The goal of this randomised controlled trial is to determine the effect of consuming a multistrain probiotic OMNi-BiOTiC® Hetox on improving the healing, pain management, and postsurgical complications after neurosurgery.

The main question it aims to answer is:

• Is the multistrain probiotic OMNi-BiOTiC® Hetox effective in in improving patient-reported disability after neurosurgery?

Researchers will compare the probiotic group and the placebo group to determine if the healing is significantly different between the groups.

Inclusion Criteria:

• adults with MRI-confirmed disc herniation, stenosis, or instability of the lumbar or cervical spine.
• Able to provide written informed consent
• Willing to comply with study procedures and follow-up assessments
• No contraindications to probiotic administration

Exclusion Criteria:

• symptoms of acute infection (vomiting, fever above 38°C, diarrhea, respiratory symptoms),
• chronic diseases,
• use of probiotics one month before inclusion.