Metabolomic Markers of Essential Fatty Acids, Carnitine, and Cholesterol Metabolism in Adults and Adolescents with Phenylketonuria. Issue 2 (27th February 2018)

• Record Type: Journal Article
• Authors: Stroup, Bridget M; Nair, Nivedita; Murali, Sangita G; Broniowska, Katarzyna; Rohr, Fran; Levy, Harvey L; Ney, Denise M
• Is Part Of: Journal of nutrition. Volume 148:Issue 2(2018)
• Page Start: 194
• Page End: 201
• Publication Date: 2018-02-27
• Subjects: 3-hydroxy 3-methylglutarate -- acylcarnitines -- dihomo-γ-linolenic acid -- deoxycarnitine -- docosahexaenoic acid -- eicosapentaenoic acid -- gamma-linolenic acid -- inflammation -- trimethylamine -- trimethylamine N-oxide; Nutrition -- Periodicals; Diet -- Periodicals; 613.205
• DOI: 10.1093/jn/nxx039
• Languages: English
• ISSNs: 0022-3166

Abstract

Abstract: Background: Individuals with phenylketonuria (PKU) have a risk of cognitive impairment and inflammation. Many follow a low-phenylalanine (low-Phe) diet devoid of animal protein in combination with medical foods (MFs). Objective: To assess lipid metabolism in participants with PKU consuming amino acid MFs (AA-MFs) or glycomacropeptide MFs (GMP-MFs), we conducted fatty acid and metabolomics analyses. Methods: We used subsets of fasting plasma and urine samples from our randomized crossover trial in which participants with early-treated classical and variant (milder) PKU consumed a low-Phe diet combined with AA-MFs or GMP-MFs for 3 wk each. Fatty acid profiles of red blood cell (RBC) membranes were determined for 25 adults (aged 18–49 y) with PKU and 143 control participants. Metabolomics analyses of plasma and urine samples were conducted by Metabolon for 9–10 adolescent and adult participants with PKU and for 15 control participants. Results: RBC fatty acid profiles were not significantly different with AA-MFs or GMP-MFs. PKU participants showed higher total n–6:n–3 (ω-6:ω-3) fatty acids (mean ± SD percentages of total fatty acids: AA-MF = 5.45% ± 1.07%; controls = 4.33%; P < 0.001) and lower docosahexaenoic acid (DHA; AA-MF = 3.21% ± 0.98%; controls = 3.70% ± 1.01%; P = 0.02) and eicosapentaenoic acid (AA-MF = 0.33% ± 0.12%; controls = 0.60% ± 0.43%; P < 0.001) in RBCs than did control participants. Despite higher carnitine intake from AA-MFs than GMP-MFs (mean ± SE intake: AA-MFs = 58.6 ± 5.3 mg/d; GMP-MFs = 0.3 ± 0.01 mg/d; P < 0.001), plasma concentrations of carnitine were similar and not different from those in the control group (AA-MF compared with GMP-MF, P = 0.73). AA-MFs resulted in higher urinary excretion of trimethylamine N-oxide (TMAO), which is synthesized by bacteria from carnitine, compared with GMP-MFs (mean ± SE scaled intensity—TMAO: AA-MFs = 1.2 ± 0.1, GMP-MFs = 0.9 ± 0.1; P = 0.005). Plasma deoxycarnitine was lower in PKU participants than in control participants, suggesting reduced carnitine biosynthesis in PKU (AA-MF = 0.9 ± 0.1; GMP-MF = 1.0 ± 0.1; controls = 1.3 ± 0.1; AA-MF compared with controls, P = 0.01; GMP-MF compared with controls, P = 0.04). Conclusions: Supplementation with DHA is needed in PKU. Carnitine supplementation of AA-MFs shows reduced bioavailability due, in part, to bacterial degradation to TMAO, whereas the bioavailability of carnitine is greater with prebiotic GMP-MFs. This trial was registered at www.clinicaltrials.gov as NCT01428258.