The Relationship between Energy-Adjusted Dietary Inammatory Index (E-DII) with Quality of Life and Inammatory Markers among Overweight and Obese Iranian Women

Overweight and obesity are associated with higher levels of inammatory markers, inammatory diseases, and lower quality of life. Recent investigations have shown that diet can modify these complications and improve quality of life. The objective of this study was to investigate associations between Energy-Adjusted Dietary Inammatory Index (EDII) with quality of life and serum inammatory markers. In the current cross-sectional study, a total of 280 females from health centers in Tehran, Iran (2018) were selected for the study using a multistage cluster random sampling method. The EDII was computed based on dietary intake, assessed by a previously validated 147-item food frequency questionnaire (FFQ). Before calculating EDII, a residual method was used to adjust energy intake. SF-36 questionnaires were used for evaluating quality of life. Concentrations of high-sensitivity C-reactive protein (hs-CRP) were determined using collected serum samples.


Objective
The objective of this study was to investigate associations between Energy-Adjusted Dietary In ammatory Index (EDII) with quality of life and serum in ammatory markers.

Methods
In the current cross-sectional study, a total of 280 females from health centers in Tehran, Iran (2018) were selected for the study using a multistage cluster random sampling method. The EDII was computed based on dietary intake, assessed by a previously validated 147-item food frequency questionnaire (FFQ). Before calculating EDII, a residual method was used to adjust energy intake. SF-36 questionnaires were used for evaluating quality of life. Concentrations of high-sensitivity C-reactive protein (hs-CRP) were determined using collected serum samples.

Conclusion
It was found that dietary in ammatory potential decreased some quality of life measurements and levels in overweight and obese Iranian women.

Page 3/17
Overweight and obesity is excessive fat accumulation, de ned as BMI (25-29.9) and BMI ≥ 30 respectively, according to WHO de nitions [1,2]. The worldwide prevalence of overweight and obesity in developed and developing countries has increased substantially in recent decades [3]. Overweight and obesity are common in Iran, and are signi cantly more prevalent among women than men [4].
Accumulating evidence indicates that obesity is closely associated with an increased risk of cardiovascular disease (CVD), hypertension (HTN), type 2 diabetes mellitus (T2DM), hyperlipidemia, strokes, certain cancers, sleep apnea, liver and gall bladder disease, osteoarthritis and poor health quality of life (HQOL) [5].
In addition to medical complications, overweight and obesity is accompanied by a decline in healthrelated quality of life factors, such as physical functioning, psychosocial functioning, and emotional wellbeing [6][7][8][9]. The results of recent studies shows that overweight and obese people with lower BMI have higher quality of life (QoL) than those with higher BMI scores [10]. The rising prevalence and healthrelated consequences of overweight and obesity make it a public health concern all over the world [3,11].
The concept of quality of life is a complex, multifaceted construct that includes various aspects, such as physical health and psychological health [12].
Obesity is typically associated with a chronic state of systemic low-grade in ammation, since adipocytes result in the expression of cytokines such as hs-CRP [13,14]. Recent studies have shown reliable associations between diet and systemic in ammation. Additionally, it has also been reported that diet can play a major and signi cant role in quality of life. Previous research has shown that adherence to an anti-in ammatory diet was signi cantly associated with better health-related quality of life [15,16]. The energy-adjusted dietary in ammatory index is a validated method developed to characterize dietary in ammatory potential [17]. In view of all the above, it was hypothesized that greater adherence to an anti-in ammatory diet would be associated with lower low-grade in ammation and greater quality of life in overweight and obese patients. To the researchers' knowledge, this is the rst study investigating the relationship between energy-adjusted dietary in ammatory index and quality of life.

Study Design and Participants
The current cross-sectional study was conducted among overweight and obese women who attended health centers in Tehran, Iran, in 2018. A random sample of 280 women was selected from 20 various health centers by a multistage cluster random sampling method. Eligible criteria included body mass index in the range of 25-40 kg/m 2 . Exclusion criteria included: history of cardiovascular disease, hypertension, diabetes mellitus, hepatic or renal disease, alcohol usage, medicine usage other than birth control pills, pregnancy or lactation, following a speci c diet or body weight uctuation over the past 1 year. Informed consent was obtained from all participants. This study was approved by the research

Dietary Assessment
Participants' dietary intake over the past year was assessed using a valid and reliable semi-quantitative food frequency questionnaire (FFQ). This FFQ consists of 147 food items with standard serving sizes, and participants were asked to specify their consumption frequency for each food item on a daily, weekly, monthly or yearly basis. Then, nutrient and energy intakes were computed using NUTRITIONIST IV software (version 7.0; N-Squared Computing, Salem, OR), which was tailored for Iranian foods. For calculating EDII, all nutrient values were adjusted for energy intake using the residual method.

Dietary In ammatory Index Calculation
To calculate EDII for the participants of this study, the dietary data were rst linked to the regionally representative world database, which provided a robust estimate of a mean and standard deviation for each parameter. These then become the multipliers to express an individual's exposure relative to the 'standard global mean' as a z-score. A z-score for each food consumed was calculated by subtracting the 'standard mean' from the actual food parameter value, and divided by its standard deviation. Next, to minimize the effect of 'right skewing', this value was then converted to a centered percentile score, which was then multiplied by the respective food parameter in ammatory effect score to obtain the subject's food parameter-speci c EDII score. All of the food-parameter-speci c EDII scores were then summed together to create an overall EDII score for every subject in the study [18]. In total, the EDII computed based on this study's FFQ includes data on 29 of the 45 possible food variables composing the EDII: energy, carbohydrate, protein, fat, ber, cholesterol, trans fat, SFAs, MUFAs, PUFAs, omega-3, omega-6, niacin, thiamin, ribo avin, vitamin B-6, vitamin B-12, iron, magnesium, selenium, zinc, vitamin A, vitamin C, vitamin D, vitamin E, folic acid, b-carotene, caffeine, onion and tea.

Quality of Life Assessment
The SF-36 is a short-form, self-administered quality of life scoring questionnaire. is a ve-item scale that evaluates feelings principally of anxiety and depression [19,20]. The SF-36 also includes a question self-evaluating health changes in the past year (reported health), which does not belong to the eight dimensions, or the total SF-36 score. Each of these 8 dimensions has a score between 0 (worst health) to 100 (best health). [21][22][23] Biochemical Assessment: Blood samples were collected early in the morning after 12-hour overnight fasting. Serum was separated from whole blood samples and stored at −80 °C until the assay Serum hs-CRP levels was measured by an immunoturbidimetric assay with a Pars Azmoon kit (Pars Azmoon Inc. Tehran, Iran).
Anthropometric Assessment: Anthropometric measures, including body weight, body mass index, waist circumferences and waist-hip ratio, were measured in an overnight fasting state, without shoes, with minimal clothing and by the use of a multi-frequency bioelectrical impedance analyzer In-body 770 scanner (In-body Co., Seoul, Korea).
Height was measured with a Seca 206 scale, based on standard protocol.

Assessment of Other Variables:
Physical activity status and socio-demographic information was obtained by questionnaire. Data on physical activity was gathered using the IPAQ questionnaire. Activity was classi ed as light, medium or heavy levels (IPAQ). The metabolic equation hours per day score (MET-min/week) was then calculated for each subject [24,25].

Statistical Analyses:
The EDII was analyzed as a dichotomous variable, categorized based on the median value of the EDII (0.05). EDII (as dichotomous) was examined across the following characteristics: age, weight, height, economic status, BMI, waist circumference, waist-hip ratio, energy intake, physical activity, and quality of life measurements, via independent sample T-test analyses. Comparisons of different food group intakes across the EDII quartiles were analyzed through an independent sample T-test. Multivariable linear regression analyses of the continuous EDII score were conducted to determine the association of the EDII with quality of life and hs-CRP levels. Variables were adjusted for the following confounding factors: age, weight, physical activity, smoking, economic status and employment status. The results are reported as percentage change (β) with 95% con dence intervals (95% CI). Statistical analysis was performed using SPSS (version 21) (SPSS Inc., Chicago, USA). Signi cance was set at a probability of ≤0.05 for all tests.

Results
The dietary in ammatory potential scores in this study, as measured by EDII, ranged from -4.14 (most anti-in ammatory score) to 3.89 (most pro-in ammatory score). The mean (SD) age of the participants at recruitment was 36 (8). Table 1 presents participants' characteristics in relation to different categories of dietary in ammatory indices. EDII was categorized into anti-in ammatory (EDII ≤ 0/05) and pro-in ammatory (EDII > 0/06) diets, based on the median value (0.05). When EDII was converted into two groups, signi cant differences were observed for IPAC (P<0.0001). The hs-CRP level showed no signi cant change in the higher EDII score group compared to the other group (PC: 4/26±4/42% vs. 4/07±4/34%; P = 0.856).
Signi cant inverse differences were found between the three dimensions of SF-36, including physical functioning (P=0.033), mental health (P=0.021) and vitality (P=0.031), with anti-in ammatory and proin ammatory diet groups. For the other ve dimensions, such as general health, role-physical, role emotional, social functioning, bodily pain and health transition, decreasing trends were observed across EDII categories, but these relationships were not signi cant (Table 2). Table 3 shows the distribution of 11 food groups: grains, re ned grains, dairy products, beans, vegetables, fruits, red meat, processed meat, white meat, nut/olive group and sweet/fat group across the EDII groups. The results showed that servings of vegetables and beans (P<0.0001) decreased signi cantly in the higher dietary in ammatory index group, whereas servings of sweet/fat group (P<0.0001) increased signi cantly in this group.
A direct association between EDII and physical functioning levels was observed after adjustment for potential confounders, such as age, weight, smoking, economic status and employment status (P=0.024) (

Discussion:
It is important to note that this is the rst study to examine the association between dietary in ammatory potential, quality of life and in ammation levels among women. This cross-sectional study of Iranian women showed evidence of a positive association between higher (i.e. more pro-in ammatory) EDII scores with lower quality of life in certain measurements, such as physical functioning, mental health and vitality. These ndings emphasize the importance of addressing overall dietary quality in future community-or population-based programs or policies to prevent chronic disease.
Some prior research has shown that in ammatory diet plays an important role in psychological health.
Almudena Sánchez-Villegas et al. also determined that a pro-in ammatory diet was associated with a signi cantly higher risk of depression in a Mediterranean population, particularly in older subjects [26]. Tasnime N. Akbaraly et al. found that a pro-in ammatory diet was associated with recurrent depression in women, which seems not to be driven by circulating in ammatory markers [27]. There is considerable evidence that has suggested a better quality of diet or anti-in ammatory diet is associated with better quality of life and better mental health. Ujué Fresán et al. have found that a Mediterranean diet was associated with reduced depression risks [28]. A recent study in Australia demonstrated that better dietary quality in older adults was related with better health-related quality of life and emotional wellbeing in women [29]. The current ndings are supported by an Australian study which reported that adherence to an MD pattern is associated with better mental and physical health, and that this association is particularly stronger in terms of mental health than physical health [30]. A possible mechanism seems to related to the fact that an anti-in ammatory diet is rich in nutrients such as vitamins, minerals, antioxidants, and ber, which have bene cial health effects that have been widely demonstrated.
The results revealed no relationship between EDII and hs-CRP levels in women. To the best of the researchers' knowledge, previous studies of dietary in ammatory indices and serum hs-CRP levels are generally consistent with the ndings of the present study. A number of other studies have suggested that a pro-in ammatory diet is associated with higher levels of in ammatory markers. Previous studies have shown that DII was associated with an increase in the odds of elevated hs-CRP levels (.3 mg/l) [31].
Another study in the USA demonstrated that higher DII scores were associated with in ammatory biomarkers including IL-6, TNF-α and hs-CRP [32]. In the Asklepios study, no signi cant associations were observed between DII and in ammatory markers CRP and brinogen, but signi cant positive associations between DII and in ammatory markers IL-6 and homocysteine were observed [33].

Conclusion:
The most interesting nding of this study is that the multivariable linear regression analysis has revealed that more anti-in ammatory diets are signi cantly associated with higher physical function, mental health and vitality in overweight and obese women. Thus, encouraging the intake of more antiin ammatory dietary factors, such as plant-based foods rich in ber and phytochemicals, and reducing intake of pro-in ammatory factors, such as fried foods or processed foods rich in saturated fat, may be a bene cial strategy for better physical and mental health.
The present study had some limitations that should be considered. First of all, the use of self-reported food-frequency questionnaires (FFQ) is known to contain a certain degree of measurement error, which might affect results. Moreover, an FFQ consisting of 29 instead of 45 food parameters was used for calculating EDII. The small sample size is another limitation, and data from larger sample size studies are more credible. In addition, casual relationship between energy-adjusted dietary in ammatory index, in ammatory markers, and quality of life cannot be inferred using retrospective observational studies; conducting prospective studies is thus highly recommended.