Table 1.
Description of studies included in the current systematic review.
| References | Study Population | Study Design | Sample Size | Prebiotic, Probiotic, Yogurt |
Dose and Duration |
Follow-Up Period (years) |
Primary Outcome | Comparison | Effect Size | Key Result |
|---|---|---|---|---|---|---|---|---|---|---|
| Castro-Espin et al. [21] | Adult men and women aged 35–69 years living in England and Scotland (EPIC-Oxford study) | Prospective cohort | 53,700 | Prebiotic fiber (total, fructan, GOS) | Frequency of intake at baseline (daily) | 16.1 | Incident CRC | Total prebiotic: Highest intake quartile compared to lowest intake quartile | HR 0.87; 95% CI 0.66–1.14 | Total prebiotic intake (total, fructan-specific, and GOS-specific) was not associated with CRC risk. |
| Total fructan: Highest intake quartile compared to lowest intake quartile | HR 0.91; 95% CI 0.70–1.19 | |||||||||
| Total GOS: Highest intake quartile compared to lowest intake quartile | HR 0.87; 95% CI 0.66–1.15 | |||||||||
| Skiba et al. [22] | Adult women aged 50–79 participating in the Women’s Health Initiative in the United States without a history of CRC | Prospective cohort | 160,195 | Prebiotic fiber (total, soluble, insoluble) | User versus nonuser at baseline | 15.4 | Incident CRC | Total prebiotic: User (any amount) compared to non-user | HR 1.12; 95% CI 0.91–1.38 | Total prebiotic supplement use was not associated with CRC risk or mortality, but insoluble fiber was associated with higher CRC mortality. |
| Soluble prebiotic: User (any amount) compared to non-user | HR 1.08; 95% CI 0.87–1.34 | |||||||||
| Insoluble prebiotic: User (any amount) compared to non-user | HR 1.48; 95% CI 0.87–2.51 | |||||||||
| Ishikawa et al. [23] | Adult men and women aged 40–65 years with 2+ CRC tumors removed in Japan | Randomized clinical trial | 398 | Probiotic (L. casei) | 1 g per meal | 4 | Incident CR tumors | L. casei group compared to no treatment group | OR 0.85; 95% CI 0.56–1.27 | There was no significant difference in risk of new CR tumors for those randomized to the L. casei group nor the wheat bran group when compared to the no treatment group. |
| Prebiotic fiber (Wheat bran biscuits) | 25 g per day | Wheat bran group compared to no treatment group | OR 1.31; 95% CI 0.87–1.97 | |||||||
| Rifkin et al. [24] | Adult men and women aged 40–75 (TCPS) and 40–85 (JHBS) undergoing routine colonoscopy without a history of CRC or inflammatory bowel disease | Case-control | 5446 (TCPS) 1061 (JHBS) |
Yogurt | Frequency of intake (daily, weekly, monthly, none) | - | Incident or recurrent colorectal polyps | Yogurt: Daily intake compared to no/rare intake (TCPS) | OR 0.54; 95% CI 0.31–0.95 | Daily yogurt intake was associated with lower odds of colorectal polyps. |
| Yogurt: Weekly use compared to no use (JHBS) | OR 0.75; 95% CI 0.54–1.04 | |||||||||
| Probiotic supplementation | Use versus non-use in the past week | Probiotic: Weekly use compared to no use (JHBS) | OR 0.72; 95% CI 0.49–1.06 | |||||||
| Barrubes et al. [25] | Adult men and women aged 55–80 at high risk of CVD participating in the PREDIMED study | Prospective cohort | 7447 | Yogurt | Frequency of intake (g per day) | 6 | Incident CRC | Yogurt: Highest intake tertile compared to lowest intake tertile | HR 0.94; 95% CI 0.56–1.59 | Yogurt and fermented dairy consumption were not associated with CRC. |
| Fermented dairy | Fermented dairy: Highest intake tertile compared to lowest intake tertile | HR 0.90; 95% CI 0.53–1.53 | ||||||||
| Zheng et al. [26] | Adult men participating in the Health Professionals Follow-up Study (HPFS) and women participating in the Nurses’ Health Study (NHS) aged 35 + years | Prospective cohort | 32,606 (men) 55,743 (women) |
Yogurt | Frequency of intake (servings per week) | 26 | Conventional adenomas | Men: Yogurt consumption ≥2 servings/week compared to no consumption | OR 0.81; 95% CI 0.71–0.94 | Higher yogurt consumption was associated with lower risk of conventional adenomas but not serrated lesions among men. No association with conventional adenomas nor serrated lesions was observed among women. |
| Women: Yogurt consumption ≥2 servings/week compared to no consumption | OR 0.98; 05% CI 0.88–1.09 | |||||||||
| Serrated lesions | Men: Yogurt consumption ≥2 servings/week compared to no consumption | OR 0.89; 95% CI 0.74–1.07 | ||||||||
| Women: Yogurt consumption ≥2 servings/week compared to no consumption | OR 0.92; 95% CI 0.82–1.04 | |||||||||
| Pala et al. [27] | Adult men and women aged 35–65 years living in Italy and free from cancer at baseline (EPIC study) | Prospective cohort | 14,178 (men) 31,063 (women) |
Yogurt | Frequency of intake (g per day) | 12 | Incident CRC | Men: Highest intake tertile compared to lowest intake tertile | HR 0.47; 95% CI 0.28–0.81 | Higher yogurt consumption was associated with lower relative rates of CRC. The effect was stronger among men than women. |
| Women: Highest intake tertile compared to lowest intake tertile | HR 0.69; 95% CI 0.47–1.03 | |||||||||
| Senesse et al. [28] | Adult men and women aged 30–79 years in France | Case-control | 789 | Yogurt | Frequency of intake (g per day) | - | Incident small adenomatous polyps | High consumption compared to no consumption | OR 1.2; 95% CI 0.8–2.1 | High yogurt consumption was associated with lower relative risk of large adenomas. No association was noted between yogurt consumption and small adenomas. |
| Incident large adenomatous polyps | High consumption compared to no consumption | OR 0.6; 95% CI 0.4–1.0 | ||||||||
| Murphy et al. [29] | Adult men and women aged 35 + years participating in the EPIC study free from cancer at enrollment | Prospective cohort | 477,122 | Yogurt | Frequency of intake (g per day) | 11 | Incident CRC | Highest intake quartile compared to no intake | HR 0.90; 95% CI 0.81–0.99 | Higher yogurt intake was inversely associated with risk of CRC. |
| Michels et al. [30] | Adult men and women aged 30–75 years participating in HPFS and NHS | Prospective cohort | 43,269 (men) 83,054 (women) |
Yogurt | Frequency of intake at baseline and cumulatively updated (servings per week, month) | 32 | Incident CRC | Baseline: 1+ serving/week compared to never or <1 serving/month | HR 0.89; 95% CI 0.80–1.0 | More frequent yogurt consumption was associated with lower incidence of CRC. |
| Cumulative update: 1+ serving/week compared to never or <1 serving/month | HR 0.97; 95% 0.87–1.07 |
Abbreviations: EPIC: European Prospective Investigation into Cancer and Nutrition; GOS: Galacto-oligosaccharides; TCPS: Tennesee Colorectal Polyp Study; JHBS: Johns Hopkins Biofilm Study; PREDIMED: Prevencion con Dieta Mediterranea; HPFS: Health Professionals Follow-up Study; NHS: Nurses’ Health Study.