Trial reportThe American journal of clinical nutrition2016
Protein ingestion acutely inhibits insulin-stimulated muscle carnitine uptake in healthy young men.
Trial report in The American journal of clinical nutrition, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
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The trial behind it
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Who cites it
4 citing papers in PubMed, 17 citations in OpenAlex.
- Caffeine ingestion stimulates plasma carnitine clearance in humans.Physiological reports · 2023Trial
- Postexercise myofibrillar protein synthesis rates do not differ following 1.5 g essential amino acids compared with 15 and 20 g of whey protein in young females.American journal of physiology. Endocrinology and metabolism · 2025Article
- Increasing skeletal muscle carnitine content in older individuals increases whole-body fat oxidation during moderate-intensity exercise.Aging cell · 2021Article
- "Nutraceuticals" in relation to human skeletal muscle and exercise.American journal of physiology. Endocrinology and metabolism · 2017Review
Corrections and comments
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Authors and funding
4 authors at 1 institution in 1 country.
Funding
Abstract
backgroundIncreasing skeletal muscle carnitine content represents an appealing intervention in conditions of perturbed lipid metabolism such as obesity and type 2 diabetes but requires chronic L-carnitine feeding on a daily basis in a high-carbohydrate beverage.
objectiveWe investigated whether whey protein ingestion could reduce the carbohydrate load required to stimulate insulin-mediated muscle carnitine accretion.
designSeven healthy men [mean ± SD age: 24 ± 5 y; body mass index (in kg/m(2)): 23 ± 3] ingested 80 g carbohydrate, 40 g carbohydrate + 40 g protein, or control (flavored water) beverages 60 min after the ingestion of 4.5 g L-carnitine tartrate (3 g L-carnitine; 0.1% (2)[H]3-L-carnitine). Serum insulin concentration, net forearm carnitine balance (NCB; arterialized-venous and venous plasma carnitine difference × brachial artery flow), and carnitine disappearance (Rd) and appearance (Ra) rates were determined at 20-min intervals for 180 min.
resultsSerum insulin and plasma flow areas under the curve (AUCs) were similarly elevated by carbohydrate [4.5 ± 0.8 U/L · min (P < 0.01) and 0.5 ± 0.6 L (P < 0.05), respectively] and carbohydrate+protein [3.8 ± 0.6 U/L · min (P < 0.01) and 0.4 ± 0.6 L (P = 0.05), respectively] consumption, respectively, compared with the control visit (0.04 ± 0.1 U/L · min and -0.5 ± 0.2 L). Plasma carnitine AUC was greater after carbohydrate+protein consumption (3.5 ± 0.5 mmol/L · min) than after control and carbohydrate visits [2.1 ± 0.2 mmol/L · min (P < 0.05) and 1.9 ± 0.3 mmol/L · min (P < 0.01), respectively]. NCB AUC with carbohydrate (4.1 ± 3.1 μmol) was greater than during control and carbohydrate-protein visits (-8.6 ± 3.0 and -14.6 ± 6.4 μmol, respectively; P < 0.05), as was Rd AUC after carbohydrate (35.7 ± 25.2 μmol) compared with control and carbohydrate consumption [19.7 ± 15.5 μmol (P = 0.07) and 14.8 ± 9.6 μmol (P < 0.05), respectively].
conclusionsThe insulin-mediated increase in forearm carnitine balance with carbohydrate consumption was acutely blunted by a carbohydrate+protein beverage, which suggests that carbohydrate+protein could inhibit chronic muscle carnitine accumulation.
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Registered trials
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