail, because product pages sometimes blur it. Filtering the United States National Drug Code directory on the generic_name field for acetylcysteine returns 53 entries. Fifty-two of those list a single active ingredient, and their marketing categories break down as 32 ANDA, 13 bulk ingredient, 5 bulk ingredient for prescription compounding, one NDA and one NDA authorised generic. Strip out the bulk powders and 34 finished products remain, and every one of them is listed as a human prescription drug, given by inhalation, intravenously or as an oral solution. The branded entry, Acetadote under NDA021539, is an intravenous injection. The 53rd entry matched only because acetylcysteine sits inside an 18-ingredient generic name on an unapproved homeopathic pellet, which is the substring hit you collect if you filter on a name field and never check the ingredient count. Two limits on all of that: it is United States data about United States listings, and the NDC directory covers drugs rather than supplements, so a capsule would never appear in it at all. Its absence there proves nothing about what sits on a shelf in Vietnam.

The Antioxidant Problem

The pitch behind most lung formulas is simple. Smoke and pollution cause oxidative stress, antioxidants reduce oxidative stress, so antioxidants should protect the lung. That reasoning was tested directly, at enormous scale, in exactly the people these products target, and it did not hold.

The ATBC study in Finland randomised 29,133 men aged 50 to 69 who smoked five or more cigarettes a day into four groups: alpha-tocopherol at 50 mg, beta carotene at 20 mg, both, or placebo, for five to eight years with a median of 6.1. Across 894 confirmed lung cancers, alpha-tocopherol did nothing either way (relative risk 0.99, 95 percent CI 0.87 to 1.13). Beta carotene was associated with more lung cancer, not less (relative risk 1.16, 95 percent CI 1.02 to 1.33, p = 0.02). The effect looked stronger in the men smoking at least 20 a day than in those smoking 5 to 19, though the authors described that difference as not substantially different. Their own conclusion used careful words: beta carotene supplementation at pharmacologic levels may modestly increase lung cancer incidence in cigarette smokers.

CARET, described by its own design paper as a two-armed trial running in Seattle, Portland, San Francisco, Baltimore, Connecticut and Irvine in the United States, randomised 18,314 smokers, former smokers and asbestos-exposed workers, so roughly half received the active combination of 30 mg beta carotene plus 25,000 IU of retinol daily. Over 73,135 person-years and a mean follow-up of four years, 388 new lung cancers were diagnosed. The active arm had a relative risk of lung cancer of 1.28 (95 percent CI 1.04 to 1.57, p = 0.02), a relative risk of death from any cause of 1.17 (1.03 to 1.33) and of death from lung cancer of 1.46 (1.07 to 2.00). The cardiovascular death figure, 1.26, had a confidence interval of 0.99 to 1.61 and so did not reach significance. The trial was stopped 21 months earlier than planned.

Zoom out from lungs and the picture stays uncomfortable. The 2012 Cochrane review by Bjelakovic and colleagues pooled 78 randomised trials and 296,707 participants, healthy people and patients with stable disease, mean age 63 and a median supplementation period of two years. Overall, antioxidant supplements had no significant effect on mortality under a random-effects model (relative risk 1.02, 0.98 to 1.05), although the same data showed a significant increase in mortality under a fixed-effect model (1.03, 1.01 to 1.05). In the 56 trials judged at low risk of bias, antioxidants significantly increased mortality (1.04, 1.01 to 1.07), with beta carotene and vitamin E carrying that signal while vitamin A, vitamin C and selenium did not significantly affect mortality. That is all-cause death across many conditions, not a lung endpoint, so read it as a caution about the category rather than a finding about breathing.

The fairest counterweight is small and specific. Grievink and colleagues followed 38 Dutch amateur cyclists across the summer of 1996, measuring lung function before and after 380 training sessions, with 20 of them taking 100 mg of vitamin E and 500 mg of vitamin C daily for 15 weeks. After excluding people with insufficient compliance, a 100 microgram per cubic metre difference in ozone exposure was linked to a 95 mL drop in FEV1 in the placebo group (95 percent CI -265 to -53) and a 1 mL change in the vitamin group (-94 to 132), and the difference between groups was statistically significant. The authors said the results suggest partial protection against the acute effects of ozone. Thirty-eight cyclists, one summer, ozone rather than particles, and an acute exercise effect rather than anything cleaned.

Ivy Leaf, Quercetin And The Rest

Ivy leaf extract, from Hedera helix, is the herbal in this space with the most published trials. Sierocinski, Holzinger and Chenot updated their systematic review in 2021, searching from December 2009 to January 2020, and found six randomised trials, one controlled clinical trial and four observational studies of ivy leaf preparations used alone or in combination. All of those studies concluded ivy leaf is effective and safe for cough due to upper respiratory infections and bronchitis, and three randomised trials reported a faster reduction in cough severity or frequency, or both. The reviewers then qualified it hard: the clinical significance of those effects appeared minimal, the overall quality of reporting was low and the risk of bias was high. Their conclusion was that ivy leaf is safe, with effects minimal at best and of uncertain clinical importance. The population there is people with an acute infection, not smokers and not commuters.

Quercetin gets cited on lung labels a lot, and the human record behind it is smaller than the citation suggests. Han and colleagues published a randomised trial in BMJ Open Respiratory Research in 2020 giving COPD patients placebo or quercetin at 500, 1,000 or 2,000 mg a day for one week in a dose-escalation design, and concluded that quercetin was safely tolerated up to 2,000 mg a day. The registry record for that study, NCT01708278, lists the University of Michigan as lead sponsor, phase 1, completed in October 2015, with an actual enrolment of 9 participants and a primary outcome measuring safety concerns. So it answers whether anyone was harmed in a week, not whether anyone breathed better. The paper's own rationale for testing it, that quercetin reduced oxidative stress markers, lung inflammation and rhinovirus-induced disease progression, came from a preclinical animal model of COPD rather than from people.

For the rest of what turns up on these labels, mullein, liquorice root, peppermint, oregano, turmeric and similar, searches of the published literature did not surface randomised human trials measuring lung clearance or lung function in smokers or in people exposed to polluted air. That is an absence of published tests rather than proof of no effect, and the two are not the same thing. It does mean that anybody printing a lung benefit next to those names on a box is going beyond what has been shown.

Air Pollution In Vietnam, And What A Pill Cannot Do

If you live in Ha Noi or Ho Chi Minh City, the reason a lung detox advert lands is that the air is a real problem, and the numbers back you up. Nhung and colleagues modelled annual average fine particle concentrations across Vietnam for 2019 on a three by three kilometre grid and applied a global exposure mortality model to the population aged over 25 in 11 provinces. Annual levels in all 11 studied provinces exceeded both the World Health Organization guideline of 5 micrograms per cubic metre and Vietnam's own proposed national standard of 15. Their highest provincial estimate was Ha Noi City, where 5,090 deaths a year (95 percent CI 4,253 to 5,888) were attributed to the gap between actual air and the WHO guideline. At district level the highest rate was Ly Nhan in Ha Nam province, at 104.6 attributable deaths per 100,000 people (87.0 to 121.5). Those are modelled estimates from a health impact assessment, not counted bodies.

The one supplement study that speaks to this directly is a pilot. Zhong and colleagues put 10 healthy adults through three controlled two-hour exposures in a crossover design: clean air with placebo, fine particles at 250 micrograms per cubic metre with placebo, and the same particles while taking B vitamins at 2.5 mg folic acid, 50 mg vitamin B6 and 1 mg vitamin B12 daily. The particles produced DNA methylation changes in genes tied to mitochondrial energy metabolism in immune cells, and the B vitamins prevented those changes. The particles also cut mitochondrial DNA content by 11.1 percent compared with clean air (95 percent CI 0.4 to 21.7, p = 0.04), and the vitamins offset that. Ten people, two hours, and a molecular marker in a blood cell. Nobody has shown that this marker translates into a symptom, a lung function reading or a disease outcome, and the paper carries a published erratum and two published comments.

The uncomfortable part. Nothing you swallow lowers the concentration of particles you breathe. The measures that move that number are the boring structural ones: air quality policy, indoor filtration, not exercising hard beside a six-lane road at rush hour, and masks that seal properly. A capsule does not compete with any of that, and selling it as though it does is the trick.

What Does Have Evidence

Stopping smoking is the intervention with the strongest data for lungs, and the trial that showed it was a proper randomised one. The Lung Health Study enrolled 5,887 smokers aged 35 to 60 with spirometric signs of early obstruction across ten centres in the United States and Canada, randomising them to a smoking intervention plus an inhaled bronchodilator, the smoking intervention plus placebo, or no intervention. Both smoking-intervention groups showed significantly smaller declines in FEV1 than the control group over five years. Most of that difference appeared in the first year and was attributable to the quitting itself, with sustained quitters getting the largest benefit. The bronchodilator's small benefit disappeared once it was stopped.

Cancer risk moves on a slower clock, and the shape of the curve is worth knowing before you get discouraged. A Korean cohort study followed 2,974,820 adults aged 30 and over through the national health insurance system, with a mean follow-up of 13.4 years and 196,829 confirmed cancers. Complete quitters had a lung cancer hazard ratio of 0.58 (95 percent CI 0.53 to 0.62) against continuous smokers. The authors also reported something counterintuitive that a summary usually drops: risk sat slightly higher than continued smoking for about 10 years after quitting before falling, reaching half the continued-smoking risk only after 15 years or more. Quitting before 50 was associated with a bigger reduction in lung cancer risk (0.43, 0.35 to 0.53) than quitting at 50 or later (0.61, 0.56 to 0.66), and every age group still benefited.

For people who already have COPD, structured exercise has better evidence than anything in a capsule. The 2015 Cochrane review by McCarthy and colleagues pooled 65 randomised trials and 3,822 participants and found pulmonary rehabilitation relieved breathlessness and fatigue, improved emotional function and sense of control over the condition, and improved health-related quality of life and exercise capacity, with improvements the reviewers called moderately large and clinically significant. That population is people with diagnosed COPD, under supervision, so it is not a general fitness claim.

Reading A Lung Detox Label

No specific product was tested for this page, and no brand claim here is verified. What follows is how to read the box yourself, which is the part that transfers to whatever is in front of you in the pharmacy.

Look for an amount next to every ingredient. A proprietary blend that lists names without amounts cannot be compared to any trial, because every trial specifies an amount.
Check whether the outcome being promised was ever measured. Exacerbations and FEV1 were measured. Toxins, sludge and tar were not.
Check who the cited study enrolled. A COPD exacerbation result does not transfer to a healthy person, and an animal or cell-culture result does not transfer to a person at all.
If you smoke, look hard at any beta carotene or vitamin A content and take that question to a pharmacist. ATBC tested beta carotene on its own in men aged 50 to 69 who smoked, and CARET tested beta carotene combined with vitamin A in smokers, former smokers and asbestos-exposed workers, and both found more lung cancer rather than less.
Check the Vietnamese import and registration details on the box, and whether an importer is named at all.
Treat any claim that a capsule removes tar as a marketing metaphor, because no published human study has measured it.

There is also a line where this stops being a shopping question. A cough that will not clear, blood in what you cough up, breathlessness that is new or getting worse, chest pain or unexplained weight loss are all reasons to see a doctor rather than to buy a supplement. Those need a stethoscope and an image, and the delay caused by trying a capsule first is the real cost of this category. If you are unsure how to get seen in Vietnam, the healthcare guide for foreigners covers how the public and private systems work.

The Short Version

Searches of PubMed do not surface a human trial of a commercial lung detox product tested for removing tar or pollution from lungs.
Lungs clear themselves through mucus, cilia and cough, which Hill and colleagues describe in Physiological Reviews as the main mechanical defence the lung has. Smoking damages the machinery rather than filling a reservoir.
NAC has the largest trials here, and they were run in patients with COPD or pulmonary fibrosis. PANTHEON cut exacerbations in 1,006 Chinese COPD patients, BRONCUS found nothing in 523 European ones, and neither measured cleaning.
Beta carotene on its own raised lung cancer incidence in the male smokers of ATBC in Finland, and CARET in the United States found the same for beta carotene combined with vitamin A in smokers, former smokers and asbestos-exposed workers, and CARET was stopped early.
Ivy leaf is safe with minimal effects on infection cough, and the human quercetin trial in COPD was a 9-person, one-week phase 1 safety study.
All 11 Vietnamese provinces studied by Nhung and colleagues exceeded the WHO fine-particle guideline, and no supplement lowers what you breathe.
Quitting, and structured pulmonary rehabilitation for people with COPD, are the interventions with real trial evidence behind them.

Frequently Asked Questions

Do lung detox supplements work?+

Searches of the published literature do not surface a human trial of a commercial lung detox product tested for the thing it is sold to do, which is removing tar or pollution from a lung. Individual ingredients have been tested, and the useful ones were tested in people who already had diagnosed lung disease. N-acetylcysteine at 600 mg twice daily cut exacerbation rates in 1,006 Chinese patients with moderate to severe COPD in the PANTHEON trial, while the same molecule at 600 mg once daily changed neither lung function decline nor exacerbation rate in 523 European COPD patients in BRONCUS. Neither trial measured cleaning, and neither enrolled a healthy smoker or a city commuter. So the honest answer is that the ingredients have a real but narrow evidence base in patients, and the product claim on the bottle has none.

Can you clean your lungs after smoking?+

Your lungs run their own clearance system whether you help them or not. Hill and colleagues, writing in Physiological Reviews in 2022, describe the mucus clearance system as the main mechanical defence the human lung has, working through cilia and airflow plus cough, with transport speed depending heavily on how concentrated the mucus is. What smoking does is not fill a bag with sludge that a pill could rinse out, it damages the airway lining and the air sacs, and that damage is structural. In one Danish study of 62 healthy adults, clearance was faster in the 53 lifelong non-smokers than in the 9 ex-smokers, which hints that clearance may not snap all the way back, though 9 people is a very small group to lean on. The intervention with large trials behind it is stopping, not swallowing.

Does NAC clean your lungs?+

NAC is a mucolytic, which means it thins mucus so it is easier to cough up, and that is a different job from removing tar or particles. The 2019 Cochrane review of mucolytics pooled 38 trials and 10,377 adults with chronic bronchitis or COPD and found a small benefit, with roughly eight people needing treatment for an average of nine months to keep one extra person free of exacerbations. The reviewers rated it moderate certainty and flagged that newer trials showed smaller effects than older ones, with limited impact on lung function or quality of life. In the US National Drug Code directory, all 34 finished single-ingredient acetylcysteine products are listed as human prescription drugs given by inhalation, injection or oral solution, not as supplement capsules, and that directory covers drugs rather than supplements so it says nothing about what a Vietnamese pharmacy stocks.

Do lung detox pills remove tar from the lungs?+

Nothing published shows that. Klein and Kiat reviewed the detox category in 2015 and reported that a handful of clinical studies suggested commercial detox diets enhanced liver detoxification and eliminated persistent organic pollutants, although those studies were hampered by flawed methods and small samples, and that to their knowledge no randomised controlled trial had tested a commercial detox programme in humans. Their review covered detox diets rather than lung products, which is itself the point: the lung version has even less behind it. A PubMed query for lung detox supplement returns a single record, a cell-culture and concept paper about patented carnosine formulations rather than a human trial, and widening the query to lung detox returns 11 records, none of them a randomised trial of a lung detox product.

Are lung supplements safe for smokers?+

Two of the largest supplement trials ever run were run in smokers and both found harm from beta carotene. In Finland, the ATBC study randomised 29,133 men aged 50 to 69 who smoked at least five cigarettes a day across four groups, and beta carotene was associated with a 16 percent higher lung cancer risk (relative risk 1.16, 95 percent CI 1.02 to 1.33). In the United States, CARET randomised 18,314 smokers, former smokers and asbestos-exposed workers across two arms, so roughly half received beta carotene plus vitamin A, and the active arm had a relative risk of lung cancer of 1.28 (95 percent CI 1.04 to 1.57). CARET was stopped 21 months early. If you smoke, the beta carotene and vitamin A content of anything sold to you for lung health is worth showing to a pharmacist before you buy it.

Do supplements protect you from air pollution?+

The human data is thin and it measures markers rather than health. Zhong and colleagues gave 10 healthy adults a controlled two hour exposure to fine particles at 250 micrograms per cubic metre with and without B vitamins, and the B vitamins prevented the DNA methylation changes the particles caused in immune cells and offset an 11.1 percent drop in mitochondrial DNA content. The authors called it a pilot. Separately, 38 Dutch cyclists were studied across a summer, and the 20 taking vitamins C and E showed less short-term lung function loss on higher-ozone days than the placebo group, after people with poor compliance were excluded. That is ozone, not particles, and it is 38 people. Nothing you swallow lowers the pollution you breathe.

How long does it take for lungs to recover after quitting smoking?+

Some of it is fast and some of it takes over a decade. In the Lung Health Study, 5,887 smokers aged 35 to 60 with early airflow obstruction were followed for five years, and both smoking-intervention groups showed significantly smaller declines in FEV1 than the control group, with most of that difference appearing in the first year and attributable to quitting. Cancer risk moves on a longer clock. A Korean cohort of 2,974,820 adults followed for a mean of 13.4 years found that overall cancer risk sat slightly higher than continued smoking for the first 10 years after quitting, then fell, reaching half the continued-smoking risk after 15 years or more. The authors add that lung cancer risk decreased 3 years earlier than that of other cancer types, with a larger relative reduction, and complete quitters had a lung cancer hazard ratio of 0.58 against continuous smokers.

Research And Sources

Every figure on this page comes from one of the papers below, read as published abstracts, plus two PubMed searches run through the NCBI E-utilities interface, one query against the openFDA National Drug Code directory and one against the ClinicalTrials.gov registry. The two PubMed searches are the ones described in the first section. Lung detox supplement returned a single record, PMID 24220875, the carnosine and carcinine paper. Lung detox returned 11 records: PMIDs 1779176, 9514698, 10946811, 12473578, 18815785, 22810344, 24010498, 24220875, 32307268, 33824121 and 34051873. Where a study hedged, the hedge is carried through. Where a result belongs to a specific population, that population is named in the same sentence.

Physiology and pathophysiology of human airway mucus · Hill DB, Button B, Rubinstein M, Boucher RC · Physiological Reviews (2022) PMID:35001665
Lung mucociliary clearance · Mortensen J, Lange P, Nyboe J, Groth S · European Journal of Nuclear Medicine (1994) PMID:7995289
Detox diets for toxin elimination and weight management: a critical review of the evidence · Klein AV, Kiat H · Journal of Human Nutrition and Dietetics (2015) PMID:25522674
Effects of N-acetylcysteine on outcomes in chronic obstructive pulmonary disease (BRONCUS): a randomised placebo-controlled trial · Decramer M, Rutten-van Molken M, Dekhuijzen PN, et al. · The Lancet (2005) PMID:15866309
Twice daily N-acetylcysteine 600 mg for exacerbations of chronic obstructive pulmonary disease (PANTHEON): a randomised, double-blind placebo-controlled trial · Zheng JP, Wen FQ, Bai CX, et al. · The Lancet Respiratory Medicine (2014) PMID:24621680
Mucolytic agents versus placebo for chronic bronchitis or chronic obstructive pulmonary disease · Poole P, Sathananthan K, Fortescue R · Cochrane Database of Systematic Reviews (2019) PMID:31107966
Randomized trial of acetylcysteine in idiopathic pulmonary fibrosis · Idiopathic Pulmonary Fibrosis Clinical Research Network; Martinez FJ, de Andrade JA, Anstrom KJ, King TE Jr, Raghu G · New England Journal of Medicine (2014) PMID:24836309
Alpha-tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study · Albanes D, Heinonen OP, Taylor PR, et al. · Journal of the National Cancer Institute (1996) PMID:8901854
Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease · Omenn GS, Goodman GE, Thornquist MD, et al. · New England Journal of Medicine (1996) PMID:8602180
The beta-carotene and retinol efficacy trial (CARET) for chemoprevention of lung cancer in high risk populations: smokers and asbestos-exposed workers · Omenn GS, Goodman G, Thornquist M, et al. · Cancer Research (1994) PMID:8137335
Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases · Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C · Cochrane Database of Systematic Reviews (2012) PMID:22419320
Double-blind intervention trial on modulation of ozone effects on pulmonary function by antioxidant supplements · Grievink L, Zijlstra AG, Ke X, Brunekreef B · American Journal of Epidemiology (1999) PMID:10025472
Ivy leaf (Hedera helix) for acute upper respiratory tract infections: an updated systematic review · Sierocinski E, Holzinger F, Chenot JF · European Journal of Clinical Pharmacology (2021) PMID:33523253
Randomised clinical trial to determine the safety of quercetin supplementation in patients with chronic obstructive pulmonary disease · Han MK, Barreto TA, Martinez FJ, Comstock AT, Sajjan US · BMJ Open Respiratory Research (2020) PMID:32071149
Mortality benefits of reduction fine particulate matter in Vietnam, 2019 · Nhung NTT, Duc VT, Ngoc VD, et al. · Frontiers in Public Health (2022) PMID:36466445
B vitamins attenuate the epigenetic effects of ambient fine particles in a pilot human intervention trial · Zhong J, Karlsson O, Wang G, et al. · Proceedings of the National Academy of Sciences (2017) PMID:28289216
Effects of smoking intervention and the use of an inhaled anticholinergic bronchodilator on the rate of decline of FEV1. The Lung Health Study · Anthonisen NR, Connett JE, Kiley JP, et al. · JAMA (1994) PMID:7966841
Cancer risk following smoking cessation in Korea · Park E, Kang HY, Lim MK, Kim B, Oh JK · JAMA Network Open (2024) PMID:38319658
Pulmonary rehabilitation for chronic obstructive pulmonary disease · McCarthy B, Casey D, Devane D, Murphy K, Murphy E, Lacasse Y · Cochrane Database of Systematic Reviews (2015) PMID:25705944