Diet scores and prediction of general and abdominal obesity in the Melbourne collaborative cohort study

Dietary inflammatory index (DII) and sleep quality, duration, and timing: A systematic review

Sleep has strong inflammatory underpinnings and diet is one of the primary determinants of systemic inflammation. A systematic literature review was conducted to synthesize current research associating dietary inflammatory potential, as measured by the dietary inflammatory index (DII®) or the energy-adjusted DII (E-DII™) and sleep quality and duration. The National Library of Medicine (Medline), Web of Science, and PsycInfo databases were searched through March 2023. Studies must have used the DII/E-DII as the independent variable and sleep outcomes as dependent variables. Study characteristics, based on STROBE guidelines, were scored based on the presence of the recommendation. Out of the initial 14 studies identified, a total of 12 studies were included for data synthesis. In all 12 studies, more anti-inflammatory diets (i.e., low DII/E-DII scores) were associated with better sleep in at least one sleep domain (most often sleep efficiency and wake-after-sleep-onset). Among those studies with more rigorous diet and sleep measurements, such as dietary recalls and actigraphy, associations between DII/E-DII and sleep outcomes were stronger and more consistent compared to studies using primarily subjective assessments. More rigorous measurement of diet and sleep, especially those relating to sleep stage structure, should be considered in future studies with prospective designs.

Predicted pro-inflammatory hs-CRP score and non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease (NAFLD) is a major contributor to liver diseases globally, yet there are limited studies investigating the impact of diet and lifestyle factors on its development. This study aimed to examine the association between the prevalence of NAFLD and predicted pro-inflammatory high-sensitivity C-reactive protein (hs-CRP) score.

Methods

We included 1,076 Korean adults who underwent a medical examination at the Seoul National University Hospital Gangnam Healthcare Center in Korea between May and December 2011 and updated in 2021. The predicted pro-inflammatory hs-CRP score was derived from pro-inflammatory demographic, lifestyle, dietary, and anthropometric factors, and NAFLD was diagnosed using liver ultrasound. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of NAFLD odds according to predicted pro-inflammatory hs-CRP score were estimated using logistic regression at a two-sided P < 0.05.

Results

Among the 1,076 participants, 320 had NAFLD. The multivariable-adjusted ORs and 95% CIs for NAFLD by tertiles of predicted pro-inflammatory hs-CRP score were 1.00, 3.30 (2.06, 5.30), 18.25 (10.47, 31.81; P < 0.0001) in men and women combined, 1.00, 1.77 (1.10, 2.84), and 3.26 (2.02, 5.28; P < 0.0001) among men only, and 1.00, 3.03 (1.39, 6.62), and 16.71 (7.05, 39.63; P < 0.0001) among women only.

Conclusions

Predicted pro-inflammatory hs-CRP score was associated with higher odds of NAFLD. Adopting dietary and lifestyle changes related to lower inflammation might be a valuable strategy for preventing NAFLD.

Ultraprocessed Foods and Obesity Risk: A Critical Review of Reported Mechanisms

Epidemiologic evidence supports a positive association between ultraprocessed food (UPF) consumption and body mass index. This has led to recommendations to avoid UPFs despite very limited evidence establishing causality. Many mechanisms have been proposed, and this review critically aimed to evaluate selected possibilities for specificity, clarity, and consistency related to food choice (i.e., low cost, shelf-life, food packaging, hyperpalatability, and stimulation of hunger/suppression of fullness); food composition (i.e., macronutrients, food texture, added sugar, fat and salt, energy density, low-calorie sweeteners, and additives); and digestive processes (i.e., oral processing/eating rate, gastric emptying time, gastrointestinal transit time, and microbiome). For some purported mechanisms (e.g., fiber content, texture, gastric emptying, and intestinal transit time), data directly contrasting the effects of UPF and non-UPF intake on the indices of appetite, food intake, and adiposity are available and do not support a unique contribution of UPFs. In other instances, data are not available (e.g., microbiome and food additives) or are insufficient (e.g., packaging, food cost, shelf-life, macronutrient intake, and appetite stimulation) to judge the benefits versus the risks of UPF avoidance. There are yet other evoked mechanisms in which the preponderance of evidence indicates ingredients in UPFs actually moderate body weight (e.g., low-calorie sweetener use for weight management; beverage consumption as it dilutes energy density; and higher fat content because it reduces glycemic responses). Because avoidance of UPFs holds potential adverse effects (e.g., reduced diet quality, increased risk of food poisoning, and food wastage), it is imprudent to make recommendations regarding their role in diets before causality and plausible mechanisms have been verified.

Prospective Associations between Dietary Patterns and Abdominal Obesity in Middle-Aged and Older Korean Adults

This study aimed to identify major dietary patterns associated with abdominal obesity in middle-aged and older Korean adults. Data from the Korean Genome and Epidemiology Study were used. A total of 48,037 Korean adults aged ≥40 years without abdominal obesity at baseline were followed-up. Dietary assessment was conducted using a validated 106-item food-frequency questionnaire, and dietary patterns were identified using factor analysis. Abdominal obesity was defined as a waist circumference of ≥90 cm for men and ≥85 cm for women, according to the Korean Society for the Study of Obesity. Multivariable Cox proportional-hazards models were used to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the future risk of abdominal obesity for each dietary pattern after adjusting for potential covariates. After an average follow-up of 4.89 years, we reported 5878 cases (1932 men and 3946 women) of abdominal obesity. Based on factor analysis, three major dietary patterns were identified in both men and women: the "healthy", "coffee and sweets", and "multi-grain" patterns. In the fully adjusted model, the "healthy" pattern was inversely associated with the incidence of abdominal obesity (HR for fourth vs. first quartile: 0.86; 95% CI: 0.75-0.98; p for trend = 0.0358 for men; HR for fourth vs. first quartile: 0.90; 95% CI: 0.83-0.99; p for trend = 0.0188 for women), whereas the "coffee and sweets" pattern was positively associated with it (HR for fourth vs. first quartile: 1.23; 95% CI: 1.08-1.40; p for trend = 0.0495 for men; HR for fourth vs. first quartile: 1.14; 95% CI: 1.04-1.25; p for trend = 0.0096 for women). In contrast, the "multi-grain" pattern in men and women showed no significant association with the incidence of abdominal obesity. Diets rich in colorful vegetables, seaweeds, mushrooms, tubers, fruits, soy products, and fish and low in coffee, sweets, and oils/fats might be favorable for reducing the future risk of abdominal obesity, particularly in middle-aged and older Korean adults.

Dietary Inflammatory Index, Alternative Healthy Eating Index-2010, Mediterranean Diet Score and the risk of pancreatic cancer

BACKGROUND

Previous studies of dietary patterns and pancreatic cancer risk have been inconclusive; we aimed to investigate the association of Mediterranean Diet Score (MDS), Alternative Healthy Eating Index-2010 (AHEI-2010), and Dietary Inflammatory Index (DII®) with risk of pancreatic cancer.

METHODS

We used data from the Melbourne Collaborative Cohort Study including 33,690 men and women aged 40-69 years at recruitment in 1990-1994. A total of 258 incident cases of pancreatic cancer was identified over an average of 23.7 years of follow-up. Hazard ratios (HR) were estimated using Cox regression, with age as the underlying time metric, adjusting for potential confounders including sex, height, country of birth, education, socio-economic position, physical activity, energy intake, smoking status, pack-years smoking, years since quitting smoking, and alcohol intake.

RESULTS

A healthier diet as assessed by the AHEI-2010 was associated with a lower risk of pancreatic cancer [HR_{Quartile4 vs Quartile1} = 0.58; 95%CI 0.40 - 0.85; p for trend 0.003]. Weaker but consistent evidence was observed for the other indexes [DII® HR_{Quartile4 vs Quartile1} = 1.30; 95%CI 0.82 - 2.06; p for trend 0.1], [MDS HR_{Category3 vs Category1} = 0.79; 95%CI 0.49 - 1.26; p for trend 0.06].

CONCLUSION

Adherence to a healthier diet, as assessed by the AHEI-2010, may reduce the risk of pancreatic cancer.

Adherence to a Mediterranean Diet for 6 Months Improves the Dietary Inflammatory Index in a Western Population: Results from the MedLey Study

Increasing evidence supports that a higher dietary inflammatory index (DII®) score is associated with inflammation and cardiovascular disease (CVD) risk, events, and mortality. This randomized trial sought to determine if a change to a Mediterranean diet resulted in a reduction in the DII score, and then it evaluated the relationship between the DII and cardiometabolic outcomes following the administration of a traditional Mediterranean diet in older Australian adults. A total of 152 Australian adults (mean age 71 ± 5 years) was randomly allocated either a MedDiet (n = 80) or to continue their habitual diet (HabDiet) (n = 72) for 6 months. Diet and cardiovascular outcomes were measured at baseline and 3 and 6 months of the intervention. DII and energy-adjusted DII (E-DIITM) scores were calculated from 3-day weighed food records. There was a significant reduction in the DII score at 2 and 4 months for the MedDiet group (−1.40 ± 0.20 p < 0.001 and −1.47 ± 0.20 p < 0.001, respectively), which was significantly different from the HabDiet group over time (p < 0.001). The HabDiet DII score did not change significantly at the 2 and 4 months timepoints (0.47 ± 0.21 p = 0.35 and 0.54 ± 0.21 p = 0.21, respectively). The improvement in the DII in the MedDiet group was not related to any cardiometabolic outcome. Baseline cross-sectional analyses identified a positive association between the E-DII score and average BMI, body weight, WHR, abdominal adiposity, and SBP, and a negative association with HDL-C. We demonstrate that a MedDiet intervention significantly reduced DII scores compared with a habitual Australian diet in older Australians. This could be beneficial for healthy ageing and the avoidance of chronic disease in Western populations.

Alternative Healthy Eating Index-2010 and Incident Non-Communicable Diseases: Findings from a 15-Year follow up of Women from the 1973–78 Cohort of the Australian Longitudinal Study on Women’s Health

Non-communicable diseases (NCDs) and multimorbidity (≥two chronic conditions), are increasing globally. Diet is a risk factor for some NCDs. We aimed to investigate the association between diet quality (DQ) and incident NCDs. Participants were from the Australian Longitudinal Study on Women’s Health 1973–78 cohort with no NCD and completed dietary data at survey 3 (2003, aged 25–30 years) who responded to at least one survey between survey 4 (2006) and survey 8 (2018). DQ was measured by the Alternative Healthy Eating Index-2010 (AHEI-2010). Outcomes included coronary heart disease (CHD), hypertension (HT), asthma, cancer (excluding skin cancer), diabetes mellitus (DM), depression and/or anxiety, multimorbidity, and all-cause mortality. Repeated cross-sectional multivariate logistic regressions were performed to investigate the association between baseline DQ and NCDs over 15 years. The AHEI-2010 mean (±sd) for participants (n = 8017) was 51.6 ± 11.0 (range: 19–91). There was an inverse association between AHEI-2010 and incident asthma at survey 4 (OR_Q5–Q1: 0.75, 95% CI: 0.57, 0.99). Baseline DQ did not predict the occurrence of any NCDs or multimorbidity between the ages of 25–45 years. Further well-planned, large prospective studies conducted in young women are needed to explore dietary risk factors before the establishment of NCDs.

The dietary inflammatory index, obesity, type 2 diabetes, and cardiovascular risk factors and diseases

An unhealthy diet is a recognized risk factor in the pathophysiology of numerous chronic noncommunicable diseases (NCD), including obesity, type 2 diabetes (T2DM), and cardiovascular diseases (CVD). This is, at least in part, due to unhealthy diets causing chronic low-grade inflammation in the gut and systemically. To characterize the inflammatory potential of diet, we developed the Dietary Inflammatory Index (DII®). Following this development, around 500 papers have been published, which examined the association between the DII, energy-adjusted DII (E-DII™), and the children's DII (C-DII™) and many chronic NCDs including obesity and cardiometabolic diseases. Although a previous narrative review published in 2019 briefly summarized the evidence in this area, there was a significant increase in papers on this topic since 2020. Therefore, the purpose of this narrative review is to provide an in-depth updated review by including all papers until July 2021 on DII and its relationship with obesity, T2DM, and CVD. Furthermore, we aim to identify potential gaps in the literature and provide future directions for research. Most studies found that DII was associated with an increased risk of obesity, T2DM, and CVD with some relationships being sex-specific. However, we identified the paucity of papers describing associations between dietary inflammation and T2DM and its risk factors. Few studies used gold-standard measures of cardiometabolic risk factors. We also identified the lack of interventional studies designed to change the inflammatory potential of diets and study its effect on cardiometabolic risk factors and diseases. We recommend that such interventional studies are needed to assess if changes in DII, representing the inflammatory potential of diet, independently of changes in body composition can modulate cardiometabolic risk factors and diseases.

Association between Diet Quality Indices and Incidence of Type 2 Diabetes in the Melbourne Collaborative Cohort Study

Type 2 diabetes mellitus is a common condition whose incidence is increasing worldwide, and for which obesity and diet are important risk factors. The aim of this study was to assess the association of three diet quality scores with diabetes risk and how much of the association was mediated through body size. The Melbourne Collaborative Cohort Study recruited 41,513 men and women aged 40-69 years during 1990-1994. At baseline, data were collected on lifestyle and diet, anthropometric measures were performed. Incident diabetes was assessed by self-report at follow-up surveys in 1994-1998 and 2003-2007. The associations between the dietary inflammatory index (DII^®), Mediterranean Diet Score (MDS) and the Alternative Healthy Eating Index-2010 and incident diabetes were assessed using Poisson regression, adjusting for age, sex, physical activity, smoking, alcohol consumption, socio-economic status (area based) and family history of diabetes. Data from 39,185 participants were included in the analysis and 1989 cases of diabetes were identified. Both DII and AHEI-2010 were associated with diabetes incidence, but MDS was not. In the top quintile of DII (most pro-inflammatory) vs. the least inflammatory quintile IRR was 1.49 95% CI (1.30, 1.72), p trend across quintiles <0.001. For AHEI-2010 the IRR was 0.67 (0.58, 0.78), p trend <0.001 for the healthiest vs. the least healthy quintile. Mediation analysis indicated that body size (body mass index/waist to hip ratio) mediated 35-48% of the association with incident diabetes for the AHEI and DII. Healthier diets may reduce risk of diabetes both by reducing weight gain and other mechanisms such as reducing inflammation.