Liquid smoke flavourings tested in lab cells for harmful effects
What it found
In lab tests on cells, most liquid smoke flavourings damaged DNA, and almost all caused oxidative stress.
The tests used cells, not people.
What they found
Animal and lab studies
DNA damage in cells
Nearly all the non-extracted samples and all the hexane-extracted samples caused DNA damage in lab-grown cells. The non-extracted samples did so more strongly. Samples extracted with ethyl acetate did not cause DNA damage.
Oxidative stress in cells
Almost all the samples, extracted and non-extracted, switched on a cell response linked to oxidative stress. The strongest response came from hickory samples 2, 4 and 5.
Cell death in lab tests
Most non-extracted samples killed the lab-grown cells at the highest concentrations tested. Extracting the samples with solvents lowered this effect, suggesting that water-loving substances are behind it.
Hormone-like activity
About half the samples showed activity at the aryl hydrocarbon receptor and the estrogen receptor in the cell tests. Three out of ten non-extracted samples showed estrogen-like activity, and more did after extraction.
Other findings
Amounts compared to limits
For oxidative stress, six of the ten flavourings gave amounts above the acceptable daily intake for one serving, based on comparison with a reference chemical. For aryl hydrocarbon activity, the calculated amounts far exceeded the tolerable weekly intake for dioxins, but the authors note this comparison is not appropriate because different chemicals are likely responsible.
What the authors conclude
“Findings in this study indicate that liquid smoke flavourings contain compounds with hazardous properties and to ensure that these widely used products are safe further studies should be carried out.”
Also in their conclusions
- They say the findings indicate that liquid smoke flavourings contain compounds with hazardous properties.
- They advise that further studies should be carried out to ensure these widely used products are safe.
- They note that the increased bioactivities seen after extraction suggest non-polar chemicals drive the DNA damage, while polar substances drive oxidative stress and cell death.
How it was done
Liquid smoke products are widely used to add smoke flavour to food, but they may contain hazardous chemicals formed when wood is burned. The authors say the toxic effects of these chemicals in the products people buy are largely unknown.
They bought ten liquid smoke flavourings sold to consumers, made from apple, hickory, mesquite, oak and pecan wood. They tested each one on lab-grown cells, both as it came and after extracting it with two different solvents, and looked at several types of cell response.
What it can’t tell you
- These are lab tests on cells, not studies in people. They cannot show what happens when someone eats these flavourings.
- The tests did not include a system that mimics how the body breaks down chemicals, so the results may not reflect real exposure.
- The authors say the amounts compared to safety limits are rough estimates and may not apply directly because the chemicals involved are different.
Who paid
- Conflicts
- The authors have no conflicts of interest to declare.
- Authors work at
- Swedish University of Agricultural Sciences, Sweden
The paper
- Title
- An in vitro-based hazard assessment of liquid smoke food flavourings
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Selin E, Mandava G, Vilcu AL, Oskarsson A, Lundqvist J (2022). An in vitro-based hazard assessment of liquid smoke food flavourings. Archives of toxicology. doi:10.1007/s00204-021-03190-1Free full textPubMed 34799742DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error