Dietary Inflammatory Index and Risk of Colorectal Cancer in the Iowa Women's Health Study

Nitin Shivappa; Anna E. Prizment; Cindy K. Blair; David R. Jacobs; Susan E. Steck; James R. Hébert

doi:10.1158/1055-9965.EPI-14-0537

DOI: 10.1158/1055-9965.EPI-14-0537 Published November 2014

Article Figures & Data

Tables

Table 1.

Prevalence of characteristics at baseline across quintiles of DII (with supplements), IWHS, 1986–2010

	DII (with supplements)^b
	Quintile 1	Quintile 2	Quintile 3	Quintile 4	Quintile 5
	<−2.75	−2.75 to −1.76	−1.75 to −0.57	−0.56 to 1.10	>1.10
	Median = −3.29	Median = −2.26	Median = −1.21	Median = 0.23	Median = 2.13
Characteristics^a [mean (SD) or %]	(N = 6,940)	(N = 6,941)	(N = 6,941)	(N = 6,941)	(N = 6,940)
Age (years)	62.0 (4.2)	61.7 (4.2)	61.6 (4.2)	61.4 (4.1)	61.2 (4.2)
Total energy intake (kcal/day)	2,119.1 (664.5)	2,009.5 (631.4)	1,816.4 (532.2)	1,684.8 (446.7)	1,362.9 (406.7)
Total fat (% kcal/day)	31.4 (5.4)	33.5 (5.3)	34.2 (5.5)	34.7 (5.6)	36.0 (6.0)
Dietary fiber (g/1,000 kcal/day)	13.5 (3.2)	11.6 (2.9)	10.8 (2.9)	10.5 (2.9)	9.5 (2.8)
Vitamin supplement use (% taking)
Any	85.0	73.9	65.5	47.3	34.1
Multivitamin	68.9	50.2	35.3	9.9	2.0
Calcium	63.2	53.0	46.6	37.4	29.2
Vitamin C	32.0	21.9	16.9	9.5	3.8
Vitamin E	28.6	19.8	14.9	7.4	2.0
BMI (%; kg/m²)
≤24.9	42.5	40.2	39.4	38.5	38.6
25–30	37.1	37.1	37.4	36.9	36.2
≥30	20.5	22.7	23.2	24.7	25.2
Education (%)
Less than high school	15.2	16.6	17.6	19.3	21.6
High school	36.4	40.8	42.1	43.7	47.5
More than high school	48.4	42.6	40.3	37.0	30.9
Smoking (%)
Never	70.3	68.5	65.7	64.6	59.0
Former	20.3	19.1	19.1	19.7	18.9
Current	9.5	12.5	15.3	15.7	22.1
Alcohol intake (%)
0 g/day	58.6	54.2	52.7	54.3	55.0
<15 g/day	34.1	39.8	41.1	39.4	38.2
≥15 g/day	7.4	6.0	6.2	6.4	6.8
Level of physical activity^c (%)
Low	33.7	42.3	48.4	51.9	61.2
Middle	29.8	30.2	27.4	27.4	22.8
High	36.5	27.5	24.2	20.7	16.1
Hormone therapy use (yes, %)	43.8	39.9	39.2	36.9	34.0
Diabetes at baseline (yes, %)	6.6	6.4	6.2	5.9	5.3
History of aspirin use (1992 survey, ever %)	73.5	72.7	71.6	71.4	71.0
History of NSAIDs use (1992 survey, ever %)	84.2	83.8	82.6	82.4	81.6

↵^aAll variables are measured at baseline (1986) unless otherwise noted. Some column percentages are presented; they do not always add to 100 because of rounding.
↵^bQuintile 1 refers to scores indicating the most antiinflammatory diet, and quintile 5 refers to scores indicating the most proinflammatory diet.
↵^cPhysical activity level: High, more than 4 times per week for moderate physical activities (e.g., bowling, golf, light sports or physical exercise, gardening, taking long walks) or more than 2 times per week for vigorous physical activities (e.g., jogging, racquet sports, swimming, aerobics, strenuous sports); Middle, more than 2 times per week for moderate physical activities or a few times a month for both moderate and vigorous physical activities; Low, those not belonging to activity level 2 or 3.

Table 2.

Distribution of food groups across quintiles of DII (with supplements)^a, IWHS, 1986–2010

			Quintile1	Quintile2	Quintile3	Quintile4	Quintile5
Food groups (servings/week)	Direction increase with DII^b	Difference (Q5 − Q1)/Q1	Mean	Mean	Mean	Mean	Mean
Other vegetables (other than green leafy vegetables or potatoes)	—	—65%	27.3	19.8	16.0	13.8	9.7
Low-fat dairy	—	—63%	10.6	9.1	7.9	6.6	3.9
Green leafy vegetables	—	—62%	7.5	5.5	4.4	3.9	2.8
Fish/seafood	—	—62%	2.6	1.9	1.5	1.3	1.0
Fruit (no juice)	—	—61%	19.9	15.6	12.9	11.2	7.7
Nuts	—	—61%	3.5	2.8	2.2	1.9	1.4
Whole grains	—	—60%	16.8	12.9	10.8	9.3	6.7
Beans without soy	—	—56%	0.7	0.6	0.5	0.4	0.3
Fruit juice	—	—52%	6.6	5.8	5.0	4.5	3.1
Poultry	—	—52%	2.6	2.0	1.8	1.6	1.2
Wine	—	—39%	0.7	0.6	0.5	0.5	0.4
Potatoes	—	—31%	3.5	3.5	3.2	3.1	2.4
Salty snacks	—	—30%	4.5	4.4	3.9	3.7	3.1
Margarine	—	—27%	10.4	10.1	9.6	9.2	7.6
Tea	—	—26%	3.4	3.3	3.0	2.9	2.5
Eggs	—	—24%	2.4	2.4	2.3	2.1	1.8
Sweets without chocolate	—	—22%	8.1	9.1	8.2	7.7	6.3
Low-calorie beverages	—	—20%	2.0	1.8	1.7	1.6	1.6
Red meat	—	—13%	5.8	6.5	6.2	5.9	5.0
Chocolate	0	—3%	0.6	0.8	0.8	0.7	0.6
High-fat dairy	0	—3%	9.6	10.9	10.4	10.2	9.3
Refined grains	0	0%	8.3	8.9	9.0	9.2	8.2
Nitrate processed meat	0	1%	1.8	2.1	2.1	2.0	1.8
French fries	+	6%	0.3	0.4	0.4	0.4	0.4
High-sugar beverages	+	18%	1.2	1.4	1.4	1.4	1.4
Liquor	+	24%	0.8	0.8	0.8	0.9	1.0
Fried food	+	29%	1.8	2.2	2.3	2.3	2.3
Coffee	+	36%	9.9	11.4	11.8	12.1	13.5
Beer	+	37%	0.5	0.6	0.6	0.7	0.7
Butter	+	56%	1.4	1.9	2.0	2.0	2.2

↵^aThe foods listed are meant to give the reader a sense of how dietary intake varies across DII quintiles; though some listed foods are indeed among the 37 parameters that are used in computation of DII in the IWHS, these are not meant to be a list of contributors to the DII.
↵^b+ indicates increase across quintiles;—indicates decrease across quintiles; 0 indicates no or <5% change.

Table 3.

DII from food and supplements and colorectal cancer risk; IWHS, 1986–2010

	Cases (n)	HR^a (95% CI)	HR^b (95% CI)	Cases (n)	HR^a (95% CI)	HR^b (95% CI)	Cases (n)	HR^a (95% CI)	HR^b (95% CI)
	Colorectal cancer			Colon cancer			Rectal cancer
DII continuous	1,636	1.09 (1.03–1.14)	1.07 (1.01–1.13)	1,329	1.08 (1.02–1.13)	1.05 (0.99–1.12)	325	1.10 (0.99–1.23)	1.11 (0.98–1.25)
DII quintiles
Quintile 1	290	1 (referent)	1 (referent)	236	1 (referent)	1 (referent)	58	1 (referent)	1 (referent)
Quintile 2	318	1.11 (0.94–1.30)	1.04 (0.89–1.22)	267	1.14 (0.96–1.34)	1.07 (0.89–1.28)	54	0.93 (0.64–1.35)	0.91 (0.62–1.32)
Quintile 3	335	1.18 (1.01–1.38)	1.11 (0.95–1.31)	270	1.17 (0.98–1.40)	1.10 (0.92–1.31)	73	1.28 (0.91–1.81)	1.23 (0.86–1.76)
Quintile 4	341	1.20 (1.03–1.40)	1.13 (0.95–1.33)	270	1.17 (0.98–1.39)	1.08 (0.89–1.29)	71	1.24 (0.88–1.76)	1.25 (0.87–1.80)
Quintile 5	352	1.29 (1.10–1.51)	1.20 (1.01–1.43)	286	1.28 (1.08–1.53)	1.19 (0.98–1.45)	69	1.25 (0.88–1.77)	1.21 (0.81–1.79)
P trend		0.001	0.03		0.008	0.10		0.09	0.16

↵^aAge-adjusted.
↵^bAdjusted for age, BMI, smoking status, pack-years of smoking, HRT use, education, diabetes, and total energy intake.

Table 4.

DII from foods only, DII from vitamin supplements, and colorectal cancer risk; IWHS, 1986–2010.

	Cases (n)	HR^a (95% CI)	HR^b (95% CI)	Cases (n)	HR^a (95% CI)	HR^b (95% CI)	Cases (n)	HR^a (95% CI)	HR^b (95% CI)
	Colorectal cancer			Colon cancer			Rectal cancer
DII from foods only^c
Continuous	1,636	1.09 (1.03–1.14)	1.08 (1.01–1.15)	1,329	1.08 (1.02–1.14)	1.06 (0.99–1.14)	325	1.11 (0.99–1.24)	1.13 (0.98–1.31)
Quintiles^d
Quintile 1	294	1 (referent)	1 (referent)	237	1 (referent)	1 (referent)	58	1 (referent)	1 (referent)
Quintile 2	323	1.11 (0.95–1.30)	1.07 (0.90–1.26)	271	1.15 (0.96–1.37)	1.10 (0.91–1.32)	60	1.07 (0.74–1.54)	1.07 (0.73–1.56)
Quintile 3	338	1.16 (0.99–1.36)	1.12 (0.94–1.33)	268	1.12 (0.94–1.34)	1.07 (0.88–1.30)	73	1.35 (0.95–1.92)	1.37 (0.93–2.01)
Quintile 4	351	1.21 (1.03–1.43)	1.16 (0.97–1.40)	293	1.23 (1.03–1.47)	1.16 (0.95–1.43)	61	1.16 (0.80–1.68)	1.20 (0.79–1.84)
Quintile 5	330	1.17 (0.99–1.38)	1.12 (0.91–1.38)	260	1.12 (0.93–1.35)	1.06 (0.84–1.33)	73	1.43 (0.99–2.05)	1.48 (0.94–2.34)
P trend		0.004	0.08		0.02	0.27		0.10	0.13
DII from supplements^e
Continuous	1,636	1.04 (0.99–1.10)	1.02 (0.97–1.08)	1,329	1.04 (0.98–1.09)	1.02 (0.96–1.08)	325	1.05 (0.93–1.17)	1.02 (0.91–1.15)
Categories^f
1 (N = 5,824)	273	0.91 (0.79–1.04)	0.94 (0.82–1.09)	226	0.84 (0.69–1.02)	0.84 (0.69–1.03)	52	1.10 (0.74–1.64)	1.10 (0.73–1.64)
2 (N = 5,824)	236	0.81 (0.70–0.94)	0.84 (0.73–0.98)	186	0.91 (0.74–1.11)	0.89 (0.72–1.09)	53	1.30 (0.88–1.92)	1.21 (0.81–1.81)
3 (N = 5,826)	256	0.89 (0.77–1.02)	0.89 (0.77–1.03)	199	1.09 (0.94–1.27)	1.05 (0.90–1.23)	61	1.08 (0.79–1.49)	1.02 (0.74–1.42)
4 (N = 17,229)	871	1 (referent)	1 (referent)	718	1 (referent)	1 (referent)	159	1 (referent)	1 (referent)
P trend		0.09	0.29		0.15	0.36		0.56	0.88

↵^aAdjusted for age and the other DII variable.
↵^bAdjusted for age, the other DII variable, BMI, smoking status, pack-years of smoking, HRT use, education, diabetes, and total energy intake.
↵^cThese are for foods only, exclusive of supplement intake.
↵^dReference category is the lowest (i.e., most antiinflammatory) quintile; increasing quintiles of DII from food groups represent increasing inflammatory scores.
↵^eThis is obtained by subtracting the DII score for foods only from the DII derived by including both foods and supplements.
↵^fReference category represents nonsupplement users; categories 1 to 3 represent tertiles of the DII from supplement users. Category 1 represents women with the greatest contribution from supplements to the DII score. DII score median (range): categories 1, −3.00 (<—2.0552); 2, −1.31 (—2.0552 to −0.7616); 3, −0.34 (—0.7615 to 0.0000); 4, 0.00 (0.0000 to 0.1765).