title: Effects of dietary creatine supplementation on systemic microvascular density and reactivity in healthy young adults.
abstract: BACKGROUND
  Dietary creatine supplementation (CrS) is a practice commonly adopted by physically active individuals. However, the effects of CrS on systemic microvascular reactivity and density have never been reported. Additionally, CrS is able to influence blood levels of homocysteine, resulting in presumed effects on vascular endothelial function. Thus, we investigated the effects of CrS on the systemic microcirculation and on homocysteine levels in healthy young individuals.
  
  
  METHODS
  This open-label study was performed on a group of 40 healthy male, moderately physically active subjects aged 27.7 ± 13.4 years who received one week of CrS at a dose of 20 g/day of commercially available micronized creatine monohydrate. Laser speckle contrast imaging was used in the evaluation of cutaneous microvascular reactivity, and intra-vital video microscopy was used to evaluate skin capillary density and reactivity, before and after CrS.
  
  
  RESULTS
  CrS did not alter plasma levels of homocysteine, although CrS increased creatinine (p = 0.0001) and decreased uric acid (p = 0.0004) plasma levels. Significant changes in total cholesterol (p = 0.0486) and LDL-cholesterol (p = 0.0027) were also observed along with a reduction in plasma levels of T3 (p = 0.0074) and an increase in T4 levels (p = 0.0003). Skin functional capillary density (p = 0.0496) and capillary recruitment during post-occlusive reactive hyperemia (p = 0.0043) increased after CrS. Increases in cutaneous microvascular vasodilation induced by post-occlusive reactive hyperemia (p = 0.0078) were also observed.
  
  
  CONCLUSIONS
  Oral supplementation with creatine in healthy, moderately physically active young adults improves systemic endothelial-dependent microvascular reactivity and increases skin capillary density and recruitment. These effects are not concurrent with changes in plasma homocysteine levels.
authors.forename: Roger de
authors.initials: Rd
authors.lastname: Moraes
authors.forename: Diogo
authors.initials: D
authors.lastname: Van Bavel
authors.forename: Beatriz Serpa de
authors.initials: BS
authors.lastname: Moraes
authors.affiliation: National Institute of Cardiology (INC), Rio de Janeiro 21045-900, Brazil. etibi@ioc.fiocruz.br.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Tibiriçá
mesh_terms: D000328:Adult; D002196:Capillaries / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003401:Creatine / Q000008:administration & dosage*; D003404:Creatinine / Q000097:blood; D004032:Diet; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D055806:Microvessels / Q000187:drug effects*; D012867:Skin / Q000098:blood supply; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014527:Uric Acid / Q000097:blood; D014664:Vasodilation; D055815:Young Adult
chemical_list: D008078:Cholesterol, LDL; D014284:Triiodothyronine; D006710:Homocysteine; D014527:Uric Acid; D002784:Cholesterol; D003404:Creatinine; D003401:Creatine; D013974:Thyroxine