Vegetarians have a reduced skeletal muscle carnitine transport capacity  

Oleh:

Stephens, Francis B ; Marimuthu, Kanagaraj ; Cheng, Yi ; Patel, Nitin

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: The American Journal of Clinical Nutrition vol. 94 no. 03 (Sep. 2011), page 938-944 .
Topik: Dietary Supplements
Fulltext: Am J Clin Nutr-2011-Stephens-938-44.pdf (159.1KB)

Ketersediaan

Perpustakaan FK Nomor Panggil: A07.K.2011.02 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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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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