Canthaxanthin and other xanthophylls tested for drug enzyme inhibition
What it found
In lab tests using human liver enzymes, canthaxanthin weakly inhibited two drug-metabolizing enzymes, UGT1A1 and UGT1A3.
The authors predict it is unlikely to cause supplement-drug interactions at normal doses.
What they found
Animal and lab studies
Canthaxanthin and UGT enzymes
In lab tests, canthaxanthin weakly inhibited UGT1A1 and UGT1A3, with IC50 values of 38.5 and 41.2 μM. It did not noticeably inhibit the other five UGT enzymes tested.
Other xanthophylls compared
Astaxanthin and zeaxanthin showed no apparent inhibition of any of the seven UGTs. Beta-cryptoxanthin was the strongest inhibitor, mildly blocking UGT1A1, UGT1A3, and UGT1A4. Lutein weakly inhibited UGT1A1 and UGT1A4.
Studies in people and animals
Predicted drug interaction
Using blood levels of beta-cryptoxanthin from a human study, the authors calculated that a drug cleared entirely by UGT1A1 might rise by about 1.2% if taken with beta-cryptoxanthin. This suggests little chance of a clinically significant interaction.
Other findings
Study limitations
The lab tests used a relatively high amount of organic solvent because the xanthophylls dissolve poorly, which might affect enzyme activity. Also, the predictions only looked at liver UGT1A1, not UGTs in the gut.
What the authors conclude
“Our data suggests that these xanthophylls are unlikely to cause dietary supplement-drug interactions mediated by inhibition of the hepatic UGTs.”
Also in their conclusions
- They conclude that these five xanthophylls are unlikely to cause clinically significant metabolic dietary supplement-drug interactions through inhibition of the major drug-metabolizing hepatic UGT isoforms.
- Their findings provide useful information for the safe clinical use of the tested xanthophylls.
How it was done
Many people take xanthophyll supplements alongside prescription drugs, and interactions could change how drugs are cleared from the body. The authors wanted to see if these five xanthophylls block UGT enzymes, which help break down many drugs.
They tested five xanthophylls, including canthaxanthin, against seven major human liver UGT enzymes in lab tests using human liver microsomes or recombinant supersomes. They measured how much each xanthophyll inhibited each enzyme and calculated inhibition values.
What it can’t tell you
- These are lab tests using human liver enzymes, not studies in people. They cannot show what happens when someone actually takes canthaxanthin with a drug.
- The predictions are based on beta-cryptoxanthin, not canthaxanthin, and only consider liver UGT1A1, not other enzymes or tissues.
Who paid
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- The Catholic University of Korea, Korea
The paper
- Title
- In Vitro Inhibition of Human UDP-Glucuronosyl-Transferase (UGT) Isoforms by Astaxanthin, β-Cryptoxanthin, Canthaxanthin, Lutein, and Zeaxanthin: Prediction of in Vivo Dietary Supplement-Drug Interactions
- Type
- Study
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Zheng YF, Min JS, Kim D, et al (2016). In Vitro Inhibition of Human UDP-Glucuronosyl-Transferase (UGT) Isoforms by Astaxanthin, β-Cryptoxanthin, Canthaxanthin, Lutein, and Zeaxanthin: Prediction of in Vivo Dietary Supplement-Drug Interactions. Molecules (Basel, Switzerland). doi:10.3390/molecules21081052Free full textPubMed 27529203DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error