Some consider potatoes to be unhealthy vegetables that may contribute to adverse cardiometabolic health outcomes. We evaluated the association between potato consumption (including fried and non-fried types) and three key cardiometabolic outcomes among middle-aged and older adults in the Framingham Offspring Study. We included 2523 subjects ≥30 years of age with available dietary data from 3-d food records. Cox-proportional hazards models were used to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs) for hypertension, type 2 diabetes or impaired fasting glucose (T2DM/IFG), and elevated triglycerides, adjusting for anthropometric, demographic and lifestyle factors. In the present study, 36 % of potatoes consumed were baked, 28 % fried, 14 % mashed, 9 % boiled and the rest cooked in other ways. Overall, higher total potato intake (≥4 v. <1 cup-equivalents/week) was not associated with risks of T2DM/IFG (HR 0⋅97, 95 % CI 0⋅81, 1⋅15), hypertension (HR 0⋅95; 95 % CI 0⋅80, 1⋅12) or elevated triglycerides (HR 0⋅99, 95 % CI 0⋅86, 1⋅13). Stratified analyses were used to evaluate effect modification by physical activity levels and red meat consumption, and in those analyses, there were no adverse effects of potato intake. However, when combined with higher levels of physical activity, greater consumption of fried potatoes was associated with a 24 % lower risk (95 % CI 0⋅60, 0⋅96) of T2DM/IFG, and in combination with lower red meat consumption, higher fried potato intake was associated with a 26 % lower risk (95 % CI 0⋅56, 0⋅99) of elevated triglycerides. In this prospective cohort, there was no adverse association between fried or non-fried potato consumption and risks of T2DM/IFG, hypertension or elevated triglycerides.

Dietary starch contains rapidly (RAG) and slowly available glucose (SAG). To establish the relationships between the RAG:SAG ratio and postprandial glucose, insulin and hunger, we measured postprandial responses elicited by test meals varying in the RAG:SAG ratio in n 160 healthy adults, each of whom participated in one of four randomised cross-over studies (n 40 each): a pilot trial comparing six chews (RAG:SAG ratio 2·4-42·7) and three studies comparing a test granola (TG1-3, RAG:SAG ratio 4·5-5·2) with a control granola (CG1-3, RAG:SAG ratio 54·8-69·3). Within studies, test meals were matched for fat, protein and available carbohydrate. Blood glucose, serum insulin and subjective hunger were measured for 3 h. Data were subjected to repeated-measures analysis of variance (ANOVA). The relationships between the RAG:SAG ratio and postprandial end points were determined by regression analysis. In the pilot trial, 0-2 h glucose incremental areas under the curve (iAUC0-2; primary end point) varied across the six chews (P = 0·014) with each 50 % reduction in the RAG:SAG ratio reducing relative glucose response by 4·0 %. TGs1-3 elicited significantly lower glucose iAUC0-2 than CGs1-3 by 17, 18 and 17 %, respectively (similar to the 15 % reduction predicted by the pilot trial). The combined means ± sem (n 120) for TC and CG were glucose iAUC0-2, 98 ± 4 v. 118 ± 4 mmol × min/l (P < 0·001), and insulin iAUC0-2, 153 ± 9 v. 184 ± 11 nmol × h/l (P < 0·001), respectively. Neither postprandial hunger nor glucose or hunger increments 2 h after eating differed significantly between TG and CG. We concluded that TGs with RAG:SAG ratios <5·5 predictably reduced glycaemic and insulinaemic responses compared with CGs with RAG:SAG ratios >54. However, compared with CG, TG did not reduce postprandial hunger or delay the return of glucose or hunger to baseline.

BACKGROUND: Starch is a principal dietary source of digestible carbohydrate and energy. Glycaemic and insulinaemic responses to foods containing starch vary considerably and glucose responses to starchy foods are often described by the glycaemic index (GI) and/or glycaemic load (GL). Low GI/GL foods are beneficial in the management of cardiometabolic disorders (e.g., type 2 diabetes, cardiovascular disease). Differences in rates and extents of digestion of starch-containing foods will affect postprandial glycaemia.
UNASSIGNED: Amylolysis kinetics are influenced by structural properties of the food matrix and of starch itself. Native (raw) semi-crystalline starch is digested slowly but hydrothermal processing (cooking) gelatinises the starch and greatly increases its digestibility. In plants, starch granules are contained within cells and intact cell walls can limit accessibility of water and digestive enzymes hindering gelatinisation and digestibility. In vitro studies of starch digestion by α-amylase model early stages in digestion and can suggest likely rates of digestion in vivo and expected glycaemic responses. Reports that metabolic responses to dietary starch are influenced by α-amylase gene copy number, heightens interest in amylolysis.
CONCLUSIONS: This review shows how enzyme kinetic strategies can provide explanations for differences in digestion rate of different starchy foods. Michaelis-Menten and Log of Slope analyses provide kinetic parameters (e.g., K m and k cat /K m ) for evaluating catalytic efficiency and ease of digestibility of starch by α-amylase. Suitable kinetic methods maximise the information that can be obtained from in vitro work for predictions of starch digestion and glycaemic responses in vivo.

Nut-based products may aid low-glycaemic dietary strategies that are important for diabetes prevention in populations at increased risk of dysglycaemia, such as Asian Chinese. This randomised cross-over trial assessed the postprandial glycaemic response (0-120 min) of a higher-protein nut-based (HP-NB) snack formulation, in bar format (1009 kJ, Nutrient Profiling Score, NPS, -2), when compared with an iso-energetic higher-carbohydrate (CHO) cereal-based bar (HC-CB, 985 kJ, NPS +3). It also assessed the ability to suppress glucose response to a typical CHO-rich food (white bread, WB), when co-ingested. Ten overweight prediabetic Chinese adults (mean, sd: age 47⋅9, 15⋅7 years; BMI 25⋅5, 1⋅6 kg/m2), with total body fat plus ectopic pancreas and liver fat quantified using dual-energy X-ray absorptiometry and magnetic resonance imaging and spectroscopy, received the five meal treatments in random order: HP-NB, HC-CB, HP-NB + WB (50 g available CHO), HC-CB + WB and WB only. Compared with HC-CB, HP-NB induced a significantly lower 30-120 min glucose response (P < 0⋅05), with an approximately 10-fold lower incremental area under the glucose curve (iAUC0-120; P < 0⋅001). HP-NB also attenuated glucose response by approximately 25 % when co-ingested with WB (P < 0⋅05). Half of the cohort had elevated pancreas and/or liver fat, with 13-21 % greater suppression of iAUC0-120 glucose in the low v. high organ fat subgroups across all five treatments. A nut-based snack product may be a healthier alternative to an energy equivalent cereal-based product with evidence of both a lower postprandial glycaemic response and modulation of CHO-induced hyperglycaemia even in high-risk, overweight, pre-diabetic adults.

The effect of modifying dietary fatty acid (FA) composition on insulin sensitivity remains unclear. We aimed to investigate whether changes in plasma phospholipid (PL) FA composition, as a result of dietary intervention, correspond with changes in insulin sensitivity. The RISCK study was a 6-month randomised controlled dietary intervention study, which assessed the effect of modifying dietary fat and the glycaemic index (GI) of carbohydrates on insulin sensitivity. Total NEFA levels, fasting plasma PL FA profiles and an insulin sensitivity index (Si), derived from intravenous glucose tolerance minimal-model analysis, were available from 533 participants, all at elevated risk of type 2 diabetes. Bivariate correlations between changes in saturated PL FA (SFA), MUFA (as a percentage of total plasma NEFA) and changes in Si were assessed according to treatment group. Age, sex, ethnicity, percentage change in body mass and change in dietary GI were controlled for. Increasing total NEFA concentration was associated with worsening Si (r -0·152; P = 0·001). In the high-MUFA/low-GI diet group, change in PL-MUFA was positively and independently associated with change in Si (r 0·297; P = 0·002). Among MUFA, change in oleic acid (18 : 1) was most strongly correlated with change in Si (r 0·266; P = 0·005), as was change in minor FA 24 : 1 (r 0·244; P = 0·011) and 17 : 1 (r 0·196; P = 0·042). In the high-SFA/high-GI group, change in SFA concentration was not significantly associated with change in Si. In conclusion, increases in the proportion of plasma PL-MUFA following a high-MUFA dietary intervention were associated with improvements in insulin sensitivity.

Currently it is estimated that about 1 billion people globally have non-alcoholic fatty liver disease (NAFLD), a condition in which liver fat exceeds 5 % of liver weight in the absence of significant alcohol intake. Due to the central role of the liver in metabolism, the prevalence of NAFLD is increasing in parallel with the prevalence of obesity, insulin resistance and other risk factors of metabolic diseases. However, the contribution of liver fat to the risk of type 2 diabetes mellitus and CVD, relative to other ectopic fat depots and to other risk markers, is unclear. Various studies have suggested that the accumulation of liver fat can be reduced or prevented via dietary changes. However, the amount of liver fat reduction that would be physiologically relevant, and the timeframes and dose-effect relationships for achieving this through different diet-based approaches, are unclear. Also, it is still uncertain whether the changes in liver fat per se or the associated metabolic changes are relevant. Furthermore, the methods available to measure liver fat, or even individual fatty acids, differ in sensitivity and reliability. The present report summarises key messages of presentations from different experts and related discussions from a workshop intended to capture current views and research gaps relating to the points above.

Kiwifruit is a carbohydrate food of low glycaemic potency which could potentially be exchanged for starch-based foods in management of postprandial glycaemia. The effect of equicarbohydrate partial exchange of kiwifruit varieties \'Hayward\' green (GR) and \'Zesy002\' (SunGold; SG) for a starchy wheat-based breakfast cereal (WB) on the characteristics of the postprandial glycaemic response and satiety was therefore determined. A total of twenty non-diabetic subjects (mean age 36 years; mean BMI 24·5 kg/m2) consumed four meals, each containing 40 g available carbohydrate, in random order, after an overnight fast. The meals were: (1) glucose; (2) 70·29 g breakfast cereal; (3) 200 g of GR plus breakfast cereal (30·93 g); and (4) 200 g of SG plus breakfast cereal (27·06 g). Throughout the 180 min postprandial period, capillary blood glucose concentrations were monitored, and satiety rated by a visual analogue scale. Partial kiwifruit substitution of WB significantly reduced postprandial glycaemic response amplitude (glucose, 3·91; WB, 3·66; WB + GR, 2·36; WB + SG, 2·31  mmol/l; least significant difference (LSD) 0·64; P < 0·001) and incremental area under the blood glucose response curve (0-120 min) (glucose, 228; WB, 180; WB + GR, 133; WB + SG, 134 mmol/l × min; LSD 22·7; P < 0·001). The area between baseline and response remained positive in kiwifruit-substituted meals but became negative after 120 min with glucose and WB, indicating that kiwifruit improved homeostatic control. Kiwifruit substitution of cereal did not significantly reduce satiety. We conclude that either \'Hayward\' or \'Zesy002\' kiwifruit may be used in equicarbohydrate partial substitution of starchy staple foods to reduce glycaemic response and improve glucose homeostasis without decreasing satiety.

Raisins are popular snacks with a favourable nutrient profile, being high in dietary fibre, polyphenols and a number of vitamins and minerals, in addition to being rich in fructose. In light of evidence demonstrating improvements in glycaemic control with moderate fructose intake and low-glycaemic index (GI) fruits, our aim was to determine the GI, insulin index (II) and postprandial responses to raisins in an acute feeding setting. A total of ten healthy participants (four male and six female) consumed breakfast study meals on four occasions over a 2- to 8-week period: meal 1: white bread (WB) (108 g WB; 50 g available carbohydrate) served as the control and was consumed on two separate occasions; meal 2: raisins (R50) (69 g raisins; 50 g available carbohydrate); and meal 3: raisins (R20) (one serving, 28 g raisins; 20 g available carbohydrate). Postprandial glucose and insulin were measured over a 2 h period for the determination of GI, glycaemic load (GL) and II. The raisin meals, R50 and R20, resulted in significantly reduced postprandial glucose and insulin responses when compared with WB (P < 0·05). Furthermore, raisins were determined to be low-GI, -GL and -II foods. The favourable effect of raisins on postprandial glycaemic response, their insulin-sparing effect and low GI combined with their other metabolic benefits may indicate that raisins are a healthy choice not only for the general population but also for individuals with diabetes or insulin resistance.