Proof of Concept Creatine Supplementation for Homocystinuria Study

Condition(s) studied

Investigational drug(s) / intervention(s)

Creatine: For 7 days, participants will take a 20mg creatine supplement each day.

Dietary methionine tracer and protein intake: On the study days participants will ingest 8 hourly meals of controlled amino acid intake, fortified with the necessary macronutrients. Each meal will provide one-twelfth of the participants' daily energy requirements as estimated by 1.5 x Resting Energy Expenditure (REE) and adequate protein at 1.0 g/kg/d, to maintain a metabolic steady state. The meals are in the form of a crystalline amino acid protein shake, and protein-free cookies.

Study summary

Homocystinuria is a rare and inherited metabolic disorder, people with this condition don't have an enzyme needed to break down an amino acid called homocysteine. When the body can't break down the homocysteine made from another amino acid methionine, it becomes toxic to the heart, brain, and bones. We are constantly eating methionine, a building block of protein, so a common treatment is eating a low-protein diet with medical foods and vitamin pills. This can be hard to follow due to bad tastes and missing out on foods a person enjoys, especially in children.

The goal of this study is to provide participants with a supplement containing creatine, another amino acid related to methionine and homocysteine, and learn if it lowers homocysteine production in healthy adult men. We would ultimately like to see if creatine supplements are a potential alternate treatment of Homocystinuria in this proof of concept study, before studying individuals with the condition.

Researchers in this study want to know:

* How does the bodies digestion of isotope methionine change in breath and urine when creatine is taken in healthy young adult men?
* How do levels of homocysteine, methionine and related metabolites change in the blood when creatine is taken by healthy young adult men?

Participants will:

* Complete two (2), 8-hour study days on-site.
* Eat a lower protein diet for one (1) week before the first study day, and eat a lower protein diet with creatine supplements for one (1) week before the second study day.
* During both study days eat special hourly meals of controlled amino acids and nutrients, along with a methionine isotope. (An isotope is a stable labelled amino acid that is colourless, odorless, tasteless, and safe for consumption. In the lab we can detect this isotope in breath and urine samples collected during the study day).
* Provide samples of breath, urine and blood. (Researchers will also take body measurements (height weight), and use non-invasive tests to measure body composition and energy needs).

Eligibility

Primary outcome measure(s)

• Carbon 13 Oxidation — 8 hours
  Urine and breath samples will be collected to measure the rate of L-\[1-13C\]methionine oxidation

Trial sites (1)

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