Effect of chromium supplementation on glucose metabolism and lipids: a systematic review of randomized controlled trials.
OBJECTIVE
A systematic review of the effect of chromium supplementation on glucose metabolism and lipid levels.


METHODS
A literature search was conducted in MEDLINE and the Commonwealth Agricultural Bureau. Eligible studies were English language randomized controlled trials of chromium supplement intake > or = 3 weeks, with > or = 10 participants receiving chromium. All trials with glucose metabolism outcomes and trials of individuals with diabetes or glucose intolerance for lipid outcomes were included. Meta-analyses were performed as appropriate.


RESULTS
Forty-one studies met criteria, almost half of which were of poor quality. Among participants with type 2 diabetes, chromium supplementation improved glycosylated hemoglobin levels by -0.6% (95% CI -0.9 to -0.2) and fasting glucose by -1.0 mmol/l (-1.4 to -0.5) but not lipids. There was no benefit in individuals without diabetes. There were some indications of dose effect and differences among chromium formulations. Larger effects were more commonly observed in poor-quality studies. The evidence was limited by poor study quality, heterogeneity in methodology and results, and a lack of consensus on assessment of chromium status.


CONCLUSIONS
No significant effect of chromium on lipid or glucose metabolism was found in people without diabetes. Chromium supplementation significantly improved glycemia among patients with diabetes. However, future studies that address the limitations in the current evidence are needed before definitive claims can be made about the effect of chromium supplementation.
Balk
Ethan M
EM
Institute for Clinical Research and Health Policy Studies, Tufts-New England Medical Center, 750 Washington St., NEMC #63, Boston, MA 02111, USA. ebalk@tufts-nemc.org
Tatsioni
Athina
A
Lichtenstein
Alice H
AH
Lau
Joseph
J
Pittas
Anastassios G
AG
D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D002857:Chromium / Q000008:administration & dosage / Q000627:therapeutic use*; D019587:Dietary Supplements; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae
D001786:Blood Glucose; D002857:Chromium