Cucumbers contain the iminosugar idoBR1. A daily dose of 20 milligrams of cucumber extract contains sufficient idoBR1 to improve the functioning of worn-out joints.

Study
In 2022, Spanish researchers affiliated with Catholic University San Antonio published a human study in Applied Sciences involving 55 people over 40. [Appl Sci. 2023;13(1):485.]

All subjects had worn knee joints. They experienced moderate to significant pain, stiffness, and loss of function in their worn knees.

For eight weeks, half of the subjects took a placebo daily. The other half took 20 milligrams of cucumber extract in the morning. The researchers used CuberUp, a product from the Spanish company Euromed. Euromed did not sponsor the study.

Results
The pain reported by the subjects in the supplementation group decreased by 69 percent. In the same group, the average WOMAC score decreased by 41 percent.

A WOMAC score provides an indication of the severity of joint conditions. Supplementation changed the average subject's symptoms from "moderate to severe" to "mild to moderate." The placebo group also reported a reduction in symptoms, but the reduction was smaller than in the supplementation group.

Click on the table and figure below for a larger version.

Supplementation had no significant effect on the concentration of Cartilage Oligomeric Matrix Protein [COMP] in the blood. This is a marker for joint breakdown. However, supplementation did reduce the concentration of matrix metalloproteinase-3 [MMP-3] by 13 percent.

MMP-3 breaks down collagen, proteoglycan, fibronectin, and laminin. These are the building blocks of cartilage. MMP-3 also activates MMP-1, MMP-9, and other MMPs, which in turn also break down joints.

MMP-3 is activated by the inflammatory factors TNF-alpha and interleukin-1-beta. The concentration of interleukin-1-beta decreased by 33 percent in the supplementation group.

A more recent study
In the fall of 2025, researchers from the University of North Florida published a similar study on the effect of supplementation with 20 milligrams of cucumber extract. [Cureus. 2025 Sep 29;17(9):e93507.] This experiment also lasted 8 weeks. The subjects in that study also had worn-out joints. And in that study, supplementation with cucumber extract also reduced the WOMAC score - by 32 percent, to be precise.

Mechanism
We were unable to find any information about the possible active ingredients in CuberUp. The manufacturer is undisclosed. Fortunately, we have more information about Q-actin. This powder consists of just over 1 percent - we believe 1.2 percent - of the iminosugar (2R,3R,4R,5S)-3,4,5-trihydroxypiperidine-2-carboxylic acid. Chemists prefer to abbreviate this to idoBR1.

A group of American researchers, to whom we owe the existence of Q-actin [and perhaps also the existence of CuberUp], has published extensively on idoBR1. These publications include further studies on the positive effect of cucumber extract on worn joints, [Curr Rheumatol Rev. 2023 Jun 5;19(3):345-51.] as well as fundamental research. [ACS Omega. 2020 Jun 23;5(26):16263-71.]

This fundamental research shows that Q-actin and idoBR1 inhibit inflammation - partly by reducing the activity of TNF-alpha and interleukin-1-beta and increasing that of interleukin-10.

Fresh cucumbers?
We haven't been able to determine exactly how much idoBR1 is present in fresh cucumbers. We also suspect that the concentration varies considerably, depending on the cultivation method and the cultivar. But we estimate that to get as much idoBR1 as is contained in 20 milligrams of extract, you would need to eat 200 to 400 grams of fresh cucumber.