Around 55 million people worldwide live with dementia, and more are expected due to population ageing. We aimed to investigate associations between healthy diet and mild cognitive impairment and dementia in 1753 older adults aged 60–64 from the PATH (Personality and Total Health Through Life Cohort) study. Healthy diet was defined by the Mediterranean-DASH diet Intervention for Neurological Delay (MIND) and two dietary guideline quality scores (Dietary Guideline Index (DGI) and Index Diet Quality (IDQ)), which were calculated from baseline FFQ. Higher dietary scores indicated higher diet quality. Incidence of Alzheimer’s disease/vascular dementia (National Institute of Neurological Disorders criteria) and mild cognitive impairment (Winbald criteria) was assessed after 12 years of follow-up using validated questionnaires with nominated proxies. Logistic regression explored associations between dietary scores and cognitive function, adjusting for demographics, lifestyle factors and medical preconditions. Adjusted logistic regression comparing the per unit linear increase in diet scores showed MIND (OR = 0·82, 95 % CI = 0·68, 0·99), but not DGI (0·99 (0·97, 1·00)) or IDQ (1·12 (0·95, 1·32)), was significantly associated with lower odds of developing cognitive impairment. In conclusion, a healthier neuroprotective dietary pattern is associated with better cognitive function over time, whereas dietary patterns generated from general dietary guidelines did not show a significant association. Further research and well-designed clinical studies are needed to determine the effects of the MIND diet on cognitive impairment in older adults without a family history of dementia.

This study examined differences in food groups consumed at eating occasions by the level of adherence to dietary guidelines in Australian adults (≤19 years) and whether consumption differed with respect to age, sex and education levels. Secondary analysis of the 2011–2012 National Nutrition and Physical Activity Survey (n 9054) was performed, using one 24-h dietary recall with self-reported eating occasions. Dietary Guideline Index scores were used to assess adherence to the 2013 Australian Dietary Guidelines. Mean differences (95 % CI) in servings of the five food groups and discretionary foods at eating occasions were estimated for adults with higher and lower diet quality, stratified by sex, age group and education. Using survey-based t-tests, differences of at least half a serving with P values < 0·05 were considered meaningful. Compared with adults with lower diet quality, women and men aged 19–50 years with higher diet quality consumed more serves of vegetables at dinner (mean difference (95 % CI), women; 1·0; 95 % CI (0·7, 1·2); men: 0·9; 95 % CI (0·6, 1·3)) and fewer serves of discretionary foods at snacks (women: −0·7; 95 % CI (−0·9, −0·5); men: −1·0; 95 % CI (−1·4, −0·7). Other food groups, such as grains, dairy products and alternatives, meats and alternatives, were not significantly different between adults with lower and higher diet quality, across any eating occasions and age groups. Discretionary food intake at lunch, dinner and snacks was consistently greater among adults with lower diet quality, regardless of education level. Our findings identify dinner and snacks as opportunities to increase vegetable intake and reduce discretionary food intake, respectively.

Changes between diet quality and health-related quality of life (HR-QoL) over 12 years were examined in men and women, in 2844 adults (46 % males; mean age 47·3 (sd 9·7) years) from the Australian Diabetes, Obesity and Lifestyle study with data at baseline, 5 and 12 years. Dietary intake was assessed with a seventy-four-item FFQ. Diet quality was estimated with the Dietary Guideline Index, Mediterranean-Dietary Approaches to Stop Hypertension Diet Intervention for Neurological Delay Index (MIND) and Dietary Inflammatory Index. HR-QoL in terms of global, physical component summary (PCS) and mental component summary (MCS) was assessed with the Short-Form Health Survey-36. Fixed effects regression models adjusted for confounders were performed. Mean MCS increased from baseline (49·0, sd 9·3) to year 12 (50·7, sd 9·1), whereas mean PCS decreased from baseline (51·7, sd 7·4) to year 12 (49·5, sd 8·6). For the total sample, an improvement in MIND was associated with an improvement in global QoL (β = 0·28, 95 % CI (0·007, 0·55)). In men, an improvement in MIND was associated with an improvement in global QoL (β = 0·28, 95 % CI (0·0004, 0·55)). In women, improvement in MIND was associated with improvements in global QoL (β = 0·62 95 % CI (0·38, 0·85)), MCS (β = 0·75, 95 % CI (0·29, 1·22)) and PCS (β = 0·75, 95 % CI (0·29, 1·22)). Positive changes in diet quality were associated with broad improvements in HR-QoL, and most benefits were observed in women when compared to men. These findings support the need for strategies to assist the population in consuming healthy dietary patterns to lead to improvements in HR-QoL.

This study investigated associations of adherence to the Australian Dietary Guidelines (ADG) with cognitive performance and cognitive decline over 6 years. We used longitudinal data from the Sydney Memory and Aging Study comprising 1037 community-dwelling non-demented participants aged 70–90 years. Dietary intake was assessed at baseline using the Dietary Questionnaire for Epidemiological Studies Version 2. Adherence to the ADG was scored using the Dietary Guideline Index 2013 (DGI-2013). Cognition was assessed using neuropsychological tests in six cognitive domains and global cognition at baseline and 2, 4 and 6 years later. Linear mixed models analysed the association between adherence to the ADG and cognitive function and cognitive decline over 6 years. Results indicated that overall adherence to the ADG was suboptimal (DGI-2013 mean score 43⋅8 with a standard deviation of 10⋅1; median score 44, range 12–73 with an interquartile range of 7). The percent of participants attaining recommended serves for the five food groups were 30⋅2 % for fruits, 11⋅2 % for vegetables, 54⋅6 % for cereals, 28⋅9 % for meat and alternatives and 2⋅1 % for dairy consumption. Adherence to the ADG was not associated with overall global cognition over 6 years (β = 0⋅000; 95 % CI: −0⋅007, 0⋅007; P = 0⋅95). Neither were DGI-2013 scores associated with change in global cognitive performance over 6 years (β = 0⋅002; 95 % CI: −0⋅002, 0⋅005; P = 0⋅41) nor in any individual cognitive domains. In conclusion, adherence to the ADG was not associated with cognitive health over time in this longitudinal analysis of older Australians. Future research is needed to provide evidence to support specific dietary guidelines for neurocognitive health among Australian older adults.

The impact of change in socio-economic status (SES) from childhood to adulthood (SES mobility) on adult diet is not well understood. This study examined associations between three SES mobility variables (area disadvantage, education, occupation) and adult diet quality. 1482 Australian participants reported childhood area-level SES in 1985 (aged 10–15 years) and retrospectively reported highest parental education and main occupation (until participant age 12) and own area-level SES, education, occupation and dietary intake in 2004–2006 (aged 26–36 years). A Dietary Guidelines Index (DGI) was calculated from food frequency and habit questionnaires. A higher score (range 0–100) indicated better diet quality. Sex-stratified linear regression models adjusted for confounders. Area-level SES mobility was not associated with diet quality. Compared with stable high (university) education, stable low (school only) was associated with lower DGI scores (males: β = –5·5, 95 % CI: −8·9, –2·1; females: β = –6·3, 95 % CI: −9·3, –3·4), as was downward educational mobility (participant’s education lower than their parents) (males: β = –5·3, 95 % CI: −8·5, –2·0; females: β = –4·5, 95 % CI: −7·2, –1·7) and stable intermediate (vocational) education among males (β = –3·9, 95 % CI: −7·0, −0·7). Compared with stable high (professional/managerial) occupation, stable low (manual/out of workforce) males (β = –4·9, 95 % CI: −7·6, –2·2), and participants with downward occupation mobility (males: β = –3·2, 95 % CI: −5·3, –1·1; females: β = –2·8, 95 % CI: −4·8, –0·8) had lower DGI scores. In this cohort, intergenerational low education and occupation, and downward educational and occupational mobility, were associated with poor adult diet quality.

Diet is a modifiable risk factor for chronic disease and a potential modulator of telomere length (TL). The study aim was to investigate associations between diet quality and TL in Australian adults after a 12-week dietary intervention with an almond-enriched diet (AED). Participants (overweight/obese, 50–80 years) were randomised to an AED (n 62) or isoenergetic nut-free diet (NFD, n 62) for 12 weeks. Diet quality was assessed using a Dietary Guideline Index (DGI), applied to weighed food records, that consists of ten components reflecting adequacy, variety and quality of core food components and discretionary choices within the diet. TL was measured by quantitative PCR in samples of lymphocytes, neutrophils, and whole blood. There were no significant associations between DGI scores and TL at baseline. Diet quality improved with AED and decreased with NFD after 12 weeks (change from baseline AED + 9·8 %, NFD − 14·3 %; P < 0·001). TL increased in neutrophils (+9·6 bp, P = 0·009) and decreased in whole blood, to a trivial extent (–12·1 bp, P = 0·001), and was unchanged in lymphocytes. Changes did not differ between intervention groups. There were no significant relationships between changes in diet quality scores and changes in lymphocyte, neutrophil or whole blood TL. The inclusion of almonds in the diet improved diet quality scores but had no impact on TL mid-age to older Australian adults. Future studies should investigate the impact of more substantial dietary changes over longer periods of time.

In a longitudinal cohort study of young Australian adults, we reported that for women higher baseline levels of fish consumption were associated with reduced incidence of new depressive episodes during the 5-year follow-up. Fish are high in both n-3 fatty acids and tyrosine. In this study, we seek to determine whether n-3 fatty acids or tyrosine explain the observed association. During 2004–2006, a FFQ (nine fish items) was used to estimate weekly fish consumption among 546 women aged 26–36 years. A fasting blood sample was taken and high-throughput NMR spectroscopy was used to measure 233 metabolites, including serum n-3 fatty acids and tyrosine. During 2009–2011, new episodes of depression since baseline were identified using the lifetime version of the Composite International Diagnostic Interview. Relative risks were calculated using log-binomial regression and indirect effects estimated using the STATA binary_mediation command. Potential mediators were added to separate models, and mediation was quantified as the proportion of the total effect due to the mediator. The n-3 DHA mediated 25·3 % of the association between fish consumption and depression when fish consumption was analysed as a continuous variable and 16·6 % when dichotomised (reference group: <2 serves/week). Tyrosine did not mediate the association (<0·1 %). Components in fish other than n-3 fatty acids and tyrosine might be beneficial for women’s mental health.

The revised Dietary Guideline Index (DGI-2013) scores individuals’ diets according to their compliance with the Australian Dietary Guideline (ADG). This cross-sectional study assesses the diet quality of 794 community-dwelling men aged 74 years and older, living in Sydney, Australia participating in the Concord Health and Ageing in Men Project; it also examines sociodemographic and lifestyle factors associated with DGI-2013 scores; it studies associations between DGI-2103 scores and the following measures: homoeostasis model assessment – insulin resistance, LDL-cholesterol, HDL-cholesterol, TAG, blood pressure, waist:hip ratio, BMI, number of co-morbidities and medications and frailty status while also accounting for the effect of ethnicity in these relationships. Median DGI-2013 score was 93·7 (54·4, 121·2); most individuals failed to meet recommendations for vegetables, dairy products and alternatives, added sugar, unsaturated fat and SFA, fluid and discretionary foods. Lower education, income, physical activity levels and smoking were associated with low scores. After adjustments for confounders, high DGI-2013 scores were associated with lower HDL-cholesterol, lower waist:hip ratios and lower probability of being frail. Proxies of good health (fewer co-morbidities and medications) were not associated with better compliance to the ADG. However, in participants with a Mediterranean background, low DGI-2013 scores were not generally associated with poorer health. Older men demonstrated poor diet quality as assessed by the DGI-2013, and the association between dietary guidelines and health measures and indices may be influenced by ethnic background.

Tools, called ‘diet/dietary quality indices’, evaluate the level of adherence to a specified pattern or a set of recommendations in populations. Yet, there are no review studies providing unanimous comprehensive results of dietary indices on obesity. We reviewed observational studies, focusing on the association of diet quality indices with general obesity or abdominal obesity in adults. We systematically conducted a search in all English language publications available on MEDLINE, ISI Web of Science and Embase between January 1990 and January 2016. Among the wide variety of indices and weight-derived variables, studies with dietary-guideline-based indices and mean changes for weight gain or OR for general obesity and abdominal obesity were selected. From a total of 479 articles, thirty-four studies were selected for the current review, ten of which had prospective designs and twenty-six had cross-sectional designs. Associations of weight status with the original Healthy Eating Index (HEI) and other versions of the HEI including alternative HEI, HEI-2005 and HEI-05 were examined in thirteen studies, with ten studies revealing significant associations. The HEI was a better general obesity predictor in men than in women. Diet scores lacked efficacy in assessing overall diet quality and demonstrated no significant findings in developing countries, in comparison with US populations. In addition, indices based on dietary diversity scores were directly associated with weight gain. Despite the insufficient evidence to draw definitive conclusions about the relation between dietary indices and obesity, HEI was found to be inversely associated with obesity and diversity-based indices were positively associated with obesity.

Evidence from longitudinal studies on the association between diet quality and change in anthropometric measures is scarce. We therefore investigated the relationship between a recently developed food-based dietary index and change in measured BMI and waist circumference (WC) in Australian adults (1992–2007). We used data from the Australian population-based Nambour Skin Cancer Study comprising 1231 adults aged 25–75 years at baseline (1992). We applied generalised estimating equations (GEE) to examine the association between diet quality and change in anthropometric measures. Dietary intake was assessed by an FFQ in 1992, 1996 and 2007. Diet quality was estimated using the dietary guideline index (DGI), developed to reflect the dietary guidelines for Australian adults; a higher score indicating increased compliance. Multivariable models, stratified by sex, were adjusted for sociodemographic and lifestyle characteristics. We show that men with higher diet quality had a lower gain in BMI as compared to those with low diet quality during the 15-year follow-up. In a multivariable adjusted model, as compared to men in quartile 1 (reference), those in the highest quartile had the lowest gain in BMI (mean (95 % CI): 0·05 (0·00, 0·09) v. 0·11 (0·06, 0·16) kg/m2 per year, P =0·01). Diet quality was inversely, but non-significantly associated with change in WC. In women, DGI score was unrelated to change in any body measure. Energy underreporting did not explain the lack of association. We conclude that adherence to a high-quality diet according to Australian dietary guidelines leads to lower gain in BMI and WC in middle-aged men, but not in women.