First author (Year)

Study Design

# studies

# participants

# CRC cases

Main findings with HR, OR, RR, 95% CI, p value                                                    

Barrubes (2019)

Systematic review and meta-analysis of cohort and case-control studies

29

1,396,167

22,654

Total dairy per 1 serving increment of 200 g had an inverse association with CRC (RR = 0.92, 95% CI 0.88, 0.96, p < 0.001)

Total milk per 1 serving increment of 200 g had an inverse association with CRC (RR = 0.90, 95% CI 0.86, 0.99, p < 0.001)

Total cheese per 1 serving increment of 30 g had an inverse association with CRC (RR = 0.93, 95% CI 0.88, 0.99, p = 0.006)

There was no significant association between CRC and low-fat dairy or whole milk

Ben [25]

Meta-analysis of observational studies

22

Not provided

11,696 CRA cases

There was no association with fruits and vegetables combined at 100 g/day or vegetables at 100 g/day with colorectal adenoma (CRA) which is the precursor to CRC

Significant reduction in CRA risk with fruits at 100 g/day (RR = 0.94, 95% CI 0.92, 0.97)

Bernstein (2015)[21]

Cohort

2

3,452,754 person-years

2731

Processed red meat consumption was positively associated with CRC risk, specifically with distal colon cancer at 30 and 50 g/day increase (HR 1.36, 95% CI 1.09-1.69, p = 0.006)

Unprocessed red meat was inversely associated with distal colon cancer at 1 serving per day of 100 and 120 gram increase (HR 0.75, 95% CI 0.68-0.82, p < 0.001)

Bradbury [26]

Prospective cohort study

27

~470,000

2819 in fruit and vegetable intake

4517 in fiber intake

Total fiber showed significant inverse associations with colorectal cancer risk (RR = 0.83, 95% CI 0.72, 0.96, p = 0.013 but when looking at different fiber types, only cereal fiber was significant (RR = 0.87, 95% CI 0.77, 0.99, p = 0.003), not fruit and vegetable fiber

No statistical significance when fruit and vegetables were combined (RR = 0.97, 95% CI 0.93, 1.01) at 100 g/day increase in intake

Carr [22]

Systematic review and meta-analysis of prospective studies

19

Ranging from 639 to 492,186

15,183

Beef had an increased CRC risk (RR = 1.11, 95% CI = 1.01, 1.22)

Pork had no CRC association (RR = 1.07, 95% CI = 0.90, 1.27)

Poultry had no CRC association (RR = 0.96, 95% CI 0.88, 1.04)

Red and processed meat at a high intake (3-4x per week or > 54 g/day) had a 10% increased CRC risk

Jones [18]

Cohort

1

32,154

465

Women with high adherence to a MedD diet showed an 18% reduced risk (HR = 0.88, 95% CI 0.78, 0.99).

Red meat and poultry had no significant association at low, medium, or high intake

Kim [33]

Systematic review and meta-analysis of original and prospective cohort studies

18

Not provided

Not provided

There was no significant association between CRC risk and total fat (RR = 1.00, 95%CI 0.90, 1.12), saturated fat (RR = 0.97, 95%CI 0.86, 1.10), monounsaturated fat (RR = 1.08, 95%CI 0.92, 1.26) and polyunsaturated fats (RR = 0.99, 95%CI 0.93, 1.04)

Ma [31]

Meta-analysis of original research and prospective cohort studies

11

~ 1,450,500

9,618

An inverse association for dietary fiber was demonstrated in high vs. low fiber intake in proximal colon cancers with a lower risk of 14% (RR = 0.86, 95%CI 0.78, 0.95, p = 0.664)

Distal colon cancer risk was 21% lower in the high vs. low fiber intake (RR = 0.79, 95%CI 0.71, 0.87, p = 0.163)

Reynolds [30]

Systematic review and meta-analysis of RCTs and prospective studies

10

8.8 million person-years

11,245

Total fiber showed an inverse association with CRC risk for every 8g more of fiber consumed per day (RR = 0.92, 95%CI 0.89, 0.95) with the greatest benefit at 25-29 g/day

Whole grains had an inverse association with CRC risk (RR = 0.97, 95%CI 0.95, 0.99) for every 15 g more per day

Schwing-shackl [17]

Systematic review and meta-analysis of cohort and case-control studies

83 total studies

11 for CRC

2,130,753 in all studies

Cohort: 15,108

No significant associations with meats or fish

Higher adherence to MedD diet showed an inverse association with colorectal cancer risk (RR = 0.82, 95% CI 0.75, 0.88)

Schwing-shackl (2018)

Systematic review and meta-analysis of prospective studies

86

Not provided

Not specifically given- broken down by food group

Increased risk of CRC with red meat at 100 g/d (RR = 1.12, 95% CI 1.06, 1.19)

Trend for an inverse association for 100 g/day of fish (RR: 0.96, 95% CI 0.90, 1.01) Inverse association for whole grains for each 30 g/day (RR = 0.95, 95% CI 0.93, 0.97) , fruit at 100 g/d (RR 0.97, 95% CI 0.95, 0.99), and dairy at 200 g/d (RR 0.93, 95% CI 0.91, 0.94)

Small inverse association in vegetables at 100 g/d (RR: 0.97, 95% CI 0.96, 0.98)

No CRC association in nuts, legumes

Shivappa [28]

Meta-analysis of case-control and cohort studies

9

881,612

18,888

Higher scores in the dietary inflammatory index (DII) are associated with colorectal cancer

High vs. low DII showed a 40% increase in CRC risk (RR = 1.40, 95% CI 1.26, 1.55, p < 0.001)

There was an increased risk of CRC of 7% for each increase in 1 point in the DII score (RR = 1.07, 95% CI 1.04, 1.10, p < 0.00001)

Vieira [19]

Systematic review and meta-analysis of prospective studies

111

Not provided

Median number of 6662

Ranging from 729 to 31,551

100 g/day of red meat was significantly associated with CRC (RR = 1.12, 95% CI 1.00, 1.25) and colon cancer (RR 1.22, 95% CI 1.06, 1.39)

11% decreased CRC risk of 100 g/day of fish (RR = 0.89, 95% CI 0.80, 0.99)

90 g/day of whole grains reduced CRC risk (RR = 0.83, 95% CI 0.79, 0.89)

100g/day of vegetables decreased CRC risk (RR = 0.98, 95% CI 0.96-0.99)

Higher dairy intake at 400g/day decreased CRC risk (RR = 0.87, 95% CI 0.83, 0.90)

Higher milk intake at 200g/day decreased CRC risk (RR = 0.94, 95% CI 0.92-0.96)

No association with CRC included: Poultry at 100 g/day, fruit intake, legumes at 50 g/day, and cheese

Vulcan [23]

Prospective cohort

1

27,931

728

High intake of beef was inversely associated with colon cancer (HR 0.60, 95% CI 0.44, 0.82, p = 0.0009).

Beef increased the risk of rectal cancer in men (HR 1.28, 95% CI 1.02, 3.25, p = 0.028)

Beef intake was inversely associated with CRC in women (HR 0.65, 95% CI 0.45 to 0.95, p 0.046)

Pork increased the incidence of CRC (HR 1.39, 95% CI 1.09, 1.78, p = 0.023)

Poultry had no CRC association

Fish intake had an inverse association with rectal cancer (HR 0.59, 95% CI 0.38, 0.92, p = 0.025)

Intake of red meat should not exceed 500 g/week

The type of meat as well as sex and tumor location influence CRC associations

Wu [29]

Meta-analysis of case-control and cohort studies

35

1,295,063

24,275

Inverse association between CV and CRC risk (RR 0.82, 95% CI 0.75, 0.90) seen better in case-control and only borderline significance in cohort studies

Yu [24]

Meta-analysis of cohort studies

42

2,325,040

24,115 GI cancers

Fish consumption had a reduced risk of CRC (RR 0.93, 95% CI 0.87, 0.99, P < 0.01)

Zamora-Ros[27]

Prospective cohort study

1

477,312

4,517

No statistical significance in total flavonoid intake (HR 1.05, 95% CI 0.93, 1.18, p = 0.58) or flavonoid subclasses was observed with CRC risk