Allura red and MSG effects on gut bacteria and cells
What it found
In lab tests, allura red and MSG did not change the mix of gut bacteria from six healthy people or harm intestinal cells.
Heating allura red broke some of it down before the bacteria got to it.
What they found
Animal and lab studies
Gut bacteria mix
The overall mix of gut bacteria stayed about the same with either additive at both doses. The main differences were between donors, not between treatments.
Short-chain fatty acids
Levels of short-chain fatty acids produced by gut bacteria were similar with and without the additives. This suggests the additives did not change bacterial metabolic activity in this test.
Allura red breakdown
Heating allura red before fermentation broke some of it down into 4A5M2M. After fermentation, no intact allura red was left, and 4A5M2M levels were higher with the higher dose.
MSG and GABA
MSG and GABA levels dropped after fermentation in most samples. One donor's sample produced a small amount of GABA.
Intestinal cells
Neither additive nor the fermented mixtures harmed HT29 intestinal cells in lab tests.
What the authors conclude
“Our findings reinforce the safety of both food additives regarding their impact on the gut microbial communities under conditions resembling acute short-term exposures, although the potential biological effects of the metabolites generated from their degradation or from chronic exposures should be further investigated.”
Also in their conclusions
- They say their findings reinforce the safety of both additives regarding their impact on gut microbial communities under short-term exposure conditions.
- They call for further investigation into the potential biological effects of the metabolites generated from their degradation or from chronic exposures.
- They note that thermal processing can affect the chemical structure of food additives and that the presence of AR-derivatives generated during food processing should be further evaluated.
How it was done
Recent research suggests that long-term consumption of these additives might contribute to intestinal inflammation, so the authors wanted to check their impact on gut bacteria and intestinal cells.
They mixed faecal samples from six healthy donors with allura red or MSG at two doses each, then fermented them for 24 hours. They also tested the additives and the fermented mixtures on HT29 intestinal cells.
What it can’t tell you
- These are lab tests with faecal samples and cells, not studies in living people. They cannot show what happens in the human body.
- The tests used only six donors and short exposure times. They cannot show the effects of long-term consumption.
- The authors did not collect dietary habits, so they cannot tell if diet affects how someone responds.
Who paid
- Funding
- Funded by European Food Safety Authority; MCIN/AEI/10.13039/501100011033 and ERDF/EU IDE/2024/000704 (from the PubMed record).
- Conflicts
- The authors declare no conflicts of interest.
- Authors work at
- Dairy Research Institute of Asturias (IPLA-CSIC), Spain; Avenida Hospital Universitario s/n, Spain; Institute of Food Science Research, Spain
The paper
- Title
- In Vitro Investigation of the Effects of the Food Additives Monosodium Glutamate and Allura Red AC on the human Gut Microbiota and Intestinal Cell Lines
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Granja-Iglesias A, Vázquez X, Sabater C, et al (2025). In Vitro Investigation of the Effects of the Food Additives Monosodium Glutamate and Allura Red AC on the human Gut Microbiota and Intestinal Cell Lines. Journal of food science. doi:10.1111/1750-3841.70504Free full textPubMed 40851259DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error