Towards objective measurements of habitual dietary intake patterns: comparing NMR metabolomics and food frequency questionnaire data in a population-based cohort.

BACKGROUND: Low-quality, non-diverse diet is a main risk factor for premature death. Accurate measurement of habitual diet is challenging and there is a need for validated objective methods. Blood metabolite patterns reflect direct or enzymatically diet-induced metabolites. Here, we aimed to evaluate associations between blood metabolite patterns and a priori and data-driven food intake patterns. METHODS: 1, 895 participants in the Northern Sweden Health and Disease Study, a population-based prospective cohort study, were included. Fasting plasma samples were analyzed with 1H Nuclear Magnetic Resonance. Food intake data from a 64-item validated food frequency questionnaire were summarized into a priori Healthy Diet Score (HDS), relative Mediterranean Diet Score (rMDS) and a set of plant-based diet indices (PDI) as well as data driven clusters from latent class analyses (LCA). Orthogonal projections to latent structures (OPLS) were used to explore clustering patterns of metabolites and their relation to reported dietary intake patterns. RESULTS: Age, sex, body mass index, education and year of study participation had significant influence on OPLS metabolite models. OPLS models for healthful PDI and LCA-clusters were not significant, whereas for HDS, rMDS, PDI and unhealthful PDI significant models were obtained (CV-ANOVA p < 0.001). Still, model statistics were weak and the ability of the models to correctly classify participants into highest and lowest quartiles of rMDS, PDI and unhealthful PDI was poor (50%/78%, 42%/75% and 59%/70%, respectively). CONCLUSION: Associations between blood metabolite patterns and a priori as well as data-driven food intake patterns were poor. NMR metabolomics may not be sufficiently sensitive to small metabolites that distinguish between complex dietary intake patterns, like lipids.

Energy - a scoping review for the Nordic Nutrition Recommendations 2023 project.

We need energy intake to provide energy and nutrients to our cells. The amount of daily energy intake should aim for energy balance, which results in good health. Under- or overconsumption of total daily energy over a longer period leads to increased risk of diseases. In this scoping review, the components of daily energy requirement are defined. Several methods to estimate energy requirements and the amount of total daily energy intake (kJ) related to health are also discussed. Reference values for energy intake in children, adults and pregnant and postpartum women, and older adults are evaluated. Results show that it is challenging to set reference values for energy intake since existing methods are not accurate and precise, and there are several factors that influence the estimated amount of energy. Energy requirement is increased during growth as in childhood, pregnancy and lactation. We conclude that more research in this area is needed, and that new high-quality studies in both Nordic and Baltic countries are needed to obtain new recommendation numbers for energy intake.

COVID-19 infection in patients on long-term home parenteral nutrition for chronic intestinal failure.

BACKGROUND AND AIMS: To investigate the incidence and the severity of COVID-19 infection in patients enrolled in the database for home parenteral nutrition (HPN) for chronic intestinal failure (CIF) of the European Society for Clinical Nutrition and Metabolism (ESPEN). METHODS: Period of observation: March 1st, 2020 March 1st, 2021. INCLUSION CRITERIA: patients included in the database since 2015 and still receiving HPN on March 1st, 2020 as well as new patients included in the database during the period of observation. Data related to the previous 12 months and recorded on March 1st 2021: 1) occurrence of COVID-19 infection since the beginning of the pandemic (yes, no, unknown); 2) infection severity (asymptomatic; mild, no-hospitalization; moderate, hospitalization no-ICU; severe, hospitalization in ICU); 3) vaccinated against COVID-19 (yes, no, unknown); 4) patient outcome on March 1st 2021: still on HPN, weaned off HPN, deceased, lost to follow up. RESULTS: Sixty-eight centres from 23 countries included 4680 patients. Data on COVID-19 were available for 55.1% of patients. The cumulative incidence of infection was 9.6% in the total group and ranged from 0% to 21.9% in the cohorts of individual countries. Infection severity was reported as: asymptomatic 26.7%, mild 32.0%, moderate 36.0%, severe 5.3%. Vaccination status was unknown in 62.0% of patients, non-vaccinated 25.2%, vaccinated 12.8%. Patient outcome was reported as: still on HPN 78.6%, weaned off HPN 10.6%, deceased 9.7%, lost to follow up 1.1%. A higher incidence of infection (p = 0.04), greater severity of infection (p < 0.001) and a lower vaccination percentage (p = 0.01) were observed in deceased patients. In COVID-19 infected patients, deaths due to infection accounted for 42.8% of total deaths. CONCLUSIONS: In patients on HPN for CIF, the incidence of COVID-19 infection differed greatly among countries. Although the majority of cases were reported to be asymptomatic or have mild symptoms only, COVID-19 was reported to be fatal in a significant proportion of infected patients. Lack of vaccination was associated with a higher risk of death.

Identification of Single and Combined Serum Metabolites Associated with Food Intake.

Assessment of dietary intake is challenging. Traditional methods suffer from both random and systematic errors; thus objective measures are important complements in monitoring dietary exposure. The study presented here aims to identify serum metabolites associated with reported food intake and to explore whether combinations of metabolites may improve predictive models. Fasting blood samples and a 4-day weighed food diary were collected from healthy Swedish subjects (n = 119) self-defined as having habitual vegan, vegetarian, vegetarian + fish, or omnivore diets. Serum was analyzed for metabolites by 1H-nuclear magnetic resonance spectroscopy. Associations between single and combined metabolites and 39 foods and food groups were explored. Area under the curve (AUC) was calculated for prediction models. In total, 24 foods or food groups associated with serum metabolites using the criteria of rho > 0.2, p < 0.01 and AUC ≥ 0.7 were identified. For the consumption of soybeans, citrus fruits and marmalade, nuts and almonds, green tea, red meat, poultry, total fish and shellfish, dairy, fermented dairy, cheese, eggs, and beer the final models included two or more metabolites. Our results indicate that a combination of metabolites improve the possibilities to use metabolites to identify several foods included in the current diet. Combined metabolite models should be confirmed in dose−response intervention studies.

Bone mass and biomarkers in young women with anorexia nervosa: a prospective 3-year follow-up study.

INTRODUCTION: Anorexia nervosa (AN) increases the risk of impaired bone health, low areal bone mineral density (aBMD), and subsequent fractures. This prospective study investigated the long-term effects of bone and mineral metabolism on bone and biomarkers in 22 women with AN. MATERIALS AND METHODS: Body composition and aBMD were measured by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography. Total and free 25-hydroxyvitamin D (25OHD), C-terminal collagen cross-links (CTX), osteocalcin, bone-specific alkaline phosphatase (BALP), leptin, sclerostin, and oxidized/non-oxidized parathyroid hormone (PTH) were analyzed before and after 12 weeks of intensive nutrition therapy and again 3 years later. An age-matched comparison group of 17 healthy women was recruited for the 3-year follow-up. RESULTS: Body mass index (BMI) and fat mass increased from baseline to 3 years in women with AN. Sclerostin decreased during nutrition therapy and further over 3 years, indicating reduced bone loss. CTX was elevated at baseline and after 12 weeks but decreased over 3 years. BALP increased during nutrition therapy and stabilized over 3 years. Free 25OHD was stable during treatment but decreased over 3 years. Non-oxidized PTH was stable during treatment but increased over 3 years. Trabecular volumetric BMD in AN patients decreased during the first 12 weeks and over 3 years despite stable BMI and bone biomarkers implying increased BMD. CONCLUSION: Our findings highlight the importance of early detection and organized long-term follow-up of bone health in young women with a history of AN.

Chronic Intestinal Failure in Children: An International Multicenter Cross-Sectional Survey.

Background: The European Society for Clinical Nutrition and Metabolism database for chronic intestinal failure (CIF) was analyzed to investigate factors associated with nutritional status and the intravenous supplementation (IVS) dependency in children. Methods: Data collected: demographics, CIF mechanism, home parenteral nutrition program, z-scores of weight-for-age (WFA), length or height-for-age (LFA/HFA), and body mass index-for-age (BMI-FA). IVS dependency was calculated as the ratio of daily total IVS energy over estimated resting energy expenditure (%IVSE/REE). Results: Five hundred and fifty-eight patients were included, 57.2% of whom were male. CIF mechanisms at age 1−4 and 14−18 years, respectively: SBS 63.3%, 37.9%; dysmotility or mucosal disease: 36.7%, 62.1%. One-third had WFA and/or LFA/HFA z-scores < −2. One-third had %IVSE/REE > 125%. Multivariate analysis showed that mechanism of CIF was associated with WFA and/or LFA/HFA z-scores (negatively with mucosal disease) and %IVSE/REE (higher for dysmotility and lower in SBS with colon in continuity), while z-scores were negatively associated with %IVSE/REE. Conclusions: The main mechanism of CIF at young age was short bowel syndrome (SBS), whereas most patients facing adulthood had intestinal dysmotility or mucosal disease. One-third were underweight or stunted and had high IVS dependency. Considering that IVS dependency was associated with both CIF mechanisms and nutritional status, IVS dependency is suggested as a potential marker for CIF severity in children.

Characteristics of adult patients with chronic intestinal failure due to short bowel syndrome: An international multicenter survey.

BACKGROUND AND AIMS: The case-mix of patients with intestinal failure due to short bowel syndrome (SBS-IF) can differ among centres and may also be affected by the timeframe of data collection. Therefore, the ESPEN international multicenter cross-sectional survey was analyzed to compare the characteristics of SBS-IF cohorts collected within the same timeframe in different countries. METHODS: The study included 1880 adult SBS-IF patients collected in 2015 by 65 centres from 22 countries. The demographic, nutritional, SBS type (end jejunostomy, SBS-J; jejuno-colic anastomosis, SBS-JC; jejunoileal anastomosis with an intact colon and ileocecal valve, SBS-JIC), underlying disease and intravenous supplementation (IVS) characteristics were analyzed. IVS was classified as fluid and electrolyte alone (FE) or parenteral nutrition admixture (PN). The mean daily IVS volume, calculated on a weekly basis, was categorized as <1, 1-2, 2-3 and >3 L/day. RESULTS: In the entire group: 60.7% were females and SBS-J comprised 60% of cases, while mesenteric ischaemia (MI) and Crohn' disease (CD) were the main underlying diseases. IVS dependency was longer than 3 years in around 50% of cases; IVS was infused ≥5 days/week in 75% and FE in 10% of cases. Within the SBS-IF cohort: CD was twice and thrice more frequent in SBS-J than SBS-JC and SBS-JIC, respectively, while MI was more frequent in SBS-JC and SBS-JIC. Within countries: SBS-J represented 75% or more of patients in UK and Denmark and 50-60% in the other countries, except Poland where SBS-JC prevailed. CD was the main underlying disease in UK, USA, Denmark and The Netherlands, while MI prevailed in France, Italy and Poland. CONCLUSIONS: SBS-IF type is primarily determined by the underlying disease, with significant variation between countries. These novel data will be useful for planning and managing both clinical activity and research studies on SBS.

Dietary intake and nutritional status in adolescents and young adults with anorexia nervosa: A 3-year follow-up study.

BACKGROUND & AIMS: Patients with anorexia nervosa (AN) restrict their dietary intake leading to malnutrition. Information is scarce on nutrition status during recovery. The aim of the study was to investigate dietary intake, body composition, biochemistry, and status in young women three years after hospital treatment due to severe restrictive AN. METHODS: Dietary intake from four-day food records were compared to a reference group and the Nordic Nutrition Recommendations. Body composition was assessed by dual-energy X-ray absorptiometry (DXA). Serum levels of vitamin A, E, D, folate, and ferritin were assessed. RESULTS: Three years after hospital treatment for AN, 12 subjects (60%) were recovered or in partial remission from AN. Subnormal values of body fat and skeletal muscle mass were present in 30% and 25%. Energy intake was 1730 kcal/day (min-max 705-2441) or 33 kcal/kg/day (16-54). Most (80%) had a total energy intake/day below the estimated needs and 6 (32%) had energy intakes below 1550 kcal/day. Micronutrient intakes from food were low; 16 (85%) had intakes below recommendations of iron, folate, and vitamin D. Serum levels of vitamins A, E, D, and folate were on average adequate; but a subnormal value (<50 nmol/L) of vitamin D was found in 20%. Ferritin levels were significantly lower at follow-up, and 25% had values below reference range. Return of menstruation was dependent of energy intake and body fat. CONCLUSIONS: A regular and careful assessment of nutritional status along with nutritional counseling during recovery is recommended to reduce malnutrition in patients with AN.

Urine Metabolite Profiles and Nutrient Intake Based on 4-Day Weighed Food Diary in Habitual Vegans, Vegetarians, and Omnivores.

BACKGROUND: Increasing interest in diets excluding meat and other products of animal origin emphasizes the importance of objective and reliable methods to measure dietary exposure, to evaluate associations and causation between diet and health, and to quantify nutrient intakes in different diets. OBJECTIVES: This study aimed to investigate if NMR analysis of urine samples can serve as an objective method to discriminate vegan, vegetarian with or without fish, and omnivore diets. A secondary aim was to assess the influence of dietary nutrient intake on the metabolomics results. METHODS: Healthy individuals (43 men and 75 women, age 19-57 y) complying with habitual vegan (n = 42), vegetarian (n = 25), vegetarian + fish (n = 13), or omnivore (n = 38) diets were enrolled. Data were collected on clinical phenotype and lifestyle including a 4-d weighed food diary. Urine was analyzed for metabolites by NMR spectroscopy and data normalized using probabilistic quotient normalization and Pareto-scaled before multivariate analysis. Before orthogonal projections to latent structures with discriminant analysis, participants were assigned as meat consumers or nonmeat consumers (vegans and vegetarians), vegans or nonvegans (omnivores, vegetarian, and vegetarian + fish). RESULTS: The main results showed that it was possible to discriminate meat and nonmeat consumers (91% correctly classified), but discrimination between vegans and nonvegans was less rigorous (75% correctly classified). Secondary outcomes showed that reported intake of protein was higher in omnivores, and saturated fat lower and fiber higher in vegans, compared with the other groups. Discriminating metabolites were mainly related to differences in protein intake. CONCLUSIONS: NMR urine metabolomics appears suitable to objectively identify and predict habitual intake of meat in healthy individuals, but results should be interpreted with caution because not only food groups but also specific foods contribute to the patterns.This trial was registered at clinicaltrials.gov as NCT02039609.

Predictive equations for estimating resting energy expenditure in women with overweight and obesity at three postpartum stages.

The objective was to investigate which predictive equations provide the best estimates of resting energy expenditure (REE) in postpartum women with overweight and obesity. Lactating women with overweight or obesity underwent REE measurement by indirect calorimetry, and fat-free mass (FFM) was assessed by dual-energy X-ray absorptiometry at three postpartum stages. Predictive equations based on body weight and FFM were obtained from the literature. Performance of the predictive equations were analysed as the percentage of women whose REE was accurately predicted, defined as a predicted REE within ±10 % of measured REE. REE data were available for women at 10 weeks (n 71), 24 weeks (n 64) and 15 months (n 57) postpartum. Thirty-six predictive equations (twenty-five weight-based and eleven FFM-based) were validated. REE was accurately predicted in ≥80 % of women at all postpartum visits by six predictive equations (two weight-based and four FFM-based). The weight-based equation with the highest performance was that of Henry (weight, height, age 30-60 years) (HenryWH30-60), with an overall mean of 83 % accurate predictions. The HenryWH30-60 equation was highly suitable for predicting REE at all postpartum visits (irrespective of the women's actual age), and the performance was sustained across changes in weight and lactation status. No FFM-based equation was remarkably superior to HenryWH30-60 for the total postpartum period.

Body Composition During Pregnancy: Longitudinal Changes and Method Comparisons.

The Pregnancy Obesity Nutrition and Child Health study is a longitudinal study of reproductive health. Here we analyzed body composition of normal-weight and obese Swedish women by three methods during each trimester of pregnancy. Cross-sectional and longitudinal fat mass estimates using quantitative magnetic resonance (QMR) and bioelectrical impedance analysis (BIA) (Tanita MC-180MA-III) were compared with fat mass determined by air displacement plethysmography (ADP) in pregnancy weeks 8-12, 24-26, and 35-37 in normal-weight women (n = 122, BMI = 22.1 ± 1.6 kg/m2) and obese women (n = 29, BMI = 34.6 ± 3.6 kg/m2). ADP results were calculated from pregnancy-adjusted fat-free mass densities. Mean fat mass by QMR and ADP were similar in obese women, although with wide limits of agreement. In normal-weight women, QMR overestimated mean fat mass in all trimesters, with systematic overestimation at low fat mass values in trimesters 1 and 3. In obese women, fat mass by BIA was grossly underestimated and imprecise in all trimesters, especially at higher values in trimester 2. In normal-weight women, fat mass by BIA was moderately lower than by ADP in trimester 1, similar in trimester 2, and moderately higher in trimester 3. QMR and ADP assessed fat mass changes similarly in obese women, whereas BIA overestimated fat mass changes in normal-weight women. Mean fat mass and fat mass changes by QMR and pregnancy-adjusted ADP were similar in pregnant obese women. Mean fat mass by QMR and fat mass changes by BIA were higher than corresponding values determined by pregnancy-adjusted ADP in normal-weight women.

Intravenous supplementation type and volume are associated with 1-year outcome and major complications in patients with chronic intestinal failure.

BACKGROUND AND AIM: No marker to categorise the severity of chronic intestinal failure (CIF) has been developed. A 1-year international survey was carried out to investigate whether the European Society for Clinical Nutrition and Metabolism clinical classification of CIF, based on the type and volume of the intravenous supplementation (IVS), could be an indicator of CIF severity. METHODS: At baseline, participating home parenteral nutrition (HPN) centres enrolled all adults with ongoing CIF due to non-malignant disease; demographic data, body mass index, CIF mechanism, underlying disease, HPN duration and IVS category were recorded for each patient. The type of IVS was classified as fluid and electrolyte alone (FE) or parenteral nutrition admixture (PN). The mean daily IVS volume, calculated on a weekly basis, was categorised as <1, 1-2, 2-3 and >3 L/day. The severity of CIF was determined by patient outcome (still on HPN, weaned from HPN, deceased) and the occurrence of major HPN/CIF-related complications: intestinal failure-associated liver disease (IFALD), catheter-related venous thrombosis and catheter-related bloodstream infection (CRBSI). RESULTS: Fifty-one HPN centres included 2194 patients. The analysis showed that both IVS type and volume were independently associated with the odds of weaning from HPN (significantly higher for PN <1 L/day than for FE and all PN >1 L/day), patients' death (lower for FE, p=0.079), presence of IFALD cholestasis/liver failure and occurrence of CRBSI (significantly higher for PN 2-3 and PN >3 L/day). CONCLUSIONS: The type and volume of IVS required by patients with CIF could be indicators to categorise the severity of CIF in both clinical practice and research protocols.

Home parenteral nutrition provision modalities for chronic intestinal failure in adult patients: An international survey.

BACKGROUND & AIMS: The safety and effectiveness of a home parenteral nutrition (HPN) program depends both on the expertise and the management approach of the HPN center. We aimed to evaluate both the approaches of different international HPN-centers in their provision of HPN and the types of intravenous supplementation (IVS)-admixtures prescribed to patients with chronic intestinal failure (CIF). METHODS: In March 2015, 65 centers from 22 countries enrolled 3239 patients (benign disease 90.1%, malignant disease 9.9%), recording the patient, CIF and HPN characteristics in a structured database. The HPN-provider was categorized as health care system local pharmacy (LP) or independent home care company (HCC). The IVS-admixture was categorized as fluids and electrolytes alone (FE) or parenteral nutrition, either commercially premixed (PA) or customized to the individual patient (CA), alone or plus extra FE (PAFE or CAFE). Doctors of HPN centers were responsible for the IVS prescriptions. RESULTS: HCC (66%) was the most common HPN provider, with no difference noted between benign-CIF and malignant-CIF. LP was the main modality in 11 countries; HCC prevailed in 4 European countries: Israel, USA, South America and Oceania (p < 0.001). IVS-admixture comprised: FE 10%, PA 17%, PAFE 17%, CA 38%, CAFE 18%. PA and PAFE prevailed in malignant-CIF while CA and CAFE use was greater in benign-CIF (p < 0.001). PA + PAFE prevailed in those countries where LP was the main HPN-provider and CA + CAFE prevailed where the main HPN-provider was HCC (p < 0.001). CONCLUSIONS: This is the first study to demonstrate that HPN provision and the IVS-admixture differ greatly among countries, among HPN centers and between benign-CIF and cancer-CIF. As both HPN provider and IVS-admixture types may play a role in the safety and effectiveness of HPN therapy, criteria to homogenize HPN programs are needed so that patients can have equal access to optimal CIF care.

Micronutrient intake and biochemistry in adolescents adherent or nonadherent to supplements 5 years after Roux-en-Y gastric bypass surgery.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) is an effective obesity treatment in adults and has become established in adolescents. Lower adherence to supplementation in adolescents confers a risk for long-term nutritional deficiencies. OBJECTIVES: To assess adherence to supplementation, micronutrient intake, and biochemistry in adolescents through 5 years after RYGB. SETTING: University hospitals, multicenter study, Sweden. METHODS: Micronutrient intake and adherence to supplementation were assessed by diet history interviews and biochemistry preoperatively, 1, 2, and 5 years after RYGB in 85 adolescents (67% females), aged 16.5 years (± 1.2) with a body mass index of 45.5 kg/m2 (± 6.0). Adherence was defined as taking prescribed supplements ≥3 times a week. Micronutrient intake and biochemistry were compared with matched controls at 5 years. RESULTS: Over 75% completed the dietary assessments across 5 years after RYGB. Adherence ranged between 44-61% through 5 years. At 5 years, ferritin and hemoglobin decreased (P < .04) and 61% had iron deficiency (P ≤ .001). Among females with iron deficiency, most did not adhere to supplementation (P = .005), and 59% of these had anemia (P < .001). Vitamin D insufficiency continued after surgery and 80% of participants who did not adhere to supplementation had insufficiency (P = .002). Adolescents not adhering had lower levels of vitamin D, B12, and ferritin (females) compared with both adhering adolescents and the control group (all P < .04). CONCLUSIONS: Half of adolescents after RYGB reported sufficient long-term adherence to supplementation. Adhering to supplements and reporting a higher micronutrient intake were associated with more favorable biochemistry. Results support the recommendations for monitoring micronutrient intake and biochemistry in all patients who have undergone RYGB surgery, and the recommendation of higher preventive supplementation of vitamin D and iron in both sexes. As hypothesized, adolescents not adhering had a higher prevalence of long-term micronutrient deficiencies.

Serum metabolite profiles of habitual diet: evaluation by 1H-nuclear magnetic resonance analysis.

BACKGROUND: Objective and reliable methods to measure dietary exposure and prove associations and causation between diet and health are desirable. OBJECTIVE: The aim of this study was to investigate if 1H-nuclear magnetic resonance (1H-NMR) analysis of serum samples may be used as an objective method to discriminate vegan, vegetarian, and omnivore diets. Specifically, the aim was to identify a metabolite pattern that separated meat-eaters from non-meat-eaters and vegans from nonvegans. METHODS: Healthy volunteers (45 men and 75 women) complying with habitual vegan (n = 43), vegetarian (n = 24 + vegetarians adding fish n = 13), or omnivore (n = 40) diets were enrolled in the study. Data were collected on clinical phenotype, body composition, lifestyle including a food-frequency questionnaire (FFQ), and a 4-d weighed food diary. Serum samples were analyzed by routine clinical test and for metabolites by 1H-NMR spectroscopy. NMR data were nonnormalized, UV-scaled, and analyzed with multivariate data analysis [principal component analysis, orthogonal projections to latent structures (OPLS) and OPLS with discriminant analysis]. In the multivariate analysis volunteers were assigned as meat-eaters (omnivores), non-meat-eaters (vegans and vegetarians), vegans, or nonvegans (lacto-ovo-vegetarians, vegetarians adding fish, and omnivores). Metabolites were identified by line-fitting of 1D 1H-NMR spectra and the use of statistical total correlation spectroscopy. RESULTS: Although many metabolites differ in concentration between men and women as well as by age, body mass index, and body composition, it was possible to correctly classify 97.5% of the meat-eaters compared with non-meat-eaters and 92.5% of the vegans compared with nonvegans. The branched-chain amino acids, creatine, lysine, 2-aminobutyrate, glutamine, glycine, trimethylamine, and 1 unidentified metabolite were among the most important metabolites in the discriminating patterns in relation to intake of both meat and other animal products. CONCLUSIONS: 1H-NMR serum metabolomics appears to be a possible objective tool to identify and predict habitual intake of meat and other animal products in healthy subjects. These results should be confirmed in larger cohort studies or intervention trials. This trial was registered at clinicaltrials.gov as NCT02039609.

The 1H NMR serum metabolomics response to a two meal challenge: a cross-over dietary intervention study in healthy human volunteers.

BACKGROUND: Metabolomics represents a powerful tool for exploring modulation of the human metabolome in response to food intake. However, the choice of multivariate statistical approach is not always evident, especially for complex experimental designs with repeated measurements per individual. Here we have investigated the serum metabolic responses to two breakfast meals: an egg and ham based breakfast and a cereal based breakfast using three different multivariate approaches based on the Projections to Latent Structures framework. METHODS: In a cross over design, 24 healthy volunteers ate the egg and ham breakfast and cereal breakfast on four occasions each. Postprandial serum samples were subjected to metabolite profiling using 1H nuclear magnetic resonance spectroscopy and metabolites were identified using 2D nuclear magnetic resonance spectroscopy. Metabolic profiles were analyzed using Orthogonal Projections to Latent Structures with Discriminant Analysis and Effect Projections and ANOVA-decomposed Projections to Latent Structures. RESULTS: The Orthogonal Projections to Latent Structures with Discriminant Analysis model correctly classified 92 and 90% of the samples from the cereal breakfast and egg and ham breakfast, respectively, but confounded dietary effects with inter-personal variability. Orthogonal Projections to Latent Structures with Effect Projections removed inter-personal variability and performed perfect classification between breakfasts, however at the expense of comparing means of respective breakfasts instead of all samples. ANOVA-decomposed Projections to Latent Structures managed to remove inter-personal variability and predicted 99% of all individual samples correctly. Proline, tyrosine, and N-acetylated amino acids were found in higher concentration after consumption of the cereal breakfast while creatine, methanol, and isoleucine were found in higher concentration after the egg and ham breakfast. CONCLUSIONS: Our results demonstrate that the choice of statistical method will influence the results and adequate methods need to be employed to manage sample dependency and repeated measurements in cross-over studies. In addition, 1H nuclear magnetic resonance serum metabolomics could reproducibly characterize postprandial metabolic profiles and identify discriminatory metabolites largely reflecting dietary composition. TRIAL REGISTRATION: Registered with ClinicalTrials.gov, identifier: NCT02039596 . Date of registration: January 17, 2014.

Distinguishing vegan-, vegetarian-, and omnivorous diets by hair isotopic analysis.

BACKGROUND: Dietary risks contribute heavily to disability-adjusted life years (DALYs), being more important than hypertension, obesity, or smoking. To measure dietary exposure remains a challenge in nutrition research. AIMS: The aim of the present study was to test the hypothesis that isotope ratios of 15N and 13C in human hair could distinguish between subjects adhering to different habitual diets. METHODS: 20 male and 29 female subjects average 31 years old (range 19-53), with stable dietary habits volunteered. Diets were vegan, vegetarian and omnivorous. Hair samples were processed on an elemental analyser coupled to isotope-ratio mass spectrometry. RESULTS: δ15N differed between vegan, vegetarian and omnivorous diets, p < 0.05 for all. δ13C differed between vegan and omnivorous diets, p < 0.05, but neither of these diets were separated from the vegetarian diet. CONCLUSION: Elemental Analysis of δ13C and especially δ15N with isotope ratio mass spectrometry seems to be a promising, non-invasive and objective way to distinguish groups of subjects on different habitual diets, at least if n=>10.