The glycemic response caused by food (changes in blood glucose concentration) is usually measured by the glycemic index (GI) and glycemic load (GL) – as I briefly explained in this post – and during the treatment of overweight it is usually interesting to prioritize foods with low or medium values of these indicators. However, it is not easy to know the GI and GL values of certain foods, since they are factors that depend on variables associated with their particular characteristics (nutritional and physical), which can be very diverse. And, although some approximations have been made to theoretical models, the only way to calculate them with any precision is through empirical experiments with people. Therefore, it is enough to consider that today there are tens of thousands of different food products to understand the reasons why it is often not easy to find information on the glycemic response of many of these products.
For all these reasons, it is appreciated that the systematic review “International tables of glycemic index and glycemic load values 2021: a systematic review” (2021) has been published, an open access investigation in which the GI has been compiled, organized and analyzed. and the GC of about 4000 foods.
The most interesting and useful part of this work is possibly the long list with the specific characteristics and results of the 4000 products (downloadable from this link, tables 1 and 2), since it can be used as a reference document when looking for the value for a particular type of food.
But the authors have also tried to synthesize all this information, generating the following table of average GI values for products grouped by families (click to enlarge):
On the other hand, in the original document the researchers summarize the general conclusions that could be deduced from their extensive work as follows:
“Several generalizations can be made. The highest mean values were found among potato products (58% categorized as high GI); rice (38% high GI); vegetables other than potatoes, including sweet potato (52% high GI); and Asian-Indian regional foods (37% high GI), while the lowest values were seen in meal replacements (100% low GI), dairy products (95% low GI), pulses (94% % low GI) and sports energy bars (94% low GI) Nuts had the lowest average GI values (100% low GI) (…) Average GI values of breads, breakfast cereals and cereals were also relatively high, but there are examples of high and low GI foods within each food category.In general, salty snacks had higher GI values (46% low GI and 34% high GI) than snacks. sweets and confectionery products (68% low GI and 11% high GI).
Although potatoes as a group have high GI values, there was a wide distribution (range, 35-103). Variety and methods of cooking and processing appear to be important, with mean values of 84 for instant mashed potatoes, 79 for regular mashed potatoes, 73 for boiled potatoes, and 49 for boiled potatoes that were chilled overnight. It is difficult to detect trends over time due to the diversity of origins, varieties, and cooking methods, although there may be regional variations. The average GI value of the potatoes tested was highest in Australia (77), followed by Europe (73) and lowest in North America (67).
Similarly, there was also a wide variation for the GI values of the rice products (range 19-116). The average GI for white rice was 73 and the average for brown rice was 65. We cannot conclude that this difference is due to differences in fiber or cooking/processing because rice variety also played a role. The highest GI values were observed in Asia (74), with lowest averages in Australia (65), Europe (61) and North America (60).
Breads also varied widely (range, 24 to 100) with 1 in 3 having a high GI (n = 75). On average, the breads tested in Asia were the highest GI (68). In particular, there was relatively little data for breads from Germany and the Scandinavian countries: that is, countries renowned for their distinctive rye breads and a high proportion of whole grain breads.
Among the breakfast cereals, one third of the products tested were high GI and more than one third were low GI. High-sugar products (eg, Coco Pops and Frosties) had an average GI of 74, similar to those with relatively low-sugar content (Cornflakes and Bran Flakes; 74). Products made with oats or rolled oats (eg mueslis) had an average GI of 55.
(…)
Dairy products, legumes, pasta and fruit were generally low GI foods (≤ 55 on the glucose scale of 100) and had consistent values across the world. However, cereals and cereal-based products, including whole-grain or whole-grain versions, showed wide variation in GI values, likely due to variations in manufacturing methods. Breads, breakfast cereals, rice, savory snacks, and regional foods were available in high, medium, and low GI versions. Most potato varieties were high GI foods, but specific low GI varieties have been identified.“
In short, an interesting and quite useful work as a reference document and, I repeat, freely accessible.