The effects of spirulina supplementation on serum iron and ferritin, anemia parameters, and fecal occult blood in adults with ulcerative colitis: A randomized, double-blinded, placebo-controlled trial

Clin Nutr ESPEN. 2023 Oct:57:755-763. doi: 10.1016/j.clnesp.2023.08.019. Epub 2023 Aug 25.


Background & aims: The present clinical trial aimed to evaluate the efficacy of spirulina administration on serum iron, ferritin, anemia parameters, and fecal occult blood test (FOBT) in adults with ulcerative colitis (UC).

Methods: Eighty participants with UC were randomly assigned to take, either 1 g/day (two 500 mg capsules) spirulina (n = 40) or placebo (n = 40) in a double-blinded clinical trial for eight weeks. Dietary intake, physical activity status, serum iron and ferritin levels, anemia parameters, and FOBT were assessed in each participant at baseline and following the intervention. Seventy-three participants completed the trial.

Results: Our results indicated significantly increased (p = 0.04) serum iron after eight weeks of spirulina supplementation compared to the placebo group. The spirulina group also demonstrated significantly increased mean corpuscular volume (p = 0.004) whereas red blood cell count (p = 0.01) and hematocrit (p = 0.03) were significantly lowered in the placebo group. No significant changes in FOBT outcomes were seen between groups at baseline (p = 0.12) and the end of the trial (p = 0.34). Eight weeks of 1 g/day spirulina supplementation improved anemia parameters in adults with UC compared to placebo.

Conclusions: These outcomes suggest that spirulina administration may be beneficial in the management of anemia in UC. Further clinical trials of longer duration are necessary to corroborate and expand our findings. Registered at: (code: IRCT20170802035460N3).

Keywords: Anemia; Clinical trial; Fecal occult blood; Spirulina; Ulcerative colitis.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anemia*
  • Colitis, Ulcerative* / therapy
  • Dietary Supplements
  • Ferritins
  • Humans
  • Iron
  • Occult Blood
  • Spirulina*


  • Ferritins
  • Iron

Associated data

  • IRCT/IRCT20170802035460N3