Glycemic index, insulinemic index, and satiety index of kefir

A collectanea of food insulinaemic index: 2023

BACKGROUND AND AIMS

To systematically update and publish the lnsulinaemic Index (II) value compilation of food/beverages.

METHODS

A literature search identified around 400 scholarly articles published between inception and December 2023. II values were pooled according to the selection criteria of at least 10 healthy, non-diabetic subjects with normal BMI. In addition, the II reported should have been derived from incremental area under the curve (iAUC) calculation of the insulin concentration over time. The reference food used from the pooled articles were either glucose or bread.

RESULTS

The II of 629 food/beverage items were found from 80 distinct articles. This is almost a five-fold increase in the number of entries from a previous compilation in 2011. Furthermore, these articles originated from 32 different countries, and were cleaved into 25 food categories. The II values ranged from 1 to 209. The highest overall recorded II was for a soy milk-based infant formula while the lowest was for both acacia fibre and gin. Upon clustering to single food, the infant formula retained the highest II while both acacia fibre and gin maintained the lowest recording. As for mixed meal, a potato dish served with a beverage recorded the highest II while a type of taco served with a sweetener, vegetable and fruit had the lowest II. Our minimum and maximum II data values replace the entries reported by previous compilations.

CONCLUSION

Acknowledging some limitations, these data would facilitate clinical usage of II for various applications in research, clinical nutrition, clinical medicine, diabetology and precision medicine. Future studies concerning II should investigate standardisation of reference food, including glucose and the test food portion. Although this collectanea adds up new food/beverages II values, priority should be given to populate this database.

The influence of dough kneading time and flour particle size distribution on white bread structure, glycemic response and aspects of appetite

BACKGROUND & AIMS

White bread is widely consumed in many countries despite being a high-glycemic index (GI) food. It has been shown that the "food matrix effect" may help with diabetes and obesity management through lowering GI and appetite. This study aimed at investigating the effects of dough kneading time and flour particle size on white bread structure, glycemic response, and aspects of appetite.

METHODS

A two-phase randomized cross-over design was used in 10 healthy subjects over the course of 2 h. In phase 1, Texture Profile Analysis (TPA) attributes, Scanning Electron Microscope (SEM) image, glycemic response, and appetite aspects of white bread made with a 15-min dough kneading time (K15) were compared with white bread made with a 10-min dough kneading time (K10). In phase 2, TPA, SEM image, glycemic response, and satiety score of white bread made with coarse flour (CF) were compared to white bread made with fine flour (FF).

RESULT

With increasing hardness (force required to compress a food between the molars to a given deformation), total blood glucose IAUC in K15 (IAUC = 119 ± 12; GI = 66) was significantly (p < 0.05) lower than in K10 (IAUC = 154 ± 10; GI = 81). No marked difference was observed between K15 and K10 on aspects of appetite except for hunger. There was no significant (p > 0.05) difference in glycemic response between CF (IAUC = 126 ± 18; GI = 64) and FF (IAUC = 147 ± 12; GI = 81). Similarly, no discernible difference in satiety between CF and FF.

CONCLUSION

Changes in processing conditions can improve blood glucose response relalated to white bread consumption.

Microbial Communities in Home-Made and Commercial Kefir and Their Hypoglycemic Properties

Kefir is a popular traditional fermented dairy product in many countries. It has a complex and symbiotic culture made up of species of the genera Leuconostoc, Lactococcus, and Acetobacter, as well as Lactobacilluskefiranofaciens and Lentilactobacillus kefiri. Though kefir has been commercialized in some countries, people are still traditionally preparing kefir at the household level. Kefir is known to have many nutritious values, where its consistent microbiota has been identified as the main valuable components of the product. Type 2 diabetes mellitus (T2DM) is a common diet-related disease and has been one of the main concerns in the world’s growing population. Kefir has been shown to have promising activities in T2DM, mostly via hypoglycemic properties. This review aims to explain the microbial composition of commercial and home-made kefir and its possible effects on T2DM. Some studies on animal models and human clinical trials have been reviewed to validate the hypoglycemic properties of kefir. Based on animal and human studies, it has been shown that consumption of kefir reduces blood glucose, improves insulin signaling, controls oxidative stress, and decreases progression of diabetic nephropathy. Moreover, probiotic bacteria such as lactic-acid bacteria and Bifidobacterium spp. and their end-metabolites in turn directly or indirectly help in controlling many gut disorders, which are also the main biomarkers in the T2DM condition and its possible treatment.

The Effects of Kefir and Kefir Components on Immune and Metabolic Physiology in Pre-Clinical Studies: A Narrative Review

Kefir, a fermented beverage made from kefir grains, has gained immense popularity around the world due to its potential health-promoting properties. Kefir beverages are both marketed commercially and brewed privately by individuals. Both milk and sugar solutions can be used as substrates with various additives included based on consumer preference. Fermentation occurs via microorganisms including lactic acid bacteria, acetic acid bacteria, and yeasts, which are naturally present in kefir grains. Health-promoting effects of kefir are thought to occur through immune, gastrointestinal, and metabolic regulation. Both clinical trials and mechanistic studies in cell culture and animal models have explored these effects. Studies in vitro and in animals have shown the ability of kefir and kefir components to antagonize pathogens, reduce proinflammatory cytokine production, contribute to cytotoxicity of tumor cell lines and reduce tumor burden, and improve serum glycemic and lipid profiles. However, some data from clinical trials are conflicting, and the precise mechanisms by which kefir promotes well-being are not completely defined. This review summarizes the current body of evidence in both cell culture and animal models that provide insight into the mechanisms by which kefir beverages may protect consumers from enteric infections and improve immune and metabolic health. We believe that readers will gain knowledge helpful for both developing more targeted mechanistic studies and selecting informative outcomes when designing clinical studies.

Kefir and Its Biological Activities

Kefir is a fermented beverage with renowned probiotics that coexist in symbiotic association with other microorganisms in kefir grains. This beverage consumption is associated with a wide array of nutraceutical benefits, including anti-inflammatory, anti-oxidative, anti-cancer, anti-microbial, anti-diabetic, anti-hypertensive, and anti-hypercholesterolemic effects. Moreover, kefir can be adapted into different substrates which allow the production of new functional beverages to provide product diversification. Being safe and inexpensive, there is an immense global interest in kefir’s nutritional potential. Due to their promising benefits, kefir and kefir-like products have a great prospect for commercialization. This manuscript reviews the therapeutic aspects of kefir to date, and potential applications of kefir products in the health and food industries, along with the limitations. The literature reviewed here demonstrates that there is a growing demand for kefir as a functional food owing to a number of health-promoting properties.

Does food insulin index in the context of mixed meals affect postprandial metabolic responses and appetite in obese adolescents with insulin resistance? A randomised cross-over trial

The food insulin index (II) is a novel classification to rank foods based on their physiological insulin demand relative to an isoenergetic reference food and may be a valid predictor of postprandial insulin responses and appetite. The present study aimed to compare the postprandial metabolic responses and appetite sensations to two macronutrient- and glycaemic index-matched meals with either high or low II in obese adolescents with insulin resistance (IR). A randomised, single-blind and cross-over trial included fifteen obese adolescents aged 12-18 years with IR. All participants were provided with two different breakfasts: low glycaemic index, low insulin index (LGI-LII) and low glycaemic index, high insulin index (LGI-HII), with a 1-week washout period between meals. At time 0 (just before breakfast), 15, 30, 45, 60, 90, 120, 180 and 240 min after the meal, serum glucose, insulin and C-peptide levels and appetite scores were measured. At the end of 4 h, participants were served ad libitum lunch. Early (0-30 min), late (45-240 min) and total (0-240 min) postprandial insulin responses were lowered by 56·1, 34·6 and 35·6 % after the LGI-LII meal v. LGI-HII meal (P < 0·05). The feeling of hunger was also decreased by 25·8 and 27·5 % after the LGI-LII meal v. LGI-HII meal during the late and total responses (P < 0·05). The calculation II of meals or diets may be a useful dietary approach to reduce postprandial hyperinsulinaemia and the perceived hunger in obese adolescents with IR.

The Effect of Probiotic Yogurt on Glycemic Control in Type 2 Diabetes or Obesity: A Meta-Analysis of Nine Randomized Controlled Trials

Probiotic yogurt is suggested as a nutritional approach in type 2 diabetes (T2D) and obesity. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating the effects of probiotic yogurt on glycemic outcomes in T2D or obesity. The databases used to search for RCTs included Medline and Scopus. The RCTs were eligible if outcomes included selected glycemic markers. In nine eligible trials, 237 and 235 subjects were in treatment (probiotic yogurt) and control (mostly conventional yogurt) groups, respectively. There was no significant difference for pooled unstandardized mean difference (USMD) hemoglobin A1c (HbA1c) by probiotic yogurt compared with the control in T2D (USMD: -0.366; 95% CI: -0.755, 0.024, p = 0.066) and obesity (USMD: 0.116, 95% CI: -0.007, 0.238, p = 0.065). Similarly, there were no effects of probiotic yogurt on fasting blood glucose, fasting insulin, or insulin resistance (estimated by homeostatic model assessment of insulin resistance (HOMA-IR)) in either T2D or obesity. In conclusion, the present meta-analysis has not demonstrated the benefits of consuming probiotic compared with conventional yogurt for improving glucose control in patients with diabetes or obesity. Larger trials are needed to verify the benefits of probiotic and/or conventional yogurt or other probiotic fermented milk (e.g., kefir) on glycemic markers in patients with diabetes and obesity.