The Dietary Inflammatory Index Is Directly Associated With Polycystic Ovary Syndrome

A Case-Control Study

Elnaz Zirak Sharkesh; Seyed A. Keshavarz; Leila Nazari; Behnood Abbasi

Clin Endocrinol. 2022;96(5):698-706.

Conclusion

In conclusion, as it found a positive association between DII index and risk of PCOS, following an anti-inflammatory diet might be as an effective strategy for preventing PCOS. Further well-designed national and international studies are warranted to establish this association.

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Acknowledgements
The authors would like to thank all the staffs of the polycystic ovary syndrome clinic of the Taleghani, Shohada, and Arash hospitals as well as patients and participants of the present study for their support and kind collaborations.

Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.

Table 1. Demographic, anthropometric, and lifestyle characteristics of participants in case and control groups
Variables	Groups, mean (SD)		p*
Variables	Case (n=) 203	Control (n=) 291	p*
Age, y	28.98 (5.43)	30.15 (6.21)	.029
Weight (kg)	67.91 (13.14)	63.79 (10.51)	<.001
BMI, kg/m²	25.74 (5.44)	23.65 (3.90)	<.001
Waist circumference (cm)	87.21 (43.38)	79.92 (9.68)	.006
Physical activity (MET. min/d)	1638.97 (572.95)	1996.65 (1258.03)	<.001
NSAIDs drug use, n (%)	71 (35.1)	108 (37.2)	.635
Multivitamins supplements use, n (%)	34 (16.7)	70 (24.1)	.05
Vitamin D supplements use, n (%)	119 (58.6)	143 (49.1)	.038
Vitamin E supplements use, n (%)	18 (8.9)	26 (8.9)	.979
Vitamin C supplements use, n (%)	17 (8.4)	34 (11.7)	.234
Vitamin B9 supplements use, n (%)	45 (22.2)	38 (13.1)	.008
Vitamin iron supplements use, n (%)	31 (15.3)	59 (20.3)	.156
Vitamin omega 3 supplements use, n (%)	7 (3.4)	24 (8.2)	.030
DII score	−3.75 (0.99)	−3.91 (0.98)	.077
Marital status, n (%)			<.001
Unmarried	53 (26.1)	153 (52.6)
Married	150 (73.9)	138 (47.4)
Education status, n (%)			<.001
Illiterate	1 (0.5)	1 (0.3)
Less than a diploma	36 (17.7)	7 (2.4)
Diploma	56 (27.6)	40 (13.7)
Bachelor	61 (30.0)	140 (48.1)
Higher than a bachelor	49 (24.1)	102 (35.1)

Abbreviation: BMI, body mass index; DII, dietary inflammatory index; MET, metabolic equivalent task; NSAIDs, nonsteroidal anti-inflammatory drugs.
*Obtained from t-test for continuous variables and χ ² for categorical variables.

Table 2. Dietary intakes of study participants across case and control groups
Nutrients	Groups, mean (SD)
Nutrients	Case (n=) 203	Control (n=) 291	p*
Energy (kcal/d)	2500.07 (696.19)	2388.03 (657.88)	.070
Carbohydrate (g/d)	344.10 (95.78)	326.06 (93.83)	.038
Protein (g/d)	86.17 (28.89)	88.26 (27.96)	.421
Fat (g/d)	92.49 (36.18)	86.98 (33.15)	.081
Saturated fatty acids (g/d)	26.53 (12.50)	26.78 (11.37)	.817
Monounsaturated fatty acids (g/d)	32.47 (14.07)	30.48 (12.32)	.097
Polyunsaturated fatty acid (g/d)	18.03 (7.99)	21.20 (9.99)	<.001
Cholesterol (g/d)	287.04 (138.18)	266.09 (130.50)	.019
Fibre (g/d)	38.01 (18.21)	44.73 (23.47)	<.001
Glucose (g/d)	16.68 (8.02)	15.53 (6.94)	.089
Fructose (g/d)	19.58 (9.53)	18.04 (8.16)	.055
Sodium (mg/d)	4893.54 (1985.86)	4618.78 (2035.73)	.137
Potassium (mg/d)	3446.41 (1132.50)	3547.29 (1097.07)	.322
Phosphor (mg/d)	1458.69 (493.98)	1507.28 (467.38)	.267
Calcium (mg/d)	953.19 (402.46)	993.86 (375.47)	.251
Iron (mg/d)	17.93 (5.65)	17.06 (5.20)	.079
Zinc (mg/d)	11.50 (3.78)	11.68 (3.67)	.599
Magnesium (mg/d)	400.31 (137.73)	396.51 (126.83)	.751
Chromium (μg/d)	0.11 (0.11)	0.099 (0.092)	.206
Vitamin C (mg/d)	134.35 (87.27)	135.42 (71.15)	.874
Caffeine (mg/d)	124.37 (111.02)	110.06 (77.37)	.092
Vitamin B6 (mg/d)	1.96 (0.63)	1.98 (0.61)	.821
Vitamin E (mg/d)
Vitamin B9 (μg/d)	572.77 (176.29)	551.78 (154.58)	.162
Vitamin B12 (μg/d)	3.82 (2.28)	4.58 (3.32)	.005
Vitamin D (μg/d)	1.63 (1.20)	2.00 (1.32)	.002
Food groups
Dairy (g/d)	122.23 (97.45)	139.29 (83.55)	.038
Whole grain (g/d)	343.76 (166.34)	333.34 (151.44)	.470
Refined grain (g/d)	137.06 (108.45)	105.63 (77.53)	<.001
Legumes (g/d)	85.53 (59.23)	92.03 (62.37)	.245
Red and processed meat (g/d)	7.71 (8.05)	8.22 (7.70)	.479
Fruits (g/d)	247.92 (151.84)	241.23 (145.96)	.623
Vegetables (g/d)	185.93 (122.14)	171.97 (87.66)	.140

*Obtained from t-test.

Table 3. Sociodemographic characteristics, anthropometry variables, and dietary intake across quartiles of DII index
Demographic variables	Quartiles of DII index				p
Demographic variables	Q1	Q2	Q3	Q4	p
Age (year)	31.10 (5.25)	30.79 (6.04)	29.25 (5.86)	27.54 (5.90)	<.001
Weight (kg)	66.73 (12.62)	64.68 (9.75)	64.04 (10.28)	66.49 (14.08)	.198
BMI (kg/m²)	24.90 (5.37)	24.27 (3.63)	24.03 (3.86)	24.83 (5.64)	.395
Waist circumference	83.14 (11.58)	86.22 (54.47)	80.38 (10.03)	81.91 (12.08)	.439
Physical activity (MET. min/d)	1933.32 (678.65)	1980.97 (1777.66)	1694.60 (568.34)	1789.99 (637.29)	.119
Dietary intake
Energy (kcal/d)	2423.52 (643.50)	2221.39 (590.33)	2356.92 (703.16)	2736.80 (659.67)	<.001
Carbohydrate (g/d)	345.01 (100.43)	309.10 (87.97)	327.64 (97.42)	352.38 (88.59)	.001
Protein (g/d)	91.33 (26.23)	82.10 (23.098)	83.04 (31.35)	93.21 (30.49)	.002
Fat (g/d)	83.16 (26.69)	78.60 (28.54)	84.76 (32.32)	110.60 (39.89)	<.001
Saturated fatty acids (g/d)	23.60 (8.09)	23.16 (8.36)	24.99 (9.88)	35.01 (15.38)	<.001
Monounsaturated fatty acids (g/d)	29.38 (10.06)	27.83 (10.84)	29.44 (12.11)	38.59 (15.87)	<.001
Polyunsaturated fatty acid (g/d)	19.30 (7.31)	17.21 (7.92)	18.79 (9.39)	22.04 (10.44)	<.001
Cholesterol (g/d)	283.84 (119.50)	268.09 (135.11)	260.32 (143.58)	301.71 (139.75)	.079
Fibre (g/d)	45.05 (19.70)	38.27 (19.81)	42.34 (23.33)	37.44 (19.34)	.012
Glucose (g/d)	19.72 (8.64)	15.32 (6.50)	14.92 (6.10)	14.07 (6.95)	<.001
Fructose (g/d)	23.05 (10.20)	18.02 (7.85)	17.58 (7.38)	16.05 (7.87)	<.001
Sodium (mg/d)	4572.42 (1770.29)	4385.07 (1772.77)	4727.68 (2146.70)	5244.43 (2256.85)	.006
Potassium (mg/d)	4132.96 (1248.93)	3391.39 (912.24)	3215.54 (1003.36)	3286.75 (1018.22)	<.001
Phosphor (mg/d)	1578.52 (467.18)	1405.13 (418.54)	1408.80 (497.69)	1558.10 (504.41)	.003
Calcium (mg/d)	1027.01 (352.47)	940.49 (362.48)	916.78 (371.06)	1025.10 (446.65)	.044
Iron (mg/d)	18.67 (5.28)	16.31 (5.14)	17.09 (5.99)	17.62 (4.93)	.006
Zinc (mg/d)	12.41 (3.62)	10.93 (3.13)	11.00 (3.98)	12.09 (3.88)	.002
Magnesium (mg/d)	462.04 (141.45)	375.88 (116.17)	376.76 (130.19)	377.95 (116.04)	<.001
Chromium (μg/d)	0.12 (0.10)	0.09 (0.09)	0.10 (0.10)	0.08 (0.08)	.022
Vitamin C (mg/d)	187.73 (90.53)	137.72 (64.42)	113.14 (54.60)	101.49 (48.62)	<.001
Caffeine (mg/d)	140.79 (83.24)	115.92 (111.44)	104.68 (79.45)	102.44 (89.94)	.004
Vitamin B6 (mg/d)	2.21 (0.65)	1.89 (0.56)	1.82 (0.62)	1.95 (0.57)	<.001
Vitamin B9 (μg/d)	597.16 (155.79)	531.34 (151.81)	553.09 (187.68)	560.32 (152.95)	.016
Vitamin B12 (μg/d)	4.00 (2.17)	4.11 (2.20)	3.73 (2.67)	5.24 (4.15)	<.001
Vitamin D (μg/d)	2.02 (1.23)	1.90 (1.28)	1.74 (1.31)	1.73 (1.30)	.232
Food groups
Dairy (g/d)	168.20 (108.54)	125.94 (70.75)	118.60 (92.23)	116.53 (73.61)	<.001
Whole grain (g/d)	331.61 (147.82)	321.14 (156.06)	330.58 (162.30)	367.36 (161.92)	.104
Refined grain (g/d)	101.62 (75.59)	105.34 (83.59)	136.30 (110.64)	130.87 (93.23)	.004
Legumes (g/d)	95.40 (52.08)	84.72 (45.38)	81.60 (68.74)	95.80 (73.37)	.153
Red and processed meat (g/d)	7.05 (6.80)	7.80 (7.07)	7.38 (8.27)	9.82 (8.84)	.026
Fruits (g/d)	310.16 (171.40)	240.09 (149.39)	207.19 (123.54)	218.81 (123.08)	<.001
Vegetables (g/d)	237.22 (115.53)	175.17 (107.97)	150.92 (80.44)	147.78 (79.53)	<.001

Note: Values are expressed as means (standard deviation) of 494 subjects. p values are resulted from Student t-test.
Abbreviations: BMI, body mass index; DII, dietary inflammatory index; MET, metabolic equivalent task.

Table 4. Odds ratio (OR) and 95% confidence interval (CI) for PCOS based on quartiles of DII index*
DII	Quartiles of DII index				p for trend
DII	Q1	Q2	Q3	Q4	p for trend
Case/total (n)	43/123	45/124	58/124	57/123	_
Crude model	1.00 (Ref)	1.06 (0.62–1.78)	1.63 (0.98–2.72)	1.60 (0.96–2.68)	.025
Model 1a	1.00 (Ref)	1.13 (0.66–1.94)	1.73 (1.02–2.96)	1.47 (0.85–2.53)	.071
Model 2b	1.00 (Ref)	1.09 (0.59–1.99)	1.42 (0.77–2.61)	1.75 (0.95–3.22)	.047

Abbreviations: BMI, body mass index; DII, dietary inflammatory index; PCOS, polycystic ovary syndrome.
^aModel 1: Adjusted for age and BMI.
^bModel 2: Adjusted for Model 1 and weight, waist circumference, education status, marital status, physical activity, use multivitamin mineral supplements, vitamin D supplements, folic acid supplements, and omega 3 supplements.
*Binary logistic regression was used to obtain OR and 95% CI. The overall trend of OR across increasing quartiles was examined by considering the median score in each category as a continuous variable.