Abstract
Background:
Excessive consumption of monosodium glutamate (MSG), a common food flavor enhancer, has been reported to adversely affect the female reproductive system. Therefore, to overcome the negative effects of consuming MSG which causes an oxidant effect, this can be overcome by consuming foods that contain sources of antioxidants.

Aim:
This study aimed to analyse the effect of Ulva lactuca ethanol extract on the estradiol hormone levels, estrus cycle and endometrial thickness in female rats exposed to MSG.

Methods:
Thirty adult female Wistar rats were divided into five groups: normal control, MSG-induced control, and three Ulva lactuca treatment groups (100, 200, and 400 mg/kgBW). Estradiol levels, endometrial thickness, and estrus cycle phases were assessed.

Results:
Administration of Ulva lactuca extract significantly improved estradiol levels (p=0.011), endometrial thickness (p=0.016), and estrus cycle regularity (p=0.005) compared to the MSG-induced group.

Conclusion:
Ulva lactuca ethanol extract showed potential in mitigating MSG-induced toxicity, supporting its use in preserving female reproductive health.

Key words: Endometrial, Estradiol hormone, Estrus Cycle, Monosodium Glutamate, Ulva Lactuca.