Trajectories of lifestyle patterns from 2 to 8 years of age and cardiometabolic risk in children: the GUSTO study

BACKGROUND

Tracking combinations of lifestyle behaviours during childhood ("lifestyle pattern trajectories") can identify subgroups of children that might benefit from lifestyle interventions aiming to improve health outcomes later in life. However, studies on the critical transition period from early to middle childhood are limited. We aimed to describe lifestyle patterns trajectories in children from 2 to 8 years of age and evaluated their associations with cardiometabolic risk markers at age 8 years in a multi-ethnic Asian cohort.

METHODS

Twelve lifestyle behaviours related to child's diet, physical activity, screen use, and sleep were ascertained using questionnaires at ages 2, 5, and 8 years. Age-specific lifestyle patterns were derived using principal component analysis and trajectories were determined using group-based multi-trajectory modelling. Child cardiometabolic risk markers were assessed at age 8 years, and associations with trajectories examined using multiple regression, adjusted for confounders.

RESULTS

Among 546 children, two lifestyle patterns "healthy" and "unhealthy" were observed at ages 2, 5, and 8 years separately. Three trajectory groups from 2 to 8 years were identified: consistently healthy (11%), consistently unhealthy (18%), and mixed pattern (71%). Children in the consistently unhealthy group (vs. mixed pattern) had increased odds of pre-hypertension (OR = 2.96 [95% CI 1.18-7.41]) and higher levels of diastolic blood pressure (β = 1.91 [0.27-3.55] mmHg), homeostasis model assessment of insulin resistance (β = 0.43 [0.13-0.74]), triglycerides (β = 0.11 [0.00-0.22] mmol/L), and metabolic syndrome score (β = 0.85 [0.20-1.49]), but not with BMI z-score or any anthropometric measurements. The consistently healthy group showed no differences in cardiometabolic outcomes compared to the mixed pattern group.

CONCLUSION

Three distinct lifestyle pattern trajectories were identified from early to middle childhood. Children in the consistently unhealthy lifestyle group did not have a raised BMI but was associated with several elevated cardiometabolic risk markers. These findings suggest the potential benefits of initiating holistic lifestyle interventions to improve children's health and well-being from an early age.

TRIAL REGISTRATION

Trial registration number: NCT01174875. Name of registry: ClinicalTrials.gov. URL of registry: https://classic.

CLINICALTRIALS

gov/ct2/show/NCT01174875 . Date of registration: August 4, 2010. Date of enrolment of the first participant to the trial: June 2009.

Isocaloric Substitution of Plant-Based Protein for Animal-Based Protein and Cardiometabolic Risk Factors in a Multiethnic Asian Population

BACKGROUND

Evidence is accumulating that intake of animal-based and plant-based proteins has different effects on cardiometabolic health, but less is known about the health effect of isocaloric substitution of animal-based and plant-based proteins. Data from Asian populations are limited.

OBJECTIVES

This study aimed to evaluate the effects of isocaloric substitution of total plant-based proteins for total and various animal-based protein food groups and to evaluate the effects of substituting protein from legumes and pulses for various animal-based protein food groups on cardiovascular disease (CVD) risk factors and predicted 10-y CVD risk.

METHODS

We conducted a cross-sectional analysis using data collected from 9211 Singapore residents (aged 21-75 y) from the Singapore Multi-Ethnic Cohort. Data on sociodemographic and lifestyle factors were collected using questionnaires. Dietary intakes were assessed using a validated FFQ. BMI, waist circumference, and blood pressure were measured during a physical examination, and blood samples were collected to measure lipid profiles. Associations were assessed by substitution models using a multiple linear regression analysis.

RESULTS

Isocaloric substitution of total plant-based proteins for total and all specific animal-based protein food groups were associated with lower BMI (β: -0.30; 95% CI: -0.38, -0.22), waist circumference (β: -0.85; 95% CI: -1.04, -0.66), and LDL cholesterol concentrations (β: -0.06; 95% CI: -0.08, -0.05) (P < 0.0056). Replacement of processed meat and processed seafood proteins with total plant-based proteins was associated with improvement in most CVD risk factors and predicted 10-y CVD risk. Replacement of oily fish with legume proteins was associated with lower HDL cholesterol and higher TG concentrations.

CONCLUSIONS

The substitution of plant-based proteins for animal-based proteins, especially from processed meat and processed seafood, was inversely associated with the established CVD risk factors such as BMI, waist circumference, and lipid concentrations and predicted 10-y CVD risk. These findings warrant further investigation in independent studies in other Asian populations.

Prospective associations of lifestyle patterns in early childhood with socio-emotional and behavioural development and BMI: An outcome-wide analysis of the EDEN mother-child cohort

BACKGROUND

Children's energy balance-related behaviours (EBRB), comprising diet, screen time, physical activity, and sleep, combine into "lifestyle patterns", which may exert a synergistic effect on health. To date, studies investigating this synergy have primarily focused on obesity risk, without addressing other facets of health.

OBJECTIVES

To examine the prospective associations of preschoolers' lifestyle patterns with socio-emotional, behavioural, and body mass index (BMI) outcomes at 8 years.

METHODS

Participants were 876 children from the EDEN mother-child cohort. Three lifestyle patterns (unhealthy, healthy, and mixed) were previously identified at age 5, separately in boys and girls. At age 8, height and weight measures generated BMI z-scores while social-emotional and behavioural development was assessed by parents using the Strengths and Difficulties Questionnaire (SDQ). Drawing from the outcome-wide approach, sex- and outcome-specific adjusted linear regressions were fitted.

RESULTS

Boys' adherence to a healthy lifestyle pattern (combining a nutrient-dense diet and limited screen time) at 5 years was positively associated with prosocial behaviours (β = 0.14; 95% confidence interval [CI] 0.01, 0.26) and inversely related to hyperactivity-inattention symptoms (β = -0.12; 95% CI -0.23, -0.01) at 8 years. Girls' mixed lifestyle pattern (sugar or artificially sweetened beverages, high screen, physical activity and low sleep times) was associated with prosocial behaviours (β = 0.12; 95% CI 0.01, 0.23). There was no evidence of associations between lifestyle patterns and BMI z-scores.

CONCLUSIONS

Findings suggest synergistic benefits of engaging in a combination of optimal EBRBs, especially in boys, and support intervention efforts at preschool age to enhance some dimensions of their later socio-emotional and behavioural development.

Timing of introduction of complementary foods, breastfeeding, and child cardiometabolic risk: a prospective multiethnic Asian cohort study

BACKGROUND

The timing of introduction of complementary foods and the duration of breastfeeding (BF) have been independently associated with child overweight and obesity; however, their combined influence on body fat partitioning and cardiometabolic risk is unclear.

OBJECTIVE

We investigated the associations of the timing of introduction of complementary foods, the duration of BF, and their interaction with child adiposity and cardiometabolic risk markers.

METHODS

We analyzed data from 839 children in the prospective Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort. Mothers reported the age at which infants were first fed complementary foods and BF duration, classified as early (≤4 mo) versus typical (>4 mo) complementary feeding (CF) and short (≤4 mo) versus long (>4 mo) duration of any BF, respectively. We measured adiposity and cardiometabolic risk markers at the age of 6 y and examined their associations with infant feeding patterns using multiple regression, adjusting for sociodemographics, parents' body mass index (BMI), maternal factors, birth weight for gestational age, and infant weight gain.

RESULTS

Of 839 children, 18% experienced early CF, whereas 54% experienced short BF. Short (vs. long) BF and early (vs. typical) CF were independently associated with higher z-scores of BMI [β (95% confidence interval), short BF, 0.18 standard deviation score (SDS) (-0.01, 0.38); early CF, 0.34 SDS (0.11, 0.57)] and sum of skinfolds [short BF, 1.83 mm (0.05, 3.61); early CF, 2.73 mm (0.55, 4.91)]. Children who experienced both early CF and short BF (vs. typical CF-long BF) had synergistically higher diastolic blood pressure [1.41 mmHg (-0.15, 2.97), P-interaction = 0.023] and metabolic syndrome score [0.81 (0.16, 1.47), P-interaction = 0.081]. Early CF-long BF (vs. early CF-short BF) was associated with a lower systolic blood pressure [-3.74 mmHg (-7.01, -0.48)], diastolic blood pressure [-2.29 mmHg (-4.47, -0.11)], and metabolic syndrome score [-0.90 (-1.80, 0.00)].

CONCLUSIONS

A combination of early CF and short BF was associated with elevated child adiposity and cardiometabolic markers. Longer BF duration may protect against cardiometabolic risk associated with early CF. This trial was registered at clinicaltrials.gov as NCT01174875.

Breastfeeding may benefit cardiometabolic health of children exposed to increased gestational glycemia in utero

PURPOSE

There is altered breastmilk composition among mothers with gestational diabetes and conflicting evidence on whether breastfeeding is beneficial or detrimental to their offspring's cardiometabolic health. We aimed to investigate associations between breastfeeding and offspring's cardiometabolic health across the range of gestational glycemia.

METHODS

We included 827 naturally conceived, term singletons from a prospective mother-child cohort. We measured gestational (26-28 weeks) fasting plasma glucose (FPG) and 2-h plasma glucose (2 hPG) after an oral glucose tolerance test as continuous variables. Participants were classified into 2 breastfeeding categories (high/intermediate vs. low) according to their breastfeeding duration and exclusivity. Main outcome measures included magnetic resonance imaging (MRI)-measured abdominal fat, intramyocellular lipids (IMCL), and liver fat, quantitative magnetic resonance (QMR)-measured body fat mass, blood pressure, blood lipids, and insulin resistance at 6 years old (all continuous variables). We evaluated if gestational glycemia (FPG and 2 hPG) modified the association of breastfeeding with offspring outcomes after adjusting for confounders using a multiple linear regression model that included a 'gestational glycemia × breastfeeding' interaction term.

RESULTS

With increasing gestational FPG, high/intermediate (vs. low) breastfeeding was associated with lower levels of IMCL (p-interaction = 0.047), liver fat (p-interaction = 0.033), and triglycerides (p-interaction = 0.007), after adjusting for confounders. Specifically, at 2 standard deviations above the mean gestational FPG level, high/intermediate (vs. low) breastfeeding was linked to lower adjusted mean IMCL [0.39% of water signal (0.29, 0.50) vs. 0.54% of water signal (0.46, 0.62)], liver fat [0.39% by weight (0.20, 0.58) vs. 0.72% by weight (0.59, 0.85)], and triglycerides [0.62 mmol/L (0.51, 0.72) vs. 0.86 mmol/L (0.75, 0.97)]. 2 hPG did not significantly modify the association between breastfeeding and childhood cardiometabolic risk.

CONCLUSION

Our findings suggest breastfeeding may confer protection against adverse fat partitioning and higher triglyceride concentration among children exposed to increased glycemia in utero.

Newborn body composition and child cardiovascular risk markers: a prospective multi-ethnic Asian cohort study

BACKGROUND

Early epidemiological studies have associated low birthweight with increased cardiovascular risk. We aimed to examine whether the fat and fat-free components of birthweight have differing relationships with childhood cardiovascular risk markers.

METHODS

In the Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort, air displacement plethysmography was conducted within 24 h after delivery in 290 naturally conceived singletons. We investigated associations of newborn cohort-specific standardized z-score of fat mass, fat-free mass, body fat percentage and birthweight on child (at 6 years of age) carotid intima-media thickness, pulse wave velocity, blood pressure, prehypertension/hypertension (>110/70 mmHg) and standardized systolic and diastolic blood pressure (SBP and DBP) trajectories (at 3-6 years of age), taking account of maternal education, height, tobacco exposure, parity, ethnicity, child's sex, gestational age, age at follow-up, and other maternal factors.

RESULTS

Clear inverse associations were seen for blood pressure with z-score of fat mass [SBP, β (95% CI): -1.31 mmHg (-2.57, -0.06); DBP: -0.79 mmHg (-1.74, 0.15)] and body fat percentage [SBP: -1.46 mmHg (-2.73, -0.19); DBP: -0.80 mmHg (-1.75, 0.16)], but not with fat-free mass [SBP: 0.27 mmHg (-1.29, 1.83)]; DBP: -0.14 mmHg (-1.30, 1.03)]. Being in the lowest tertile of fat mass or body fat percentage was associated with higher blood pressure trajectories and prehypertension/hypertension risk [OR (95% CI), fat mass: 4.23 (1.41, 12.68); body fat percentage: 3.22 (1.09, 9.53)] without concomitantly higher overweight/obesity risk.

CONCLUSIONS

At birth, low adiposity was associated with increased childhood blood pressure. Low newborn adiposity might serve as a marker of poor fetal growth or suboptimal intrauterine conditions associated with hypertension risk later in life.

Evaluation of Preconception Dietary Patterns in Women Enrolled in a Multisite Study

Background

Diet indices are widely used in nutritional research across communities but do not "capture" the full extent of diet variability across multiple countries. Empirically derived dietary patterns can provide additional information because they reflect combinations of foods potentially associated with health outcomes. Limited studies have evaluated preconception dietary patterns in heterogeneous populations.

Objectives

In the multisite Nutritional Intervention Preconception and During Pregnancy to Maintain Healthy Glucose Metabolism and Offspring Health (NiPPeR) study, the secondary aims included: 1) derive pooled and site-specific preconception dietary patterns, and 2) evaluate these patterns using anthropometric measures and metabolic biomarkers.

Methods

Women planning pregnancy (n = 1720) in the United Kingdom, Singapore, and New Zealand completed interviewer-administered harmonized FFQs and lifestyle questionnaires at recruitment. Across-cohort ("pooled") and site-specific dietary patterns were derived, and associations between dietary pattern scores and BMI, waist-to-hip ratio, plasma lipids, and glycemia assessed using multivariable linear regression, expressing results as SD change in outcome per SD change in dietary pattern score.

Results

The pooled analysis identified 3 dietary patterns: "Vegetables/Fruits/Nuts" ("Healthy"), "Fried potatoes/Processed meat/Sweetened beverages" ("Less Healthy"), and "Fish/Poultry/Noodles/Rice" ("Mixed"). The "Healthy" and "Less Healthy" pooled pattern scores were highly correlated with their corresponding site-specific dietary pattern scores ("Healthy": ρ = 0.87-0.93; "Less Healthy": ρ = 0.65-0.88). Women with higher scores for the "Healthy" pooled pattern had a lower waist-to-hip ratio (standardized β: -0.10; 95% CI: -0.18, -0.01); those with higher scores for the "Less Healthy" pooled pattern had a higher BMI (standardized β: 0.17; 95% CI: 0.09, 0.24), higher LDL cholesterol (standardized β: 0.10; 95% CI: 0.01, 0.19), and less optimal glucose profiles. However, we noted higher adherence to the "Healthy" pooled pattern with higher BMI.

Conclusions

The "Healthy" and "Less Healthy" pooled patterns were comparable to the corresponding site-specific patterns. Although the associations between these patterns and objective anthropometric/metabolic measures were largely in the expected directions, future studies are required to confirm these findings.This trial is registered at clinicaltrials.gov (NCT02509988).

Family-focused contextual factors associated with lifestyle patterns in young children from two mother-offspring cohorts: GUSTO and EDEN

BACKGROUND

Integrated patterns of energy balance-related behaviours of preschool children in Asia are sparse, with few comparative analyses.

PURPOSE

Using cohorts in Singapore (GUSTO) and France (EDEN), we characterized lifestyle patterns of children and investigated their associations with family-focused contextual factors.

METHODS

Ten behavioural variables related to child's diet, walking, outdoor play and screen time were ascertained by parental questionnaires at age 5-6 years. Using principal component analysis, sex-specific lifestyle patterns were derived independently for 630 GUSTO and 989 EDEN children. Contextual variables were organised into distal (family socio-economics, demographics), intermediate (parental health, lifestyle habits) and proximal (parent-child interaction factors) levels of influence and analysed with hierarchical linear regression.

RESULTS

Three broadly similar lifestyle patterns were identified in both cohorts: "discretionary consumption and high screen time", "fruit, vegetables, and low screen time" and "high outdoor playtime and walking". The latter two patterns showed small differences between cohorts and sexes. The "discretionary consumption and high screen time" pattern was consistently similar in both cohorts; distal associated factors were lower maternal education (EDEN boys), no younger siblings (GUSTO boys) and Malay/Indian ethnicity (GUSTO), while intermediate and proximal associated factors in both cohorts and sexes were poor maternal diets during pregnancy, parents allowing high child control over food intake, snacking between meals and having television on while eating.

CONCLUSIONS

Three similar lifestyle patterns were observed among preschool children in Singapore and France. There were more common associated proximal factors than distal ones. Cohort specific family-focused contextual factors likely reflect differences in social and cultural settings. Findings will aid development of strategies to improve child health.

Dietary patterns of 5-year-old children and their correlates: findings from a multi-ethnic Asian cohort

There is limited data on the dietary patterns of 5-year-old children in Asia. The study examined childhood dietary patterns and their maternal and child correlates in a multi-ethnic Asian cohort. Based on caregiver-reported 1-month quantitative FFQ of 777 children from the Growing Up in Singapore Towards healthy Outcomes cohort, cluster analysis identified two mutually exclusive clusters. Children in the 'Unhealthy' cluster (43·9 %) consumed more fries, processed meat, biscuits and ice cream, and less fish, fruits and vegetables compared with those in the 'Healthy' cluster (56·1 %). Children with mothers of lower educational attainment had twice the odds of being assigned to the 'Unhealthy' cluster (adjusted OR (95 % CI) = 2·19 (95 % CI 1·49-3·24)). Children of Malay and Indian ethnicities had higher odds of being assigned to the 'Unhealthy' cluster (adjusted OR = 25·46 (95 % CI 15·40, 42·10) and 4·03 (95 % CI 2·68-6·06), respectively), relative to Chinese ethnicity. In conclusion, this study identified two dietary patterns in children, labelled as the 'Unhealthy' and 'Healthy' clusters. Mothers' educational attainment and ethnicity were two correlates that were associated with the children's assignments to the clusters. These findings can assist in informing health promotion programmes targeted at Asian children.

Diet and risk of myopia in three-year-old Singapore children: the GUSTO cohort

BACKGROUND

To investigate the relationship between dietary intakes at six, nine and 12 months and risk of myopia in three-year-old children in a birth cohort.

METHODS

Three hundred and seventeen children from the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study were included. Dietary intake at six, nine and 12 months of age was ascertained using either 24-hour recalls or three-day food diaries completed by parents. Cycloplegia was achieved with three drops of one per cent cycloplentolate instilled at five minute intervals. Cycloplegic autorefraction and axial length (AL) were measured at three years of age with a table-mounted autorefractor and optical biometer, respectively. Myopia was defined as spherical equivalent (SE) of ≤ -0.50 D. Associations of dietary intake with SE, AL and myopia were examined by single dietary factor models using two multivariable regression models. Model 1 included adjusting for age, gender and total energy intake. Model 2 included additional adjustments for ethnicity, time spent outdoors, maternal education and parental myopia.

RESULTS

In the single dietary factor adjusted models, dietary intakes at six, nine and 12 months were not associated with SE, AL and myopia. In model 1, protein, fat and carbohydrate intakes were not associated with SE, AL and myopia at any of the three time points (p > 0.05). In model 2, protein, fat and carbohydrate intakes were not associated with SE, AL and myopia at any of the three time points (p > 0.05).

CONCLUSIONS

In this study, there was no evidence that diet at ages six, nine and 12 months was related to SE, AL or myopia at age three years. Further prospective studies with larger sample sizes are needed to understand the influence of diet on eye development in young children.

A novel combined biomarker including plasma carotenoids, vitamin C, and ferric reducing antioxidant power is more strongly associated with fruit and vegetable intake than the individual components

BACKGROUND

Monitoring of fruit and vegetable (F&V) intake is fraught with difficulties. Available dietary assessment methods are associated with considerable error, and the use of biomarkers offers an attractive alternative. Few studies to date have examined the use of plasma biomarkers to monitor or predict the F&V intake of volunteers consuming a wide range of intakes from both habitual F&V and manipulated diets.

OBJECTIVE

This study tested the hypothesis that an integrated biomarker calculated from a combination of plasma vitamin C, cholesterol-adjusted carotenoid concentration and Ferric Reducing Antioxidant Power (FRAP) had more power to predict F&V intake than each individual biomarker.

METHODS

Data from a randomized controlled dietary intervention study [FLAVURS (Flavonoids University of Reading Study); n = 154] in which the test groups observed sequential increases of 2.3, 3.2, and 4.2 portions of F&Vs every 6 wk across an 18-wk period were used in this study.

RESULTS

An integrated plasma biomarker was devised that included plasma vitamin C, total cholesterol-adjusted carotenoids, and FRAP values, which better correlated with F&V intake (r = 0.47, P < 0.001) than the individual biomarkers (r = 0.33, P < 0.01; r = 0.37, P < 0.001; and r = 0.14, respectively; P = 0.099). Inclusion of urinary potassium concentration did not significantly improve the correlation. The integrated plasma biomarker predicted F&V intake more accurately than did plasma total cholesterol-adjusted carotenoid concentration, with the difference being significant at visit 2 (P < 0.001) and with a tendency to be significant at visit 1 (P = 0.07).

CONCLUSION

Either plasma total cholesterol-adjusted carotenoid concentration or the integrated biomarker could be used to distinguish between high- and moderate-F&V consumers. This trial was registered at www.controlled-trials.com as ISRCTN47748735.

Dietary disinhibition modulates neural valuation of food in the fed and fasted states

BACKGROUND

Dietary disinhibition is a behavioral trait associated with weight gain and obesity. Because food choices are made according to the relative value assigned to each option, examination of valuation signals through functional magnetic resonance imaging (fMRI) may elucidate the neural basis for the association between dietary disinhibition and weight gain.

OBJECTIVE

We examined how food valuation signals differ in the fed and fasted states between persons with high dietary disinhibition (HD) and low dietary disinhibition (LD).

DESIGN

Sixteen men with HD and 14 with LD underwent fMRI once while fasted and once after being fed in a counterbalanced order. In-scanner preference to consume a test food relative to a neutral-tasting, neutral-health reference food was examined. The slope of magnetic resonance signal change corresponding to these food preferences constituted the food valuation signal that was compared across disinhibition group and satiety state.

RESULTS

Both the HD and LD participants reported being less hungry (F(1,28) = 113.11, P < 0.001) after being fed than when fasted. However, food valuation signals in the ventromedial prefrontal cortex (vmPFC) differed between the groups (F(1,28) = 21.34, P < 0.001). Although LD participants showed attenuated vmPFC activity after being fed (t(13) = 4.11, P < 0.001), HD participants showed greater vmPFC activity in the fed than in the fasted state (t(15) = -2.56, P < 0.05).

CONCLUSIONS

Despite reporting normal decreases in hunger ratings after being fed, persons with HD have an altered neural valuation of food. This may be a mechanism underlying their propensity to overeat and gain weight. This trial was registered at clinicaltrials.gov as NCT00988819.

Long chain n-3 PUFA-rich meal reduced postprandial measures of arterial stiffness

BACKGROUND & AIMS

The consumption of long chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) is known to be cardio-protective. Data on the influence of LC n-3 PUFA on arterial stiffness in the postprandial state is limited. The aim of this study was to investigate the acute effects of a LC n-3 PUFA-rich meal on measures of arterial stiffness.

METHODS

Twenty-five healthy subjects (12 men, 13 women) received a control and a LC n-3 PUFA-rich meal on two occasions in a random order. Arterial stiffness was measured at baseline, 30, 60, 90, 120, 180 and 240 min after meal consumption by pulse wave analysis and digital volume pulse to derive an augmentation index and a stiffness index respectively. Blood samples were taken for measurement of lipids, glucose and insulin.

RESULTS

Consumption of the LC n-3 PUFA-rich meal had an attenuating effect on augmentation index (P=0.02) and stiffness index (P=0.03) compared with the control meal. A significant treatment effect (P=0.036) was seen for plasma non-esterified fatty acids concentrations.

CONCLUSIONS

These data indicate that acute LC n-3 PUFA-rich meal consumption can improve postprandial arterial stiffness. This has important implications for the beneficial properties of LC n-3 PUFA and cardiovascular risk reduction.

Reduced oxidation of dietary fat after a short term high-carbohydrate diet

BACKGROUND

Short-term high-carbohydrate (HC) diets induce metabolic alterations, including hypertriacylglycerolemia, in both the fasting and postprandial states. The underlying tissue-specific alterations in fatty acid metabolism are not well understood.

OBJECTIVE

We investigated alterations in exogenous and endogenous fatty acid metabolism by using stable isotope tracers to label meal triacylglycerol and plasma fatty acids.

DESIGN

Eight healthy subjects consumed isocaloric diets containing a high percentage of energy from carbohydrates or a higher percentage of energy from fat for 3 d in a randomized crossover dietary intervention study. A test meal containing [U-13C] palmitate was combined with intravenous infusion of [2H2] palmitate to label plasma fatty acids and VLDL triacylglycerol. Blood and breath samples were taken before the meal and for 6 h postprandially. Blood samples were drawn from the femoral artery and from veins draining subcutaneous adipose tissue and forearm muscle for monitoring of tissue-specific metabolic substrate partitioning.

RESULTS

Systemic triacylglycerol concentrations were increased in both fasting (P = 0.02) and postprandial (P = 0.02) periods, and a greater amount of infused labeled fatty acid appeared in VLDL triacylglycerol after the HC diet than after the higher-fat diet (P = 0.05). Significantly less 13CO2 was exhaled after the HC diet (P = 0.04) and significantly less production of 13CO2 was seen across forearm muscle (P = 0.04). Systemic 3-hydroxybutyrate was significantly lower, postprandially, after the HC diet (P = 0.02).

CONCLUSION

Metabolic alterations suggestive of repartitioning of fatty acids away from oxidation toward esterification in both liver and muscle occur in response to short-term adaptation to a HC diet.

Parallel activation of de novo lipogenesis and stearoyl-CoA desaturase activity after 3 d of high-carbohydrate feeding

BACKGROUND

High-carbohydrate (HC) diets increase de novo lipogenesis (DNL), but effects on stearoyl-CoA desaturase (SCD) are not so well studied.

OBJECTIVE

The objective was to investigate DNL and SCD in liver and adipose tissue by using fatty acid ratios after short-term dietary intervention.

DESIGN

Eight subjects consumed isoenergetic 3-d HC (10% fat; 75% carbohydrates) or higher fat (HF; 40% fat; 45% carbohydrates) diets (sugar to starch ratio: 60:40 for both) in a crossover study. Blood was taken from an artery and a vein draining subcutaneous adipose tissue. DNL and SCD activity were investigated by using the ratios of 16:0 to 18:2n-6 and of 16:1n-7 to 16:0, respectively. A test meal, including [U-(13)C]palmitate was given to trace dietary fatty acid incorporation into VLDL-triacylglycerol (TG). The conversion of intravenously infused [(2)H(2)]palmitic acid to [(2)H(2)]palmitoleic acid in VLDL-TG was quantified as a specific marker of hepatic SCD activity.

RESULTS

The VLDL-TG 16:0/18:2n-6 ratio, which reflects hepatic DNL, was greater after the HC diet than after the HF diet (P = 0.02). With the HC diet, increased plasma TG concentrations correlated with 16:0/18:2n-6 ratios (r = 0.76, P = 0.028). Plasma VLDL-TG and adipose venous nonesterified fatty acid (NEFA) 16:1n-7/16:0 ratios were higher after the HC diet (fasting: P = 0.01 and P = 0.05, respectively; postprandial: P = 0.03 and P = 0.05, respectively). Changes in fasting VLDL-TG 16:0/18:2n-6 and 16:1n-7/16:0 ratios were associated (P = 0.06). The contribution of total fatty acids from splanchnic sources (including DNL) was higher after the HC diet (P = 0.02). Expression of lipogenic genes in subcutaneous adipose tissue was not significantly affected by diet.

CONCLUSION

Parallel activation of DNL and SCD was found after a short period of HC feeding.

Mechanisms for the acute effect of fructose on postprandial lipemia

BACKGROUND

A high fructose intake can lead to postprandial hypertriacylglycerolemia. The underlying mechanism is unclear.

OBJECTIVE

The objective of the study was to investigate the mechanisms involved in fructose-induced hypertriacylglycerolemia and the contribution of de novo lipogenesis in an acute setting.

DESIGN

In a randomized, crossover study, 14 subjects were given a fructose or glucose test meal after an overnight fast. [(2)H2]Palmitate and [U(13)C]d-fructose or [U(13)C]d-glucose were added to trace the handling of dietary fats and the fate of dietary sugars in the body. Blood samples were taken before and after the meal. Respiratory exchange ratio was measured by using indirect calorimetry, and breath samples were collected.

RESULTS

Plasma triacylglycerol and VLDL-triacylglycerol concentrations were significantly higher (P = 0.001 for both), whereas the concentrations of insulin and [(2)H2]palmitate in nonesterified fatty acids were significantly lower after fructose than after glucose (P = 0.002 and 0.03, respectively). The respiratory exchange ratio was higher after fructose (P = 0.04); significantly (P = 0.003) more carbon from sugars was recovered in breath carbon dioxide over 6 h after fructose (30.5%) than after glucose (24.5%). At 240 min, newly synthesized fatty acids from fructose made up approximately 0.4% of circulating VLDL-triacylglycerol, whereas newly synthesized triacylglycerol-glycerol made up 38%. Newly synthesized fatty acids and triacylglycerol-glycerol from glucose contributed almost none of VLDL-triacylglycerol (P = 0.002 and 0.007 for glucose and fructose, respectively).

CONCLUSIONS

The lower insulin excursion after fructose may result in less activation of adipose tissue lipoprotein lipase, which led to impaired triacylglycerol clearance. The contribution of de novo lipogenesis to fructose-induced hypertriacylglycerolemia is small, but its effect on altering the partitioning of fatty acids toward esterification may be considerable.