A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance: part 24

Journal Title (Medline/Pubmed accepted abbreviation): Br. J. Sports Med.
Year: 2011
Volume: 45
Page numbers: 1005-1007
doi (if applicable): 10.1136/bjsports-2011-090397

Summary of article:

Leptin:  Leptin is a hormone that is secreted by fat cells that reduces the feeling of hunger.  Some individuals experience leptin resistance, which can lead to increased hunger levels and, consequently, being overweight.  It has been shown that exercise reduces leptin resistance.  Theoretically, athletes could use exogenous leptin to tinker with the leptin system to help them reach target body compositions by inducing hunger or preventing uncomfortable feeling of hunger.  Leptin infusion does not appear to be a widespread problem in sports today, but should be kept on the radar.

Magnesium:  Magnesium (Mg) is an essential trace mineral that has predominant roles in bone, muscle, or other tissues.  Good food sources of Mg include vegetables, fish, nuts, and whole grains.  Magnesium is a necessary component of many enzymes and a regulator of important cellular functions.  Single exercise sessions can induce a redistribution of Mg and induce low Mg concentrations in the blood.  Furthermore, Mg can be lost in sweat and urine and may put frequent exercisers at risk for Mg deficiencies.  Mg supplementation has not consistently shown benefits to athletes but it may be recommended, especially in athletes who are restricting calories.

Medium-chain triglycerides:  A triglyceride is a fat molecule composed of 3 fatty acids on a glycerol backbone.  In a medium chain triglyceride (MCT), the fatty acids are 6-14 carbon atoms in length.  MCTs can be metabolized by cells that line the small intestine and therefore the fatty acids can be absorbed and transported more efficiently than the typical long chain fatty acids.  Therefore, they can be used efficiently as fuels (sparing glucose) and are less likely to be stored.  There are large variations in their effectiveness between individuals and situations, but they may be recommended for long endurance activities.  MCTs can cause gastrointestinal distress in some individuals so, as always, it is recommended to try them in practice before using them during a competition.

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