Creatine Monohydrate: The Most Studied Form, Micronized and Anhydrous Explained

What monohydrate is

A review describes monohydrate as a form that readily separates into creatine and water after it is swallowed. [1] By weight, a gram of monohydrate is theoretically 87.9% creatine; the rest is the water. [1] The 2021 position paper describes it as the form with the highest creatine percentage other than anhydrous creatine. [2]

Micronized

Micronized means the powder is ground to smaller particles (a smaller "mesh size"). The 2022 review states there is no evidence that micronized monohydrate is more bioavailable than monohydrate with normal particle size. [1] The sources we read did not test whether micronizing changes how easily the powder mixes. Proper evidence not found for a controlled comparison of micronized and non-micronized monohydrate on muscle creatine in the sources we searched (PubMed for "micronized creatine"; reviews above).

Anhydrous

Heating monohydrate at about 100 degrees C removes the water and gives anhydrous creatine, which is 100% creatine by weight. [1] The same review notes that the extra heating gives anhydrous creatine higher amounts of the impurity creatinine. [1] So "100% creatine" on paper is not the same as "more of what you want" in the tub: the review's table lists anhydrous creatine as 13.8% more creatine by weight than monohydrate, which only matters when comparing grams of powder. [1] Proper evidence not found for trials comparing anhydrous and monohydrate creatine in people in the sources we searched.

Purity is about manufacturing, not the word "monohydrate"

• A review states that monohydrate made in Germany with water as the solvent has been reported as 99.9% pure with no contaminants. [1] The same review says other sources, particularly from China, have been reported to contain dicyandiamide, dihydrotriazine, creatinine and higher heavy-metal levels. [1] That is a statement by the review's authors, two of whom disclose that they consult with industry on raw ingredients and once worked for a creatine maker. It is not a ranking of products. [1]
• A study of 149 creatine supplement samples found 32 adulterated by chemical analysis. [3]
• A 2021 paper says the effects of ingesting these impurities on health are unknown. [2]
• Only 8% of 175 products in one marketplace survey were third-party certified. [4]

See Reading a creatine label and Quality testing and certifications.

Solubility and the powder at the bottom of the glass

Monohydrate dissolves slowly in cold water, so some powder can stay at the bottom of the glass. The review says this does not affect bioavailability, since monohydrate is nearly 100% bioavailable. [1] About 14 g dissolves per liter of water at 20 degrees C. [1] A 2021 paper says higher temperatures improve solubility, but solubility has no influence on tissue uptake. [2] More on powder storage, clumping and taste.