1.
Cardiovascular Biomarkers in Association with Dietary Intake in a Longitudinal Study of Youth with Type 1 Diabetes.
Sanjeevi, N, Lipsky, LM, Nansel, TR
Nutrients. 2018;10(10)
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Plain language summary
Cardiovascular disease (CVD) is the major cause of mortality and morbidity in patients with type 1 diabetes, whose risk is several-fold higher than the general population. The objective of this study was to investigate relationships of CVD biomarkers with overall diet quality, and its dietary components in youth with type 1 diabetes. This study is a secondary analysis of a randomised controlled trial of a family-based behavioural nutrition intervention. The control group had an equal frequency of contact with the research staff but did not receive any nutrition advice besides that included as part of regular type 1 diabetes care. Results indicate that greater intake of whole grains and whole fruits, and lower added sugar and polyunsaturated fatty acids were associated with more favourable CVD biomarkers. Authors conclude that overall diet quality was not associated with CVD biomarkers in youth with type 1 diabetes. However, specific dietary components were associated with CVD biomarkers, independent of glycaemic control.
Abstract
Despite cardioprotective effects of a healthy diet in the general population, few studies have investigated this relationship in individuals with type 1 diabetes, who are at elevated risks of cardiovascular disease (CVD) due to hyperglycemia. The objective of this study was to examine the association of CVD biomarkers with overall diet quality, as measured by the Healthy Eating Index-2015 (HEI-2015), and its dietary components in youth with type 1 diabetes. Youth with type 1 diabetes (n = 136, 8⁻16.9 years) were enrolled in an 18-month behavioral nutrition intervention trial. Dietary intake from three-day diet records, CVD biomarkers (total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C); triglycerides (TG), C-reactive protein (CRP), 8-iso-prostaglandin-F2alpha (8-iso-PGF2α), systolic and diastolic blood pressure (SBP and DBP, respectively), and glycated hemoglobin (HbA1c) were assessed at baseline, 6, 12 and 18 months. Linear mixed-effects models estimated associations of dietary intake with CVD biomarkers, adjusting for HbA1c and other covariates. Separate models estimated associations of time-varying change in dietary intake with time-varying change in CVD biomarkers. HEI-2015 was not associated with CVD biomarkers, but whole grain intake was inversely associated with TC, HDL-C and DBP, and a greater increase in whole fruit intake was associated with lower DBP. Added sugar, saturated fat and polyunsaturated fat were positively related to serum TG, HDL-C, and DBP, respectively. Findings suggest that the intake of specific dietary components, including whole grains, whole fruits, added sugar and PUFA, may influence cardiometabolic health in youth with type 1 diabetes, independent of glycemic control.
2.
Methionine-adequate cysteine-free diet does not limit erythrocyte glutathione synthesis in young healthy adult men.
Courtney-Martin, G, Rafii, M, Wykes, LJ, Ball, RO, Pencharz, PB
The Journal of nutrition. 2008;138(11):2172-8
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Plain language summary
The amino acid cysteine is believed to be a rate-limiting substrate for synthesis of the antioxidant glutathione. The aim of this study was to determine whether cysteine supplementation increased glutathione synthesis in healthy men. Four healthy men of average age 20 years were each given five levels of cysteine intake ranging from 0 to 40mg per kg body weight per day. Each level of intake was given for a period of 3 days, with glutathione levels in red blood cells measured on the 3rd day of each period. Subjects were also provided with a standardised diet, an amino acid mixture equivalent to that found in egg protein, a daily multivitamin supplement, a choline supplement and methionine throughout the study. In this study, increasing cysteine intake did not result in increased glutathione synthesis. The authors concluded that a diet with adequate protein intake is sufficient for glutathione synthesis in healthy adults.
Abstract
Most methods of determining amino acid (AA) requirements are based on endpoints that determine adequacy for protein synthesis. However, the sulfur AA (SAA) cysteine is believed to be the rate-limiting substrate for synthesis of the most abundant intracellular antioxidant, glutathione (GSH). Our objectives were to determine whether supplementation of cysteine in a diet containing adequate SAA for protein synthesis, as methionine, increased GSH synthesis by measuring the fractional and absolute synthesis rates, and if concentration of GSH changed in response to feeding 5 graded intakes of cysteine (0, 10, 20, 30, and 40 mg x kg(-1) x d(-1)) in a random order with a fixed methionine intake of 14 mg x kg(-1) x d(-1) and a protein intake of 1 g x kg(-1) x d(-1). Each subject received a multivitamin and choline supplement during the study. Four healthy adult men each underwent 5 isotope infusion studies of 7-h duration after a 2-d adaptation to the level of cysteine intake being studied on the isotope infusion day. The isotope used was [U-(13)C(2)-(15)N]glycine. Analyses included erythrocyte GSH synthesis rates and concentration and urinary sulfate excretion. The GSH synthesis rates and concentration, measured at a methionine intake of 14 mg x kg(-1) x d(-1), did not change with increasing intakes of cysteine. Urinary sulfate excretion showed a significant positive relationship with cysteine intake (r = 0.92; P < 0.01). In conclusion, this study provides preliminary evidence that consumption of SAA adequate to meet the requirement for protein synthesis does not limit GSH synthesis in healthy adult men receiving an otherwise adequate diet.