Evidence that carbohydrate-to-fat ratio and taste, but not energy density or NOVA level of processing, are determinants of food liking and food reward.

This virtual (online) study tested the common but largely untested assumptions that food energy density, level of processing (NOVA categories), and carbohydrate-to-fat (CF) ratio are key determinants of food reward. Individual participants (224 women and men, mean age 35 y, 53% with healthy weight, 43% with overweight or obesity) were randomised to one of three, within-subjects, study arms: energy density (32 foods), or level of processing (24 foods), or CF ratio (24 foods). They rated the foods for taste pleasantness (liking), desire to eat (food reward), and sweetness, saltiness, and flavour intensity (for analysis averaged as taste intensity). Against our hypotheses, there was not a positive relationship between liking or food reward and either energy density or level of processing. As hypothesised, foods combining more equal energy amounts of carbohydrate and fat (combo foods), and foods tasting more intense, scored higher on both liking and food reward. Further results were that CF ratio, taste intensity, and food fibre content (negatively), independent of energy density, accounted for 56% and 43% of the variance in liking and food reward, respectively. We interpret the results for CF ratio and fibre in terms of food energy-to-satiety ratio (ESR), where ESR for combo foods is high, and ESR for high-fibre foods is low. We suggest that the metric of ESR should be considered when designing future studies of effects of food composition on food reward, preference, and intake.

The association of dietary animal and plant protein with putative risk markers of colorectal cancer in overweight pre-diabetic individuals during a weight-reducing programme: a PREVIEW sub-study.

PURPOSE: Diets with increased protein content are popular strategies for body weight regulation, but the effect of such diets for the colonic luminal environment is unclear. We aimed to investigate the associations between putative colorectal cancer-related markers and total protein intake, plant and animal proteins, and protein from red and processed meat in pre-diabetic adults (> 25 years). METHODS: Analyses were based on clinical and dietary assessments at baseline and after 1 year of intervention. Protein intake was assessed from 4-day dietary records. Putative colorectal cancer-related markers identified from 24-h faecal samples collected over three consecutive days were: concentration of short-chain fatty acids, phenols, ammonia, and pH. RESULTS: In total, 79 participants were included in the analyses. We found a positive association between change in total protein intake (slope: 74.72 ± 28.84 µmol per g faeces/E%, p = 0.01), including animal protein intake (slope: 87.63 ± 32.04 µmol per g faeces/E%, p = 0.009), and change in faecal ammonia concentration. For change in ammonia, there was a dose-response trend from the most negative (lowest tertile) to the most positive (highest tertile) association (p = 0.01): in the high tertile, a change in intake of red meat was positively associated with an increase in ammonia excretion (slope: 2.0 ± 0.5 µmol per g faeces/g/day, p < 0.001), whereas no such association was found in the low and medium tertile groups. CONCLUSION: Increases in total and animal protein intakes were associated with higher excretion of ammonia in faeces after 1 year in overweight pre-diabetic adults undertaking a weight-loss intervention. An increase in total or relative protein intake, or in the ratio of animal to plant protein, was not associated with an increase in faeces of any of the other putative colorectal cancer risk markers. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01777893.

Glycemic index, glycemic load and glycemic response: An International Scientific Consensus Summit from the International Carbohydrate Quality Consortium (ICQC).

BACKGROUND AND AIMS: The positive and negative health effects of dietary carbohydrates are of interest to both researchers and consumers. METHODS: International experts on carbohydrate research held a scientific summit in Stresa, Italy, in June 2013 to discuss controversies surrounding the utility of the glycemic index (GI), glycemic load (GL) and glycemic response (GR). RESULTS: The outcome was a scientific consensus statement which recognized the importance of postprandial glycemia in overall health, and the GI as a valid and reproducible method of classifying carbohydrate foods for this purpose. There was consensus that diets low in GI and GL were relevant to the prevention and management of diabetes and coronary heart disease, and probably obesity. Moderate to weak associations were observed for selected cancers. The group affirmed that diets low in GI and GL should always be considered in the context of diets otherwise understood as healthy, complementing additional ways of characterizing carbohydrate foods, such as fiber and whole grain content. Diets of low GI and GL were considered particularly important in individuals with insulin resistance. CONCLUSIONS: Given the high prevalence of diabetes and pre-diabetes worldwide and the consistency of the scientific evidence reviewed, the expert panel confirmed an urgent need to communicate information on GI and GL to the general public and health professionals, through channels such as national dietary guidelines, food composition tables and food labels.

Prospective associations of dietary insulin demand, glycemic index, and glycemic load during puberty with body composition in young adulthood.

BACKGROUND: Puberty is a so-called critical period for overweight development and is characterized by physiological insulin resistance during mid-puberty. This study addressed the hypothesis that habitual consumption of a diet inducing higher levels of postprandial glycemia or insulinemia during puberty may have an unfavorable effect on the body composition in young adulthood. METHODS: Multivariate regression analysis was performed on 262 participants of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study with at least two 3-day weighed dietary records during puberty (baseline: girls 9-14 years; boys 10-15 years) and anthropometric measurements in young adulthood (18-25 years). A published dietary glycemic index was assigned to each carbohydrate-containing food. Similarly, each food was assigned a food insulin index (insulinemic response to a 1 MJ portion of food relative to 1 MJ of glucose) using 121 values measured at Sydney University. RESULTS: Dietary glycemic index or glycemic load during puberty was not related to body composition in young adulthood. In contrast, a higher dietary insulin index and a higher dietary insulin load during puberty were associated with higher levels of percentage of body fat (%BF) in young adulthood, even after adjustment for early life, socioeconomic and nutritional factors; %BF in energy-adjusted tertiles of dietary insulin index were 22.9 (95% confidence intervals (CI): 21.6, 24.1), 24.5 (23.2, 25.7), 24.7 (23.5, 25.9) %, P (for trend)=0.01; %BF in energy-adjusted tertiles of dietary insulin load were 22.8 (95% CI: 21.5, 24.0), 24.5 (23.2, 25.7), 24.8 (23.6, 26.0) %, P (for trend)=0.01. Adjustment for baseline %BF attenuated these relationships (P (for trend)=0.1 and=0.08, respectively). Dietary insulin demand was not related to body mass index. CONCLUSION: This study suggests a prospective adverse influence of dietary insulin demand during puberty on %BF in young adulthood. Postprandial increases in insulinemia rather than increases in glycemia appear to be implicated in an unfavorable development of body composition.

Dietary glycemic index, glycemic load, insulin index, fiber and whole-grain intake in relation to risk of prostate cancer.

OBJECTIVE: Insulin may play a role in prostate cancer tumorigenesis. Postprandial blood glucose and insulin responses of foods depend importantly on the carbohydrate quality and quantity, represented by glycemic index (GI), glycemic load (GL), fiber and whole-grain content, but are also influenced by intake of protein and other characteristics. The recently developed insulin index (II) quantifies the postprandial insulin secretion, also taking into account these additional characteristics. METHODS: We investigated the association between dietary GI, GL, II, fiber, and whole grains and risk of total prostate cancer (n = 5,112) and subgroups of prostate cancer as defined by stage or grade in 49,934 male participants of the Health Professionals Follow-up Study. Multivariate adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated using Cox proportional hazards regression. RESULTS: Dietary GI, GL, II, or fiber was not associated with risk of total or subgroups of prostate cancer. We observed a positive association between dietary intake of whole grains and total prostate cancer (HR highest versus lowest quintile 1.13, 95% CI 1.03-1.24), which was attenuated after restriction to PSA-screened participants (HR 1.03, 95% CI 0.91-1.17). CONCLUSIONS: These results suggest that long-term exposure to a diet with a high insulin response does not affect prostate cancer incidence.

Optimal dietary approaches for prevention of type 2 diabetes: a life-course perspective.

In recent years, several alternative dietary approaches, including high-protein and low-glycaemic-load diets, have produced faster rates of weight loss than traditional low-fat, high-carbohydrate diets. These diets share an under-recognised unifying mechanism: the reduction of postprandial glycaemia and insulinaemia. Similarly, some food patterns and specific foods (potatoes, white bread, soft drinks) characterised by hyperglycaemia are associated with higher risk of adiposity and type 2 diabetes. Profound compensatory hyperinsulinaemia, exacerbated by overweight, occurs during critical periods of physiological insulin resistance such as pregnancy and puberty. The dramatic rise in gestational diabetes and type 2 diabetes in the young may therefore be traced to food patterns that exaggerate postprandial glycaemia and insulinaemia. The dietary strategy with the strongest evidence of being able to prevent type 2 diabetes is not the accepted low-fat, high-carbohydrate diet, but alternative dietary approaches that reduce postprandial glycaemia and insulinaemia without adversely affecting other risk factors.

Hypoglycaemia in cystic fibrosis in the absence of diabetes: A systematic review.

BACKGROUND: Hypoglycaemia in CF in the absence of diabetes or glucose lowering therapies is a phenomenon that is receiving growing attention in the literature. These episodes are sometimes symptomatic and likely have variable aetiologies. Our first aim was to conduct a systematic review of the literature to determine what is known about hypoglycaemia in CF. Our second aim was to assess evidence based guidelines for management strategies. METHODS: A comprehensive search of databases and guideline compiler entities was performed. Inclusion criteria were primary research articles and evidence based guidelines that referred to hypoglycaemia in CF in the absence of insulin treatment or other glucose lowering therapies. RESULTS: A total of 11 studies (four manuscripts and seven abstracts) and five evidence-based guidelines met the inclusion criteria. Prevalence rates of hypoglycaemia unrelated to diabetes varied between studies (7-69%). Hypoglycaemia was diagnosed during oral glucose tolerance testing or continuous glucose monitoring (CGM). Associations between hypoglycaemia and clinical parameters of BMI, lung function, liver disease and pancreatic insufficiency were measured in some studies. There was no unifying definition of hypoglycaemia in the absence of diabetes. Only two evidence based guidelines reported possible management strategies. CONCLUSION: The systematic review found limited data on this clinical problem and supports the need for high quality methodological studies that are able to describe the experience and the aetiology(ies) of hypoglycaemia in CF.

Assigning glycemic index to foods in a recent Australian food composition database.

This paper describes the compilation of a special edition of the AUSNUT2011-2013 food composition database that includes glycemic index (GI) values. A 6-step, systematic methodology was used to assign GI to 5644 foods included in AUSNUT2011-2013. A total of 1752 (31%) foods were assigned a GI of 0 owing to low carbohydrate content; 363 (6%) had a direct match in 1 of the 4 data tables used; 1738 (31%) were assigned the GI of a 'closely related' food item; 1526 (27%) were assigned the weighted mean GI of ingredients; 205 (4%) were assigned the median GI of their corresponding food subgroup; 49 (<1%) were assigned a GI of 0 because they were not a significant source of carbohydrate in typical diets; and 5 (<1%) were assigned a default GI. We propose that this database should be used for all future Australian GI research until a subsequent version/update is compiled.

Glycaemic and insulin index of four common German breads.

BACKGROUND/OBJECTIVES: German-style breads are recommended as a lower glycaemic index (GI) alternative, yet little data is available. Our aim was to test the GI and insulin index (II) of four breads and rolls commonly consumed in Germany. SUBJECTS/METHODS: Four German bread products were tested for their GI and II in 12 healthy subjects according to the International Standard Organization guidelines. RESULTS: Only the wholemeal rye bread with visible intact grains and sunflower seeds was identified as low GI (GI=55). Both the wholemeal spelt wheat (GI=63) and the rye wheat sourdough bread (GI=62) were classified as medium GI, whereas soft pretzel was high GI (GI=80, P<0.05 compared with other products). The II of soft pretzels (II=102) was also highest and differed significantly from wholemeal rye (II=70) and rye sourdough bread (II=72) but not from wholemeal spelt wheat (II=77). CONCLUSIONS: Contrary to popular belief, these German-style breads are medium to high GI, with the exception of the rye bread with intact grains and seeds. The results highlight the need to test, rather than 'guestimate', the GI of local products, and develop a broader range of low-GI breads.

The effect of maternal and post-weaning low and high glycaemic index diets on glucose tolerance, fat deposition and hepatic function in rat offspring.

Clinical studies have reported beneficial effects of a maternal low glycaemic index (GI) diet on pregnancy and neonatal outcomes, but the impact of the diet on the offspring in later life, and the mechanisms underlying these effects, remain unclear. In this study, Albino Wistar rats were fed either a low GI (n=14) or high GI (n=14) diet during pregnancy and lactation and their offspring weaned onto either the low or high GI diet. Low GI dams had better glucose tolerance (AUC[glucose], 1322±55 v. 1523±72 mmol min/l, P<0.05) and a lower proportion of visceral fat (19.0±2.9 v. 21.7±3.8% of total body fat, P<0.05) compared to high GI dams. Female offspring of low GI dams had lower visceral adiposity (0.45±0.03 v. 0.53±0.03% body weight, P<0.05) and higher glucose tolerance (AUC[glucose], 1243±29 v. 1351±39 mmol min/l, P<0.05) at weaning, as well as lower hepatic PI3K-p85 mRNA at 12 weeks of age. No differences in glucose tolerance or hepatic gene expression were observed in male offspring, but the male low GI offspring did have reduced hepatic lipid content at weaning. These findings suggest that consuming a low GI diet during pregnancy and lactation can improve glucose tolerance and reduce visceral adiposity in the female offspring at weaning, and may potentially produce long-term reductions in the hepatic lipogenic capacity of these offspring.

The effect of flexible low glycemic index dietary advice versus measured carbohydrate exchange diets on glycemic control in children with type 1 diabetes.

OBJECTIVE: To determine the long-term effect of low glycemic index dietary advice on metabolic control and quality of life in children with type 1 diabetes. RESEARCH DESIGN AND METHODS: Children with type 1 diabetes (n = 104) were recruited to a prospective, stratified, randomized, parallel study to examine the effects of a measured carbohydrate exchange (CHOx) diet versus a more flexible low-glycemic index (GI) dietary regimen on HbA(1c) levels, incidence of hypo- and hyperglycemia, insulin dose, dietary intake, and measures of quality of life over 12 months. RESULTS: At 12 months, children in the low-GI group had significantly better HbA(1c) levels than those in the CHOx group (8.05 +/- 0.95 vs. 8.61 +/- 1.37%, P = 0.05). Rates of excessive hyperglycemia (>15 episodes per month) were significantly lower in the low-GI group (35 vs. 66%, P = 0.006). There were no differences in insulin dose, hypoglycemic episodes, or dietary composition. The low-GI dietary regimen was associated with better quality of life for both children and parents. CONCLUSIONS: Flexible dietary instruction based on the food pyramid with an emphasis of low-GI foods improves HbA(1c) levels without increasing the risk of hypoglycemia and enhances the quality of life in children with diabetes.

Effects of human milk and formula on postprandial glycaemia and insulinaemia.

BACKGROUND/OBJECTIVES: Consumption of formula in place of human milk may produce differences in postprandial glycaemia and insulinaemia that contribute to metabolic programming in the first year of life. The objective of the current study was to determine glycaemic and insulinaemic responses to human milk compared with a typical commercial formula, and then compare 11 other formulas. SUBJECTS/METHODS: On separate mornings in random order, 10 healthy breastfeeding mothers consumed 25 g available carbohydrate portions of their own milk, a formula and reference food (25 g glucose on two occasions). In the second study, 10 different healthy subjects consumed 25 g available carbohydrate portions of 11 different commercial formulas and three reference foods (25 g glucose on three occasions). Fingerpick blood samples were taken at regular intervals over 2 h, and the glycaemic index (GI) and insulin index determined according to a standardised protocol. RESULTS: There were no significant differences in postprandial glycaemia or insulinaemia after human milk vs a typical formula (P = 0.3). Both produced a low GI (mean ± s.e.m.: 38 ± 7 vs 34 ± 7, respectively) and high insulin index (87 ± 14 vs 94 ± 16). The GI and insulin indices of the other formulas ranged from 18 ± 3 to 67 ± 6 and 53 ± 9 to 209 ± 33, respectively. CONCLUSIONS: Human milk and a typical formula elicit similar postprandial glycaemic and insulinaemic responses, but there is a wide range of responses to other formulas.

A systematic methodology to estimate added sugar content of foods.

BACKGROUND/OBJECTIVES: The effect of added sugar on health is a topical area of research. However, there is currently no analytical or other method to easily distinguish between added sugars and naturally occurring sugars in foods. This study aimed to develop a systematic methodology to estimate added sugar values on the basis of analytical data and ingredients of foods. SUBJECTS/METHODS: A 10-step, stepwise protocol was developed, starting with objective measures (six steps) and followed by more subjective estimation (four steps) if insufficient objective data are available. The method developed was applied to an Australian food composition database (AUSNUT2007) as an example. RESULTS: Out of the 3874 foods available in AUSNUT2007, 2977 foods (77%) were assigned an estimated value on the basis of objective measures (steps 1-6), and 897 (23%) were assigned a subjectively estimated value (steps 7-10). Repeatability analysis showed good repeatability for estimated values in this method. CONCLUSIONS: We propose that this method can be considered as a standardised approach for the estimation of added sugar content of foods to improve cross-study comparison.

Concentration and distribution of sialic acid in human milk and infant formulas.

BACKGROUND: In animal studies, sialic acid supplementation is associated with increases of gangliosides in the brain and improved learning ability. Only limited data are available on the sialic acid content of human milk and infant formulas. OBJECTIVE: We compared the concentrations of oligosaccharide-bound, protein-bound, and free sialic acid in milk from mothers of full-term and preterm infants and in a range of infant formulas. DESIGN: The milk from 20 and 14 mothers of full-term and preterm infants (mean gestational age: 31 +/- 3 wk), respectively, was collected at 4 stages of lactation (colostrum, transition, 1 mo, and 3 mo) and compared with 21 different infant formulas. RESULTS: Total sialic acid concentrations were highest in colostrum (x +/- SEM: 5.04 +/- 0.21 mmol/L in full term) and decreased by nearly 80% over the next 3 mo. Human milk from mothers of preterm infants contained 13-23% more sialic acid than did milk from mothers of full-term infants at 3 of the 4 lactation stages (P < 0.02). The sialic acid content of most formulas was <25% of that found in mature human milk (P < 0.01). Most of the sialic acid in the formulas ( approximately 70%) was bound to glycoproteins, whereas in human milk most sialic acid was bound to free oligosaccharides. CONCLUSIONS: Human milk, including milk from mothers of preterm infants, is a rich source of oligosaccharide-bound sialic acid, which contrasts with the relatively small amounts found in infant formulas. The nutritional significance of sialic acid is presently unknown, but it is plausible that it is a conditional nutrient that contributes to sialic acid accretion in the brain.

Insulin sensitivity predicts glycemia after a protein load.

Protein ingestion results in small but distinct changes in plasma glucose and insulin. We hypothesized that the glycemic and/or insulin response to protein might be related to the degree of insulin sensitivity. Our aim was to determine the relationships between insulin sensitivity (assessed by euglycemic-hyperinsulinemic clamp) and postprandial glucose, insulin, C-peptide, and glucagon responses to a 75-g protein meal and a 75-g glucose load. Sixteen lean healthy Caucasian subjects (mean +/- SD age, 25 +/- 6 years; body mass index [BMI], 23.1 +/- 1.7 kg/m2) participated in the study. After the protein meal, the mean plasma glucose declined gradually below fasting levels to a nadir of -0.36 +/- 0.46 mmol/L from 60 to 120 minutes, showing wide intraindividual variation. Insulin sensitivity (M value) was 1.1 to 3.9 mmol/L/m2 min in the subjects and correlated inversely with the plasma glucose response to the protein meal (r = -.58, P = .03), ie, the most insulin-sensitive subjects showed the greatest decline in plasma glucose. In contrast, there was no correlation between insulin sensitivity and the insulin or glucagon response to the protein load, or between the M value and the metabolic responses (glucose, insulin, C-peptide, and glucagon) to the glucose load. Our study suggests that the net effect of insulin and glucagon secretion on postprandial glucose levels after a protein meal might depend on the individual's degree of insulin sensitivity. Gluconeogenesis in the liver may be less susceptible to inhibition by insulin in the more highly resistant subjects, thereby counteracting a decline in plasma glucose.

The metabolic syndrome: from inherited survival trait to a health care problem.

A critical role is proposed for the quantity and quality of dietary carbohydrate in the pathogenesis of the insulin resistance and hyperinsulinaemia which characterise the Metabolic Syndrome. We propose that an insulin-resistant genotype evolved to provide survival and reproductive advantages for the cold-climate, large game hunters of the last Ice Age who consumed a low carbohydrate, high protein diet with periodic starvation. Insulin resistance would have minimised glucose utilisation by muscles thereby facilitating the preferential utilisation of glucose by the brain, foetus and mammary gland. But beginning about 10,000 years ago following the end of the last Ice Age and the development of agriculture, dietary carbohydrate increased and the selection pressure for insulin resistance decreased in some groups. Agriculture began in the Middle East and spread throughout Europe long before it was developed elsewhere. Hence the prevalence of the insulin-resistant genotype decreased in Europeans and other groups exposed to a high carbohydrate intake for sufficiently long. Some geographically isolated groups such as the Pima Indians and Nauruans experienced conditions which further diminished the gene pool diversity and resulted in particularly insulin resistant populations. Traditional carbohydrate foods have a low glycaemic index and produce only modest increases in plasma insulin. However, the constant supply of highly refined high glycaemic index carbohydrate in modern diets, results in postprandial hyperinsulinaemia. The insulin-resistant genotype is now disadvantageous and predisposes to the development of the Metabolic Syndrome.

The effects of equal-energy portions of different breads on blood glucose levels, feelings of fullness and subsequent food intake.

OBJECTIVE: This study compared the effects of equal-energy portions of 7 different breads on feelings on fullness and subsequent ad libitum food intake. A satiety index score (SI) was calculated for each of the breads. DESIGN: Within-subject, repeated-measures design. SUBJECTS AND INTERVENTION: Ten healthy subjects participated in the study. Subjects fasted for > or =10 hours overnight and then reported to the research center the next morning, where they first completed baseline satiety ratings, gave a fasting blood sample, and then consumed a test bread. Additional finger prick blood samples and satiety ratings were collected at 15-minute intervals over 120 minutes, after which the subjects' ad libitum intake of food was recorded. A satiety index (SI) score was calculated for each test food by dividing the area under the 120-m satiety response curve (AUC) for the test bread by the satiety AUC for the reference bread (regular white bread) and multiplying by 100%. RESULTS: The mean SI scores for the breads ranged from 100% to 561%, with regular white bread having the lowest SI score. Mean SI scores were negatively correlated with energy intake at a test meal after 120 m (r=-0.88, P<.01, n=7) and total day energy intakes (r=-0.72, P<.05, n=7). The strongest predictor of the breads' SI scores was their portion size and thus energy density. The breads' glycemic responses were not significantly associated with fullness responses. APPLICATIONS: Ingredients and food processing methods are available for the production of palatable, high-satiety versions of processed foods, which may be useful for weight control diets. SI scores would be a useful addition to food labels to indicate which foods are less likely to be overeaten and could be used by dietitians to develop weight control plans to help reduce energy intakes without increased hunger.

The role and potential of sialic acid in human nutrition.

Sialic acids are a family of nine-carbon acidic monosaccharides that occur naturally at the end of sugar chains attached to the surfaces of cells and soluble proteins. In the human body, the highest concentration of sialic acid (as N-acetylneuraminic acid) occurs in the brain where it participates as an integral part of ganglioside structure in synaptogenesis and neural transmission. Human milk also contains a high concentration of sialic acid attached to the terminal end of free oligosaccharides, but its metabolic fate and biological role are currently unknown. An important question is whether the sialic acid in human milk is a conditional nutrient and confers developmental advantages on breast-fed infants compared to those fed infant formula. In this review, we critically discuss the current state of knowledge of the biology and role of sialic acid in human milk and nervous tissue, and the link between sialic acid, breastfeeding and learning behaviour.

The glycaemic index of potatoes: the effect of variety, cooking method and maturity.

OBJECTIVE: The aim of this study was to determine the impact of variety, cooking method and maturity on the GI of potatoes, it was hypothesised that new potatoes may have a relatively lower GI. DESIGN AND SUBJECTS: Ten healthy volunteers were recruited as subjects through advertising on the campus of the University of Sydney. Equal (50 g) carbohydrate portions of eight potato meals (three varieties, four cooking methods, two states of maturity) and two reference white bread meals were fed in random order to each of the subjects over a period of 10 weeks. Capillary blood samples were taken in the fasting state and then at 15, 30, 45, 60, 90 and 120 min from the start of each meal. Samples were analysed for plasma glucose concentrations and incremental areas under plasma glucose curves were calculated. The GI of the potato was calculated as the AUC of the potato expressed as a percentage of the individual's average AUC of the white bread. This was then multiplied by 0.7 to index the GI to glucose as the reference food. RESULTS: GI values (mean +/- s.e.m.) ranged from 65+/-9 (canned new potatoes) to 10+/-15 (boiled Desiree potatoes), glucose = 100. No significant difference was found among the three varieties of potato tested (P = 0.38) or among the four different cooking methods (P = 0.55). The GI values of the canned new potato and boiled Desiree potato were significantly different (P = 0.047). The average size of the tuber was found to correlate with the GI (r = 0.83, P<0.05). CONCLUSIONS: Potatoes, regardless of variety, cooking method and maturity, have exceptionally high GI values. New potatoes have relatively lower GI values which is attributed to differences in starch structure.