Effects of raw red onion consumption on metabolic features in overweight or obese women with polycystic ovary syndrome: a randomized controlled clinical trial

J Obstet Gynaecol Res. 2014 Apr;40(4):1067-76. doi: 10.1111/jog.12311. Epub 2014 Mar 10.


Aim: We aimed to evaluate the effects of raw red onion consumption on metabolic features in overweight and obese women with polycystic ovary syndrome.

Material and methods: In this randomized controlled clinical trial, the patients (n=54) were randomly allocated to the intervention group as 'high-onion' (raw red onions: 2 × 40-50 g/day if overweight and 2 × 50-60 g/day if obese) or to the control group as 'low-onion' (raw red onions: 2 × 10-15 g/day) along with limited liliaceous vegetables for 8 weeks. Body mass index, dietary record, and metabolic parameters (fasting blood sugar, triglycerides, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and lipoprotein (a)) were evaluated in the follicular phase of the menstrual cycle at baseline and after 8 weeks. Hormonal variables (progesterone, prolactin, and 17-OH progesterone) were also measured at baseline.

Results: Onion significantly decreased the levels of total cholesterol within each group; however, these changes were stronger in the high-onion group (weighted mean differences [WMD]: -5.60 [95% confidence interval [CI]: -9.16, -2.03]; P=0.003) than in the low-onion group (WMD: -6.42 [95%CI: -11.97, -0.87]; P=0.025). Similarly, low-density lipoprotein cholesterol decreased significantly (WMD: -5.13 [95%CI: -9.46, -0.81); P=0.022) in the high-onion group, and (WMD: -2.90 [95%CI -5.57, -0.21]; P=0.035) in the low-onion group after treatment. The levels of fasting blood sugar, triglycerides, high-density lipoprotein cholesterol and lipoprotein (a) did not differ significantly after 8-week onion treatment. Adjustment for confounders did not make any significant changes in any of the parameters in post-treatment levels.

Conclusion: Raw red onion consumption appears to be effective as a cholesterol-lowering food agent in women with polycystic ovary syndrome. However, further investigation is warranted.

Keywords: blood glucose; diabetes; lipid profile; onion; polycystic ovary syndrome.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • Body Mass Index
  • Female
  • Functional Food*
  • Humans
  • Hypercholesterolemia / etiology
  • Hypercholesterolemia / prevention & control*
  • Iran
  • Obesity / complications*
  • Onions*
  • Overweight / complications*
  • Plant Roots*
  • Polycystic Ovary Syndrome / blood
  • Polycystic Ovary Syndrome / complications
  • Polycystic Ovary Syndrome / diet therapy*
  • Polycystic Ovary Syndrome / physiopathology
  • Single-Blind Method
  • Young Adult