Effects of Various Dietary Amino Acid Preparations for Phenylketonuric Patients on the Metabolic Profiles along with Postprandial Insulin and Ghrelin Responses

Abstract

Aim: We investigated the metabolic profiles along with insulin and ghrelin responses following ingestion of various amino acid (AA) substitutes commonly used in the treatment of phenylketonuria to study the effects of added macronutrients. Methods: Twenty healthy and 6 phenylketonuric adults ingested AA mixtures with or without carbohydrates and fat (Anamix, Easiphen, or p-am 3; 0.35 g AA/kg body weight); milk powder shakes were used for control purposes. Serum AA, glucose, urea, insulin, and ghrelin were measured over 5 h. Results: Peak AA concentrations were achieved at around 60 min postprandially for supplemented AA powders and control shakes, significantly later than for pure AA. Of interest, the mean Phe/Tyr ratio declined by 40–50% in phenylketonuric patients following intake of Easiphen, Anamix, or p-am 3. The insulin peaks, up to 500% as compared with baseline, occurred at 30 min and were approximately 100% higher after intake of AA plus macronutrients. Glucose and urea remained constant. Ghrelin showed a nadir at 60 min, followed by a rise leading to a 30% increase of initial concentrations for pure AA as compared with more constant levels for preparations with macronutrients. Conclusion: An oral AA bolus together with macronutrients retards hyperaminoacidemia, displays a higher insulin secretion, normoglycemia, and more stable ghrelin concentrations, whereas the pure AA tested here exerted weaker anabolic effects.

Breakfast with glycomacropeptide compared with amino acids suppresses plasma ghrelin levels in individuals with phenylketonuria

“…Similarly, our results show that postprandial plasma insulin concentration is higher and ghrelin lower after a breakfast containing GMP compared with an AA-based breakfast. Weigel et al [47] found oral AAs given with macronutrients increased insulin concentration to a greater degree and gave a more stable ghrelin concentration than pure AAs in individuals with PKU. Moreover, whey proteins have been shown to be insulinotrophic [48].…”

Carnitine Status in Early-Treated Children, Adolescents and Young Adults with Phenylketonuria on Low Phenylalanine Diets

“…Body weight was measured with calibrated devices. Acylcarnitines were analyzed in dried blood spots by tandem mass spectrometry [7] ; AA analysis was carried out as reported previously [8] . Briefly, samples were deproteinized with a 10% sulfosalicylic acid solution.…”

Evaluation of Plasma Trace Element and Mineral Status in Children and Adolescents with Phenylketonuria Using Data from Inductively-Coupled-Plasma Atomic Emission and Mass Spectrometric Analysis

“…Our group has previously reported distinctive alterations in the metabolic profiles following ingestion of various dietary amino acid mixtures commonly used in the treatment of PKU [11]. We thus proposed to study bio-element status in children and adolescents with PKU, using highly specific ICP-AES and ICP-MS technologies which provide superior sensitivity (down to part per trillion and/or billion levels in solution, respectively).…”