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Cited by 28Muscle metabolism and nutritionMetabolism and Genetic DisordersNutrition and Health in Aging

Vegetarians have a reduced skeletal muscle carnitine transport capacity

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Stephens, Francis B, Marimuthu, Kanagaraj, Cheng, Yi, Patel, Nitin, Constantin, Despina, Simpson, Elizabeth J, Greenhaff, Paul L·2011·The American Journal of Clinical Nutrition
DOI 10.3945/ajcn.111.012047
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Abstract

Background Ninety-five percent of the body carnitine pool resides in skeletal muscle where it plays a vital role in fuel metabolism. However, vegetarians obtain negligible amounts of carnitine from their diet.Objective We tested the hypothesis that muscle carnitine uptake is elevated in vegetarians compared with that in nonvegetarians to maintain a normal tissue carnitine content.Design Forty-one young (aged ≈22 y) vegetarian and nonvegetarian volunteers participated in 2 studies. The first study consisted of a 5-h intravenous infusion of l-carnitine while circulating insulin was maintained at a physiologically high concentration (≈170 mU/L; to stimulate muscle carnitine uptake) or at a fasting concentration (≈6 mU/L). The second study consisted of oral ingestion of 3 g l-carnitine.Results Basal plasma total carnitine (TC) concentration, 24-h urinary TC excretion, muscle TC content, and muscle carnitine transporter [organic cation transporter 2 (OCTN2)] messenger RNA and protein expressions were 16% (P < 0.01), 58% (P < 0.01), 17% (P < 0.05), 33% (P < 0.05), and 37% (P = 0.09) lower, respectively, in vegetarian volunteers. However, although nonvegetarians showed a 15% increase (P < 0.05) in muscle TC during l-carnitine infusion with hyperinsulinemia, l-carnitine infusion in the presence or absence of hyperinsulinemia had no effect on muscle TC content in vegetarians. Nevertheless, 24-h urinary TC excretion was 55% less in vegetarians after l-carnitine ingestion.Conclusions Vegetarians have a lower muscle TC and reduced capacity to transport carnitine into muscle than do nonvegetarians, possibly because of reduced muscle OCTN2 content. Thus, the greater whole-body carnitine retention observed after a single dose of l-carnitine in vegetarians was not attributable to increased muscle carnitine storage.

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  • Some, but not all, studies report that vegetarian individuals have a lower muscle carnitine content compared with omnivores.

    “Some [198], but not all [200], studies also report that vegetarian individuals have a lower muscle carnitine content compared with omnivores.”

    From Nutritional Considerations for the Vegan Athlete (2023) · cites this paper as [198]

  • Vegetarians (vegans) typically consume ~0.04 to 0.4 μmol/kg/d of carnitine, which results in 20% to 30% lower plasma concentrations compared with omnivores, although this does not fall outside normal limits.

    “Vegetarians (vegans) typically only consume ∼0.04 to 0.4 μmol∙kg/d of carnitine [197], which results in 20% to 30% lower plasma concentrations compared with omnivores [197,198], although this does not fall outside the normal limits [199].”

    From Nutritional Considerations for the Vegan Athlete (2023) · cites this paper as [198]

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Authors
Stephens, F. B., Marimuthu, K., Cheng, Y., Patel, N., Constantin, D., Simpson, E. J., & Greenhaff, P. L.
Affiliations
University of Nottingham (GB)
ORCID
Venue
The American Journal of Clinical Nutrition
Publisher
Elsevier BV
Published
2011-09
Volume
94
Issue
3
Pages
938-944
ISSN
0002-9165 (ISSN-L)
DOI
10.3945/ajcn.111.012047
OpenAlex
W2131738662
Cited by
28
References
28
Citations by year
2025: 3 · 2024: 2 · 2023: 5 · 2020: 1 · 2019: 3 · 2018: 5 · 2017: 2 · 2016: 1 · 2015: 2 · 2014: 2 · 2013: 1 · 2012: 1
FWCI
0.61
Type
journal article
Language
en
Open access
Licence
Locations
  • American Journal of Clinical Nutrition (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Clinical Biochemistry › Metabolism and Genetic Disorders
  • Health Sciences › Medicine › Physiology › Nutrition and Health in Aging
Keywords
vegetarian diet, L-carnitine, skeletal muscle, carnitine transport, organic cation transporter 2, OCTN2, hyperinsulinemia, urinary carnitine excretion, carnitine supplementation
MeSH terms
Adult, Biological Transport, Carnitine, Humans, Hyperinsulinism, Male, RNA, Messenger, Diet, Vegetarian, Muscle, Skeletal, Organic Cation Transport Proteins, Young Adult

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