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Heat-Formed Food Compound Worsens Lung Scarring in Mice

A compound formed when carbs are heated worsened chemical-induced lung scarring in mice, at a dose far above typical dietary exposure.

By PJ Howland · November 7, 2026 · 1 source · Watch

5-hydroxymethylfurfural (5-HMF), a compound that forms when carbohydrate-rich foods like bread, coffee and fruit juice are heated, made bleomycin-induced lung scarring worse in mice, according to a study published November 2, 2026 in PLOS One.

100mg/kg/day dose

5of 7 genes shifted

Researchers built a computational profile of 5-HMF, a compound formed when carbohydrate-rich foods and drinks like coffee, bread and fruit juice are heated, and compared its predicted protein targets against genes altered in idiopathic pulmonary fibrosis. The overlap pointed to seven candidate genes: CA2, CA4, ESR2, F10, HSP90AA1, PLA2G1B and PTPRB.

In mice, researchers induced lung scarring with bleomycin and gave one group 100 mg/kg of 5-HMF daily by mouth for 21 days, while a separate group got the scarring chemical alone. The 5-HMF group showed a higher lung injury score and more collagen buildup on two separate stains than the bleomycin-only group. Five of the seven candidate genes, plus two fibrosis marker genes, rose further with 5-HMF; two genes did not change. Computer docking placed 5-HMF in binding pockets of all seven target proteins, though the fit was weak and far less selective than a reference inhibitor tested under the same conditions.

Fibrosis involves repeated lung tissue injury followed by overactive scar formation; the gene findings point toward blood-clotting and fat-processing pathways already linked to that process in other research. 5-HMF forms through the same browning chemistry that darkens bread crusts and roasted coffee, and is also present in tobacco smoke.

Collagen Buildup: Bleomycin Alone vs. Plus 5-HMF

PLOS One, 2026, Yang et al.

No group received 5-HMF alone, so this shows the compound worsened existing injury, not that it starts fibrosis on its own. The mouse dose translates to roughly 486 mg a day for a 60-kg adult, against an estimated 4 to 30 mg typical daily intake, or roughly ten to a hundred times typical dietary intake, making this an experimental exposure rather than a simulation of normal eating. Only male mice were tested, and the docking results need lab confirmation.

Dr. Axe’s Take

A mouse dose equal to roughly ten to a hundred times what people actually eat worsened existing lung scarring, which tells me the compound is worth watching, not panicking over. It forms through the same browning reaction that darkens dark-roast coffee, baked goods and heavily heated ultra-processed snacks, so I favor lighter-roast coffee and home baking at moderate temperatures over frequent charred or heavily browned foods. If you already have a lung condition, treating heavily heated snacks as occasional rather than daily is a reasonable way to cut avoidable exposures while you stay on your pulmonologist's treatment plan exactly as prescribed.

— Dr. Axe

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Study summary

Who: Male C57BL/6J mice, 20-25g, in three groups of 5: control, bleomycin-induced lung scarring, and bleomycin plus 5-HMF.
Design: Network toxicology and machine learning target prediction combined with a 21-day bleomycin-induced mouse model of lung scarring.
Dose: 100 mg/kg/day of 5-HMF by oral gavage, equivalent to about 486 mg/day in a 60-kg adult versus 4-30 mg typical daily dietary intake.
Primary result: 5-HMF plus bleomycin caused a higher lung injury score and more collagen deposition (two stains) than bleomycin alone.
Secondary: 5 of 7 candidate genes (Hsp90aa1, Pla2g1b, Ca4, F10, Ca2) plus fibrosis markers Acta2 and Col1a1 rose further with 5-HMF; Esr2 and Ptprb did not differ.
Funding / conflicts: Funder listed in the journal record: National Natural Science Foundation of China. Competing interests: The authors have declared that no competing interests exist.
Date: Nov 2, 2026