Modelling the replacement of red and processed meat with plant-based alternatives and the estimated effect on insulin sensitivity in a cohort of Australian adults.

Dietary guidelines are increasingly promoting mostly plant-based diets, limits on red meat consumption, and plant-based sources of protein for health and environmental reasons. It is unclear how the resulting food substitutions associate with insulin resistance, a risk factor for type 2 diabetes. We modelled the replacement of red and processed meat with plant-based alternatives and the estimated effect on insulin sensitivity. We included 783 participants (55 % female) from the Childhood Determinants of Adult Health study, a population-based cohort of Australians. In adulthood, diet was assessed at three time points using FFQ: 2004­2006, 2009­2011 and 2017­2019. We calculated the average daily intake of each food group in standard serves. Insulin sensitivity was estimated from fasting glucose and insulin concentrations in 2017­2019 (aged 39­49 years) using homoeostasis model assessment. Replacing red meat with a combination of plant-based alternatives was associated with higher insulin sensitivity (ß = 10·5 percentage points, 95 % CI (4·1, 17·4)). Adjustment for waist circumference attenuated this association by 61·7 %. Replacing red meat with either legumes, nuts/seeds or wholegrains was likewise associated with higher insulin sensitivity. Point estimates were similar but less precise when replacing processed meat with plant-based alternatives. Our modelling suggests that regularly replacing red meat, and possibly processed meat, with plant-based alternatives may associate with higher insulin sensitivity. Further, abdominal adiposity may be an important mediator in this relationship. Our findings support advice to prioritise plant-based sources of protein at the expense of red meat consumption.

Select dietary changes towards sustainability: Impacts on dietary profiles, environmental footprint, and cost.

Healthy sustainable diets have the power to improve dietary intakes and environmental resource use. However, recommendations for improving food choices need to consider the effects of any changes across multiple dimensions of health, environmental sustainability, and dietary cost to promote long-lasting behaviour change. The aim of this study was to identify differences between original diets, and the diets that can be achieved through the implementation of select small dietary changes towards sustainability. Twelve hypothetical sustainable actions were investigated for the potential effects of these actions on dietary markers (protein, saturated fat, sugars, salt, iron, and calcium), environmental footprints (greenhouse gas emissions, freshwater withdrawals, and land use), and dietary cost. Dietary data from 1235 individuals, aged 19-94 years, participating in the UK National Diet and Nutrition Survey (2017/19) provided the original diet. Dietary changes were implemented as required by each sustainable action, and differences between the original diet and each new diet were investigated. Results revealed benefits to dietary markers and environmental characteristics from eleven sustainable actions (range: F(1,728) = 5.80, p < .001 to F(1,506) = 435.04, p < .001), but effects were stronger for some actions than for others. Greatest benefits for all three outcomes were found for actions which reduced meat consumption and/or replaced meat with pulses or eggs. The remaining sustainable actions tended to be beneficial for improving outcomes individually or to some degree. Our results demonstrate the possible impacts of a number of small sustainable dietary actions for dietary, environmental, and cost outcomes, and provide a hierarchy of actions based on benefit. Findings may facilitate dietary behaviours towards improved health, whilst also offering fruitful contributions towards environmental footprint targets in the UK.

Protein foods from animal sources and risk of nonalcoholic fatty liver disease in representative cohorts from North and South China.

BACKGROUND: Emerging evidence suggests that animal protein foods may increase the risk of nonalcoholic fatty liver disease (NAFLD). We therefore examined the NAFLD risk reduction related to substituting plant protein foods for animal protein foods. METHODS: The cohort in North China included 14,541 participants from the Tianjin Chronic Low-Grade Systemic Inflammation and Health (TCLSIH) study, and the cohort in South China included 1297 participants from the Guangzhou Nutrition and Health Study (GNHS). Dietary intake was assessed using validated food frequency questionnaires. NAFLD was ascertained by abdominal ultrasound. The Cox model was used to fit the substitution analysis. RESULTS: In the TCLSIH cohort, when replacing one type of animal protein food (eggs, processed meat, unprocessed red meat, poultry, and fish) with an equivalent serving of plant protein foods (nuts, legumes, and whole grains), the replacement of animal protein foods with whole grains showed the strongest benefit; substituting one serving per day of whole grains for an equal amount of eggs (hazard ratio [HR] = 0.89; 95% confidence interval [CI]: 0.79, 1.00), processed meat (HR = 0.76; 95% CI: 0.64, 0.91), unprocessed red meat (HR = 0.90; 95% CI: 0.81, 1.00), poultry (HR = 0.81; 95% CI: 0.72, 0.92), or fish (HR = 0.87; 95% CI: 0.78, 0.97) was associated with a lower risk of NAFLD. In both the TCLSIH and GNHS cohorts, replacing poultry with fish, nuts, legumes, or whole grains was associated with a lower risk of NAFLD. When different numbers of protein foods were simultaneously replaced, the risk reduction of NAFLD was stronger. CONCLUSIONS: Our findings suggest that replacing animal protein foods with plant protein foods is related to a significant reduction in NAFLD risk.

Cereal intake and mortality in older Chinese: a 15-year follow-up of a prospective cohort study.

PURPOSE: We examined the association between whole grain and refined grain intake with all-cause, cancer and cardiovascular disease (CVD) mortality using the data from the Guangzhou Biobank Cohort Study. METHODS: 19,597 participants aged 50+ years were recruited from 2003 to 2006 and followed-up until April 2021. Multivariable Cox regression was used to calculate hazard radios (HRs) and 95% confidence intervals (CIs). Substitution analysis was used to replace a serving (50 g/day) of whole grain with a serving of refined grain. RESULTS: During 286,821 person-years of follow-up, 4385 deaths occurred, including 1450 from cancer, 1678 from CVD and 1257 from other causes. Compared with never whole grain intake, the highest intake category of whole grain (> 300 g/week) was associated with lower risk of all-cause (HR 0.90, 95% CI 0.82-0.98) and CVD mortality (HR 0.85, 0.74-0.98). Compared with the low-intake category of refined grain (< 500 g/day), the highest intake category (> 900 g/week) was associated with a lower risk of cancer mortality (HR 0.76, 0.62-0.95), but a higher risk of CVD mortality (HR 1.25, 1.03-1.51). No significant associations were found between whole grain intake and cancer mortality nor refined grain and all-cause mortality. The HRs of all-cause, cancer and CVD mortality substituting a serving of whole grain for refined grain were 0.96 (0.94-0.99), 1.01 (0.99-1.02) and 0.95 (0.90-0.99), respectively. CONCLUSION: We have first shown that in older Chinese, whole grain intake was associated with lower risk of all-cause and CVD mortality. Our results suggest that intake of whole grain of at least 300 g/week and refined grain of ≤ 900 g/day might be suitable for older Asian. Substituting 50 g/day of whole grain for refined grain was associated with a 4-5% lower risk of all-cause and CVD mortality.

Postpartum sedentary behaviour and pelvic floor support: A prospective cohort study.

We evaluated the association between sedentary time and pelvic floor support in primiparas delivered vaginally. The 532 participants (29.2 ± 4.9 years) wore wrist accelerometers 6 months postpartum to assess sedentary time, light physical activity (LPA) and moderate to vigorous physical activity (MVPA). We assessed pelvic floor support 1 year postpartum, considered worse if vaginal walls or apex prolapsed to or beyond the hymen. We used multivariable isotemporal substitution analyses to determine the prevalence of worse support when replacing sedentary time with equal time spent in either LPA or MVPA. In 1 year, 9.4% demonstrated worse pelvic floor support. Decreasing sedentary time by 30 min/day with a concomitant increase in MVPA, controlling for LPA, was associated with increased prevalence of worse support (PR 1.43 (95% CI 1.15, 1.77), P < 0.01). Decreasing the sedentary time by 30 min/day with a concomitant increase in LPA, controlling for MVPA, was not significant (PR 0.89 (95% CI 0.80, 0.99), P = 0.04, > pre-set alpha of 0.02). Increasing MVPA while decreasing LPA, controlling for sedentary time, also increased the prevalence of worse support (PR 1.66 (95% CI 1.28, 2.16), P < 0.001). In conclusion, decreasing sedentary time increased the prevalence of worse pelvic floor support when replaced by MVPA, but not LPA.

Theoretical substitutions between dairy products and all-cause and cause-specific mortality. Results from the Danish diet, cancer and health cohort.

A daily intake of dairy products is recommended in many countries in order to maintain optimal health throughout life. However, evidence regarding the association between intake of individual dairy products and mortality is limited. We therfore, explored associations between intake of different dairy products and all-cause and cause-specific mortality using specified theoretical substitution analyses. We analysed data from 55 775 Danish men and women aged 50-64 years between 1993 and 1997. Information about dairy product intake at baseline was collected using a validated food frequency questionnaire. Information about vital status and causes of death was obtained through national registers. Measures of associations were calculated using Cox proportional hazards regression. During a median follow-up of 19·0 years, 11 586 participants died. For all-cause mortality, we observed that the intake of low-fat milk, whole-fat milk or low-fat yogurt products in place of cheese was associated with a higher rate of death (hazard ratios between 1·03 and 1·12 per serving/d substituted). The same pattern was present for CVD mortality. For cancer mortality, whole-fat milk and low-fat yogurt products in place of cheese were also associated with a higher rate of death for men while for women, whole-fat milk in place of buttermilk was associated with a higher cancer mortality rate. The results appeared robust in several sensitivity analyses. Our results suggest that intake of low-fat milk, whole-fat milk or low-fat yogurt products in place of cheese is associated with a higher rate of all-cause and cause-specific mortality.

Red meat consumption and all-cause and cardiovascular mortality: results from the UK Biobank study.

PURPOSE: To investigate the prospective associations between red meat consumption and all-cause and cardiovascular diseases (CVD) mortality, and to assess the modification effects of lifestyle and genetic risk factors. METHODS: 180,642 individuals free of CVD or cancer were enrolled from 2006 to 2010 and followed up to 2018 in the UK Biobank. Information on demographics, lifestyles, and medical history was collected through a baseline touchscreen questionnaire. The information on diet was collected through a single touchscreen food-frequency questionnaire. A total of ten single-nucleotide polymorphisms were used to calculate the genetic risk score (GRS) of trimethylamine N-oxide (TMAO), a gut microbiota metabolite from red meat. Adjusted Cox proportional hazard regression models were used to assess the association of red meat consumption with mortality. RESULTS: We documented 3596 deaths [655 CVD deaths, 285 coronary heart disease (CHD) deaths, and 149 stroke deaths] during median 8.6 years of follow-up. Compared with the lowest red meat intake (< 1.5 times/week), the highest red meat intake (≥ 3.0 times/week) was associated with a 20%, 53%, and 101% elevated risk for CVD, CHD, and stroke mortality (P for trend = 0.04, 0.007, and 0.02, respectively), but not all-cause mortality. We found that the associations between red meat intake and mortality were not modified by dietary and lifestyle factors, as well as TMAO GRS. In addition, substitution analyses showed that a decrease in red meat consumption and an increase in the consumption of poultry or cereal was significantly associated with 9%-16% lower CVD or CHD mortality risk. CONCLUSION: Our results indicated that red meat consumption was associated with higher risks of CVD, CHD, and stroke mortality, and the associations were not modified by lifestyle and genetic risk factors. Replacing red meat by poultry or cereal was related to lower risks of CVD and CHD mortality.

Association between animal source foods consumption and risk of hypertension: a cohort study.

PURPOSE: This study assessed the association between animal source foods (ASF) consumption and hypertension, a recognised risk factor for cardiovascular disease. Adverse effects of red and processed meat (RPM) consumption and beneficial effects of the consumption of dairy products and other ASF have been discovered separately; however, the constrained nature of food intake has been typically ignored. We assessed the effects of substituting RPM and other ASF. METHODS: We followed-up 5394 Chinese adults (age 18-60 years) at baseline using the China Health and Nutrition Survey from 2004 to 2011. Food consumption was assessed using individual-based consecutive 24-h recall and household-based food weighing approaches. Both traditional substitution analysis and substitution analysis based on compositional transformation were used to assess substitution effects. RESULTS: In total, 1267 participants were newly diagnosed with hypertension during the median follow-up time of 6.81 years (range, 2.97-6.99 years). The traditional substitution analysis found that substituting eggs for RPM was associated with a lower risk of hypertension. The compositional transformation substitution analysis revealed that replacing RPM with any other ASF was associated with a lower risk of hypertension; it implemented substitutions of one or many ASF for RPM; it also revealed different substitution effects of RPM and dairy products, and substituting dairy products for RPM was associated with reduced hypertension risks. CONCLUSION: The compositional transformation substitution analysis considers the constrained and relative nature of food consumption. It is a flexible approach to estimating substitution effects using different patterns to obtain personalised estimation effects and provide individualised dietary recommendations.

Various proline food sources and blood pressure: substitution analysis.

The aim of this study was to investigate the association of total proline intake, proline of various food sources, and substitution analysis for proline of food sources with blood pressure (BP) and 3.1-year incidence of hypertension in the framework of the Tehran Lipid and Glucose Study. The cohort consisted of 4287 participants (41.9% male), aged ≥ 20-70 years. In fully-adjusted model, individuals in the highest tertile for proline intake had an increased risk of incident hypertension than those in the lowest one (OR: 1.45; 95%CI: 1.06-1.97; p for trend: .017). Replacing proline of cheese and legumes source with that of yogurt, poultry, milk, and red meat source was associated with significant negative ß coefficient for BP. The present study indicated that high dietary intakes of proline may increase the risk of incident hypertension. Also, substituting proline intake of cheese and legumes by those of proline intake of meats and milk is associated with a lower risk of high BP.

Redefining Peptide 14D: Substitutional Analysis for Accelerated TB Diagnosis and Enhanced Activity against Mycobacterium tuberculosis.

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains a predominant cause of mortality, especially in low- and middle-income nations. Recently, antimicrobial peptides have been discovered that at low concentrations could stimulate the growth of M. tuberculosis (hormetic response). In this study, such a peptide was used to investigate the effects on the time to positivity (TTP). A systematic substitution analysis of peptide 14D was synthesized using Spot synthesis technology, resulting in 171 novel peptides. Our findings revealed a spectrum of interactions, with some peptides accelerating M. tuberculosis growth, potentially aiding in faster diagnostics, while others exhibited inhibitory effects. Notably, peptide NH2-wkivfiwrr-CONH2 significantly reduced the TTP by 25 h compared to the wild-type peptide 14D, highlighting its potential in improving TB diagnostics by culture. Several peptides demonstrated potent antimycobacterial activity, with a minimum inhibitory concentration (MIC) of 20 µg/mL against H37Rv and a multidrug-resistant M. tuberculosis strain. Additionally, for two peptides, a strongly diminished formation of cord-like structures was observed, which is indicative of reduced virulence and transmission potential. This study underscores the multifaceted roles of antimicrobial peptides in TB management, from enhancing diagnostic efficiency to offering therapeutic avenues against M. tuberculosis.

Defecation Habits in Preschoolers Are Associated with Physical Activity: A Cross-Sectional and Isotemporal Substitution Analysis.

There is a lack of research on the relationship between defecation habits (DF) and physical activity (PA) in preschoolers. This study aimed to clarify the relationship between sedentary behaviour (SB), PA time, and DF in preschoolers and to estimate the effect of DF replacement in an isotemporal substitution (IS) model. The participants included 166 children (aged 4-6 years) attending childcare facilities. PA was measured using an accelerometer to calculate the daily activity and wearing time for SB, light-intensity physical activity (LPA), and moderate-to-vigorous-intensity physical activity (MVPA). DF were classified based on defecation frequency and timing. A multinomial logistic regression analysis was used for the IS model. One-way analysis of variance detected significant differences in MVPA between the DF groups (F(2) = 3.12, p < 0.05). According to the analysis results of the IS model, replacing 5 min of SB with MVPA resulted in improved DF (odds ratio [OR], 0.89; 95% confidence interval [CI], 0.81-0.97). Conversely, replacing 5 min of MVPA with SB worsened DF (OR, 1.13; 95% CI, 1.03-1.23). The findings suggest that PA is associated with DF among preschoolers. It also indicates that replacing SB with MVPA could help improve DF in children.

Pre-pubertal accelerometer-assessed physical activity and timing of puberty in British boys and girls: the Millennium Cohort Study.

BACKGROUND: Early puberty timing is associated with adverse health outcomes. We aimed to examine prospective associations between objectively measured physical activity and puberty timing in boys and girls. METHODS: In the UK Millennium Cohort Study, physical activity volume and intensities at 7 years were measured using accelerometers. Status of several pubertal traits and age at menarche were reported at 11, 14 and 17 years. Age at menarche in girls was categorized into tertiles. Other puberty traits were categorized into earlier or later than the median ages calculated from probit models, separately in boys and girls. Multivariable regression models, with adjustment for maternal and child characteristics including body mass index (BMI) at age 7 years as potential confounders, were performed to test the associations of total daily activity counts and fractions of activity counts across intensities (in compositional models) with puberty timing, separately in boys (n = 2531) and girls (n = 3079). RESULTS: Higher total daily activity counts were associated with lower risks for earlier (vs later) growth spurt, body hair growth, skin changes and menarche in girls, and more weakly with lower risks for earlier skin changes and voice breaking in boys (odds ratios = 0.80-0.87 per 100 000 counts/day). These associations persisted on additional adjustment for BMI at 11 years as a potential mediator. No association with puberty timing was seen for any physical activity intensity (light, moderate or vigorous). CONCLUSIONS: More physical activity regardless of intensity may contribute to the avoidance of earlier puberty timing, independently of BMI, particularly in girls.

A Prospective Study of Fruit Juice Consumption and the Risk of Overall and Cardiovascular Disease Mortality.

There is little evidence for the association between fruit juice, especially 100% fruit juice, and mortality risk. In addition, whether 100% fruit juice can be a healthy alternative to whole fruit remains uncertain. This prospective study utilized the data from the US National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014. After a median follow-up of 7.8 years, 4904 deaths among 40,074 participants aged 18 years or older were documented. Compared to non-consumption, daily consumption of 250 g or more of 100% fruit juice was associated with higher overall mortality (hazard ratio (HR) = 1.30, 95% confidence interval (CI): 1.11-1.52) and mortality from heart disease (HR = 1.49, 95 CI: 1.01-2.21). A similar pattern was observed for total fruit juice, with HRs of 1.28 (95% CI: 1.09-1.49) for overall mortality and 1.48 (95% CI: 1.01-2.17) for heart disease mortality. Replacing 5% of energy from whole fruit with 100% or total fruit juice was associated with a 9% (95% CI: 2-16%) and 8% (95% CI: 1-15%) increased mortality risk, respectively. Our findings suggest that both total and 100% fruit juice could be associated with high mortality risk, and need to be validated in well-designed studies given the potential misclassification of diet and death reasons.

Association between intake of marine fat and adiposity development among children ages 2 to 6 y: Substitution analyses from the Healthy Start intervention study.

OBJECTIVES: A few previous studies have described a potential role of Ω-3 long-chain polyunsaturated fatty acids from marine animals in obesity in children, but the results are conflicting. The objectives of this study were to examine if intake of marine fat was related to less gain in body mass index (BMI) and body fat (BF) over a 15-mo period among Danish children age 2 to 6 y, and if potential associations depended on which types of fatty acids were replaced. METHODS: A total of 355 children age 2 to 6 y were included in the study. Weight, height, and BF percentage (BF%) assessed by bioimpedance were measured by trained research personnel. Multivariable linear regression models were used to investigate associations between marine fat intake and changes in BMI or BF% over the subsequent 15 mo. To investigate substitution effects, we constructed regression models that included marine fat and all other energy yielding dietary components, except for the nutrient to be substituted for either all fats or specific subgroups (saturated, monounsaturated, or other polyunsaturated fatty acids). RESULTS: No significant associations were observed between intake of marine fat and development in BMI or BF% in any of the analyses, either with or without specified substitutions. Furthermore, the results were independent on whether intake was expressed in g/d or percentage of energy, and were not modified by age or BMI status. CONCLUSIONS: This study suggests that marine fat intake and fat composition in a diet may have little or no effect on weight and adiposity development among preschool-aged children.

Theory and performance of substitution models for estimating relative causal effects in nutritional epidemiology.

BACKGROUND: Estimating relative causal effects (i.e., "substitution effects") is a common aim of nutritional research. In observational data, this is usually attempted using 1 of 2 statistical modeling approaches: the leave-one-out model and the energy partition model. Despite their widespread use, there are concerns that neither approach is well understood in practice. OBJECTIVES: We aimed to explore and illustrate the theory and performance of the leave-one-out and energy partition models for estimating substitution effects in nutritional epidemiology. METHODS: Monte Carlo data simulations were used to illustrate the theory and performance of both the leave-one-out model and energy partition model, by considering 3 broad types of causal effect estimands: 1) direct substitutions of the exposure with a single component, 2) inadvertent substitutions of the exposure with several components, and 3) average relative causal effects of the exposure instead of all other dietary sources. Models containing macronutrients, foods measured in calories, and foods measured in grams were all examined. RESULTS: The leave-one-out and energy partition models both performed equally well when the target estimand involved substituting a single exposure with a single component, provided all variables were measured in the same units. Bias occurred when the substitution involved >1 substituting component. Leave-one-out models that examined foods in mass while adjusting for total energy intake evaluated obscure estimands. CONCLUSIONS: Regardless of the approach, substitution models need to be constructed from clearly defined causal effect estimands. Estimands involving a single exposure and a single substituting component are typically estimated more accurately than estimands involving more complex substitutions. The practice of examining foods measured in grams or portions while adjusting for total energy intake is likely to deliver obscure relative effect estimands with unclear interpretations.

The Compositional Impacts of 2 Distinct 24-Hour Movement Behavior Change Patterns on Physical Fitness in Chinese Adolescents.

BACKGROUND: The study aimed to examine predicted differences of 2 different behavior change patterns on physical fitness (PF). METHODS: Participants were 241 students (51% girls) aged 11-14 years from China. Light physical activity, moderate to vigorous physical activity (MVPA), and sedentary behavior (SB) were objectively measured. Sleep was obtained by subtracting from awake time. According to Chinese National student PF standards, 5 components of PF, including body mass index, cardiorespiratory fitness, speed, muscular explosive power and strength endurance, and flexibility, were assessed. The effects of different time reallocations between 24-hour movement behaviors on PF were estimated based on adjusted compositional multiple linear regression models with isometric log ratios. RESULTS: Compared with MVPA substituting for the remaining behaviors, MVPA replacing SB or light physical activity produced more favorable changes on the comprehensive PF score, cardiorespiratory fitness, explosive power, and speed. MVPA replacing 30 minutes of SB was associated with favorable changes in PF (+1.9 [0.53, 3.18] points), 50-m run (-0.17 [-0.31, -0.04] s), long-distance running (-5.54 s [for girls]/7.25 s [for boys]), and long jump (+0.05 [0.01, 0.09] m). When sleep replaced SB, PF improved. CONCLUSIONS: MVPA substituting SB or light physical activity is a strategy with a greater improvement in PF.

Associations between intake of starchy and non-starchy vegetables and risk of hepatic steatosis and fibrosis.

BACKGROUND: Current dietary guidelines generally treat all types of vegetables the same. However, whether specific vegetables are more beneficial or deleterious for preventing chronic liver disease (CLD) remains uncertain. METHODS: We investigated the associations between starchy and non-starchy vegetables and the odds of hepatic steatosis and fibrosis in a US nationwide cross-sectional study. Diet was assessed by the 24-h dietary recalls. Hepatic steatosis and fibrosis were defined based on vibration-controlled transient elastography (TE). Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Among 4170 participants with reliable TE test, 1436 were diagnosed with steatosis, 255 with advanced fibrosis. Increased intake of total starchy vegetables was associated with higher odds of steatosis (OR per 1-SD increment 1.11, 95% CI 1.01-1.24) and advanced fibrosis (OR = 1.39, 95% CI 1.15-1.69). Similar positive associations were observed for potatoes. Conversely, intakes of total non-starchy (OR = 0.82, 95% CI 0.71-0.95) and dark-green vegetables (OR = 0.89, 95% CI 0.82-0.97) were inversely associated with steatosis prevalence. Replacing 5% of energy from starchy vegetables (OR = 0.65, 95% CI 0.44-0.97) or potatoes (OR = 0.65, 95% CI 0.43-0.97) with equivalent energy from dark-green vegetables was associated with lower odds of steatosis. CONCLUSIONS: These findings support the recommendation to limit starchy vegetable intake and increase non-starchy vegetable intake in CLD prevention, and provide evidence for the potential health benefit from dietary substitution of non-starchy vegetables for starchy vegetables.

Food substitution models for nutritional epidemiology.

The advantage of using specified substitution analysis in nutritional epidemiology has been clearly demonstrated in studies of macronutrient intake and disease risk. However, the method has not been widely applied in studies of food intake. The aim of this article is to describe and compare the interpretation and application of different food substitution models in epidemiologic studies on diet and disease development. Both theoretically and in the context of a specific example, we discuss methodologic issues to be considered, including modeling of food substitutions using diet at a single time point or at multiple time points (focusing on dietary changes), choice of substitution unit, adjustment for total energy intake, and adjustment for confounding. We argue that specified food substitution analyses can be used to identify optimal food composition of the diet and that these analyses are thus highly relevant to inform public health policy decision makers.

Are Reallocations between Sedentary Behaviour and Physical Activity Associated with Better Sleep in Adults Aged 55+ Years? An Isotemporal Substitution Analysis.

Physical activity has been proposed as an effective alternative treatment option for the increasing occurrence of sleep problems in older adults. Although higher physical activity levels are associated with better sleep, the association between specific physical activity intensities and sedentary behaviour (SB) with sleep remains unclear. This study examines the associations of statistically modelled time reallocations between sedentary time and different physical activity intensities with sleep outcomes using isotemporal substitution analysis. Device-measured physical activity data and both objective and subjective sleep data were collected from 439 adults aged 55+ years. Replacing 30 min of SB with moderate to vigorous intensity physical activity (MVPA) was significantly associated with an increased number of awakenings. Moreover, a reallocation of 30 min between light physical activity (LPA) and MVPA was significantly associated with increased sleep efficiency. Furthermore, reallocating 30 min of SB to LPA showed a significant association with decreased sleep efficiency. There were no significant associations of time reallocations for wake time after sleep onset, length of awakenings, and sleep quality. These results improve our understanding of the interrelationships between different intensities of movement behaviours and several aspects of sleep in older adults.

Association between Macronutrient Intake and Excessive Daytime Sleepiness: An Iso-Caloric Substitution Analysis from the North West Adelaide Health Study.

Epidemiological evidence on the association between macronutrient intake and excessive daytime sleepiness (EDS) is scarce. Using data from the North West Adelaide Health Study, we aimed to determine the association between iso-caloric substitution of macronutrients and EDS. Data from 1997 adults aged ≥ 24 years were analyzed. Daytime sleepiness was measured using the Epworth Sleepiness Scale, a score ≥ 11 was considered EDS. Dietary intake data were collected using a food frequency questionnaire. We determined absolute and relative energy intake based on consumption of saturated and unsaturated fats, protein, and carbohydrate. Odds ratios (ORs) were used to determine the associations using log-binomial logistic regression with and without iso-caloric substitution methods, and models were adjusted for confounders. The prevalence of EDS in the sample was 10.6%. After adjusting for potential confounders, substituting 5% energy intake from protein with an equal amount of saturated fat (OR = 1.57; 95% CI: 1.00-2.45) and carbohydrate (OR = 1.23; 95% CI: 0.92-1.65) increased the odds of EDS. When carbohydrate was substituted with saturated fat (OR = 1.27; 95% CI: 0.93-1.59), the odds of EDS were increased. The odds of EDS were lower when saturated fat was substituted with unsaturated fat (OR = 0.74; 95% CI: 0.51-1.06), protein (OR = 0.63; 95% CI: 0.41-0.99) or carbohydrate (OR = 0.79; 95% CI: 0.57-1.08). While these results were consistent over different iso-caloric substitution methods, inconsistent results were found with standard regression. While substitution of fat and carbohydrate with protein was inversely associated with EDS, substitution of protein with fat and carbohydrate was positively associated with EDS. Randomized trials are needed to confirm if dietary interventions can be used to improve daytime alertness in those with EDS.