PEP Topic 
Sleep-Wake Disturbances

Kefir is a natural probiotic produced from the fermentation of milk with kefir grains, which contain yeast and bacteria, similar to the bacteria found in yogurt. Kefir was studied in patients with cancer to assess its effects for various symptoms and impact on overall quality of life.

Effectiveness Not Established

Research Evidence Summaries

Can, G., Topuz, E., Derin, D., Durna, Z., & Aydiner, A. (2009). Effect of kefir on the quality of life of patients being treated for colorectal cancer. Oncology Nursing Forum, 36, E335-E342.

doi: 10.1188/09.ONF.E335-E342

Study Purpose:

To determine the effectiveness of kefir in preventing treatment-related gastrointestinal complaints and to determine the effects of kefir on quality of life (QOL) among patients receiving chemotherapy treatment for colorectal cancer.

Intervention Characteristics/Basic Study Process:

Patients were included if they had stage II, III, or IV colorectal cancer; were 18 years or older; had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2; and were receiving standard treatment with 5 FU or oral fluoropyrimidine. Patients were randomized to either the control group or the experimental (kefir) group. Kefir (500 mL) was industrially prepared by Altinkilic Company in Istanbul. Patients were instructed to use 250 mL of kefir two times per day for one week during chemotherapy treatment. Side effects of treatment were evaluated in both groups one week after each chemotherapy cycle. QOL was evaluated after the third and sixth cycles of treatment.

Sample Characteristics:

  • The sample was comprised of 37 patients (65% male, 35% female).  
  • Mean age was 54.32 years (standard deviation = 12.77 years).
  • Patients had colorectal cancer stage II to IV.
  • Of the patients, 29 (78%) were married.


  • Single site 
  • Istanbul University Oncology Institute

Phase of Care and Clinical Applications:

Patients were undergoing the active treatment phase of care.

Study Design:

The study was a randomized, controlled trial.

Measurement Instruments/Methods:

  • Memorial Symptom Assessment Scale (MSAS)    
  • Functional Assessment of Cancer Therapy–General (FACT-G):  A Turkish version of the FACT-G was validated in this study by the authors. Cronbach's alpha values for subscales varied from 0.69 to 0.76, with a value of 0.9 for the total scale.


There were no statistically significant differences between groups in patients’ disease-related complaints before the intervention. No statistically significant changes were observed between pre- or posttreatment for the control group for the MSAS-GDI subscale scores; however, statistically significant increases in symptom distress (p < 0.05) were observed in the experimental (kefir) group from pre- to posttreatment. For the MSAS-PHYS subscale, the control group experienced a significant increase in symptoms over pretreatment scores (p < 0.05); however, a significant increase occurred in physical symptoms after each treatment cycle (p < 0.05) in the experimental group, with physical scores significantly higher (p = 0.03) in the experimental group after the fifth cycle compared to the control group. Scores for the MSAS-PSYCH were also significantly higher (p = 0.01) in the experimental group compared to the control group after the sixth treatment cycle. Total MSAS scores were significantly higher for each treatment cycle compared to pretreatment for the experimental group (p < 0.05) and were significantly higher than the control group after the fifth treatment cycle (p = 0.02). The experimental group reported significantly fewer problems sleeping than the control group after all rounds of chemotherapy (p = 0.05). No significant differences were observed between groups for QOL (p > 0.05).


The kefir intervention did not affect QOL. Patients receiving kefir reported increased physical and psychological systems and increased symptom distress compared to patients not receiving kefir but reported fewer problems sleeping.


  • The study had a small sample size, with less than 100 patients.
  • The approach to sleep measurement was limited.

Nursing Implications:

Kefir may increase physical complaints, including gastrointestinal complaints, in patients with colorectal cancer receiving chemotherapy. Kefir does not have a significant effect on QOL. Further study is needed to determine the effects of kefir on sleep problems in this population.