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In a nutshell
- Cinnamaldehyde in cinnamon supplements can potentially interact with medications by affecting drug-processing systems in your body, which may alter how effectively your medications work.
- While sprinkling cinnamon on food is likely safe, concentrated supplements might pose risks, especially for people taking blood thinners, NSAIDs, antidepressants, or diabetes medications.
- Always discuss any supplements with your healthcare provider before adding them to your regimen, particularly if you take prescription medications.
OXFORD, Miss. — You might want to think twice before adding that cinnamon supplement to your daily routine. Researchers have found that while a dash of cinnamon in your coffee or oatmeal is probably fine, concentrated cinnamon supplements could interfere with how your body processes medications – potentially creating dangerous interactions.
Scientists at the University of Mississippi recently discovered that cinnamaldehyde – the compound that gives cinnamon its distinctive flavor and smell – can affect the body’s drug-processing systems in ways that could reduce medication effectiveness or increase side effects.
“While controlled ingestion of cinnamon-containing foods or supplements may have beneficial effects, overconsumption could induce … herb-drug interactions (HDIs) which can bring deleterious effects on human health, particularly in individuals with chronic health conditions,” the researchers wrote in their study published in Food Chemistry: Molecular Sciences.
Popular Supplement, Hidden Risks
Cinnamon has surged in popularity as a supplement in recent years, particularly among people looking to manage blood sugar levels. Many consumers view it as a “natural” alternative without realizing it contains powerful bioactive compounds that can affect bodily functions.
The research team ran a series of lab tests to track what happens when cinnamaldehyde enters the digestive system and interacts with the body’s drug-processing machinery.
In simulated digestive fluids mimicking both empty and full stomachs, 100% of cinnamaldehyde became available for absorption – meaning your body readily takes it all in, whether you’ve eaten or not.
When they exposed cinnamaldehyde to human liver cells, it vanished within minutes, quickly converting to cinnamic acid. This rapid metabolism shows the compound transforms quickly once inside the body.
How Cinnamon Affects Your Medicine
The most concerning findings involved how cinnamon oil and its compounds affected certain biological switches in the body called xenobiotic receptors (PXR and AhR). Think of these receptors as traffic controllers that regulate how your body handles foreign substances, including medications.
At higher concentrations, cinnamon oil activated AhR, while both cinnamon oil and cinnamic acid activated PXR in liver and intestinal cells. When activated, these receptors can boost production of drug-metabolizing enzymes, potentially causing medications to break down too quickly or ineffectively.
Testing revealed that cinnamon oil and cinnamaldehyde inhibited specific enzyme systems (CYP2C9 and CYP1A2) that break down many common medicines. The CYP2C9 enzyme processes drugs like warfarin (a blood thinner), many NSAIDs including ibuprofen, and some diabetes medications. CYP1A2 handles caffeine, some antipsychotics, and certain antidepressants.
Should You Be Worried?
The authors note that “the clinical significance of such interactions appears to be minimal. However, additional clinical studies will be necessary to confirm this hypothesis.”
This doesn’t mean you need to panic about the cinnamon sprinkled on your toast. The researchers believe normal food quantities likely pose minimal risk. It’s the concentrated forms found in supplements that raise concerns, particularly because they’re increasingly marketed for blood sugar management to people who may already be taking diabetes medications.
Only one human clinical study has examined cinnamaldehyde pharmacokinetics, looking at it in cinnamon powder consumed with a high-fat meal. In that study, cinnamaldehyde wasn’t detectable in blood plasma, suggesting it undergoes rapid metabolism before reaching the bloodstream – which aligns with this new research.
The findings add cinnamon to a growing list of seemingly innocent natural supplements that can interfere with medications. Similar interactions have been documented with grapefruit juice, St. John’s wort, and other botanical products.
If you’re managing a chronic condition with medication and considering cinnamon supplements, talking with your healthcare provider first is essential. While a sprinkle of cinnamon in your food is probably harmless, concentrated supplements might affect how well your medicines work.
Paper Summary
Methodology
Researchers conducted several laboratory tests to evaluate cinnamaldehyde’s bioaccessibility, metabolism, and potential interactions with drug-processing systems. They used simulated gastric and intestinal fluids (both fasted and fed states) to test cinnamaldehyde’s bioaccessibility. For metabolism studies, they used human liver microsomes (HLMs) and S-9 fraction with appropriate cofactors to evaluate phase I and II metabolism. They also conducted cell-based assays using human cell lines (HepG2, LS174T, and AhR-reporter cells) to test the effects of cinnamon oil, cinnamaldehyde, and cinnamic acid on xenobiotic receptors (PXR and AhR). Additionally, they performed enzyme inhibition assays to evaluate effects on specific CYP enzymes (CYP3A4, CYP2D6, CYP2C9, and CYP1A2).
Results
The study found that cinnamaldehyde had 100% bioaccessibility in both fasted and fed-state gastric and intestinal fluids. In metabolism studies, cinnamaldehyde was rapidly converted to cinnamic acid in both HLMs and S-9 fraction, with a half-life of just a few minutes. Cinnamon oil activated AhR in a dose-dependent manner, while cinnamon oil and cinnamic acid (but not cinnamaldehyde alone) activated PXR in human cells. Both cinnamon oil and cinnamaldehyde inhibited CYP2C9 and CYP1A2 enzyme activity but did not affect CYP3A4 or CYP2D6. These findings suggest that while controlled consumption of cinnamon in foods is likely safe, concentrated supplements could potentially alter drug metabolism through PXR/AhR activation or direct enzyme inhibition.
Limitations
The study primarily used in vitro models, which may not fully represent what happens in the human body. No clinical human studies were conducted to confirm these potential interactions. The researchers note that only one human clinical pharmacokinetic study has examined cinnamaldehyde (in the context of cinnamon powder), where it was not detectable in plasma, suggesting rapid metabolism. The clinical relevance of these findings, especially the threshold at which cinnamon consumption might become problematic, remains to be determined through further research.
Funding and Disclosures
The study was supported by the United States Department of Agriculture, ARS, Specific Cooperative Agreement No. 58-6060-6-015 and “Analysis and Evaluation of Essential Oils” by doTerra International. The authors declared no competing financial interests or personal relationships that could have influenced the work.
Publication Information
The paper “Evaluation of bioaccessibility, metabolic clearance and interaction with xenobiotic receptors (PXR and AhR) of cinnamaldehyde” was published in Food Chemistry: Molecular Sciences (Volume 10, 2025). The research was conducted by scientists from the National Center for Natural Products Research and Department of Bio-Molecular Sciences at the University of Mississippi, along with a collaborator from the Department of Pharmaceutical Sciences at the University of Milan, Italy.
