Table 3 Characteristics of included studies

Nashar and Almurshed, 2008 [18]

Saudi Arabia in King Faisal Specialist Hospital and Research Center (KFSH&RC)

Case-control study

50 cases and 50 controls

Exposures: Dietary intake

Confounders: Frequency of consumption

CC

Group I: 50 CRC cases were recruited in the KFSH&RC.

Group II: 50 controls were selected in the same hospital of cases.

Lamb meat: OR = 13.5, 95% CI 2.64–68.84

Chicken with skin: OR = 4, 95% CI 1.53–10.41

Beef meat: OR = 0.18, 95% CI 0.03–0.090

Bener et al., 2010 [19]

Qatar in Al-Amal Hospital and Primary Health Care Centers

Case-control study

146 cases and 282 controls matched by age and gender

Exposures: Family history and lifestyle habits

Confounders: BMI, smoking, family history, soft drinks, bakery products

CRC

Group I: 146 CRC cases were selected from the registered cases during the period January 2003 to December 2008.

Group II: 282 controls were identified from the primary heath care centers as healthy with no history of any malignant tumor.

Frozen meat/chicken: OR = 1.20, 95% CI 0.77–1.87

Guesmi et al., 2010 [20]

Tunis in Charles Nicolle Hospital

Case-control study

32 cases and 61 controls

Exposures: Food group

Confounders: Age, frequency of consumption (frequently/rarely), milk

CRC

Group I: 32 CRC cases were selected in the Charles Nicolle hospital.

Group II: 31 patients with digestive pathology noncancerous were selected in the same hospital of the CRC cases.

Group III: 30 patients with Traumatic pathology noncancerous were recruited from the same hospital of the other groups.

Delicatessen meat: OR = 5.1, 95% CI 1.4–18.5

Arafa et al., 2011 [21]

Jordan in Al-Bashir Hospital

Case-control study

220 cases and 220 controls matched by age and gender

Exposures: Dietary intake

Confounders: Vegetables group, fruits, milk , yogurt, tea, bread

CRC

Group I: 220 CRC cases were recruited in Al-Bashir hospital.

Group II: 220 controls were selected in the same hospital of cases.

Red meat: OR = 2.66, 95% CI 1.83–3.88

Saturated fat: OR = 1.03, 95% CI 1.01–1.05

Safari et al., 2013 [22]

Surgical units of the Cancer Institute of Imam Khomeini, Hospital Complex, and three major general hospitals (Shariati, Imam Hussein and Ayatollah Taleghani) in

Tehran city, Iran

Case-control study

71 cases and 142 controls matched by age (within 5-year categories) and sex

Exposures: Dietary intake

Confounders: Family history of CRC in first and second-degree relative, vegetable preparation, aspirin, acetaminophen, mineral and energy intake

CRC

Group 1: 71 cases with pathologically confirmed CRC, diagnosed no longer than six months before the interview, aged 40–75 years of age at the time of diagnosis and had no previous diagnosis of cancer at other sites, prior history of inflammatory bowel disease or familial adenomatous polyposis.

Group 2: 142 controls were selected randomly from patients admitted to the same hospitals as cases during the same time period for acute, nonneoplastic conditions and not afflicted with diet-related chronic diseases.

“Western” dietary pattern (included sugar, processed and red meat, animal butter, refined cereals, tea, pickles, solid oil, mayonnaise, soft drink, legumes, sweets and desserts) increased the risk of CRC by OR = 2.616 (1.361–5.030) p = 0.004

Mahfouz et al., 2014 [23]

Egypt in El-Minia Oncology Centre

Case-control study

150 cases and 300 controls matched by age and sex

Exposures: Dietary intake

Confounders: Alcohol intake, obesity, smoking, physical activity, alcohol, preserved food

CRC

Group I: 150 CRC cases were recruited in El-Minia Oncology Centre.

Group II: 300 controls were selected in the same hospital of cases.

Red meat: OR = 57.1, 95% CI 12.1–270.3

Abu Mweis et al., 2015 [24]

Jordan in the King Hussein Cancer Center, King Abdullah University, Prince Hamzeh, Jordan University Hospital, and Al-Basheer Hospital

Case-control study

167 cases and 240 controls matched by age, sex, occupation, and marital status

Exposures: Food group

Confounders: Age, sex, total energy intake, education level, marital status, work income, and family history

CRC

Group I: 167 CRC cases were recruited from the five major Jordanian hospitals, including an oncology center.

Group II: 240 controls were selected randomly from among hospital personnel, out patients, visitors, and accompanying individuals.

Chicken: OR = 2.52, 95% CI 1.33–4.77

Red meat: OR = 0.64, 95% CI 0.37–1.11

Tayyem et al., 2015 [25]

Jordan in the King Hussein Cancer Center, King Abdullah University, Prince Hamzeh, Jordan University Hospital, and Al-Basheer Hospital

Case-control study

169 cases and 248 controls matched by age, sex, occupation, and marital status

Exposures: Macro-micronutrients consumption

Confounders: Total energy intake, BMI , physical activity, family history, household income, marital status, and tobacco consumption

CRC

Group I: 169 CRC cases were recruited from five Jordanian hospitals specializing in oncology diagnosis and treatment.

Group II: 248 controls were recruited from hospital personnel, outpatients, visitors.

Saturated fat: OR = 5.23 , 95% CI 2.33–11.76

Cholesterol: OR = 2.48, 95% CI 1.18–5.21

Azizi et al., 2015 [26]

Hospitals in Tabriz City of Iran

Case-control study

417 (207 cases and 207 controls) matched by age and sex (within 10-year categories)

Exposures: Dietary intake

Confounders: History of diabetes, family history of CRC in first-degree relative, physical activity, BMI

CRC

Group 1: 207 cases with CRC (confirmed by pathology and colonoscopy findings, diagnosed no longer than 6 months before the interview).

Group 2: 207 controls free of neoplastic conditions and diet-related chronic diseases (from the same hospital at the same period as the cases selected).

Inclusion criteria were age 35–75 years old, CRC confirmed for the cases, being free of CRC for the controls and informed consent.

Significant association was observed between Iranian dietary pattern (included fried chicken, processed and red meat, black tea, carbonated beverage) and colorectal cancer after adjusting for history of CRC in first-degree relative, history of diabetes, and physical activity: OR = 1.46 (1.05–2.19), p = 0.021

Tayyem et al., 2016 [27]

Five large Jordanian hospitals with oncology services.

Case-control study

220 cases and 281 controls matched by age, sex, occupation, and marital status

Exposures: Meat, dairy products and fats

Confounders: Age, sex, BMI, physical activity level, total energy intake, income, occupation, education level, marital status, cigarette smoking (current or lifelong; ever or never), other health problems and family history of CRC

CRC

Group I: 220 were diagnosed CRC cases were recruited conveniently from five large Jordanian hospitals with oncology services.

Group II: 281 controls were recruited from hospital personnel, outpatients and visitors.

Chicken (OR = 15.32, 95% CI = 3.28–71.45, Ptrend = 0.009) and Mortadella, a type of processed meat (OR = 9.08, 95% CI = 1.02–80.58, Ptrend = 0.049)

Steak: 0.42 (0.14–1.24)

Liver: 2.88 (0.25–32.81)

El-Moselhy et al., 2017 [28]

General Surgery, Tropical Medicine, and Internal Medicine Clinics, Al-Azhar University Hospitals, Assiut and Cairo

Case-control study

160 cases and 300 controls

Exposures: Lifestyle, and socio-demographic and dietary data

Confounders: BMI, physical activity

CRC

Group I: 160 patients with CRC attending the General Surgery, Tropical Medicine, and Internal Medicine Clinics, Al-Azhar University Hospitals, Assiut and Cairo.

Group II: 300 healthy subjects (relatives to other patients attending these clinics and free from any type of cancer).

Processed meats intake (OR = 5.12, 95% CI 3.08–8.53)

Low white meats intake (OR = 2.17, 95% CI 1.4–3.37)

High animal fat intake (OR = 5.59, 95% CI 3.52–8.9)