Creatine Ethyl Ester
An esterified creatine once marketed as more bioavailable than monohydrate. Controlled trials found it actually degrades rapidly to creatinine and is inferior to monohydrate for raising muscle creatine. A cautionary example of a marketing claim not surviving testing.
01 Overview
Creatine ethyl ester (CEE) was promoted on the theory that the ester improves membrane permeability and absorption. In practice, the ester is unstable at stomach pH and converts substantially to creatinine, an inert breakdown product, before reaching muscle.
A controlled trial comparing CEE with monohydrate found monohydrate produced greater increases in muscle creatine and serum creatine, with CEE raising serum creatinine instead. It is retained here as a documented instance of a supplement whose central claim failed under scrutiny.
02 Mechanism
Intended to deliver creatine via an ethyl ester, but converts largely to inert creatinine before absorption, blunting any rise in muscle phosphocreatine.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Marketed | 2.5–5 g/day | Oral | Historically marketed dose; not recommended given inferior uptake. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Intended creatine deliveryClaimed to raise muscle creatine, but controlled data show smaller increases than monohydrate. | Inferior to monohydrate | Disputed |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Elevated serum creatinineRaises serum creatinine due to ester breakdown, which can confound renal blood-test interpretation. | Mild | Frequent | Clinical | |
| Bitter taste and poor palatabilityNotably bitter, prompting encapsulation. | Mild | Frequent | Anecdotal |