Are glycemic index and glycemic load tools useful?

Strong evidence exists that low-glycemic and low-glycemic-load diets reduce risk of diabetes mellitus, obesity, insulin resistance, cardiovascular disease and cancer (1-4). However, glycemic index and glycemic load are subject of controversy among nutritionists because they are inconsistent in their findings due to high variability, are poorly standardized and their results are difficult to reproduce (1;2).

Despite methodological problems, however, studies are showing glycemic index and glycemic load are effective as clinical tools (3-5). According to one systemic review of 11 randomized controlled trials of four weeks or longer, low-glycemic diets helped patients control glycemic response in diabetes (3). One randomized, controlled trial also showed that a low-glycemic load diet may be more effective than a conventional low-fat, reduced-calorie diet in reducing risk of cardiovascular disease (5).

Athletes have also found glycemic index and glycemic load to be useful in improving performance. Moderate- to high-glycemic carbohydrates consumed after exercise have been found to enhance glycogen storage, and it’s thought that consumption of low-glycemic, carbohydrate-rich foods hours before an endurance event may provide lasting energy, although more research is needed to support this theory (6-8).

Reference List

1. Barclay AW, Petocz P, McMillan-Price J et al. Glycemic index, glycemic load, and chronic disease risk–a meta-analysis of observational studies. Am J Clin Nutr 2008;87:627-37.
2. Arteaga LA. The glycemic index. A current controversy. Nutr Hosp 2006;21 Suppl 2:53-60.
3. Thomas D, Elliott EJ. Low glycaemic index, or low glycaemic load, diets for diabetes mellitus. Cochrane Database Syst Rev 2009;CD006296.
4. Wolever TM, Jenkins DJ, Jenkins AL, Josse RG. The glycemic index: methodology and clinical implications. Am J Clin Nutr 1991;54:846-54.
5. Ebbeling CB, Leidig MM, Sinclair KB, Seger-Shippee LG, Feldman HA, Ludwig DS. Effects of an ad libitum low-glycemic load diet on cardiovascular disease risk factors in obese young adults. Am J Clin Nutr 2005;81:976-82.
6. Burke LM, Collier GR, Hargreaves M. Glycemic index–a new tool in sport nutrition? Int J Sport Nutr 1998;8:401-15.
7. Mitchell JB, Braun WA, Pizza FX, Forrest M. Pre-exercise carbohydrate and fluid ingestion: influence of glycemic response on 10-km treadmill running performance in the heat. J Sports Med Phys Fitness 2000;40:41-50.
8. Burke LM. Nutrition for post-exercise recovery. Aust J Sci Med Sport 1997;29:3-10.

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