Randomised controlled trial of lifestyle interventions for abdominal obesity in primary health care

AIM

Assess effects on waist circumference from diet with or without cereal grains and with or without long-term physical exercise.

BACKGROUND

Elevated waist circumference is an indicator of increased abdominal fat storage and is accordingly associated with increased cardiovascular mortality. This is likely due to the association between lifestyle-induced changes in waist circumference and cardiovascular risk factors. Reductions in waist circumference may be facilitated by diet without cereal grains combined with long-term physical exercise.

METHODS

Two-year randomised controlled trial with factorial trial design in individuals at increased risk of cardiovascular disease with increased waist circumference. Participants were allocated diet based on current Swedish dietary guidelines with or without cereal grains (baseline diet information supported by monthly group sessions) and with or without physical exercise (pedometers and two initial months of weekly structured exercise followed by written prescription of physical activity) or control group. The primary outcome was the change in waist circumference.

FINDINGS

The greatest mean intervention group difference in the change in waist circumference among the 73 participants (47 women and 26 men aged 23-79 years) was at one year between participants allocated a diet without cereal grains and no exercise and participants allocated a diet with cereal grains and no exercise [M = -5.3 cm and -0.9 cm, respectively; mean difference = 4.4 cm, 4.0%, 95% CI (0.0%, 8.0%), P = 0.051, Cohen's d = 0.75]. All group comparisons in the change in waist circumference were non-significant despite the greatest group difference being more than double that estimated in the pre-study power calculation. The non-significance was likely caused by too few participants and a greater than expected variability in the change in waist circumference. The greatest mean intervention group difference strengthens the possibility that dietary exclusion of cereal grains could be related to greater reduction in waist circumference.

Inverse association between Paleolithic Diet Fraction and mortality and incidence of cardiometabolic disease in the prospective Malmö Diet and Cancer Study

PURPOSE

Paleolithic Diet Fraction (PDF) estimates how large a portion of the absolute dietary intake stems from food groups included in the Paleolithic diet. In randomized controlled trials higher PDFs have been associated with healthier levels of cardiometabolic risk markers. Our aim was to build upon these findings by examining associations between PDF and mortality and incidence of cardiometabolic disease in the prospective Malmö Diet and Cancer Study.

METHODS

PDF was calculated from an interview-based, modified diet history method, and associations were estimated by using multivariable Cox proportional hazards regression. The examined cohort consisted of 24,104 individuals (44-74 years, 63% women) without previous coronary events, diabetes, or stroke at baseline (1992-1996). A total of 10,092 individuals died during a median follow-up of 18 years.

RESULTS

Median PDF was 40% (0-90%). The adjusted hazard ratios (HR) for PDF as a continuous variable (from 0 to 100%) were for risk of death from all causes 0.55 [95% CI 0.45, 0.66], tumor 0.68 [95% CI 0.49, 0.93], cardiovascular 0.55 [95% CI 0.39, 0.78], respiratory 0.44 [95% CI 0.21, 0.90], neurological 0.26 [95% CI 0.11, 0.60], digestive, 0.10 [95% CI 0.03, 0.30], and other diseases 0.64 [95% CI 0.41, 1.00]. The corresponding HR for risk of coronary event was 0.61 [95% 0.43, 0.86], for ischemic stroke it was 0.73 [95% 0.48, 1.09] and for type 2 diabetes it was 0.82 [95% 0.61, 1.10].

CONCLUSION

Observational data suggest an inverse association between PDF and all-cause as well as cause-specific mortality and incidence of cardiometabolic disease.

C-reactive protein in traditional melanesians on Kitava

Background

Population-based levels of the chronic low-grade systemic inflammation biomarker, C-reactive protein (CRP), vary widely among traditional populations, despite their apparent absence of chronic conditions associated with chronic low-grade systemic inflammation, such as type 2 diabetes, metabolic syndrome and cardiovascular disease. We have previously reported an apparent absence of aforementioned conditions amongst the traditional Melanesian horticulturalists of Kitava, Trobriand Islands, Papua New Guinea. Our objective in this study was to clarify associations between chronic low-grade systemic inflammation and chronic cardiometabolic conditions by measuring CRP in a Kitava population sample. For comparison purposes, CRP was also measured in Swedish controls matched for age and gender.

Methods

Fasting levels of serum CRP were measured cross-sectionally in ≥ 40-year-old Kitavans (N = 79) and Swedish controls (N = 83).

Results

CRP was lower for Kitavans compared to Swedish controls (Mdn 0.5 mg/L range 0.1—48 mg/L and Mdn 1.1 mg/L range 0.1—33 mg/L, respectively, r = .18 p = .02). Among Kitavans, there were small negative associations between lnCRP for CRP values < 10 and total, low-density lipoprotein (LDL) and non-high-density lipoprotein (non-HDL) cholesterol. Among Swedish controls, associations of lnCRP for CRP values < 10 were medium positive with weight, body mass index, waist circumference, hip circumference and waist-hip ratio and low positive with triglyceride, total cholesterol-HDL cholesterol ratio, triglyceride-HDL cholesterol ratio and serum insulin.

Conclusions

Chronic low-grade systemic inflammation, measured as CRP, was lower among Kitavans compared to Swedish controls, indicating a lower and average cardiovascular risk, respectively, for these populations.

Effect of fermentation and dry roasting on the nutritional quality and sensory attributes of quinoa

BACKGROUND

Quinoa is a pseudocereal with relatively high content of proteins and minerals that also contains mineral inhibitors such as phytate. The aim of the present study was to evaluate lactic acid fermentation and dry roasting on the nutritional quality and sensory attributes of quinoa. Various processes were evaluated, and quinoa grains were dry-roasted, milled, and fermented, either with or without the addition of wheat phytase or activated quinoa phytase (added as back-slop starter), for 10 hr. In other processes, raw quinoa flour was fermented for 10 hr or 4 hr and dry-roasted. Hedonic sensory evaluation was then performed to evaluate the acceptability of the fermented flours prepared as porridges.

RESULTS

The combined dry roasting and fermentation processes significantly (p < .05) degraded phytate between 30% and 73% from initial content. The most effective process was fermentation of raw quinoa flour followed by dry roasting, which improved the estimated zinc and iron bioavailability. Particularly, estimated zinc bioavailability improved from low (Phy:Zn 25.4, Phy·Zn:Ca 295) to moderate (Phy:Zn 7.14, Phy·Zn:Ca 81.5). Phytate degradation was mainly attributed to the activation of endogenous phytase during fermentation. Dry roasting was effective in improving the sensory attributes of the fermented quinoa flour. Porridge made with raw quinoa flour fermented for 4 hr and dry-roasted was more favorable to overall acceptability than that which was fermented for 10 hr and dry-roasted.

CONCLUSION

Fermentation of quinoa flour for 4 hr followed by dry roasting was successful in improving both nutritional and sensory attributes of the final product.

Phytate, iron, zinc, and calcium content of common Bolivian foods and their estimated mineral bioavailability

There is a scarcity of information on mineral and phytate content in plant-based foods in Bolivia. This study aimed to analyze iron, zinc, calcium, and phytate content and estimate the mineral bioavailability of foods consumed in Chapare, Bolivia. Minerals and phytate were analyzed, and bioavailability was estimated in 17 food samples. Leafy vegetables and green legumes had the highest mineral content, followed by pseudocereals. Estimated mineral bioavailability was low for cereals, dry legumes, pseudocereals, and flaxseeds foods mainly due to phytate content. But estimated zinc bioavailability for black cornmeal, yellow corn, and dry peas was moderate. Strong correlations (p < 0.01) were found between the three minerals, while phytate correlated negatively to iron, zinc, and calcium. To get an overview of the estimated mineral bioavailability of plant-based diets, we have included foods, from the same area, analyzed in a previous study where the evaluated diet covers 80% of RNI for iron and zinc, but <40% of calcium. In conclusion, leafy vegetables and green legumes had the highest contents of minerals and the lowest phytate content of the foods analyzed in the study. The usage of processing strategies and dietary diversification to reduce phytate content would significantly improve estimated mineral bioavailability in plant-based diets.

Fermentation of pseudocereals quinoa, canihua, and amaranth to improve mineral accessibility through degradation of phytate

BACKGROUND

Pseudocereals are nutrient-rich grains with high mineral content but also phytate content. Phytate is a mineral absorption inhibitor. The study's aim was to evaluate phytate degradation during spontaneous fermentation and during Lactobacillus plantarum 299v® fermentation of quinoa, canihua, and amaranth grains and flours. It also aimed to evaluate the accessibility of iron, zinc, and calcium and to estimate their bioavailability before and after the fermentation of flours with starter culture. Lactic acid, pH, phytate, and mineral content were analyzed during fermentation.

RESULTS

Higher phytate degradation was found during the fermentation of flours (64-93%) than during that of grains (12-51%). Results suggest that phytate degradation was mainly due to endogenous phytase activity in different pseudocereals rather than the phytase produced by added microorganisms. The addition of Lactobacillus plantarum 299v® resulted in a higher level of lactic acid (76.8-82.4 g kg^-1 DM) during fermentation, and a relatively quicker reduction in pH to 4 than in spontaneous fermentation. Mineral accessibility was increased (1.7-4.6-fold) and phytate : mineral molar ratios were reduced (1.5-4.2-fold) in agreement with phytate degradation (1.8-4.2-fold) in fermented flours. The reduced molar ratios were still above the threshold value for the improved estimated mineral bioavailability of mainly iron.

CONCLUSION

Fermentation proved to be effective for degrading phytate in pseudocereal flours, but less so in grains. Fermentation with Lactobacillus plantarum 299v® improved mineral accessibility and estimated bioavailability in flours. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Probiotic fruit beverages with different polyphenol profiles attenuated early insulin response

BACKGROUND

Consumption of polyphenol-rich fruits and vegetables may improve postprandial glucose and insulin levels and hence promote well-being. Previously it has been observed that consumption of bilberry decreases the postprandial insulin demand. The intention with the present study was to compare the impact of different supplements with various polyphenol profiles, on the postprandial glucose and insulin responses in healthy young adults.

METHODS

In a randomized, controlled, crossover study the postprandial glycemic and insulin responses were observed in eleven healthy adults after intake of five different beverages containing bilberry (European blueberry), blackcurrant, beetroot, mango and rose hip, respectively; all drinks were enriched with the same composition of fermented oatmeal and probiotics. The control was a glucose drink. The profile and content of the polyphenols in the different beverages were determined by HPLC-DAD analysis. The antioxidative capacity of the different beverages were measured by TEAC and DPPH assays.

RESULTS

Beverages containing bilberry, blackcurrant, mango or rose hip significantly attenuated the early postprandial insulin response (0-90 min), but showed no effect on glucose response. Drinks with bilberry or rose hip reduced the insulin response from the very early phase (0-30 min), and had significantly lower insulin index compared with the control. The efficiency of the bilberry and rose hip to decrease early postprandial insulin responses correlated with higher phenolic contents.

CONCLUSIONS

Supplements with bilberry, blackcurrant, mango or rose hip in the tested probiotic and oatmeal enriched beverage attenuated early-phase insulin response, but had no effect on the postprandial glycemic response. The improved ability of bilberry and rose hip to lower the very early phase of insulin response seems to be due to a higher phenolic content.

TRIAL REGISTRATION

The study was retrospectively registered at ClinicalTrials.gov with number NCT03159065 .

Palaeolithic diet decreases fasting plasma leptin concentrations more than a diabetes diet in patients with type 2 diabetes: a randomised cross-over trial

Background

We have previously shown that a Palaeolithic diet consisting of the typical food groups that our ancestors ate during the Palaeolithic era, improves cardiovascular disease risk factors and glucose control compared to the currently recommended diabetes diet in patients with type 2 diabetes. To elucidate the mechanisms behind these effects, we evaluated fasting plasma concentrations of glucagon, insulin, incretins, ghrelin, C-peptide and adipokines from the same study.

Methods

In a randomised, open-label, cross-over study, 13 patients with type 2 diabetes were randomly assigned to eat a Palaeolithic diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts, or a diabetes diet designed in accordance with current diabetes dietary guidelines during two consecutive 3-month periods. The patients were recruited from primary health-care units and included three women and 10 men [age (mean ± SD) 64 ± 6 years; BMI 30 ± 7 kg/m²; diabetes duration 8 ± 5 years; glycated haemoglobin 6.6 ± 0.6 % (57.3 ± 6 mmol/mol)] with unaltered diabetes treatment and stable body weight for 3 months prior to the start of the study. Outcome variables included fasting plasma concentrations of leptin, adiponectin, adipsin, visfatin, resistin, glucagon, insulin, C-peptide, glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1 and ghrelin. Dietary intake was evaluated by use of 4-day weighed food records.

Results

Seven participants started with the Palaeolithic diet and six with the diabetes diet. The Palaeolithic diet resulted in a large effect size (Cohen’s d = −1.26) at lowering fasting plasma leptin levels compared to the diabetes diet [mean difference (95 % CI), −2.3 (−5.1 to 0.4) ng/ml, p = 0.023]. No statistically significant differences between the diets for the other variables, analysed in this study, were observed.

Conclusions

Over a 3-month study period, a Palaeolithic diet resulted in reduced fasting plasma leptin levels, but did not change fasting levels of insulin, C-peptide, glucagon, incretins, ghrelin and adipokines compared to the currently recommended diabetes diet.

Trial registration: ClinicalTrials.gov NCT00435240

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0398-1) contains supplementary material, which is available to authorized users.

Zinc bioavailability in rats fed a plant-based diet: a study of fermentation and zinc supplementation

BACKGROUND

Zinc deficiency is a significant problem, in developing countries and in vegetarians, which can be caused by plant-based diets. Thus, dietary strategies, such as fermentation, to improve zinc bioavailability of diets should be investigated.

OBJECTIVE

To improve zinc bioavailability in a plant-based diet by the inclusion of fermented food.

DESIGN

Cassava tubers were fermented and made to replace the unfermented cassava in a basal plant-based diet, and compared with plant-based diets with and without zinc supplement. The zinc bioavailability of the diets was evaluated in Wistar rats that were fed these diets for 28 days. The evaluation was for zinc apparent absorption (ZnAA), serum zinc levels, and zinc deposits in liver and femur; in addition, the feed efficiency ratio (FER) of the diets and femur weight (FW) of the rats were evaluated.

RESULTS

During the cassava fermentation, lactic acid increased and pH decreased (from 6.8 to 3.9), which is favorable for native phytase activity, resulting in a 90.2% reduction of phytate content in cassava. The diet containing fermented cassava showed significantly higher levels of ZnAA, FER, and FW (p<0.001). Moreover, the zinc levels in serum and femur were significantly higher (p<0.001) compared with the results of the diet with unfermented cassava. The results clearly show a higher zinc bioavailability in the diet containing fermented cassava and are comparable with the results obtained with the plant-based diet with zinc supplement.

CONCLUSIONS

In conclusion, the fermentation of cassava reduces the phytate content. The diet containing the fermented cassava represents a better nutritional alternative than the diet with unfermented cassava and is comparable with the zinc-supplemented diets.

Diet inequality prevails among consumers interested and knowledgeable in nutrition

Background

Previous studies have demonstrated a correlation between diet cost and adherence to nutritional recommendations among consumers in general. This has adverse effects on diet and health inequality. It could be hypothesized that consumers knowledgeable in nutrition escape this correlation.

Objective

Investigate whether the previously observed relationship between diet cost and nutritional quality prevails among consumers with an above-average interest in and knowledge of nutrition.

Design

Full open diet registrations of 330 students taking a basic university-level course in nutrition over a total of 780 days.

Results

The consumers with the highest daily average diet cost differ from the lowest cost quartile: The diets had higher micronutrient density, more fruits and vegetables, and lower energy density. The highest cost daily diet quartile had a significantly higher energy adjusted intake of the micronutrients that were on average consumed below the recommendation (vitamin D, folate, and iron for women). On the other hand, alcohol intake was significantly higher among the high diet cost group. The highest diet cost respondents consumed more fish, meat, coffee, and spreads, whereas the lowest diet cost respondents had a higher consumption of cereals, bread, jam, sausage, and milk.

Conclusions

Dietary differences prevail even in the above-average interested and knowledgeable group. The respondents did not use their higher level of knowledge to break this commonly observed relationship. This suggests that an increased minimum level of knowledge in nutrition may not by itself eliminate dietary inequality.

From diets to foods: using linear programming to formulate a nutritious, minimum-cost porridge mix for children aged 1 to 2 years

BACKGROUND

Linear programming has been used extensively as a tool for nutritional recommendations. Extending the methodology to food formulation presents new challenges, since not all combinations of nutritious ingredients will produce an acceptable food. Furthermore, it would help in implementation and in ensuring the feasibility of the suggested recommendations.

OBJECTIVE

To extend the previously used linear programming methodology from diet optimization to food formulation using consistency constraints. In addition, to exemplify usability using the case of a porridge mix formulation for emergency situations in rural Mozambique.

METHODS

The linear programming method was extended with a consistency constraint based on previously published empirical studies on swelling of starch in soft porridges. The new method was exemplified using the formulation of a nutritious, minimum-cost porridge mix for children aged 1 to 2 years for use as a complete relief food, based primarily on local ingredients, in rural Mozambique.

RESULTS

A nutritious porridge fulfilling the consistency constraints was found; however, the minimum cost was unfeasible with local ingredients only. This illustrates the challenges in formulating nutritious yet economically feasible foods from local ingredients. The high cost was caused by the high cost of mineral-rich foods. A nutritious, low-cost porridge that fulfills the consistency constraints was obtained by including supplements of zinc and calcium salts as ingredients.

CONCLUSIONS

The optimizations were successful in fulfilling all constraints and provided a feasible porridge, showing that the extended constrained linear programming methodology provides a systematic tool for designing nutritious foods.

A healthy diet with and without cereal grains and dairy products in patients with type 2 diabetes: study protocol for a random-order cross-over pilot study--Alimentation and Diabetes in Lanzarote--ADILAN

Background

Research on the role of nutrition in type 2 diabetes has largely focused on macro/micronutrient composition and dietary fiber intake, while fewer studies have tested the effects of differing food choice. Some observational studies and short-term intervention studies suggest that a food pattern mimicking the diet with which humans evolved positively influences glucose control and associated endocrine systems. Such a food pattern mainly differs from other common healthy food patterns in its absence of cereal grains and dairy products. The primary aim of this pilot study is to determine the effect of two healthy diets with or without cereal grains and dairy products on glucose control, while keeping participants’ weight stable and other food parameters, such as macro/micronutrient composition, dietary fiber and glycemic load, the same in both diets.

Methods/Design

We intend to include 15 adult patients with a medical diagnosis of type 2 diabetes mellitus with or without medication and with an increased waist circumference (≥ 80 cm for women and ≥ 94 cm for men) in a random-order cross-over diet intervention study during two periods of four-weeks separated by a six-week washout period. Patients will be instructed to eat two healthy diets according to official dietary guidelines with respect to macro/micronutrient composition and fiber content, but differing in the type of food included, with one diet being without cereal grains and dairy products. Lunch will be served in a hospital kitchen for control of nutrient intake, while the rest of the meals will be eaten at home according to specific directions. The energy content of the diets will be individually adjusted to maintain a stable body weight during the two four-week intervention periods. Primary outcomes will be change in fasting plasma glucagon and fructosamine, while secondary outcomes include change in fasting glucose and glycated hemoglobin, glucose and glucagon response during oral glucose tolerance test, blood lipids, blood pressure, C-reactive protein, body composition, quality of life, subjective experience with the two diets, satiety scores and changes in medication.

Discussion

Using these results, we will assess the need to conduct larger and longer studies with similar design.

Trial registration

This trial was registered at clinicaltrials.gov as NCT01891955 and Spanish Agency of Medication and Sanitary Products (AEMPS) registration code: MFV-ADI-2013-01.

Subjective satiety and other experiences of a Paleolithic diet compared to a diabetes diet in patients with type 2 diabetes

Background

We found marked improvement of glycemic control and several cardiovascular risk factors in patients with type 2 diabetes given advice to follow a Paleolithic diet, as compared to a diabetes diet. We now report findings on subjective ratings of satiety at meal times and participants’ other experiences of the two diets from the same study.

Methods

In a randomized cross-over study, 13 patients with type 2 diabetes (3 women and 10 men), were instructed to eat a Paleolithic diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts, and a diabetes diet designed in accordance with dietary guidelines, during two consecutive 3-month periods. In parallel with a four-day weighed food record, the participants recorded their subjective rating of satiety. Satiety quotients were calculated as the intra-meal quotient of change in satiety during a meal and consumed energy or weight of food and drink for that specific meal. All participants answered the same three open-ended questions in a survey following each diet: “What thoughts do you have about this diet?”, “Describe your positive and negative experiences with this diet” and “How do you think this diet has affected your health?”.

Results

The participants were equally satiated on both diets. The Paleolithic diet resulted in greater satiety quotients for energy per meal (p = 0.004), energy density per meal (p = 0.01) and glycemic load per meal (p = 0.02). The distribution of positive and negative comments from the survey did not differ between the two diets, and the comments were mostly positive. Among comments relating to recurring topics, there was no difference in distribution between the two diets for comments relating to tastelessness, but there was a trend towards more comments on the Paleolithic diet being satiating and improving blood sugar values, and significantly more comments on weight loss and difficulty adhering to the Paleolithic diet.

Conclusions

A Paleolithic diet is more satiating per calorie than a diabetes diet in patients with type 2 diabetes. The Paleolithic diet was seen as instrumental in weight loss, albeit it was difficult to adhere to.

Trial registration

ClinicalTrials.gov: NCT00435240

Validation of digital photographs, as a tool in 24-h recall, for the improvement of dietary assessment among rural populations in developing countries

BACKGROUND

Improvement of traditional methods for dietary assessment is necessary, especially in rural areas where it is more difficult to succeed with self-reporting methods. This study presents and validates a method for improving accuracy when measuring food and nutrient intake of individuals in rural areas. It is called the "Food photography 24-h recall method" (FP 24-hR) and is a modified 24-h recall with the addition of a digital food photography record and a photo atlas.

METHODS

The study was carried out in a rural area in the tropical region of Bolivia; 45 women participated. Validation of the method was made by comparing it with a reference method, the Weighed Food Record (WFR). During the FP 24-hR, digital photographs were taken by the subjects of all food consumed during a day and a 24-h recall questionnaire was conducted by an interviewer. An estimate of the amount of food consumed was made using a photo atlas and the photographs taken by the subjects. For validation, comparison was made between the calculations, by both methods, of the levels of food, and nutrient, intake.

RESULTS

The comparison was made in 10 food categories; most of which were somewhat underestimated from -2.3% (cassava) to -6.8% (rice), except for beverages (+1.6%) and leafy vegetables (+8.7%), which were overestimated. Spearman's correlation coefficients were highly significant (r from 0.75 for eggs to 0.98 for potato and cassava). Nutrient intakes calculated with data from both methods showed small differences from -0.90% (vitamin C) to -5.98% (fat). Although all nutrients were somewhat underestimated, Pearson's coefficients are high (>0.93 for all) and statistically significant. Bland Altman analysis showed that differences between both methods were random and did not exhibit any systematic bias over levels of food and nutrient intake, with acceptable 95% limits of agreement.

CONCLUSION

The FP 24-hR exhibits acceptable differences when compared with a WFR, digital photos are useful as a memory aid for the subjects during 24-h recall and as an estimation tool. The method is suitable for assessing dietary intake among rural populations in developing countries.

A paleolithic diet is more satiating per calorie than a mediterranean-like diet in individuals with ischemic heart disease

Background

We found marked improvement of glucose tolerance and lower dietary energy intake in ischemic heart disease (IHD) patients after advice to follow a Paleolithic diet, as compared to a Mediterranean-like diet. We now report findings on subjective ratings of satiety at meals and data on the satiety hormone leptin and the soluble leptin receptor from the same study.

Methods

Twenty-nine male IHD patients with impaired glucose tolerance or diabetes type 2, and waist circumference > 94 cm, were randomized to ad libitum consumption of a Paleolithic diet (n = 14) based on lean meat, fish, fruit, vegetables, root vegetables, eggs, and nuts, or a Mediterranean-like diet (n = 15) based on whole grains, low-fat dairy products, vegetables, fruit, fish, and oils and margarines during 12 weeks. In parallel with a four day weighed food record the participants recorded their subjective rating of satiety. Satiety Quotients were calculated, as the intra-meal quotient of change in satiety during meal and consumed energy or weight of food and drink for that specific meal. Leptin and leptin receptor was measured at baseline and after 6 and 12 weeks. Free leptin index was calculated as the ratio leptin/leptin receptor.

Results

The Paleolithic group were as satiated as the Mediterranean group but consumed less energy per day (5.8 MJ/day vs. 7.6 MJ/day, Paleolithic vs. Mediterranean, p = 0.04). Consequently, the quotients of mean change in satiety during meal and mean consumed energy from food and drink were higher in the Paleolithic group (p = 0.03). Also, there was a strong trend for greater Satiety Quotient for energy in the Paleolithic group (p = 0.057). Leptin decreased by 31% in the Paleolithic group and by 18% in the Mediterranean group with a trend for greater relative decrease of leptin in the Paleolithic group. Relative changes in leptin and changes in weight and waist circumference correlated significantly in the Paleolithic group (p < 0.001) but not in the Mediterranean group. Changes in leptin receptor and free leptin index were not significant.

Conclusions

A Paleolithic diet is more satiating per calorie than a Mediterranean-like diet.

Trial registration

ClinicalTrials.gov NCT00419497

Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study

BACKGROUND

Our aim was to compare the effects of a Paleolithic ('Old Stone Age') diet and a diabetes diet as generally recommended on risk factors for cardiovascular disease in patients with type 2 diabetes not treated with insulin.

METHODS

In a randomized cross-over study, 13 patients with type 2 diabetes, 3 women and 10 men, were instructed to eat a Paleolithic diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts; and a Diabetes diet designed in accordance with dietary guidelines during two consecutive 3-month periods. Outcome variables included changes in weight, waist circumference, serum lipids, C-reactive protein, blood pressure, glycated haemoglobin (HbA1c), and areas under the curve for plasma glucose and plasma insulin in the 75 g oral glucose tolerance test. Dietary intake was evaluated by use of 4-day weighed food records.

RESULTS

Study participants had on average a diabetes duration of 9 years, a mean HbA1c of 6,6% units by Mono-S standard and were usually treated with metformin alone (3 subjects) or metformin in combination with a sulfonylurea (3 subjects) or a thiazolidinedione (3 subjects). Mean average dose of metformin was 1031 mg per day. Compared to the diabetes diet, the Paleolithic diet resulted in lower mean values of HbA1c (-0.4% units, p = 0.01), triacylglycerol (-0.4 mmol/L, p = 0.003), diastolic blood pressure (-4 mmHg, p = 0.03), weight (-3 kg, p = 0.01), BMI (-1 kg/m2, p = 0.04) and waist circumference (-4 cm, p = 0.02), and higher mean values of high density lipoprotein cholesterol (+0.08 mmol/L, p = 0.03). The Paleolithic diet was mainly lower in cereals and dairy products, and higher in fruits, vegetables, meat and eggs, as compared with the Diabetes diet. Further, the Paleolithic diet was lower in total energy, energy density, carbohydrate, dietary glycemic load, saturated fatty acids and calcium, and higher in unsaturated fatty acids, dietary cholesterol and several vitamins. Dietary GI was slightly lower in the Paleolithic diet (GI = 50) than in the Diabetic diet (GI = 55).

CONCLUSION

Over a 3-month study period, a Paleolithic diet improved glycemic control and several cardiovascular risk factors compared to a Diabetes diet in patients with type 2 diabetes.

Effect of cereal test breakfasts differing in glycemic index and content of indigestible carbohydrates on daylong glucose tolerance in healthy subjects

BACKGROUND

Frequent hyperglycemic episodes are increasingly being associated with an increased risk of type 2 diabetes and cardiovascular disease.

OBJECTIVE

We studied the extent to which acute glycemia and glycemia after subsequent meals can be modulated by the characteristics of cereal foods, such as glycemic index (GI) and content of indigestible carbohydrates.

DESIGN

Twelve healthy subjects consumed test meals in a random order. In series 1, the test meals were consumed at breakfast, and postprandial blood glucose incremental areas under the curve (IAUCs) were calculated after the test breakfast, standardized lunch, and standardized dinner. In series 2, the subjects consumed test evening meals and IAUCs were calculated after a subsequent standardized breakfast. Breath hydrogen was measured as an indicator of colonic fermentation.

RESULTS

Barley or rye kernel breakfasts lowered the blood glucose IAUC (0-120 min) at breakfast, at a subsequent lunch, and the cumulative IAUCs (breakfast+lunch+dinner) when compared with white-wheat bread (P < 0.05). The lunch blood glucose IAUCs were positively correlated with breakfast IAUCs (r = 0.30, P < 0.05). Breath hydrogen excretion was negatively correlated with blood glucose IAUCs after lunch (r = -0.33, P < 0.05) and dinner (r = -0.22, P < 0.05). A barley kernel evening meal resulted in lower IAUCs (P < 0.05) and higher breath hydrogen (P < 0.001) after a subsequent breakfast compared with white-wheat bread.

CONCLUSIONS

Glucose tolerance at subsequent meals can be notably improved during the course of a whole day or overnight by choosing specific low-GI, whole-grain cereal products. A low GI may be sufficient to achieve a second-meal effect from breakfast to lunch. A specific indigestible carbohydrate mixture appears to be required to show benefits on glucose tolerance in a longer time frame (9.5 h), most likely mediated through colonic fermentation.

Measuring the glycemic index of foods: interlaboratory study

BACKGROUND

Many laboratories offer glycemic index (GI) services.

OBJECTIVE

We assessed the performance of the method used to measure GI.

DESIGN

The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 laboratories (n=311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally.

RESULTS

Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P=0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean+/-SD) for cheese-puffs and fruit-leather were 74.3+/-10.5 and 33.2+/-7.2, respectively. The mean laboratory GI was related to refCV (P=0.003) and the type of restrictions on alcohol consumption before the test (P=0.006, r2=0.509 for model). The within-laboratory SD of GI was related to refCV (P<0.001), the glucose analysis method (P=0.010), whether glucose measures were duplicated (P=0.008), and restrictions on dinner the night before (P=0.013, r2=0.810 for model).

CONCLUSIONS

The between-laboratory SD of the GI values is approximately 9. Standardized data analysis and low within-subject variation (refCV<30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.

A Palaeolithic diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease

AIMS/HYPOTHESIS

Most studies of diet in glucose intolerance and type 2 diabetes have focused on intakes of fat, carbohydrate, fibre, fruits and vegetables. Instead, we aimed to compare diets that were available during human evolution with more recently introduced ones.

METHODS

Twenty-nine patients with ischaemic heart disease plus either glucose intolerance or type 2 diabetes were randomised to receive (1) a Palaeolithic ('Old Stone Age') diet (n = 14), based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts; or (2) a Consensus (Mediterranean-like) diet (n = 15), based on whole grains, low-fat dairy products, vegetables, fruits, fish, oils and margarines. Primary outcome variables were changes in weight, waist circumference and plasma glucose AUC (AUC Glucose(0-120)) and plasma insulin AUC (AUC Insulin(0-120)) in OGTTs.

RESULTS

Over 12 weeks, there was a 26% decrease of AUC Glucose(0-120) (p = 0.0001) in the Palaeolithic group and a 7% decrease (p = 0.08) in the Consensus group. The larger (p = 0.001) improvement in the Palaeolithic group was independent (p = 0.0008) of change in waist circumference (-5.6 cm in the Palaeolithic group, -2.9 cm in the Consensus group; p = 0.03). In the study population as a whole, there was no relationship between change in AUC Glucose(0-120) and changes in weight (r = -0.06, p = 0.9) or waist circumference (r = 0.01, p = 1.0). There was a tendency for a larger decrease of AUC Insulin(0-120) in the Palaeolithic group, but because of the strong association between change in AUC Insulin(0-120) and change in waist circumference (r = 0.64, p = 0.0003), this did not remain after multivariate analysis.

CONCLUSIONS/INTERPRETATION

A Palaeolithic diet may improve glucose tolerance independently of decreased waist circumference.

Muesli with 4 g oat β-glucans lowers glucose and insulin responses after a bread meal in healthy subjects

OBJECTIVE

To evaluate the impact of an extruded muesli product based on beta-glucan-rich oat bran on postprandial glycaemia and insulinaemia.

SUBJECT/DESIGN

The study is divided in two series. Blood glucose and serum insulin responses were studied after subjects consuming test meals including a serving of muesli with 3 g (series 1) and 4 g (series 2) of beta-glucans, respectively. The muesli was a component in a single serving packet with muesli and yoghurt. This was served together with white wheat bread in the morning after an overnight fast. The compositions were standardized to contain 50 g available carbohydrates. As a reference meal a serving packet without beta-glucans was included. The study was performed at Applied Nutrition and Food Chemistry, Lund University, Sweden. Nineteen and thirteen healthy volunteers with normal body mass index were recruited for series 1 and 2, respectively.

RESULTS

Muesli with 3 g of beta-glucans, included in a mixed bread meal, gave no significant differences in glycaemic response compared to a reference meal without muesli and beta-glucans. In contrast, muesli with 4 g of beta-glucans significantly (P<0.05) lowered the glucose and insulin responses compared to the reference meal.

CONCLUSIONS

Muesli enriched with 4 g of beta-glucans reduces postprandial glucose and insulin levels to a breakfast based on high glycaemic index products. A total of 4 g of beta-glucans from oats seems to be a critical level for a significant decrease in glucose and insulin responses in healthy people.

Effects of GI and content of indigestible carbohydrates of cereal-based evening meals on glucose tolerance at a subsequent standardised breakfast

OBJECTIVE

To evaluate the impact of four low-glycaemic index (GI) and one high-GI cereal-based evening meals on glucose tolerance at a subsequent standardised breakfast.

DESIGN

Wheat kernels, barley kernels, spaghetti, spaghetti with added wheat bran and white wheat bread (WWB) were consumed in the evening in a random order at five different occasions. At the subsequent breakfast, blood glucose, serum insulin, plasma short chain fatty acid, plasma free fatty acid (FFA) and breath hydrogen were measured.

SETTING

The study was performed at Applied Nutrition and Food Chemistry, Lund University, Sweden.

SUBJECTS

Fifteen healthy volunteers were recruited. One subject was later excluded owing to abnormal blood glucose values.

RESULTS

The blood glucose response (0-120 min) to the standardised breakfast was significantly lower after consuming barley kernels in the evening compared with evening meals with WWB (P=0.019) or spaghetti+wheat bran (P=0.046). There were no significant differences in insulin concentrations at breakfast. Breath hydrogen excretion at breakfast was significantly higher after an evening meal with barley kernels compared with WWB, wheat kernels or spaghetti (P=0.026, 0.026 and 0.015, respectively), and the concentration of plasma propionate at breakfast was significantly higher following an evening meal with barley kernels compared with an evening meal with WWB (P=0.041). In parallel, FFA concentrations were significantly lower after barley kernels compared with WWB (P=0.042) or spaghetti evening meals (P=0.019).

CONCLUSIONS

The improved glucose tolerance at breakfast, following an evening meal with barley kernels appeared to emanate from suppression of FFA levels, mediated by colonic fermentation of the specific indigestible carbohydrates present in this product, or, to the combination of the low-GI features and colonic fermentation.

Determination of glycaemic index; some methodological aspects related to the analysis of carbohydrate load and characteristics of the previous evening meal

OBJECTIVES

To determine the possible differences in glycaemic index (GI) depending on (1) the analytical method used to calculate the 'available carbohydrate' load, that is, using carbohydrates by difference (total carbohydrate by difference, minus dietary fibre (DF)) as available carbohydrates vs available starch basis (total starch minus resistant starch (RS)) of a food rich in intrinsic RS and (2) the effect of GI characteristics and/or the content of indigestible carbohydrates (RS and DF) of the evening meal prior to GI testing the following morning.

DESIGN

Blood glucose and serum insulin responses were studied after subjects consuming (1) two levels of barley kernels rich in intrinsic RS (15.2%, total starch basis) and (2) after a standard breakfast following three different evening meals varying in GI and/or indigestible carbohydrates: pasta, barley kernels and white wheat bread, respectively.

SUBJECTS

Healthy adults with normal body mass index.

RESULTS

(1) Increasing the portion size of barley kernels from 79.6 g (50 g 'available carbohydrates') to 93.9 g (50 g available starch) to adjust for its RS content did not significantly affect the GI or insulin index (11). (2) The low GI barley evening meal, as opposed to white wheat bread and pasta evening meals, reduced the postprandial glycaemic and insulinaemic (23 and 29%, respectively, P < 0.05) areas under the curve at a standardized white bread breakfast fed the following morning.

CONCLUSION

(1) Increasing portion size to compensate for the considerable portion of RS in a low GI barley product had no significant impact on GI or II. However, for GI testing, it is recommended to base carbohydrate load on specific analyses of the available carbohydrate content. (2) A low GI barley evening meal containing high levels of indigestible carbohydrates (RS and DF) substantially reduced the GI and II of white wheat bread determined at a subsequent breakfast meal.

Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal in healthy subjects

OBJECTIVE

To investigate the potential of acetic acid supplementation as a means of lowering the glycaemic index (GI) of a bread meal, and to evaluate the possible dose-response effect on postprandial glycaemia, insulinaemia and satiety.

SUBJECTS AND SETTING

In all, 12 healthy volunteers participated and the tests were performed at Applied Nutrition and Food Chemistry, Lund University, Sweden.

INTERVENTION

Three levels of vinegar (18, 23 and 28 mmol acetic acid) were served with a portion of white wheat bread containing 50 g available carbohydrates as breakfast in randomized order after an overnight fast. Bread served without vinegar was used as a reference meal. Blood samples were taken during 120 min for analysis of glucose and insulin. Satiety was measured with a subjective rating scale.

RESULTS

A significant dose-response relation was seen at 30 min for blood glucose and serum insulin responses; the higher the acetic acid level, the lower the metabolic responses. Furthermore, the rating of satiety was directly related to the acetic acid level. Compared with the reference meal, the highest level of vinegar significantly lowered the blood glucose response at 30 and 45 min, the insulin response at 15 and 30 min as well as increased the satiety score at 30, 90 and 120 min postprandially. The low and intermediate levels of vinegar also lowered the 30 min glucose and the 15 min insulin responses significantly compared with the reference meal. When GI and II (insulinaemic indices) were calculated using the 90 min incremental area, a significant lowering was found for the highest amount of acetic acid, although the corresponding values calculated at 120 min did not differ from the reference meal.

CONCLUSION

Supplementation of a meal based on white wheat bread with vinegar reduced postprandial responses of blood glucose and insulin, and increased the subjective rating of satiety. There was an inverse dose-response relation between the level of acetic acid and glucose and insulin responses and a linear dose-response relation between acetic acid and satiety rating. The results indicate an interesting potential of fermented and pickled products containing acetic acid.

Determination of the glycaemic index of foods: interlaboratory study

OBJECTIVE

Practical use of the glycaemic index (GI), as recommended by the FAO/WHO, requires an evaluation of the recommended method. Our purpose was to determine the magnitude and sources of variation of the GI values obtained by experienced investigators in different international centres.

DESIGN

GI values of four centrally provided foods (instant potato, rice, spaghetti and barley) and locally obtained white bread were determined in 8-12 subjects in each of seven centres using the method recommended by FAO/WHO. Data analysis was performed centrally.

SETTING

University departments of nutrition.

SUBJECTS

Healthy subjects (28 male, 40 female) were studied.

RESULTS

The GI values of the five foods did not vary significantly in different centres nor was there a significant centrexfood interaction. Within-subject variation from two centres using venous blood was twice that from five centres using capillary blood. The s.d. of centre mean GI values was reduced from 10.6 (range 6.8-12.8) to 9.0 (range 4.8-12.6) by excluding venous blood data. GI values were not significantly related to differences in method of glucose measurement or subject characteristics (age, sex, BMI, ethnicity or absolute glycaemic response). GI values for locally obtained bread were no more variable than those for centrally provided foods.

CONCLUSIONS

The GI values of foods are more precisely determined using capillary than venous blood sampling, with mean between-laboratory s.d. of approximately 9.0. Finding ways to reduce within-subject variation of glycaemic responses may be the most effective strategy to improve the precision of measurement of GI values.

An examination of the possibility of lowering the glycemic index of oat and barley flakes by minimal processing

Differences in glycemic responses to various starchy foods are related to differences in the rate of starch digestion and absorption. In this study, the importance of the degree of gelatinization and the product thickness for postprandial glycemic and insulinemic responses to rolled oats and barley were studied in healthy subjects (5 men and 5 women). Thick (1.0 mm) rolled oats were made from raw or preheated (roasted or steamed) kernels. In addition, thin (0.5 mm) rolled oats were made from roasted or roasted and steamed (processed under conditions simulating commercial production) oat kernels. Finally, steamed rolled barley kernels (0.5 or 1.0 mm) were prepared. All thin flakes elicited high glucose and insulin responses [glycemic index (GI), 88-118; insulinemic index (II), 84-102], not significantly different from white wheat bread (P: > 0.05). In contrast, all varieties of thick oat flakes gave significantly lower metabolic responses (GI, 70-78; II, 58-77) than the reference bread (P: < 0.05). Thick barley flakes, however, gave high glucose and insulin responses (GI, 94; II, 84), probably because the botanical structure underwent more destruction than the corresponding oat flakes. We conclude that minimal processing of oat and barley flakes had a relatively minor effect on GI features compared with the more extensive commercial processing. One exception was thick oat flakes, which in contrast to the corresponding barley flakes, had a low GI.

Metabolic responses to starch in oat and wheat products. On the importance of food structure, incomplete gelatinization or presence of viscous dietary fibre

OBJECTIVE

Evaluate the importance of incomplete gelatinization, food structure and presence of viscous dietary fibre for the postprandial glycaemic and insulinaemic responses to oat and wheat products.

DESIGN

Three common breakfast meals were tested, 'raw' rolled oats (muesli), boiled rolled oats (oat porridge) and white wheat bread. Boiled intact oat and wheat kernels (kernel porridges) were also included. For comparison, glycaemic indices (GIs) were calculated both from analysis of capillary and venous blood samples.

SETTING

The study was performed at the research laboratory, Dalby Health Sciences Centre (primary care).

SUBJECTS

Nine healthy male volunteers between 65 and 70 years of age participated in the study.

RESULTS

The rolled oats and oat porridge elicited high metabolic responses. No differences in the glycaemic and insulinaemic indices (IIs) were seen between these products and white wheat bread. In contrast, the kernel porridges produced low glucose and insulin responses. No differences were obtained in GI values whether based on capillary or venous blood. However, with some products capillary blood allowed smaller differences to be detected.

CONCLUSIONS

Neither incomplete gelatinization in rolled oats nor naturally occurring viscous dietary fibre in oats affect postprandial glycaemia, whereas enclosure of intact kernels significantly blunt metabolic responses.

Arepas made from high amylose corn flour produce favorably low glucose and insulin responses in healthy humans

The importance of the amylose: amylopectin ratio in the postprandial glycemic and insulinemic responses to corn was studied in food products that might realistically be consumed. Healthy subjects were given test meals in the form of arepas made from ordinary (25% amylose) or high amylose (70% amylose) corn flour. The ordinary corn meal contained 45 g of potentially available starch. To exclude the possible influence of a lowered content of potentially available starch due to formation of resistant starch in the high amylose product, this product was evaluated at two levels and included either on the basis of potentially available starch (45 g) or total starch (including resistant starch) (45 g, i.e., 29 g potentially available starch), respectively. The rate of starch hydrolysis, measured in vitro employing a method based on chewing, was studied. In addition, the content of in vitro resistant starch was analyzed in all products. The meals containing high amylose corn flour produced lower areas under the glucose and insulin response curves (57 and 42% lower, respectively) than did the meals containing ordinary cornmeal. This could not be explained by a lower amount of potentially available starch. No differences were noted when subjects consumed the two high amylose meals of arepas, despite 36% lower potentially available starch in one of the meals. The rate of starch hydrolysis measured in vitro was slower in the high amylose corn products than in the ordinary corn product. Resistant starch in the ordinary product was 3 g/100 g dry matter, vs. approximately 20 g/100 g dry matter in the high amylose products. We concluded that high amylose corn products have a potential to promote favorably low metabolic responses and high resistant starch contents.

Glucose and insulin responses to barley products: influence of food structure and amylose-amylopectin ratio

Postprandial glycemic and insulinemic responses and satiety with various barley products were evaluated in normal subjects. Also studied were the rate of in vitro starch digestion and the content of in vitro resistant starch (RS). Products tested were boiled intact (rice extender) and milled kernels (porridge) from four barley genotypes of Glacier with different amylose-amylopectin ratios (7-44% amylose). All barley products elicited lower metabolic responses and higher satiety scores when compared with white wheat bread. The lente behavior of the boiled flours was probably due to the viscous properties of the beta-glucans. However, the boiled flours produced higher glucose and insulin responses than did the corresponding boiled kernels. The impact of amylose: amylopectin on the metabolic responses was marginal. The high-amylose products released starch more slowly from a dialysis tubing during enzymic incubation of chewed samples compared with the corresponding products with less amylose. The RS content ranged from 0.4% in waxy to 5.6% in the high-amylose flour product (starch basis).

Food properties affecting the digestion and absorption of carbohydrates

Carbohydrate foods differ considerably in their effects on postprandial glucose and insulin responses. Qualitative differences among starchy foods are particularly intriguing because of the dominance of starch in human diets. This paper focuses on food properties in cereal (eg, pasta, bread, Arepas, and porridge) and legume products (eg, red kidney beans and lentils) that affect metabolic responses to starch. Studies in healthy subjects have found that postprandial blood glucose and insulin responses are greatly affected by food structure. Any process that disrupts the physical or botanical structure of food ingredients will increase the plasma glucose and insulin responses. The glycemic responses to bread products were reduced by the use of ingredients with an intact botanical or physical structure or a high amylose content or by enrichment with viscous dietary fiber. However, the important of a moderate increase in the amylose-amylopectin ratio and the naturally occurring levels of viscous cereal fiber is less clear. The rate of starch digestion in vitro was shown to be a key determinant of metabolic responses to most products. Assuming the sample preparation mimics chewing, in vitro enzymic procedures can be used to facilitate ranking. One such procedure, based on chewed rather than artificially disintegrated products, was recently developed and correlates well with glycemic and insulinemic indices for several starchy foods.

pH measurements of human dental plaque after consumption of starchy foods using the microtouch and the sampling method

The aim was to study the effect of different starch-containing food items on pH changes in dental plaque. The pH was, in 10 subjects, simultaneously measured at various occasions up to 60 min in: (1) two approximal spaces in the premolar-molar region with the microtouch method, and (2) pooled samples of dental plaque with the sampling method. Six starchy products were tested: (1) spaghetti, (2) macaroni, (3) potato, (4) rice, (5) unsweetened bread, and (6) sweetened bread. A glucose chewing tablet and a mouthrinse with 10% sucrose served as controls. Saliva was collected for HPLC analysis of maltose and maltotriose when testing the spaghetti, rice and unsweetened bread. The glucose tablet and the sucrose solution resulted in the greatest pH drops. However, all starchy products resulted in obvious pH falls, which were most pronounced for sweetened bread, followed, in order, by unsweetened bread and potato. Significantly more maltose and maltotriose were found in saliva after consumption of unsweetened bread compared to spaghetti. There seemed to be a relationship between the amount of starch hydrolysates in saliva and the area of the plaque pH curve (AUC). The microtouch method gave consistently lower pH values than the sampling method. Both methods, however, ranked the eight test products roughly in the same order with respect to minimum pH, maximum pH decrease and AUC.

An in vitro procedure based on chewing to predict metabolic response to starch in cereal and legume products

A new method for measuring the rate of in-vitro starch digestion in products with a structure 'as eaten' is introduced. An equivalent amount of potentially available starch from each product was chewed by subjects, expectorated into a beaker and incubated with pepsin. The incubate was thereafter transferred to a dialysis tubing and incubated with pancreatic alpha-amylase for 3 h. Samples were removed from the dialysate at time intervals and the degree of hydrolysis was calculated as the proportion of the potentially available starch degraded to maltose. A hydrolysis index (HI) was calculated as the area under the hydrolysis curve with the product as a percentage of the corresponding area with white wheat bread. The method was applied to 21 cereal and legume products, chosen to cover as wide a range as possible with respect to metabolic response, and to include several of the proposed mechanisms to differences in metabolic behaviour of starch. The accuracy of the in-vitro method was evaluated versus the metabolic responses obtained with the same products in healthy subjects. A significant correlation between HI and glycaemic index (GI) was obtained in cereal as well as in legume products. A significant correlation was also obtained between HI and insulin index (II) with pooled data from all products. However, in the case of II no correlation was obtained with the legume products only. It is concluded that the presently described in-vitro procedure offers a good potential to predict the metabolic behaviour of starchy foods.

Metabolic responses to starch in bread containing intact kernels versus milled flour

In the present study, the potential of including intact kernels from different cereals was evaluated as a means of developing bread with 'lente' characteristics. Postprandial glucose and insulin responses to bread products were studied in healthy subjects. In parallel, the in-vitro enzymic starch availability was investigated. Also studied were the contents of in-vitro indigestible starch. Coarse bread (CB) products composed of 80% pre-boiled kernels from wheat, rye, oats or barley and 20% white wheat flour were baked. In the case of barley, two forms for pre-treatments was used, boiling and scalding. A bread with 80% wholemeal barley flour and 20% white wheat flour (WMB) was also included and a white wheat bread (WWB) was used as reference. The glycaemic and insulinaemic indexes (GI and II, respectively) were calculated from the 95 and 120 min incremental blood glucose and insulin areas. The GIs were significantly lower with CB from wheat, rye and barley than with WWB. In contrast, the GIs with CB from oats and WMB from barley were similar to that with WWB. The GIs and IIs were generally closely correlated. However, the II with CB from oats was significantly lower than with WWB despite similar GI. The GIs, and in particular IIs, were closely correlated with the hydrolysis rate index (HI) obtained in vitro, and this procedure can be recommended as a tool for ranking of starchy food. It is concluded that the botanical structure is an important determinant of the enzymic availability and hence of the metabolic responses. The in-vitro indigestible starch content was highest in CB from barley (1.2% dry weight basis) and lowest in CB from oats (0.5%).

On the importance of processing conditions, product thickness and egg addition for the glycaemic and hormonal responses to pasta: a comparison with bread made from 'pasta ingredients'

The importance of processing conditions, product thickness and effect of egg addition for the glycaemic and hormonal responses to pasta was studied. Healthy subjects were given test meals with an equivalent amount of available carbohydrate from extruded high-temperature dried spaghetti and three varieties of fresh roll-sheeted linguine (thick, thin, thin with egg) made from the same ingredients (durum wheat, water and monoglycerides). As a reference bread was baked from the same ingredients as in the pasta products. Glucose, insulin and C-peptide levels were measured over a 3 h period. Glycaemic, insulin and C-peptide indexes (GI, II, CI) were calculated using 120 min areas under the curves. Glycaemic index was also calculated using the 90 min area. Also studied were the rates of in vitro starch digestion. The four pasta products produced significantly lower peak values (glucose, insulin, C-peptide) and lower GI (90 min), II (120 min) and CI (120 min) than the corresponding bread. The rate of in vitro starch digestion in pasta was also slower than in bread. In contrast to the pasta products, bread resulted in a prominent hypoglycaemia in the late phase, that is a drop below fasting blood glucose level. Minor differences in metabolic responses also appeared in the pasta products. In particular, the insulin and C-peptide response to the thin linguine was accentuated in the phase around 120 min.