Glycaemic index of fruits and fruit products in patients with diabetes

Concord and Niagara Grape Juice and Their Phenolics Modify Intestinal Glucose Transport in a Coupled in Vitro Digestion/Caco-2 Human Intestinal Model

While the potential of dietary phenolics to mitigate glycemic response has been proposed, the translation of these effects to phenolic rich foods such as 100% grape juice (GJ) remains unclear. Initial in vitro screening of GJ phenolic extracts from American grape varieties (V. labrusca; Niagara and Concord) suggested limited inhibitory capacity for amylase and α-glucosidase (6.2%-11.5% inhibition; p < 0.05). Separately, all GJ extracts (10-100 µM total phenolics) did reduce intestinal trans-epithelial transport of deuterated glucose (d7-glu) and fructose (d7-fru) by Caco-2 monolayers in a dose-dependent fashion, with 60 min d7-glu/d7-fru transport reduced 10%-38% by GJ extracts compared to control. To expand on these findings by assessing the ability of 100% GJ to modify starch digestion and glucose transport from a model starch-rich meal, 100% Niagara and Concord GJ samples were combined with a starch rich model meal (1:1 and 1:2 wt:wt) and glucose release and transport were assessed in a coupled in vitro digestion/Caco-2 cell model. Digestive release of glucose from the starch model meal was decreased when digested in the presence of GJs (5.9%-15% relative to sugar matched control). Furthermore, transport of d7-glu was reduced 10%-38% by digesta containing bioaccessible phenolics from Concord and Niagara GJ compared to control. These data suggest that phenolics present in 100% GJ may alter absorption of monosaccharides naturally present in 100% GJ and may potentially alter glycemic response if consumed with a starch rich meal.

Glycaemic indices of three Sri Lankan wheat bread varieties and a bread-lentil meal

The glycaemic index (GI) concept ranks individual foods and mixed meals according to the blood glucose response. Low-GI foods with a slow and prolonged glycaemic response are beneficial for diabetic people, and several advantages have been suggested also for non-diabetic individuals. The recent investigations imply an increasing prevalence of diabetes mellitus in Sri Lanka. Thus, the present study was designed primarily to determine the glycaemic indices of some bread varieties in Sri Lanka as bread has become a staple diet among most of the urban people. A second objective was to observe the effects of macronutrients and physicochemical properties of starch on GI. Glycaemic responses were estimated according to FAO/WHO guidelines and both glucose and white bread were used as standards. Non-diabetic individuals aged 22-30 years (n=10) participated in the study. The test meals included white sliced bread, wholemeal bread, ordinary white bread and a mixed meal of wholemeal bread with lentil curry. The GI values (+/-standard error of the mean) of the meals were 77+/-6, 77+/-6, 80+/-4, 61+/-6, respectively (with glucose as the standard). The GI values of the bread varieties or the meal did not differ significantly (P >0.05). However, the meal can be categorized as a medium-GI food while the other bread varieties belong to the high-GI food group. A significant negative correlation was obtained with protein (P=0.042) and fat (P=0.039) contents of the food items and GI. Although the GI values of the foods are not significantly different, the inclusion of lentils caused the GI to decrease from a high-GI category to a medium-GI category. According to the present study, a ratio of 1.36 can be used to interconvert the GI values obtained with the two standards.

Glycemic index, glycemic load, and cancer risk: a meta-analysis

BACKGROUND

Factors linked to glucose metabolism play an important role in the development of cancers, and both glycemic index (GI) and glycemic load (GL) have been investigated as potential etiologic factors.

OBJECTIVE

A meta-analysis was performed to explore the association between GI and GL and cancer risk from published studies.

DESIGN

A comprehensive, systematic bibliographic search of the medical literature was conducted to identify relevant studies. Case-control and cohort studies published before October 2007 that reported cancer risk estimates for GI and GL were included. Pooled relative risks (RRs) were estimated for breast, colorectal, endometrial, and pancreatic cancer.

RESULTS

Thirty-nine studies were included in the meta-analysis. The interquantile ranges of GL were significantly wider in case-control studies, most of which were conducted in European countries, than in cohort studies. Cohort studies that presented lower ranges of GL also reported lower risk estimates. Overall, both GL and GI were significantly associated with a greater risk of colorectal (summary RR = 1.26; 95% CI: 1.11, 1.44 and RR = 1.18; 95% CI: 1.05, 1.34, respectively) and endometrial (RR = 1.36; 95% CI: 1.14, 1.62 and RR = 1.22; 95% CI: 1.01, 1.49) cancer than of breast and pancreatic cancer. There was, however, a significant between-study heterogeneity for colorectal cancer (P < 0.0001). The association between GL and breast cancer disappeared when publication bias was taken into account. No association was found for pancreatic cancer.

CONCLUSION

This comprehensive meta-analysis of GI and GL and cancer risk suggested an overall direct association with colorectal and endometrial cancer.

Effect of carbohydrate source on post-prandial blood glucose in subjects with type 1 diabetes treated with insulin lispro

Our purpose was to determine if the glycemic index (GI) and proportion of carbohydrate absorbed as glucose (Pg) affected glycemic responses and occurrence of post-prandial hypoglycemia in subjects with type 1 diabetes treated with insulin lispro. Subjects (n=8) were studied on five separate occasions after 10-12 h overnight fasts following a standard dinner. After their morning insulin dose, subjects ate 50 g carbohydrate from a starchy food (Pg=1; mashed potato GI=83, white bread GI=71, spaghetti GI=41, barley GI=25) or pineapple juice (Pg=0.5; GI=46). Blood glucose was measured fasting and at 30 min intervals for 4 h. Glucose responses after different foods differed significantly from 30 to 180 min, with mean incremental area under the curve being closely related to GI (r=0.98, P<0.01). By multiple regression analysis, occurrence of post-prandial hypoglycemia was influenced (P<0.05) by subject and Pg. Time to hypoglycemia was affected by subject, fasting glucose, and GI. Thus, in subjects with type 1 diabetes treated with insulin lispro, GI predicts glycemic responses of carbohydrate foods. Pg may affect the occurrence of post-prandial hypoglycemia, while GI may affect its timing. Further studies using mixed meals are required to confirm how carbohydrate source affects glycemic responses and occurrence of hypoglycemia in normal meal setting.

Whole-grain intake and the risk of type 2 diabetes: a prospective study in men

BACKGROUND

Certain dietary components may play a role in the prevention of type 2 diabetes.

OBJECTIVE

We examined prospectively the associations between whole- and refined-grain intake and the risk of type 2 diabetes in a large cohort of men.

DESIGN

Men from the Health Professionals Follow-up Study without a history of diabetes or cardiovascular disease in 1986 (n = 42898) were followed for </=12 y. Intakes of whole and refined grains, measured every 4 y by use of food-frequency questionnaires, were used to predict subsequent type 2 diabetes risk through multivariate analysis.

RESULTS

We ascertained 1197 cases of incident type 2 diabetes. After adjustment for age; physical activity; cigarette smoking; alcohol consumption; family history of diabetes; and fruit, vegetable, and energy intakes, the relative risk of type 2 diabetes was 0.58 (95% CI: 0.47, 0.70; P for trend < 0.0001) comparing the highest with the lowest quintile of whole-grain intake. The association was moderately attenuated when additionally adjusted for body mass index (relative risk: 0.70; 95% CI: 0.57, 0.85; P for trend = 0.0006). Intake of refined grains was not significantly associated with risk of type 2 diabetes. After further adjustment for magnesium intake, cereal fiber intake, and glycemic load, the association between whole grains and type 2 diabetes was attenuated and the trend no longer significant.

CONCLUSIONS

In men, a diet high in whole grains is associated with a reduced risk of type 2 diabetes in men that may be mediated by cereal fiber. Efforts should be made to replace refined-grain with whole-grain foods.

No important differences in glycaemic responses to common fruits in type 2 diabetic patients

The aim of this study was to determine the glycaemic indices (GIs), peak incremental indices (PI), and time of peak increment (TPI) of eight kinds of fruits and their relationship with the type and amount of simple sugars directly assayed in the fruits. Sixty-one type 2 diabetic patients randomized into eight groups--one for each category of fruit--participated in the study. GIs consisted of the following: pears = 60 +/- 4.9; apples = 63 +/- 8.3; oranges = 68 +/- 6.5; grapes = 70 +/- 7.5; plums = 75 +/- 8.4; peaches = 80 +/- 7.4; apricots = 82 +/- 9.1; bananas = 83 +/- 8.5. The PI values (mmol I-1) were the following: grapes = 2.52 +/- 0.26; apples = 3.13 +/- 0.75; pears = 3.48 +/- 0.55; oranges = 4.02 +/- 0.42; peaches = 4.07 +/- 0.38; apricots = 4.08 +/- 0.47; plums = 4.2 +/- 0.45; bananas = 4.45 +/- 0.39. There was no statistical differences in GI, and PI, within the different fruits. TPI of grapes (43.3 +/- 5.2 min), oranges (45 +/- 5.6 min), and peaches (45 +/- 5.6 min) were statistical different (p < 0.01) in respect to apricots (81.4 +/- 5.5 min). GIs were positively correlated with total glucose contained in the fruits (p < 0.05) and with PI (p < 0.0002); negatively with fructose both free (p < 0.02) and total (sum of free and present in sucrose (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)