Respiratory Health

Nutrients connected to Respiratory Health

A link means the body needs the nutrient for this, or that low intake is linked to it. It does not mean extra supplements help if your intake is already adequate; each link shows how strong the evidence is.

• Beta-caroteneDocumented risk

  High-dose beta-carotene pills raised lung cancer risk in smokers and asbestos-exposed workers in two large trials. This is a risk, not a benefit.

• LobeliaDocumented risk

  Higher amounts of lobeline depress breathing. It is also sold for asthma and smoking, but it is not effective for either.

• Split gill mushroomDocumented risk

  Its spores have caused sinus infections, lung infections and allergic lung disease in rare cases. Reports describe breathing spores, not eating the mushroom.

• Poison hemlockDocumented risk

  Paralysis of the breathing muscles can be fatal.

• Royal JellyDocumented risk

  Asthma attacks after eating royal jelly are documented.

• N-acetylcysteinePreliminary or mixed

  Acetylcysteine is used as a medicine to thin mucus, and a Cochrane review of oral mucolytics (NAC among them) found a small benefit for flare-ups in chronic bronchitis and COPD, with smaller effects in newer studies. Not specific to supplements.

• ElderberryPreliminary or mixed

  Studied for symptoms of colds, flu and other upper respiratory infections; evidence is preliminary and uncertain.

• EchinaceaPreliminary or mixed

  Studied for colds and other upper respiratory infections; benefit is small or unproven.

• Marshmallow rootPreliminary or mixed

  Used traditionally for throat irritation with dry cough; the EU committee accepts this on traditional use and says trial evidence is insufficient. Uncontrolled surveys and a narrative review are encouraging but not firm proof.

• AndrographisPreliminary or mixed

  Studied for cough and sore throat in acute respiratory infections; promising but limited evidence.

• Pelargonium (Umckaloabo)Preliminary or mixed

  Low-quality Cochrane evidence suggests the liquid extract may ease acute bronchitis symptoms; tablets did not show the same result. EU regulators accept use for cold symptoms on the basis of long-standing use, not trials.

• Ivy leafClinically supported

  Ivy leaf extracts are accepted in the EU as an expectorant for chesty cough, but a systematic review judged the benefit minimal and trial quality low.

• MulleinPreliminary or mixed

  Accepted in the EU as a traditional medicine for sore throat with dry cough and cold; clinical studies are lacking.

• Tiger milk mushroomLab or animal research only

  Traditionally used for cough and asthma. Animal studies show less allergic airway inflammation; human evidence is limited to one small hay fever trial and a single reported asthma study.

• Cs-4 and cultured Cordyceps myceliumPreliminary or mixed

  Pooled Chinese trials found better lung-function numbers with Jinshuibao added to COPD care, but the trials were low quality and the authors could not confirm efficacy and safety.

• White sageDocumented risk

  Smoke from burning plants adds fine particles to indoor air; Health Canada says these are most harmful to people with breathing or heart conditions, and a case report linked regular burning of sage and oils with lung disease. No study measured sage bundle smoke itself.

• Nasturtium (garden)Preliminary or mixed

  A 2023 placebo-controlled trial of the combination reported faster bronchitis symptom improvement; evidence is one trial of one product.

• Cowslip (primula)Preliminary or mixed

  Cowslip flower and root are traditional EU cough remedies based on long use only; EMA found no trials of cowslip alone, and a thyme-primula combination trial cannot be credited to it.

• Sweet violetPreliminary or mixed

  Violet flower syrup shortened cough time in one trial of children with asthma; folk use for cough is long but is not proof. Evidence is limited to that trial.

• Lemongrass OilDocumented risk

  EFSA lists lemongrass oil as a respiratory sensitizer; ask a clinician before diffusing if you have asthma.

• Pine OilDocumented risk

  EFSA lists a respiratory-sensitiser hazard; mouse inhalation study urges caution in lung inflammation.

• Thyme TeaPreliminary or mixed

  Chesty cough with colds, traditional use; combination extracts positive in two trials.

• Cajeput OilDocumented risk

  EFSA lists the oil as a respiratory sensitizer; traditional use for breathing complaints is not backed by a trial.

• Diatomaceous EarthDocumented risk

  Dust is the main hazard.

• Salt-Water Gargles and Nasal RinsesPreliminary or mixed

  Saline rinses are recommended in a 2022 review for most sinonasal diseases, but a 2026 review found the trial results fragile.

• Salt Therapy (Halotherapy)Preliminary or mixed

  Studied for asthma and COPD with small trials; safety questions include room hygiene and dust.

• Neti Pot and Saline Nasal RinseClinically supported

  Cochrane and 2022 reviews support saline rinsing for symptoms of chronic sinus disease.

• HoneyClinically supported

  Trials in children with acute cough found honey probably eases cough symptoms; short follow-up.

• Buckwheat HoneyClinically supported

  Honey probably eases acute cough in children over 12 months better than no treatment, per Cochrane (moderate certainty); the buckwheat trial was one small parent-reported study.

• Immune Support FormulasPreliminary or mixed

  The studied outcome is mostly upper respiratory infection and cold symptoms.

• HorseradishPreliminary or mixed

  One trial of a nasturtium-horseradish combination reported faster relief of acute bronchitis symptoms. It did not test horseradish alone.

• EucalyptusPreliminary or mixed

  The EMA accepts eucalyptus leaf for cough with a cold on long-standing use only; no clinical trial of the leaf was found. Trials of purified cineole capsules showed limited, short-term benefit.

• ForsythiaPreliminary or mixed

  Cold symptoms improved with a formula containing forsythia in one small trial; lab work suggests virus-related actions but not in people.

• HyssopPreliminary or mixed

  One small 2024 trial of hyssop syrup in asthma showed benefit in some people and harm in others; it needs confirming.

• HorehoundPreliminary or mixed

  Traditionally used (EU) to help loosen phlegm in a cough with a cold. This rests on long use, not trial results.

• Oyster mushroomPreliminary or mixed

  Pleuran products were tested for infections and asthma control in children; results are from abstracts of trials by one group and concern purified products.

• Caterpillar fungusPreliminary or mixed

  One 2025 active-controlled COPD trial of a fungal capsule found fewer flare-ups against a similar capsule; no placebo group, and the reviews rate certainty low to moderate.

• Fritillaria (chuan bei mu)Lab or animal research only

  Traditionally used for cough with phlegm. Cough-easing effects are seen in animal experiments; no human trial of the bulb on its own was found.

• Vervain (European)Preliminary or mixed

  Vervain is one of five herbs in a sinus-infection extract that beat placebo in adult trials, but the result belongs to the mix and the manufacturer funded the work.

• Iceland mossPreliminary or mixed

  Accepted in the EU as a traditional soothing product for mouth and throat irritation with dry cough; the studies are small and have no placebo group.

• SundewLab or animal research only

  Traditionally used for cough, but human evidence for sundew alone was not found. Lab studies in mouse airway tissue show muscle-relaxing and mucus-moving effects, which are not proof of benefit in people.

• Common sorrelPreliminary or mixed

  Sorrel herb is one of five herbs in a sinus-infection extract. Trials favoured the mix in acute infection but the chronic-infection trial missed its main goal; the effect of sorrel alone is unknown.

• Clubmoss (lycopodium)Documented risk

  One case report of lung inflammation after inhaling Lycopodium spores; frequency unknown.

• Petitgrain OilDocumented risk

  EFSA says to consider the oil an irritant to the respiratory tract. A regulatory finding, not a diffuser trial.

• Cedarwood OilDocumented risk

  EFSA lists a respiratory-sensitiser hazard for cedarwood Texas oil.

• Patchouli OilDocumented risk

  EFSA advises treating patchouli oil as a respiratory sensitiser, which matters for diffusing.

• Mullein TeaPreliminary or mixed

  Traditional use for sore throat with dry cough and cold in the EU; the committee noted clinical studies are lacking. No trial of the tea was found.

• Elderflower TeaPreliminary or mixed

  The EU traditional-use statement is for early cold symptoms; no trial of the tea was found.

• Marshmallow Root TeaPreliminary or mixed

  Traditional EU use for throat irritation with dry cough; trial evidence is insufficient and mostly on extract products, not tea.

• Anise TeaPreliminary or mixed

  The EU accepts aniseed tea as a traditional expectorant in cough with a cold; no trial of the tea.

• DunaliellaPreliminary or mixed

  A one-week 1999 test found 20 of 38 patients protected from exercise-induced asthma with Dunaliella beta-carotene.

• Clover HoneyPreliminary or mixed

  Trials of honey (other types, not clover) for acute cough in children: promising but limited.

• Eucalyptus HoneyPreliminary or mixed

  Cough relief evidence is for honey in general in children over 1 year, not for eucalyptus honey.

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