Ingredient Spotlight — Glutathione (OPITAC™)

The Objection That Doesn't Hold Anymore

You've heard the knock on glutathione pills: your gut destroys them before they ever reach your blood. It's the smartest-sounding objection in the category — and a human absorption study is exactly what it takes to answer it.

You're the kind of buyer who asks the harder question. Not "does the ingredient work," but "does it even get in." For years, the honest answer on oral glutathione was a shrug — a tripeptide, in theory chopped apart by digestion before it could matter. If you've ever quietly suspected your glutathione supplement was expensive urine, you were asking the right question. This study went looking for the answer in actual blood.

The trial

Researchers at Kyoto Prefectural University gave healthy volunteers a single oral dose of reduced glutathione, then drew venous blood before and after. The clever part was how they measured it: they separated plasma into its free (deproteinized) fraction and its protein-bound fraction, using mass spectrometry precise enough to track glutathione in each — because how it travels matters as much as whether it arrives.

What they found

• It showed up in the blood — bound to plasma proteins. The protein-bound fraction of plasma glutathione rose significantly (P < 0.01) between 60 and 120 minutes after ingestion.
• A specific route, not a vague spike. The free-floating and blood-cell fractions didn't change much — the increase was concentrated in the protein-bound pool, pointing to a real transport mechanism rather than measurement noise.
• A fast window. The rise happened within the first two hours, showing oral glutathione reaching circulation acutely, not just theoretically.

In plain terms: orally administered glutathione increased a measurable, protein-bound pool of glutathione in human blood — direct evidence that it gets in.

The best objection in the category, met with the one thing that settles it: measurement in human blood.

Why it matters for what we build

Two human studies, two halves of the same answer. This one shows oral glutathione reaching the bloodstream within hours; the six-month body-stores trial shows those levels building across the body over time. We formulate with OPITAC™ — a USP-grade reduced L-glutathione, the same active form studied here — because in a premium system, "bioavailable" can't be a hopeful adjective. It has to be a measured result.

Reference: Park EY, Shimura N, Konishi T, Sauchi Y, Wada S, Aoi W, Nakamura Y, Sato K. Increase in the protein-bound form of glutathione in human blood after the oral administration of glutathione. Journal of Agricultural and Food Chemistry. 2014;62(26):6183–6189. doi:10.1021/jf501338z.
Read it: pubmed.ncbi.nlm.nih.gov/24877771

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.