Glycemic load

The glycemic load (GL) of food is a number that estimates how much the food will raise a person's blood glucose level after eating it. One unit of glycemic load approximates the effect of consuming one gram of glucose.[1] Glycemic load accounts for how much carbohydrate is in the food and how much each gram of carbohydrate in the food raises blood glucose levels. Glycemic load is based on the glycemic index (GI), and is calculated by multiplying the grams of available carbohydrate in the food by the food's glycemic index, and then dividing by 100.

Description

Glycemic load estimates the impact of carbohydrate consumption using the glycemic index while taking into account the amount of carbohydrate that is consumed. GL is a GI-weighted measure of carbohydrate content. For instance, watermelon has a high GI, but a typical serving of watermelon does not contain much carbohydrate, so the glycemic load of eating it is low. Whereas glycemic index is defined for each type of food, glycemic load can be calculated for any size serving of a food, an entire meal, or an entire day's meals.

Glycemic load of a serving of food can be calculated as its carbohydrate content measured in grams (g), multiplied by the food's GI, and divided by 100. For example, watermelon has a GI of 72. A 100 g serving of watermelon has 5 g of available carbohydrates (it contains a lot of water), making the calculation 5 × 72/100=3.6, so the GL is 4. A food with a GI of 100 and 10 g of available carbohydrates has a GL of 10 (10 × 100/100=10), while a food with 100 g of carbohydrate and a GI of just 10 also has a GL of 10 (100 × 10/100=10).

For one serving of a food, a GL greater than 20 is considered high, a GL of 11–19 is considered medium, and a GL of 10 or less is considered low. Foods that have a low GL in a typical serving size almost always have a low GI. Foods with an intermediate or high GL in a typical serving size range from a very low to very high GI.

One 2007 study has questioned the value of using glycemic load as a basis for weight-loss programmes. Das et al. conducted a study on 36 healthy, overweight adults, using a randomised test to measure the efficacy of two diets, one with a high glycemic load and one with a low GL. The study concluded that there is no statistically significant difference between the outcome of the two diets.[2]

Glycemic load appears to be a significant factor in dietary programs targeting metabolic syndrome, insulin resistance, and weight loss; studies have shown that sustained spikes in blood sugar and insulin levels may lead to increased diabetes risk.[3] The Shanghai Women's Health Study concluded that women whose diets had the highest glycemic index were 21 percent more likely to develop type 2 diabetes than women whose diets had the lowest glycemic index.[4] Similar findings were reported in the Black Women's Health Study.[5] A diet program that manages the glycemic load aims to avoid sustained blood-sugar spikes and can help avoid onset of type 2 diabetes.[6] For diabetics, glycemic load is a highly recommended tool for managing blood sugar.

The data on GI and GL listed in this article is from the University of Sydney (Human Nutrition Unit) GI database.[7]

The GI was invented in 1981 by Dr Thomas Wolever and Dr David Jenkins at the University of Toronto and is a measure of how quickly a food containing 25 or 50 grams of carbohydrate raises blood-glucose levels. Because some foods typically have a low carbohydrate content, Harvard researchers created the GL, which takes into account the amount of carbohydrates in a given serving of a food and so provides a more useful measure. Liu et al. were the first to show that based on their calculation, the glycemic load of a specific food—calculated as the product of that food's carbohydrate content and its glycemic index value—has direct physiologic meaning in that each unit can be interpreted as the equivalent of 1 g carbohydrate from white bread (or glucose depending on the reference used in determining the glycemic index).[8][9][10][11] It became immediately apparent that such direct physiological quantification of glycemic load would allow patients with diabetes to do “glycemic load” counting as opposed to the conventional “carbohydrate counting” for monitoring the glycemic effect of foods.[12][13][10][11] The concept of glycemic load addresses the concern about rating foods as good or bad solely on the basis of their glycemic index. For example, although the glycemic index for carrots is reported to be as high as 131, the glycemic load for one serving of carrots is small because the amount of carbohydrate in one serving of carrots is minimal (≈7 g carbohydrate). Indeed, ≈700 g carrots (which provides 50 g carbohydrate) must be consumed to produce an incremental glucose response 1.3 times that of 100 g white bread containing 50 g carbohydrate.[14][15][10]

List of foods and their glycemic load for 100g serving

All numeric values provided in the table are approximate. Note that 100g may not represent a typical serving size. For example, a typical rice serving would be 150-200g with a corresponding increase in GL, whilst a banana may weigh more than 100g. Reference tables which give GL by typical serving size will show different values.
FoodGlycemic indexCarbohydrate
content
(g)		Glycemic Load (100g serving)Insulin index
Baguette, white, plain95 (high)5048—
Banana, Mean of 10 studies52 (low) – 55 ± 7 (low–medium)[16]2010 – 11 ± 1[17]57 ± 4[16]
Cabbage10 (low)59<1—
Carrots, mean of 4 studies47 (low)<8<4—
Corn tortilla52 (low)4825—
Potato, mean of 5 studies50 (low) – 99 ± 25 (high)[16]199 – 18 ± 5[17]85 ± 8[16]
Rice, boiled white, mean of 12 studies64 - 93[18]25[18]16 - 23[19]40 ± 10[18] – 55 ± 8[16] – 67 ± 15[18]
Watermelon72 (high)5<4—

See also

References

  1. ↑ "Glycemic Load Defined". Glycemic Research Institute. Retrieved 8 February 2013.
  2. ↑ Das, Sai Krupa; et al. (April 2007). "Long-term effects of 2 energy-restricted diets differing in glycemic load on dietary adherence, body composition, and metabolism in CALERIE: a 1-y randomized controlled trial". American Journal of Clinical Nutrition. 85 (4): 1023–30. PMID 17413101. Retrieved 8 February 2013.
  3. ↑ Ludwig, Daniel S. (May 2002). "The glycemic index: physiological mechanisms relating to obesity, diabetes, and cardiovascular disease". Journal of the American Medical Association. 287 (18): 2414–2423. doi:10.1001/jama.287.18.2414. PMID 11988062.
  4. ↑ Villegas, Raquel; Liu, Simin; Gao, Yu-Tang; Yang, Gong; Li, Honglan; Zheng, Wei; Shu, Xiao Ou (2007). "Prospective Study of Dietary Carbohydrates, Glycemic Index, Glycemic Load, and Incidence of Type 2 Diabetes Mellitus in Middle-aged Chinese Women". Archives of Internal Medicine. 167 (21): 2310–16. doi:10.1001/archinte.167.21.2310. PMID 18039989. Retrieved 8 February 2013.
  5. ↑ Krishnan, Supriya; Rosenberg, Lynn; Singer, Martha; Hu, Frank B.; Djoussé, Luc; Cupples, L. Adrienne; Palmer, Julie R. (2007). "Glycemic Index, Glycemic Load, and Cereal Fiber Intake and Risk of Type 2 Diabetes in US Black Women". Archives of Internal Medicine. 167 (21): 2304–09. doi:10.1001/archinte.167.21.2304. PMID 18039988. Retrieved 8 February 2013.
  6. ↑ "Simple Steps to Preventing Diabetes". The Nutrition Source. Harvard School of Public Health. Retrieved 8 February 2013.
  7. ↑ "Glycemic Index Database". University of Sydney. Retrieved 8 February 2013.
  8. ↑ Liu S, Willett WC, Stampfer MJ, Hu FB, Franz M, Sampson L, Hennekens CH, Manson JE. "A prospective study of dietary glycemic load, carbohydrate intake, and risk of coronary heart disease in US women". Am J Clin Nutr 2000; 71(6): 1455–61. PMID 10837285
  9. ↑ Ford ES, Liu S. "Glycemic index and serum high-density lipoprotein cholesterol concentration among us adults". JAMA Int Med 2001; 161: 572–76. PMID 11252117
  10. 1 2 3 Liu S, Manson JE, Stampfer MJ, Holmes MD, Hu FB, Hankinson SE, Willett WC. "Dietary glycemic load assessed by food-frequency questionnaire in relation to plasma high-density-lipoprotein cholesterol and fasting plasma triacylglycerols in postmenopausal women". Am J Clin Nutr 2001; 73: 560–66. PMID 11237932
  11. 1 2 Liu S, Manson JE, Buring JE, Stampfer MJ, Willett WC, Ridker PM. "Relation between a diet with a high glycemic load and plasma concentrations of high-sensitivity C-reactive protein in middle-aged women". Am J Clin Nutr. 2002 Mar; 75(3): 492–98. PMID 11864854
  12. ↑ Schulze MB, Liu S, Rimm EB, Manson JE, Willett WC, Hu FB. "Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women". Am J Clin Nutr. 2004 Aug; 80(2): 348–56. PMID 15277155
  13. ↑ Qi L, Rimm E, Liu S, Rifai N, Hu FB. "Dietary glycemic index, glycemic load, cereal fiber, and plasma adiponectin concentration in diabetic men". Diabetes Care. 2005 May; 28(5): 1022–28. PMID 15855561
  14. ↑ Gross LS, Li L, Ford ES, Liu S. "Increased consumption of refined carbohydrates and the epidemic of type 2 diabetes in the United States: an ecologic assessment". Am J Clin Nutr. 2004 May; 79(5): 774–79. PMID 15113714
  15. ↑ Liu S. "Intake of refined carbohydrates and whole grain foods in relation to risk of type 2 diabetes mellitus and coronary heart disease". J Am Coll Nutr 2002; 21: 298–306. PMID 12166526
  16. 1 2 3 4 5 Holt, Susanne H. A.; Miller, Janette C. Brand; Petocz, Peter (November 1997). "An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods" (PDF). The American Journal of Clinical Nutrition. 66 (5): 1264–76. PMID 9356547. Retrieved 8 February 2013. Lay summary – David Mendosa (14 October 2009).
    Note: Glucose Score & Insulin Score multiplied by 0.7 for Glycemic index & Insulin index respectively.
  17. 1 2 Calculation using data already tabulated and data from Holt, 1997.
  18. 1 2 3 4 Miller, Janette Brand; Pang, Edna; Bramall, Lindsay (December 1992). "Rice: a high or low glycemic index food?" (PDF). The American Journal of Clinical Nutrition. 56 (6): 1034–36. PMID 1442654. Retrieved 8 February 2013.
  19. ↑ Calculation based on Miller, 1992
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