Acute effects of oral mesna administration on the full amino acid profile and 3-methylhistidine: secondary results from the CYLOB dose-finding study.

Plasma total cysteine (tCys) is strongly associated with fat mass in humans. Mesna lowers plasma tCys in a dose-dependent manner, but it is not known whether it interferes with metabolism of other amino acids or protein. In this Phase-1 study, we show that a single dose of mesna administered at 400, 800, 1200 or 1600 mg to 6-7 individuals per dose only slightly affects amino acid profiles, with increases in plasma valine across dose levels. There were no effects of mesna on 3-methylhistidine, a marker of protein breakdown.

The Effect of Alginate Encapsulated Plant-Based Carbohydrate and Protein Supplementation on Recovery and Subsequent Performance in Athletes.

The main purpose of this study was to investigate the effect of a novel alginate-encapsulated carbohydrate-protein (CHO-PRO ratio 2:1) supplement (ALG) on cycling performance. The ALG, designed to control the release of nutrients, was compared to an isocaloric carbohydrate-only control (CON). Alginate encapsulation of CHOs has the potential to reduce the risk of carious lesions. METHODS: In a randomised cross-over clinical trial, 14 men completed a preliminary test over 2 experimental days separated by ~6 days. An experimental day consisted of an exercise bout (EX1) of cycling until exhaustion at W~73%, followed by 5 h of recovery and a subsequent time-to-exhaustion (TTE) performance test at W~65%. Subjects ingested either ALG (0.8 g CHO/kg/hr + 0.4 g PRO/kg/hr) or CON (1.2 g CHO/kg/hr) during the first 2 h of recovery. RESULTS: Participants cycled on average 75.2 ± 5.9 min during EX1. Levels of plasma branched-chain amino acids decreased significantly after EX1, and increased significantly with the intake of ALG during the recovery period. During recovery, a significantly higher plasma insulin and glucose response was observed after intake of CON compared to ALG. Intake of ALG increased plasma glucagon, free fatty acids, and glycerol significantly. No differences were found in the TTE between the supplements (p = 0.13) nor in the pH of the subjects' saliva. CONCLUSIONS: During the ALG supplement, plasma amino acids remained elevated during the recovery. Despite the 1/3 less CHO intake with ALG compared to CON, the TTE performance was similar after intake of either supplement.

Determination of underivatized amino acids in human plasma using ion pair liquid chromatography/tandem mass spectrometry.

Accurate quantification of amino acids (AA) is essential for several applications, including clinical research, food analysis, and pharmaceutical studies. In this study, we developed an analytical method based on liquid chromatography with electrospray ionization coupled to tandem mass spectrometry detection (LC-ESI-MS/MS). This method was devised to accurately quantify a spectrum of amino acids, notably taurine, creatinine, glutathione (GSH), and sulfur-containing amino acids (SAAs) such as methionine, cysteine, and homocysteine, using only 10 µL of human plasma. A stable isotope derivative of each AA is used as an internal standard (IS) for accurate quantification. For retention and separation on a C18 column, heptafluorobutyric acid (HFBA) was employed as an ion pair agent. Multiple reaction monitoring (MRM) in positive mode with the precursor-to-product ion transitions at m/z is used for quantification. The method showed excellent linearity for all AA with a high correlation coefficient (r > 0.9927). The linear fit indicates that the detector response is linear over the tested range of standard concentrations. The accuracy and precision of the method were within the acceptable range of 92-110% and < 15%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were in the range of 0.001-1.80 µM and 0.004-6.0 µM, respectively. No significant ion suppression or carry over was observed. In conclusion, the assay was validated and found to have adequate accuracy, precision, linearity, sensitivity and selectivity. The assay has been successfully applied to the analysis of human plasma.

Cysteine-lowering treatment with mesna against obesity: Proof of concept and results from a human phase I, dose-finding study.

AIM: To investigate whether mesna-sodium-2-mercaptoethane sulfonate) can reduce diet-induced fat gain in mice, and to assess the safety of single ascending mesna doses in humans to find the dose associated with lowering of plasma tCys by at least 30%. METHODS: C3H/HeH mice were shifted to a high-fat diet ± mesna in drinking water; body composition was measured at weeks 0, 2 and 4. In an open, phase I, single ascending dose study, oral mesna (400, 800, 1200, 1600 mg) was administered to 17 men with overweight or obesity. Mesna and tCys concentrations were measured repeatedly for a duration of 48 hours postdosing in plasma, as well as in 24-hour urine. RESULTS: Compared with controls, mesna-treated mice had lower tCys and lower estimated mean fat mass gain from baseline (week 2: 4.54 ± 0.40 vs. 6.52 ± 0.36 g; week 4: 6.95 ± 0.35 vs. 8.19 ± 0.34 g; Poverall = .002), but similar lean mass gain. In men with overweight, mesna doses of 400-1600 mg showed dose linearity and were well tolerated. Mesna doses of 800 mg or higher decreased plasma tCys by 30% or more at nadir (4h post-dosing). With increasing mesna dose, tCys AUC0-12h decreased (Ptrend < .001), and urine tCys excretion increased (Ptrend = .004). CONCLUSIONS: Mesna reduces diet-induced fat gain in mice. In men with overweight, single oral doses of mesna (800-1600 mg) were well tolerated and lowered plasma tCys efficiently. The effect of sustained tCys-lowering by repeated mesna administration on weight loss in humans deserves investigation.

Acute changes in antioxidants and oxidative stress to vigorous arm exercise: an intervention trial in persons with spinal cord injury and healthy controls.

STUDY DESIGN: Intervention trial. BACKGROUND: Literature remains unclear on possible health benefits and risks assosciated with high intensity exercise for persons with SCI. Elevated oxidative stress levels might influence their ability to exercise at high intensity. We investigated several biomarkers of oxidative stress and antioxidant defense at rest, during and after vigorous exercise among persons with chronic SCI. SETTING: Sunnaas Rehabilitation Hospital, Norway. METHODS: Six participants (five males) with chronic SCI (AIS A, injury level thoracic 2-8, >1 year postinjury) and six matched able-bodied controls performed two maximal arm-cranking tests, with one-three days in between. During the second exercise test, participants performed three bouts with four minutes arm cranking at high intensity (85-95% of peak heart rate (HRpeak)), before they reached maximal effort. Blood and urine biomarkers for oxidative stress and antioxidant levels were collected at six time points at the day of the second exercise test; baseline, at high intensity exercise, at maximal effort, at five, 30 and 60 min post-exercise, and 24 h post exercise. RESULTS: Participants with SCI had significant lower levels of creatinine (∆16 µmol/L, p = 0.03), α-carotene (∆0.14 nmol/L, p < 0.001) and ß-carotene (∆0.51 nmol/L, p = 0.001) at baseline compared to controls. Urine and blood biomarkers of oxidative stress and antioxidant levels showed similar response to vigorous exercise in the SCI and control group. CONCLUSIONS: SCI participants showed similar changes in redox status during high intensity exercise compared to matched able-bodied. SCI participants had lower levels of exogen antioxidants both before, during and after vigorous exercise.

The Associations of Habitual Intake of Sulfur Amino Acids, Proteins and Diet Quality with Plasma Sulfur Amino Acid Concentrations: The Maastricht Study.

BACKGROUND: Plasma sulfur amino acids (SAAs), i.e., methionine, total cysteine (tCys), total homocysteine (tHcy), cystathionine, total glutathione (tGSH), and taurine, are potential risk factors for obesity and cardiometabolic disorders. However, except for plasma tHcy, little is known about how dietary intake modifies plasma SAA concentrations. OBJECTIVE: To investigate whether the intake of SAAs and proteins or diet quality is associated with plasma SAAs. METHODS: Data from a cross-sectional subset of The Maastricht Study (n = 1145, 50.5% men, 61 interquartile range: [55, 66] y, 22.5% with prediabetes and 34.3% with type 2 diabetes) were investigated. Dietary intake was assessed using a validated food frequency questionnaire. The intake of SAAs (total, methionine, and cysteine) and proteins (total, animal, and plant) was estimated from the Dutch and Danish food composition tables. Diet quality was assessed using the Dutch Healthy Diet Index, the Mediterranean Diet Score, and the Dietary Approaches to Stop Hypertension score. Fasting plasma SAAs were measured by liquid chromatography (LC) tandem mass spectrometry (MS) (LC/MS-MS). Associations were investigated with multiple linear regressions with tertiles of dietary intake measures (main exposures) and z-standardized plasma SAAs (outcomes). RESULTS: Intake of total SAAs and total proteins was positively associated with plasma tCys and cystathionine. Associations were stronger in women and in those with normal body weight. Higher intake of cysteine and plant proteins was associated with lower plasma tHcy and higher cystathionine. Higher methionine intake was associated with lower plasma tGSH, whereas cysteine intake was positively associated with tGSH. Higher intake of methionine and animal proteins was associated with higher plasma taurine. Better diet quality was consistently related to lower plasma tHcy concentrations, but it was not associated with the other SAAs. CONCLUSION: Targeted dietary modifications might be effective in modifying plasma concentrations of tCys, tHcy, and cystathionine, which have been associated with obesity and cardiometabolic disorders.

Associations between dietary intake and glucose tolerance in clinical and metabolomics-based metabotypes.

BACKGROUND: Metabotyping is a novel concept to group metabolically similar individuals. Different metabotypes may respond differently to dietary interventions; hence, metabotyping may become an important future tool in precision nutrition strategies. However, it is not known if metabotyping based on comprehensive omic data provides more useful identification of metabotypes compared to metabotyping based on only a few clinically relevant metabolites. AIM: This study aimed to investigate if associations between habitual dietary intake and glucose tolerance depend on metabotypes identified from standard clinical variables or comprehensive nuclear magnetic resonance (NMR) metabolomics. METHODS: We used cross-sectional data from participants recruited through advertisements aimed at people at risk of type 2 diabetes mellitus (n = 203). Glucose tolerance was assessed with a 2-h oral glucose tolerance test (OGTT), and habitual dietary intake was recorded with a food frequency questionnaire. Lipoprotein subclasses and various metabolites were quantified with NMR spectroscopy, and plasma carotenoids were quantified using high-performance liquid chromatography. We divided participants into favorable and unfavorable clinical metabotypes based on established cutoffs for HbA1c and fasting and 2-h OGTT glucose. Favorable and unfavorable NMR metabotypes were created using k-means clustering of NMR metabolites. RESULTS: While the clinical metabotypes were separated by glycemic variables, the NMR metabotypes were mainly separated by variables related to lipoproteins. A high intake of vegetables was associated with a better glucose tolerance in the unfavorable, but not the favorable clinical metabotype (interaction, p = 0.01). This interaction was confirmed using plasma concentrations of lutein and zeaxanthin, objective biomarkers of vegetable intake. Although non-significantly, the association between glucose tolerance and fiber intake depended on the clinical metabotypes, while the association between glucose tolerance and intake of saturated fatty acids and dietary fat sources depended on the NMR metabotypes. CONCLUSION: Metabotyping may be a useful tool to tailor dietary interventions that will benefit specific groups of individuals. The variables that are used to create metabotypes will affect the association between dietary intake and disease risk.

The association of fasting plasma thiol fractions with body fat compartments, biomarker profile, and adipose tissue gene expression.

People with high plasma total cysteine (tCys) have higher fat mass and higher concentrations of the atherogenic apolipoprotein B (apoB). The disulfide form, cystine, enhanced human adipogenesis and correlated with total fat mass in a Middle-Eastern cohort. In 35 European adults with overweight (88.6% women) and with dual-X-ray absorptiometry measurements of regional fat, we investigated how cystine compared to other free disulfides in their association with total regional adiposity, plasma lipid and glucose biomarkers, and adipose tissue lipid enzyme mRNA (n = 19). Most total plasma homocysteine (tHcy) (78%) was protein-bound; 63% of total glutathione (tGSH) was reduced. tCys was 49% protein-bound, 30% mixed-disulfide, 15% cystine, and 6% reduced. Controlling for age and lean mass, cystine and total free cysteine were the fractions most strongly associated with android and total fat: 1% higher cystine predicted 1.97% higher android fat mass (95% CI 0.64, 3.31) and 1.25% (0.65, 2.98) higher total fat mass (both p = 0.005). A positive association between tCys and apoB (ß: 0.64%; 95% CI 0.17, 1.12%, p = 0.009) was apparently driven by free cysteine and cystine; cystine was also inversely associated with the HDL-associated apolipoprotein A1 (ß: -0.57%; 95% CI -0.96, -0.17%, p = 0.007). No independent positive associations with adiposity were noted for tGSH or tHcy fractions. Plasma cystine correlated with CPT1a mRNA (Spearman's r = 0.68, p = 0.001). In conclusion, plasma cystine-but not homocysteine or glutathione disulfides-is associated with android adiposity and an atherogenic plasma apolipoprotein profile. The role of cystine in human adiposity and cardiometabolic risk deserves investigation. ClinicalTrials.gov identifiers: NCT02647970 and NCT03629392.

Cysteine restriction-specific effects of sulfur amino acid restriction on lipid metabolism.

Decreasing the dietary intake of methionine exerts robust anti-adiposity effects in rodents but modest effects in humans. Since cysteine can be synthesized from methionine, animal diets are formulated by decreasing methionine and eliminating cysteine. Such diets exert both methionine restriction (MR) and cysteine restriction (CR), that is, sulfur amino acid restriction (SAAR). Contrarily, SAAR diets formulated for human consumption included cysteine, and thus might have exerted only MR. Epidemiological studies positively correlate body adiposity with plasma cysteine but not methionine, suggesting that CR, but not MR, is responsible for the anti-adiposity effects of SAAR. Whether this is true, and, if so, the underlying mechanisms are unknown. Using methionine- and cysteine-titrated diets, we demonstrate that the anti-adiposity effects of SAAR are due to CR. Data indicate that CR increases serinogenesis (serine biosynthesis from non-glucose substrates) by diverting substrates from glyceroneogenesis, which is essential for fatty acid reesterification and triglyceride synthesis. Molecular data suggest that CR depletes hepatic glutathione and induces Nrf2 and its downstream targets Phgdh (the serine biosynthetic enzyme) and Pepck-M. In mice, the magnitude of SAAR-induced changes in molecular markers depended on dietary fat concentration (60% fat >10% fat), sex (males > females), and age-at-onset (young > adult). Our findings are translationally relevant as we found negative and positive correlations of plasma serine and cysteine, respectively, with triglycerides and metabolic syndrome criteria in a cross-sectional epidemiological study. Controlled feeding of low-SAA, high-polyunsaturated fatty acid diets increased plasma serine in humans. Serinogenesis might be a target for treating hypertriglyceridemia.

Endogenous glutamine is rate-limiting for anti-CD3 and anti-CD28 induced CD4+ T-cell proliferation and glycolytic activity under hypoxia and normoxia.

To meet the demand for energy and biomass, T lymphocytes (T cells) activated to proliferation and clonal expansion, require uptake and metabolism of glucose (Gluc) and the amino acid (AA) glutamine (Gln). Whereas exogenous Gln is converted to glutamate (Glu) by glutaminase (GLS), Gln is also synthesized from the endogenous pool of AA through Glu and activity of glutamine synthase (GS). Most of this knowledge comes from studies on cell cultures under ambient oxygen conditions (normoxia, 21% O2). However, in vivo, antigen induced T-cell activation often occurs under moderately hypoxic (1-4% O2) conditions and at various levels of exogenous nutrients. Here, CD4+ T cells were stimulated for 72 h with antibodies targeting the CD3 and CD28 markers at normoxia and hypoxia (1% O2). This was done in the presence and absence of the GLS and GS inhibitors, Bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl) ethyl sulfide (BPTES) and methionine sulfoximine (MSO) and at various combinations of exogenous Gluc, Gln and pyruvate (Pyr) for the last 12 h of stimulation. We found that T-cell proliferation, viability and levels of endogenous AA were significantly influenced by the availability of exogenous Gln, Gluc and Pyr as well as inhibition of GLS and GS. Moreover, inhibition of GLS and GS and levels of oxygen differentially influenced oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Finally, BPTES-dependent down-regulation of ECAR was associated with reduced hexokinase (HK) activity at both normoxia and hypoxia. Our results demonstrate that Gln availability and metabolism is rate-limiting for CD4+ T-cell activity.

The dihydrofolate reductase 19-bp deletion modifies the beneficial effect of B-vitamin therapy in mild cognitive impairment: pooled study of two randomized placebo-controlled trials.

BACKGROUND: Higher serum homocysteine is associated with cognitive decline in older people. But homocysteine-lowering trials including folic acid (FA) show inconsistent results on cognitive decline. The reduction of FA to dihydrofolate by dihydrofolate reductase (DHFR) is slow in humans. OBJECTIVE: We examined the effects of the DHFR 19-bp deletion/insertion (del/ins) polymorphism on FA-containing treatment on cognitive decline and brain atrophy in older people with mild cognitive impairment (MCI). METHODS: This study used pooled data from two randomized B-vitamin trials on 545 MCI subjects who received either FA-containing B vitamins or placebo for 24 months. Subjects were typed for the DHFR genotype. Primary outcome was the Clinical Dementia Rating scale-global score (CDR-global). Secondary outcomes were CDR-sum of boxes score (CDR-SOB), memory and executive Z-scores and whole brain atrophy rate by serial MRI. RESULTS: The proportions of subjects with del/del, del/ins and ins/ins genotype were 29.5, 44.3 and 26.1%, respectively. DHFR genotypes modified the effects of B vitamins on CDR-global, CDR-SOB and executive function Z-score (Pinteraction = 0.017, 0.014 and 0.052, respectively), with significant benefits being observed only in those with ins/ins genotype (Beta = -1.367, -0.614 and 0.315, P = 0.004, 0.014 and 0.012, respectively). The interaction was not significant for memory Z-score and whole brain atrophy rate. Notably, the supplements only slowed brain atrophy in members of the 'ins/ins' group who were not using aspirin. CONCLUSIONS: Our data indicate that the beneficial effects of B vitamins including FA on cognitive function are only apparent in those with ins/ins genotype, i.e. relatively better preserved DHFR activity.

Bilberry/red grape juice decreases plasma biomarkers of inflammation and tissue damage in aged men with subjective memory impairment -a randomized clinical trial.

BACKGROUND: Few randomized clinical trials have explored the health effects of bilberries in humans. The aim was to test the effect of bilberry and red grape-juice consumption on visual memory, motor speed and dexterity as well as inflammatory and tissue damage biomarkers of plasma in aged men with subjective memory impairment. METHODS: Nine-week double-blind, placebo-controlled, dietary intervention study of aged men (n = 60, age ≥ 67 years) with subjective memory impairment randomized to consume a 50/50 mix of bilberry/red grape-juice or an iso-caloric placebo juice. A selection of Cambridge Cognition Test Battery (CANTAB), Grooved Pegboard tests and blood-sampling for biomarker analysis were performed before and after the intervention. RESULTS: Compared to placebo the selected memory and motor test scores were un-affected by the bilberry/red grape intervention. However, the plasma levels of tissue damage biomarkers decreased significantly more in the bilberry/red grape group. In particular lactate dehydrogenase (LDH) decreased from 362 U/L (median, baseline) to 346 U/L (median, post intervention) in the bilberry/red grape group. Also, several biomarkers of inflammation (EGF, IL6, IL9, IL10 and TNFα) decreased significantly more in the bilberry/red grape group. Furthermore, several plasma polyphenols; p-coumaric acid, hippuric acid, protocatechuic acid, 3HPAA and vanillic acid, increased significantly more in the bilberry/red grape group compared to placebo with the largest increase in p-coumaric acid with 116%; from 2.2 [1.0,5.5] to 4.7 [2.8,8.1] µM/L (median [95% CL]). CONCLUSIONS: The results indicate that a nine-week bilberry/red grape juice intervention has no measurable effects on the selected memory scores in aged men experiencing memory problems but decreases the level of biomarkers of inflammation and tissue damage. Whether the dampening effects on inflammation and tissue damage biomarkers have relevance for neuroinflammatory brain pathology remains to be established. TRIAL REGISTRATION: Registration number ( ClinicalTrials.gov : NCT00972972 ), September 9, 2009.

Effects of short-term methionine and cysteine restriction and enrichment with polyunsaturated fatty acids on oral glucose tolerance, plasma amino acids, fatty acids, lactate and pyruvate: results from a pilot study.

OBJECTIVE: In this 7-day pilot study we randomized healthy, normal-weight men and women to either a dietary intervention with methionine and cysteine restriction enriched in PUFA (Met/Cyslow + PUFA, n = 7) or with high contents of methionine, cysteine and SFA (Met/Cyshigh + SFA, n = 7). The objective was to describe the short-term responses in oral glucose tolerance, amino acid profile, total fatty acid profile, pyruvate and lactate following a Met/Cyslow + PUFA diet vs. Met/Cyshigh + SFA. RESULTS: The diet groups consisted of five women and two men, aged 20-38 years. After the 7-d intervention median pre- and post-oral glucose tolerance test (OGTT) glucose concentrations were 5 mmol/L and 4 mmol/L respectively in the Met/Cyslow + PUFA group. In the Met/Cyshigh + SFA group, median pre- and post-OGTT glucose concentrations were 4.8 mmol/L and 4.65 mmol/L after the 7-d intervention. The responses in the amino acid profiles were similar in both groups during the intervention with the exception of serine. Fatty acids decreased from baseline to day 7 in both groups. Plasma lactate and pyruvate were similar for both groups with an increase to day 3 before approaching baseline values at day 7. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02647970, registration date: January 6th 2016.

Dietary Adjustments to Altitude Training in Elite Endurance Athletes; Impact of a Randomized Clinical Trial With Antioxidant-Rich Foods.

Background: Altitude training stresses several physiological and metabolic processes and alters the dietary needs of the athletes. International Olympic Committee (IOC)'s Nutrition Expert Group suggests that athletes should increase intake of energy, carbohydrate, iron, fluid, and antioxidant-rich foods while training at altitude. Objective: We investigated whether athletes adjust their dietary intake according to the IOC's altitude-specific dietary recommendations, and whether an in-between meal intervention with antioxidant-rich foods altered the athletes' dietary composition and nutrition-related blood parameters (mineral, vitamin, carotenoid, and hormone concentrations). Design: The dietary adjustments to altitude training (3 weeks at 2,320 m) were determined for 31 elite endurance athletes (23 ± 5 years, 23 males, 8 females) by six interviewer-administered 24-h dietary recalls on non-consecutive days; three before and during the altitude camp. The additional effect of in -between meal intervention with eucaloric antioxidant-rich or control snacks (1,000 kcal/day) was tested in a randomized controlled trial with parallel design. Results: At altitude the athletes increased their energy intake by 35% (1,430 ± 630 kcal/day, p < 0.001), the provided snacks accounting for 70% of this increase. Carbohydrate intake increased from 6.5 ± 1.8 g/kg body weight (BW) (50 E%) to 9.3 ± 2.1 g/kg BW (53 E%) (p < 0.001), with no difference between the antioxidant and control group. Dietary iron, fluid, and antioxidant-rich food intake increased by 37, 38, and 104%, respectively, in the whole cohort. The intervention group had larger increases in polyunsaturated fatty acids (PUFA), ω3 PUFA (n-3 fatty acids), ω6 PUFA (n-6 fatty acids), fiber, vitamin C, folic acid, and copper intake, while protein intake increased more among the controls, reflecting the nutritional content of the snacks. Changes in the measured blood minerals, vitamins, and hormones were not differentially affected by the intervention except for the carotenoid; zeaxanthin, which increased more in the intervention group (p < 0.001). Conclusions: Experienced elite endurance athletes increased their daily energy, carbohydrate, iron, fluid, and antioxidant-rich food intake during a 3-week training camp at moderate altitude meeting most of the altitude-specific dietary recommendations. The intervention with antioxidant-rich snacks improved the composition of the athletes' diets but had minimal impact on the measured nutrition-related blood parameters. Clinical Trial Registry Number: NCT03088891 (www.clinicaltrials.gov), Norwegian registry number: 626539 (https://rekportalen.no/).

Postprandial effects of a meal low in sulfur amino acids and high in polyunsaturated fatty acids compared to a meal high in sulfur amino acids and saturated fatty acids on stearoyl CoA-desaturase indices and plasma sulfur amino acids: a pilot study.

OBJECTIVE: The sulfur amino acid (SAA) cysteine is positively related, whereas polyunsaturated fatty acids (PUFAs) are inversely related to activity of the lipogenic enzyme stearoyl-CoA desaturase (SCD). High SCD activity promotes obesity in animals, and plasma activity indices positively associates with fat mass in humans. SCD may thus be a target for dietary intervention with SAA restriction and PUFA enrichment with unknown potential benefits for body composition. We randomized ten healthy individuals to a meal restricted in SAAs and enriched with PUFAs (Cys/Metlow + PUFA) (n = 5) or a meal enriched in SAA and saturated fatty acids (Cys/Methigh + SFA) (n = 5). We measured plasma SCD activity indices (SCD16 and SCD18) and SAAs response hourly from baseline and up to 4 h postprandial. RESULTS: SCD16 was unchanged whereas SCD18 tended to increase in the Cys/Metlow + PUFA compared to the Cys/Methigh + SFA group (ptime*group interaction = 0.08). Plasma concentrations of total cysteine fractions including free and reduced cysteine decreased in the Cys/Metlow + PUFA compared to the Cys/Methigh + SFA group (both ptime*group interaction < 0.001). In conclusion, a meal low in SAA but high in PUFAs reduced plasma cysteine fractions but not SCD activity indices. This pilot study can be useful for the design and diet composition of future dietary interventions that targets SCD and SAA. Trial registration ClinicalTrials.gov: NCT02647970, registration date: 6 January 2016.

Effects of dietary methionine and cysteine restriction on plasma biomarkers, serum fibroblast growth factor 21, and adipose tissue gene expression in women with overweight or obesity: a double-blind randomized controlled pilot study.

BACKGROUND: Dietary restriction of methionine and cysteine is a well-described model that improves metabolic health in rodents. To investigate the translational potential in humans, we evaluated the effects of dietary methionine and cysteine restriction on cardiometabolic risk factors, plasma and urinary amino acid profile, serum fibroblast growth factor 21 (FGF21), and subcutaneous adipose tissue gene expression in women with overweight and obesity in a double-blind randomized controlled pilot study. METHODS: Twenty women with overweight or obesity were allocated to a diet low (Met/Cys-low, n = 7), medium (Met/Cys-medium, n = 7) or high (Met/Cys-high, n = 6) in methionine and cysteine for 7 days. The diets differed only by methionine and cysteine content. Blood and urine were collected at day 0, 1, 3 and 7 and subcutaneous adipose tissue biopsies were taken at day 0 and 7. RESULTS: Plasma methionine and cystathionine and urinary total cysteine decreased, whereas FGF21 increased in the Met/Cys-low vs. Met/Cys-high group. The Met/Cys-low group had increased mRNA expression of lipogenic genes in adipose tissue including DGAT1. When we excluded one participant with high fasting insulin at baseline, the Met/Cys-low group showed increased expression of ACAC, DGAT1, and tendencies for increased expression of FASN and SCD1 compared to the Met/Cys-high group. The participants reported satisfactory compliance and that the diets were moderately easy to follow. CONCLUSIONS: Our data suggest that dietary methionine and cysteine restriction may have beneficial effects on circulating biomarkers, including FGF21, and influence subcutaneous adipose tissue gene expression. These results will aid in the design and implementation of future large-scale dietary interventions with methionine and cysteine restriction. Trial registration ClinicalTrials.gov Identifier: NCT03629392, registration date: 14/08/2018 https://clinicaltrials.gov/ct2/show/NCT03629392.

Vitamin B12 concentrations in milk from Norwegian women during the six first months of lactation.

BACKGROUND: Human milk vitamin B12 (B12) concentrations depend on maternal status and intake; only few data are available in high-income countries. OBJECTIVE: We assessed human milk B12 concentrations during the first 6 months postpartum in Norwegian women and its association with maternal dietary B12 intake and maternal urinary methylmalonic acid (MMA) concentration. METHODS: In this cross-sectional study, 175 mothers, exclusively (80%) or partially (20%) breastfeeding, were included. Milk B12 was measured by IMMULITE®/IMMULITE® 1000 B12 competitive protein binding assay and urinary MMA relative to creatinine (MMA/Cr) by liquid chromatography-tandem-mass spectrometry. Maternal habitual B12 intake and supplement use were estimated using a food frequency questionnaire. RESULTS: Mean human milk B12 concentration was 327 pmol/L (range 140-1089), with 402 pmol/L at 1 month (n = 21), 333 pmol/L at four months (n = 32), and 299 pmol/L at 6 months (n = 21). Maternal B12 intake was 5 µg/d, 89% met the Estimated Average Requirement, and supplement use did not affect milk B12 concentrations. MMA/Cr was low in all women compared with published data. In exclusively breastfeeding women, MMA/Cr (beta (95% CI) -42.5 (-82.5, -2.5) and time since birth (-4.9 (-9.6, -0.3)) were significant predictors of human milk B12 concentrations. There was no association between total B12 intake and milk B12 concentration or between total B12 intake and MMA/Cr. CONCLUSIONS: Maternal B12 status and human milk B12 concentrations are likely sufficient, based on adequate maternal B12 dietary intake combined with low urinary MMA concentrations. Nevertheless, milk B12 concentration fell during 6 months postpartum while maternal B12 status did not change.

Combining Dietary Sulfur Amino Acid Restriction with Polyunsaturated Fatty Acid Intake in Humans: A Randomized Controlled Pilot Trial.

Dietary and plasma total cysteine (tCys) have been associated with adiposity, possibly through interaction with stearoyl⁻CoA desaturase (SCD), which is an enzyme that is involved in fatty acid and energy metabolism. We evaluated the effect of a dietary intervention with low cysteine and methionine and high polyunsaturated fatty acids (PUFAs) on plasma and urinary sulfur amino acids and SCD activity indices. Fourteen normal-weight healthy subjects were randomized to a seven-day diet low in cysteine and methionine and high in PUFAs (Cys/Metlow + PUFA), or high in saturated fatty acids (SFA), cysteine, and methionine (Cys/Methigh + SFA). Compared with the Cys/Methigh + SFA group, plasma methionine and cystathionine decreased (p-values < 0.05), whereas cystine tended to increase (p = 0.06) in the Cys/Metlow + PUFA group. Plasma total cysteine (tCys) was not significantly different between the groups. Urinary cysteine and taurine decreased in the Cys/Metlow + PUFA group compared with the Cys/Methigh + SFA group (p-values < 0.05). Plasma SCD-activity indices were not different between the groups, but the change in cystine correlated with the SCD-16 index in the Cys/Metlow + PUFA group. A diet low in methionine and cysteine decreased plasma methionine and urinary cysteine and taurine. Plasma tCys was unchanged, suggesting that compensatory mechanisms are activated during methionine and cysteine restriction to maintain plasma tCys.

Plasma amino acids, adiposity, and weight change after gastric bypass surgery: are amino acids associated with weight regain?

PURPOSE: Plasma concentrations of several amino acids (AAs) are positively correlated with obesity. The aim of this study was to examine if selected plasma AAs are associated with weight regain from 2 to 4 years after Roux-en-Y gastric bypass (RYGB). METHODS: In a prospective study with 165 patients, we examined the relationship between plasma aromatic AAs (AAAs), branched chain AAs (BCAAs), and total cysteine (tCys) 2 years after RYGB, with BMI at 2 years and with weight change from 2 to 4 years after surgery. Analyses were adjusted for relevant covariates. RESULT: The investigated AAs at 2 years correlated positively with BMI at 2 years (P ≤ 0.003 for all). BCAAs and AAAs at 2 years correlated inversely with % weight loss from 0 to 2 years (P = 0.002 and P = 0.001, respectively), while the association was not significant for tCys (r = -0.14, P = 0.08). Plasma tCys at 2 years correlated positively with BMI at 4 years (P = 0.010) and with weight regain from 2 to 4 years (P = 0.015). CONCLUSION: Plasma AAAs, BCAAs, and tCys at 2 years were associated with BMI at 2 years. In addition, plasma AAAs and BCAAs at 2 years were associated with weight loss from 0 to 2 years, while tCys at 2 years was associated with weight regain from 2 to 4 years after RYGB. These results suggest that high tCys at 2 years may be used as a prognostic marker for future weight regain. The study was registered in ClinicalTrials.gov (NCT0 1270451).