A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance—Part 23

Journal Title (Medline/Pubmed accepted abbreviation): Br J Sports Med
Year: 2011
Volume: 45
Page numbers: 830-831
doi: 10.1136/ bjsports-2011-090294

Article type:

Review (brief)

Summary of article:

The authors have written a brief review of available evidence supporting supplementation with lecithin, leucine, linoleic acid, and γ-linoleic acid (GLA) to improve human health and performance. Leucine is an essential amino acid (EAA) that serves as both a building block for protein synthesis and a regulator of the rate of protein translation in muscle. Lecithin is a phosphatidylcholine-rich phospholipid that is present in many animal- and plant-based foods. Lecithin reverses exercise-induced reduction in plasma choline level through resynthesis of acetylcholine or through support of adenosine triphosphate (ATP) synthesis. Linoleic acid is an essential fatty acid (EFA; omega [ω]-6) synthesized in plant tissues, seeds, and nuts that contributes to skin integrity, water retention, and synthesis of arachidonic acid, but which may competitively inhibit biosynthesis of the ω-3 fatty acid eicosapentaenoic acid. Because linoleic acid is ubiquitous in Western diets, no supplementation is recommended among athletes. GLA, a ω-6 fatty acid, is a derivative of linoleic acid that is relatively rare in the diet and may exert anti-inflammatory effects and have analgesic properties, likely through effects on prostaglandin E1. GLA may also reduce claudication (pain or fatigue in the legs or discomfort while walking) and improve neuropathic symptoms (in combination with α-lipoic acid). Scientific evidence of benefit is lacking and, like linoleic acid, GLA may adversely affect mood at high doses by increasing arachidonic acid synthesis. Claims that GLA supports fat loss in bodybuilders have not been rigorously tested.

Interpretation of findings/Key practice applications:

Lecithin may be useful to maintain plasma choline levels after strenuous exercise. Leucine supplementation appears to be safe for young and elderly athletes, although evidence of benefit (such as in reducing sarcopenia in elderly athletes) is lacking. Linoleic acid is widely available in the typical diet; therefore supplementation is unnecessary. Although GLA is rare in most diets, scientific evidence supporting supplementation is lacking, and excessive intake may adversely affect mood. Athletes should review their supplement options with a qualified nutritionist.

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