Dietary Macronutrient Composition Research Articles

Associations between dietary macronutrient composition and cardiometabolic health: data from NHANES 1999–2014

PurposeDietary macronutrients significantly impact cardiometabolic health, yet research often focuses on individual macronutrient relationships. This study aimed to explore the associations between dietary macronutrient composition and cardiometabolic health.MethodsThis study included 33,681 US adults (49.7 ± 18.3 years; 52.5% female) from the National Health and Nutrition Examination Survey during 1999–2014. Dietary data was derived from 1 to 2 separate 24-hour recalls and cardiometabolic health included lipid profile, glycemic control, blood pressure, and adiposity collected in a mobile examination center. Associations between dietary macronutrient composition and cardiometabolic health were examined using generalized additive models adjusted for age, socio-demographics, lifestyle, and diet quality.ResultsIn females, triglycerides (P < 0.01) and HDL cholesterol (P < 0.01) were the least optimal in diets containing lower fat (10%) and higher carbohydrate (75%). In males, HDL cholesterol was positively associated with fat (P < 0.01) and no association with triglycerides was detected. Total-C associations were male specific (P = 0.01) and highest in diets composed of 25% protein, 30% carbohydrate, and 45% fat. In both sexes, systolic blood pressure (P ≤ 0.02) was highest in diets containing lower fat (10%) coupled with moderate protein (25%). Diastolic blood pressure associations were female specific (P < 0.01) with higher values in those consuming the upper range of fat (55%). There were no associations of macronutrient composition with glycemic control or adiposity.ConclusionThis study revealed sex-specific relationships between macronutrient composition and cardiometabolic health. Future research is needed to explore these relationships across age groups.

Liver proteomics identifies a disconnect between proteins associated with de novo lipogenesis and triglyceride storage

De novo lipogenesis (DNL) has been implicated in the development and progression of liver steatosis. Hepatic DNL is strongly influenced by dietary macronutrient composition with diets high in carbohydrate increasing DNL while diets high in fat decrease DNL. The enzymes in the core DNL pathway have been well characterized; however, less is known about other liver proteins that play accessory or regulatory roles. In the current study, we associate measured rates of hepatic DNL and fat content with liver proteomic analysis in mice to identify known and unknown proteins that may have a role in DNL. Male mice were fed either a standard chow diet, a semipurified high starch or high-fat diet. Both semipurified diets resulted in increased body weight, fat mass, and liver triglyceride content compared to chow controls, and hepatic DNL was increased in the high starch and decreased in high fat-fed mice. Proteomic analysis identified novel proteins associated with DNL that are involved in taurine metabolism, suggesting a link between these pathways. There was no relationship between proteins that associated with DNL and those associated with liver triglyceride content. Further analysis identified proteins that are differentially regulated when comparing a nonpurified chow diet to either of the semipurified diets, which provide a set of proteins that are influenced by dietary complexity. Finally, we compared the liver proteome between 4- and 30-week diet-fed mice and found remarkable similarity suggesting that metabolic remodeling of the liver occurs rapidly in response to differing dietary components. Together, these findings highlight novel proteins associated with hepatic DNL independently of liver fat content and suggest rapid liver metabolic remodeling in response to dietary composition changes.

Dietary macronutrient composition and partial soybean meal replacement with slow-release urea: Effects on performance, digestibility, rumen fermentation, and nitrogen metabolism in dairy cows

A 2 × 2 factorial arrangement of treatments was used to investigate the interactive effects of dietary macronutrient composition [high-starch, low-fat, low-fiber (HsLFF) than low-starch, high-fat, high-fiber (LsHFF)] and N source [soybean meal (SBM) or partially replaced by slow-release urea (SRU)] on lactation performance, rumen fermentation, N utilization efficiency, nutrient digestibility, blood metabolites, and feeding behavior in cows. A replicated 4 × 4 Latin square design was used involving 12 multiparous Holstein cows (milk yield of 40.5 ± 5.6 kg/d, BW of 590 ± 20 kg; 81 ± 12 d in milk). The HsLFF diet contained 300 g/kg starch, 31.3 g/kg fat, and 301 g/kg NDF, without straw or additional fat. In contrast, the LsHFF diet contained 195.5 g/kg starch, 60.8 g/kg fat, and 367.5 g/kg NDF, enriched with wheat straw (100 g/kg), and additional fat (34 g/kg). The diets were formulated to be iso-nitrogenous and isocaloric. Cows fed the HsLFF diet had greater DM intake, digestibility of DM and CP, milk yield and milk protein %, but lower intakes of NDF, and physically effective NDF, and milk fat % than cows fed the LsHFF diet. Replacing SBM with SRU significantly increased milk solids yield without affecting other lactation performance or BW. Cows fed the LsHFF diet had higher ruminal pH and branched-chain VFA proportions but lower total VFA concentrations compared with the HsLFF diet, while those on the LsHFF-SRU diet had the highest ruminal ammonia levels. Compared with the HsLFF diet, cows fed LsHFF had lower NE intake, milk energy output and energy requirement for maintenance, although energy balances were similar among groups. The HsLFF diet improved N utilization, resulting in higher N content in milk and lower N excretion in feces. Blood metabolite studies showed significant interactions between the main factors, particularly for blood glucose and creatinine, with the lowest levels in cows fed the LsHFF-SRU and LsHFF-SBM diets. In addition, alanine aminotransferase levels were higher in cows fed the LsHFF diet than in cows fed the HsLFF diet. This could indicate early-stage liver stress due to the metabolic imbalance caused by a high-fat, low-starch diet, which can alter energy metabolism. Cows on the HsLFF-SRU diet had the highest glucose levels, indicating possible changes in carbohydrate metabolism or a higher metabolic rate. The concentration of BUN increased steadily after feeding in the LsHFF diet and peaked after 4 h in the LsHFF-SRU diet, with no difference between N sources in the HsLFF diet. Partial replacement of SRU with SBM had no effect on BUN. The interaction between the main factors had a significant effect on MUN content, which was highest in LsHFF-SRU and lowest in HsLFF-SRU, with no difference between the N sources in the HsLFF diets. Overall, while diets with reduced starch and increased fiber and fat compromised lactation performance, partially substituting SRU with SBM helped maintain milk production and milk nitrogen efficiency. However, the LsHFF-SRU diet was less efficient in N utilization, as shown by higher levels of ruminal ammonia, BUN and MUN.

Purified fibers in chemically defined synthetic diets destabilize the gut microbiome of an omnivorous insect model.

The macronutrient composition of a host's diet shapes its gut microbial community, with dietary fiber in particular escaping host digestion to serve as a potent carbon source for gut microbiota. Despite widespread recognition of fiber's importance to microbiome health, nutritional research often fails to differentiate hyper-processed fibers from cell-matrix derived intrinsic fibers, limiting our understanding of how individual polysaccharides influence the gut community. We use the American cockroach (Periplaneta americana) as a model system to dissect the response of complex gut microbial communities to diet modifications that are impossible to test in traditional host models. Here, we designed synthetic diets from lab-grade, purified ingredients to identify how the cockroach microbiome responds to six different carbohydrates (chitin, methylcellulose, microcrystalline cellulose, pectin, starch, xylan) in otherwise balanced diets. We show via 16S rRNA gene profiling that these synthetic diets reduce bacterial diversity and alter the phylogenetic composition of cockroach gut microbiota in a fiber-dependent manner, regardless of the vitamin and protein content of the diet. Comparisons with cockroaches fed whole-food diets reveal that synthetic diets induce blooms in common cockroach-associated taxa and subsequently fragment previously stable microbial correlation networks. Our research leverages an unconventional microbiome model system and customizable lab-grade artificial diets to shed light on how purified polysaccharides, as opposed to nutritionally complex intrinsic fibers, exert substantial influence over a normally stable gut community.

Gut-derived appetite hormones do not explain energy intake differences in humans following low-carbohydrate versus low-fat diets.

The objective of this study was to explore how dietary macronutrient composition influences postprandial appetite hormone responses and subsequent energy intake. A total of 20 adults (mean [SEM], age 30 [1] years, BMI 27.8 [1.3] kg/m2, n = 8 with normal weight, n = 6 with overweight, n = 6 with obesity) consumed a low-fat (LF) diet (10% fat, 75% carbohydrate) and a low-carbohydrate (LC) diet (10% carbohydrate, 75% fat) for 2 weeks each in an inpatient randomized crossover design. At the end of each diet, participants consumed isocaloric macronutrient-representative breakfast test meals, and 6-h postprandial responses were measured. Ad libitum energy intake was measured for the rest of the day. The LC meal resulted in greater mean postprandial plasma active glucagon-like peptide-1 (GLP-1; LC: 6.44 [0.78] pg/mL, LF: 2.46 [0.26] pg/mL; p < 0.0001), total glucose-dependent insulinotropic polypeptide (GIP; LC: 578 [60] pg/mL, LF: 319 [37] pg/mL; p = 0.0004), and peptide YY (PYY; LC: 65.6 [5.6] pg/mL, LF: 50.7 [3.8] pg/mL; p = 0.02), whereas total ghrelin (LC: 184 [25] pg/mL, LF: 261 [47] pg/mL; p = 0.0009), active ghrelin (LC: 91 [9] pg/mL, LF: 232 [28] pg/mL; p < 0.0001), and leptin (LC: 26.9 [6.5] ng/mL, LF: 35.2 [7.5] ng/mL; p = 0.01) were lower compared with LF. Participants ate more during LC at lunch (244 [85] kcal; p = 0.01) and dinner (193 [86] kcal; p = 0.04), increasing total subsequent energy intake for the day compared with LF (551 [103] kcal; p < 0.0001). In the short term, endogenousgut-derived appetite hormones do not necessarily determine ad libitum energy intake.

Macronutrient composition of plant-based diets and breast cancer risk: the E3N prospective cohort study.

Recent evidence suggests that plant-based diets may reduce the risk of breast cancer (BC). However, the macronutrient composition of plant-based diets and its potential impact on BC risk has not been well explored. This analysis investigated the association of macronutrient composition with BC risk across a spectrum of plant-based diet indexes using a multidimensional approach. This study followed 64,655 participants from the Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l'Education Nationale (E3N) cohort from 1993 to 2014. Diets were evaluated using validated 208-item diet history questionnaires at baseline (1993) and follow-up (2005), to calculate adherence to the overall plant-based diet (PDI), healthful plant-based diet (hPDI), and unhealthful plant-based diet (uPDI). The association of macronutrient composition with BC risk was assessed via generalized additive time-dependent Cox models across different levels of these indexes. Response surfaces were generated to visualize compositional associations at the 25th, 50th, and 75th percentile of each index (low, moderate, and high). A total of 3,932 incident BC cases were identified during the 21-year follow-up. There was a significant association between macronutrient composition and BC risk for hPDI, uPDI, and PDI (all P < 0.001). Akaike information criterion favored the hPDI model for characterizing the association between macronutrients and BC. BC risk was highest for individuals with a lower hPDI score who also consumed a diet containing lower protein (10%), lower carbohydrate (35%), and higher fat (55%). The lowest risk of BC was observed in those with higher hPDI scores with the lowest intake of protein (10%). At higher PDI and uPDI, diets containing higher protein (30%) and fat (45%) had the highest BC risk. These results demonstrate a complex relationship between macronutrient composition, plant-based diet quality, and BC risk. Further research is needed to examine specific foods that may be driving these associations. The protocol is registered at clinicaltrials.gov as NCT03285230.

Dietary macronutrient composition and its effect on 24-h substrate oxidation: A study of diurnal variations in carbohydrate and fat intake

IntroductionIn recent times, the complexity of food styles and meal content has increased, leading to significant variations in macronutrient composition between meals. This has coincided with a rise in obesity rates. ObjectiveTo determine if a larger variation in macronutrient composition between meals results in lower fat oxidation. MethodsA cross-over study was conducted on 13 healthy young male individuals using whole-body indirect calorimetry to test energy metabolic responses under three conditions: regular meals (R), high-carbohydrate breakfast (CB), or high-fat breakfast (FB), each with different macronutrient contents. R included three meals daily with the same macronutrient composition. CB included a high-carbohydrate meal at breakfast, a high-fat meal at lunch, and a high-carbohydrate meal at dinner. FB included a high-fat meal at breakfast, a high-carbohydrate meal at lunch, and a high-carbohydrate meal at dinner. The daily macronutrient compositions were similar across the three conditions, except CB and FB had larger variations in carbohydrate and fat balance between meals than R. The participants were tested in random order. ResultsThere were no significant differences in the measures of energy expenditure among the three conditions. However, after adjusting for the sleeping respiratory quotient (RQ) on the preceding day, the 24-hour RQ was lower under FB than under R (β=−0.0087, P=0.0077) or CB conditions (β=−0.0078, P=0.016). There was no difference in the magnitude of the 5-hour RQ change from lunch to dinner under the CB condition and in the magnitude of change from breakfast to lunch under the FB condition. ConclusionsA large variation in carbohydrate and fat balance between meals does not decrease daily fat oxidation. A FB may increase daily fat oxidation compared to a CB when the daily food quotient is equal, but this impact may not involve radical acceleration of fat oxidation.

ECONOMIC STABILITY AND NUTRITIONAL CHOICES: A COMPARATIVE STUDY OF FOOD EXPENDITURE AND DIETARY QUALITY ACROSS DEVELOPMENT LEVELS

Food is essential to human well-being, as it provides the nourishment that ensures a longer, healthier lifespan. As food habits are ever-evolving and economic instability is rising, it is vital to critically analyze the intersection between wealth, health, and societal development. This research investigates the relationship between economic conditions and nutritional choices by analyzing the proportion of household income spent on food and the macronutrient composition of diets in developed, developing, and underdeveloped countries, aiming to understand how economic stability impacts dietary quality and overall health outcomes. It aims to elucidate the intricate dynamics between economic conditions and nutritional choices.

Changes in Android Fat and Total Fat Are Proportional Despite Varying Dietary Macronutrient Compositions

Changes in Android Fat and Total Fat Are Proportional Despite Varying Dietary Macronutrient Compositions

Does sex differ the relationship between macronutrients adequacy and aerobic power?

Background: Sex is a recognized factor influencing physiological and biochemical changes in response to physical activity and nutrient intake. Dietary intake may impact athletic performance, including aerobic power. However, these effects may be sex-dependent. Aims: to evaluate pattern and adequacy of macronutrient intake; to evaluate predicted VO2max, and investigate potential correlations between macronutrients and aerobic power, stratified by sex. Subjects and Methods: A correlational design was employed, targeting recreational athletes. Participants (n = 52) were recruited using purposive sampling (aerobic dancers n = 15, runners n = 18, pesilat n = 10, badminton players n = 9). Three-day food records were collected and analyzed using the NutriSurvey application to determine dietary intake and macronutrient composition. Predicted VO2max was assessed via the Beep Test. The study protocol was approved by the Institutional Health Research Ethics Commission. Bivariate correlation analysis was conducted to explore associations between macronutrients and aerobic power. Results: Mean daily energy intake was 1,417.19 ± 56.12 kcal/day distributed as carbohydrate (46%), fat (40%), and protein (14%). The majority of participants (57.69%, n=30) demonstrated average VO2max, while the remaining 42.31% (n = 22) exhibited below-average values. Interestingly, a significant negative moderate correlation (r -.565 as p &lt; 0.05) was observed between fat intake and predicted VO2max in females only. No significant correlations were identified between carbohydrate or protein intake and predicted VO2max for either sex. Conclusion: Despite consuming a low-carbohydrate, high-fat (LCHF) diet, participants maintained adequate energy intake. Notably, fat intake in females displayed a strong negative association with predicted VO2max. Keywords: Sports for all, public health nutrition, cardiorespiratory endurance, physical fitness.

The effects of dietary macronutrient composition on resting energy expenditure following active weight loss: A systematic review and meta-analysis.

A systematic review and meta-analysis was conducted to evaluate the relative effectiveness of different dietary macronutrient patterns on changes in resting energy expenditure (REE) in relation to weight loss, categorized as minimal (<5%) and moderate to high (>5%). Changes in REE were assessed using a DerSimonian and Laird random-effects meta-analysis. A diet lower in carbohydrates (CHO) or higher in fat and protein was associated with smaller reductions in REE, with these trends being more pronounced among participants who experienced moderate to high weight loss. Adjusted meta-regression analysis indicated that, within the participants who experienced moderate to high weight loss, each 1% increase in CHO intake was associated with a reduction of 2.30 kcal/day in REE (95% CI: -4.11 to -0.47, p = 0.013). In contrast, a 1% increase in protein and fat intake was correlated with an increase in REE by 3.00 (95% confidence interval [CI] [1.02, 5.07], p = 0.003) and 0.5 (95% CI [-2.43, 3.41], p = 0.740) kcal/day, respectively. No significant associations were found among participants who experienced minimal weight loss. These findings indicate that, under a caloric deficit, the impact of dietary macronutrient composition on REE may vary depending on the degree of weight loss and individual metabolic responses.

Abstract P409: Maternal Macronutrient Intake at Pregnancy and Offspring Growth Trajectory Before Adulthood: A Prospective Analysis in the Growing Up Today Study 2 Cohort

Background: Childhood obesity has become a public health challenge globally, with increasing prevalence worldwide. Existing studies have indicated a potential link between maternal macronutrients intake and subsequent weight changes in their offspring during childhood. However, the long-term relationship between maternal macronutrient consumption at pregnancy and the growth trajectory of offspring into adulthood remains unclear. Objectives: We aim to investigate the relationship between maternal macronutrients intake at pregnancy and the trajectory of the offspring BMI z-score, as well as the risk of becoming overweight or obese before adulthood. Method: We included 5,700 children from the Growing Up Today Study 2 born to 4,697 mothers who participated in the Nurses’ Health Study II . Diet was assessed using a validated food frequency questionnaire in 1991 approximately during or before the pregnancy at issue. Age- and gender-specific BMI thresholds described by the International Obesity Task Force were used to define overweight and obesity in childhood and adolescence. Multivariable linear and log-binomial regression models with generalized estimating equations were used to evaluate the association between maternal macronutrients intake at pregnancy and offspring BMI z-score trajectory and the risk of overweight or obesity. Results: During follow-up, 2145 (37.6%) GUTS2 participants met the criteria of overweight or obesity.After multivariate adjustment for maternal, offspring risk factors, total maternal total energy and carbohydrate percent energy, comparing to the 1 st quartile, the highest quartile of total protein consumption at pregnancy was associated with 0.14-unit [β: 0.14 (95% CI: 0.02, 0.26; P-trend = 0.03)] increase in BMI z-score, while no significant association was observed for the risk of offspring overweight or obesity [RR: 1.17 (95% CI: 0.94, 1.46; P-trend = 0.12)]. The relationship persisted for the top quartile of animal protein energy intake [β: 0.14 (95% CI: 0.01, 0.27; P-trend = 0.03)], but not for vegetable protein consumption. Intakes of dietary fats and carbohydrates were not associated with BMI z-score or risk of overweight or obesity. Furthermore, individual macronutrient subgroups, such as saturated fats, mono- and poly-unsaturated fats, or whole grains and refined grains, were not associated with the outcomes of interest, either. Conclusion: Maternal animal protein intake at pregnancy is positively associated with higher offspring BMI z-score before adulthood, but not the risk of developing overweight or obesity during childhood. Other macronutrients are not significantly associated with these childhood body weight outcomes. Overall, these data suggest that the macronutrient composition of maternal diet at peri-pregnancy period has minimal impact on offspring body weight in this well-nourished population.

Role of Dietary Macronutrient Composition and Fibre Intake in Development of Double Diabetes in Indian Youth.

Insulin resistance (IR) and obesity are common presentations of double diabetes (DD) in subjects with type-1 diabetes (T1D). There is evidence that dietary composition has an impact on developing IR. Objectives were to assess the impact of macronutrient and fibre intake on glycaemic control and the role of macronutrient composition of diet in the development of DD in subjects with T1D. This cross-sectional study included 77 young adults (10-25 years) with T1D. Data related to demography, anthropometry, biochemistry and body composition were collected. Dietary data was collected by fourteen-day food diary. IR was calculated using eGDR, SEARCH and CACTI equations, and metabolic syndrome (MS) was diagnosed using the International Diabetes Federation Consensus Definition. Subjects at risk of DD had higher age, leptin levels, percentage carbohydrate consumption in diet and IR. A positive association of insulin sensitivity with fibre intake and %protein intake was noted. Poor glycaemic control, adiponectin/leptin ratio, fibre intake and insulin/carbohydrate ratio were significant negative predictors of IR. Addition of dietary factors to the regression model improved the R square and percentage of subjects identified correctly. Inclusion of dietary parameters significantly improves the prediction of the risk of development of DD in subjects with T1D. Good glycaemic control and increased intake of dietary fibre may prevent the development of IR in subjects with T1D and reduce the burden of DD.

Association between dietary macronutrient composition and plasma one-carbon metabolites and B-vitamin cofactors in patients with stable angina pectoris.

Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.

Dietary macronutrient composition impacts gene regulation in adipose tissue

Diet is a key lifestyle component that influences metabolic health through several factors, including total energy intake and macronutrient composition. While the impact of caloric intake on gene expression and physiological phenomena in various tissues is well described, the influence of dietary macronutrient composition on these parameters is less well studied. Here, we use the Nutritional Geometry framework to investigate the role of macronutrient composition on metabolic function and gene regulation in adipose tissue. Using ten isocaloric diets that vary systematically in their proportion of energy from fat, protein, and carbohydrates, we find that gene expression and splicing are highly responsive to macronutrient composition, with distinct sets of genes regulated by different macronutrient interactions. Specifically, the expression of many genes associated with Bardet-Biedl syndrome is responsive to dietary fat content. Splicing and expression changes occur in largely separate gene sets, highlighting distinct mechanisms by which dietary composition influences the transcriptome and emphasizing the importance of considering splicing changes to more fully capture the gene regulation response to environmental changes such as diet. Our study provides insight into the gene regulation plasticity of adipose tissue in response to macronutrient composition, beyond the already well-characterized response to caloric intake.

Low-Glycemic Load Diets and Thyroid Function: A Narrative Review and Future Perspectives.

Nutrition and calorie intake are associated with subtle changes of thyroid function tests in subjects with an intact Hypothalamic-Pituitary-Thyroid axis. Iodine deficiency and extreme fluctuations in calorie intake, such as those that occur during periods of starvation or overfeeding could lead to alterations in thyroid hormones. The dietary macronutrient and micronutrient composition could also influence the thyroid function. Recently, Low-Glycemic Load (LGL) diets have become very popular and are effective in the treatment and/or prevention of several medical conditions, including diabetes, obesity, cardiovascular disease, and epilepsy. In this review, we report on the available data from the literature regarding the association between LGL diets and thyroid function or dysfunction. Several studies conducted in this field to date have yielded inconsistent results.

The Relationship between Dietary Macronutrient Composition and Telomere Length Among US Adults.

The role of dietary macronutrients and energy intake in the aging process has been well-established. However, previous research has mainly focused on the association between leukocyte telomere length (LTL) and individual macronutrients, while the effects of macronutrient composition on LTL remain unclear. This cross-sectional analysis involved 4130 US adults (44.8±17.0years; 51% female) from the National Health and Nutrition Examination Survey during 1999-2002. A single 24-h dietary recall is used to collect dietary data. The relationship between dietary macronutrient composition and LTL is examined using three-dimensional generalized additive models. After adjustment for age, sex, ethnicity, education, physical activity, BMI, and dietary quality, a three-dimensional association of macronutrient composition with LTL (P=0.02) is revealed. Diets lower in protein (5-10%), higher in carbohydrates (75%), and lower in fat (15-20%) are associated with the longest LTL corresponding to 7.7years of slower biological aging. Diets lowest in protein (5%) and carbohydrate (40%), while highest in dietary fat (55%) are associated with the shortest LTL, corresponding to accelerated biological aging of 4.4years. The associations appeared magnified with higher energy intake. These findings support a complex relationship between dietary macronutrients and biological aging independent of diet quality.

Evaluation of Energy Utilisation Efficiencies of Digestible Macronutrients in Juvenile Malabar Snapper (Lutjanus malabaricus) Reveals High Protein Requirement for Optimal Growth Using Both Factorial and Multifactorial Approaches.

Malabar snapper (Lutjanus malabaricus) is an economically important marine fish throughout the Indo-Pacific, with an emerging aquaculture industry. Although generic marine feeds are available for production, these are not optimised for this species. Understanding energy utilisation and balance can provide insight into suitable macronutrient profiles for new species to provide a baseline for future development. This study, therefore, evaluated the effect of dietary macronutrient composition (i.e., protein, fat, and carbohydrate) on the utilisation efficiencies of digestible energy (DE) in juvenile Malabar snapper using two isonitrogenous diets (high fat: HF and low fat: LF) with contrasting fat and carbohydrate content. Each diet was fed at four feeding levels (100%, 75%, 50%, and 25% apparent satiation) for 56 days, creating a 2 by 4 factorial design. The maintenance energy requirement of Malabar snapper was estimated to be 76.7 kJ kg-0.8 day-1, while the utilisation efficiencies of digestible protein (DP) and fat were 73.6% and 68.3%, respectively. Fish fed with LF, which has lower dietary fat and higher dietary carbohydrate levels, had significantly reduced energy utilisation efficiency for growth and significantly higher partial energy utilisation efficiency of digestible fat (DF) (p < 0.05). Since body moisture is usually proportional to body fat content in fish, this implies that the energy from carbohydrates preferentially enters lipogenesis rather than being available for somatic growth, and adiposity does not directly result in weight gain. Malabar snapper utilises DF in preference to protein for metabolism, demonstrating a protein-sparing effect from lipids at DE intake levels below the maintenance requirement. Conversely, given the higher efficiency of fat retention than protein retention, protein is likely used before fat when energy intake is above maintenance. These findings suggest that Malabar snapper requires high levels of DP in its diet to support growth and that energy from dietary carbohydrates is diverted towards adiposity, consequently reducing growth.

Effects of bioavailability of macronutrients on overall control of plasma glucose: a review

Macronutrients play a crucial role in management of type 2 diabetes. This is seen in their ability to modulate plasma glucose concentrations. However, the ideal proportions of macronutrients to be consumed in order to maintain ideal plasma glucose concentrations remains elusive. Therefore, this paper set out to conduct a review to investigate the relationship between macronutrients and plasma glucose concentrations from a physiological perspective. The review was conducted using papers obtained from various databases such as MEDLINE (Pubmed), Open Access Journals Elsevier, Free Medical Journals and Google Scholar. The research papers included general reviews, systemic reviews, meta-analyses, and randomized control trials that examined the effect of macronutrients on plasma glucose concentration as well as papers on mathematical models describing the relationship between macronutrient bioavailability and plasma glucose concentration. The review assessed the effect of various macronutrients on post-prandial plasma glucose concentration, post-prandial plasma insulin, post-prandial glucose-dependent insulinotropic peptide plasma concentration, and post-prandial glucose-like peptide-1 plasma concentration. The results of the review showed that carbohydrates influence plasma glucose concentration in a dose dependant manner but this is dependent on their bioavailability. This bioavailability was shown to be subject to fluctuations determined by food processing techniques, food structure, and food matrix. The results also showed that some specific types of fats and proteins indirectly influence plasma glucose concentration through their effect on incretin hormones. The effect of fats and proteins on incretin hormones was through different mechanisms and pathways. In-lieu of the findings, the review concludes that the macronutrient composition of diets designed for type 2 diabetic patients should take into consideration the physiological relationship between the macronutrients and plasma glucose concentrations. In this way, diet proportions can be made in such a manner as to determine the exact amounts that will realize near normal plasma glucose concentrations for a type 2 diabetic patient. Key words: bioavailability, glucose-insulin system, macronutrients, incretin hormones, type 2 diabetes, glucose absorption models

Effects of Diet Macronutrient Composition on Weight Loss during Caloric Restriction and Subsequent Weight Regain during Refeeding in Aging Mice.

Caloric restriction (CR) induces weight loss, but is associated with rapid weight regain upon return to ad libitum feeding. Our aim was to investigate effects of the macronutrient composition of the diet on weight loss and regain in elderly mice. Males, 18 months old, of the C57BL/6J strain were subjected to 4-week 30% CR followed by 4 weeks of ad libitum refeeding on either high-carb (HC), high-fat (HF) or high-protein (HP) diets (n = 22 each). Mice (n = 11) fed a chow diet ad libitum served as a control group (CON). Body mass and food intake were monitored daily. Twenty-four-hour indirect calorimetry was used to assess energy expenditure and substrate oxidation. Muscle and fat mass were evaluated with dissection of the tissues. Serum leptin and ghrelin levels were also measured. CR-induced weight loss did not differ between the diets. Weight regain was particularly fast for HF as mice overshot their initial weight by 12.8 ± 5.7% after 4-week refeeding when HC and HP mice reached the weight of the CON group. Weight regain strongly correlated with energy intake across the groups. The respiratory exchange ratio was lower in HF mice (0.81 ± 0.03) compared to HC (0.94 ± 0.06, p < 0.001), HP (0.89 ± 0.04, p < 0.001) and CON mice (0.91 ± 0.06, p < 0.01) during the refeeding. Serum leptin levels were higher in HF mice (1.03 ± 0.50 ng/mL) compared to HC (0.46 ± 0.14, p < 0.001), HP (0.63 ± 0.28, p < 0.05) or CON mice (0.41 ± 0.14, p < 0.001). Thus, CR induces similar weight loss in aging mice irrespective of the diet's macronutrient composition. An HF diet leads to excessive energy intake and pronounced gain in body fat in spite of increased fat oxidation and serum leptin during the refeeding after CR.