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Effect of a family and interdisciplinary intervention to prevent T2D: randomized clinical trial.
Vargas-Ortiz, K, Lira-Mendiola, G, Gómez-Navarro, CM, Padilla-Estrada, K, Angulo-Romero, F, Hernández-Márquez, JM, Villa-Martínez, AK, González-Mena, JN, Macías-Cervantes, MH, Reyes-Escogido, ML, et al
BMC public health. 2020;20(1):97
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In individuals at high risk of type 2 diabetes, lifestyle interventions rather than medication have been more successful in preventing development of the disease, however the benefits of lifestyle strategies diminishes over time due to possible adherence issues. Prolonged lifestyle changes may be affected by lack of family support, but research on family support during lifestyle changes in individuals prior to diabetes is lacking. This parallel randomised control trial of 122 patients with prediabetes and 101 of their family members aimed to assess the impact of family supported diet and exercise changes compared to self-motivation on individuals with prediabetes. At 6 months, body measurements and markers of prediabetes improved in both groups. Lipids were significantly improved in the group with family support compared to having no support. At 12 months there were a high number of dropouts due to lack of patient interest. Benefits shown at 6 months in both groups were only maintained or improved upon with family support and the lipid profile of the individual intervention group actually worsened in comparison to when participants entered the trial. After 12 months the incidence rate of type 2 diabetes was similar in both groups. Individuals with prediabetes who had family support whilst undergoing a diet and exercise regime were more successful at maintaining improvements of factors contributing to diabetes, compared to individuals without support. However this did not affect the occurrence of type 2 diabetes. Clinicians could use this paper to communicate the importance of family support during lifestyle changes in patients at high risk of developing type 2 diabetes, although close monitoring may be required to ensure compliance.
Abstract
BACKGROUND Lifestyle changes can reduce the risk of T2D; however, no study has evaluated the effect of a lifestyle intervention involving patients´ family. The aim of this study was to compare the impact of an interdisciplinary family (FI) Vs individual intervention (II) on glucose metabolism, insulin resistance (IR), pancreatic β-cell function and cardiovascular risk markers in patients with prediabetes, as well as to measure the impact on their families' metabolic risk. METHODS Randomized Clinical Trial (RCT) to compare the impact of FI and II on IR and pancreatic β-cell function in subjects with prediabetes. There were 122 subjects with prediabetes (and 101 family members) randomized to FI or II. Data were collected in 2015-2016 and analyzed in 2017-2018. FI group had the support of their family members, who also received personalized diet and exercise recommendations; patients and their family members attended monthly a lifestyle enhancement program. II group received personalized diet and exercise recommendations. The follow-up was for 12 months. Glucose, IR, pancreatic β-cell function and secondary outcomes (body composition and lipid profile) were assessed at baseline, 6 and 12 months. RESULTS FI group improved area under the glucose curve (AUC) (from 18,597 ± 2611 to 17,237 ± 2792, p = 0.004) and the Matsuda index (from 3.5 ± 2.3 to 4.7 ± 3.5, p = 0.05) at 12 months. II group improved Disposition Index (from 1.5 ± 0.4 to 1.9 ± 0.73, p < .0001) at 12 months. The improvements achieved in weight and lipids at 6 months, were lost in II group at 12 moths, whereas in FI persisted. Adherence up to 12 months was not different between the study groups (FI 56% Vs II 60%). CONCLUSIONS FI intervention was more effective by improving glucose AUC, insulin sensitivity and lipid profile, besides that, metabolic risk in family members of the FI group was maintained, while the risk of II group was increased. TRIAL REGISTRATION This study was retrospectively registered at clinicaltrials.gov on December 15, 2015 (NTC026365646).
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Long-term effects of a three-component lifestyle intervention on emotional well-being in women with Polycystic Ovary Syndrome (PCOS): A secondary analysis of a randomized controlled trial.
Jiskoot, G, Dietz de Loos, A, Beerthuizen, A, Timman, R, Busschbach, J, Laven, J
PloS one. 2020;15(6):e0233876
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Polycystic Ovary Syndrome (PCOS) is a common endocrine disorder affecting women in their reproductive years. The condition is often associated with higher rates of depression and anxiety, particularly with a Body Mass Index (BMI) of >30. As weight-loss has shown to improve a host of symptoms experienced in PCOS, the authors sought to investigate whether weight-loss would also lead to a reduction in depressive symptoms. This secondary analysis of a longitudinal, randomised trial of 155 women, compared a combined lifestyle intervention of diet advice, eating behaviour, exercise and standardised Cognitive Behaviour Therapy (CBT) to standard advice for weight reduction. Over a 12-months the chosen lifestyle interventions demonstrated a sustained improvement in self-assessed depression scores, though independent of weight-loss. However, weight-loss itself was closely linked with improved body image and self-esteem. Additional monitoring of hormones (androgens, insulin, cortisol) and calculations for insulin sensitivity (HOMA-IR ) did not show any direct link with depressive scores. This study affirms the benefit of integrative lifestyle approaches on emotional well-being in women with PCOS. Practitioners might find it of interest that improvements in emotional well-being can occur independent of weight loss in individuals experiencing depressive symptoms with PCOS.
Abstract
Many women with Polycystic Ovary Syndrome (PCOS) report high depression rates. The relationship between PCOS and these high depression rates is unclear. Two-component lifestyle interventions have revealed short-term effects on depression scores in this group of women. In general, 3-component interventions including diet, exercise, and cognitive behavioral therapy (CBT) are more effective in the long-term to improve emotional well-being. This has not yet been studied in women with PCOS. This study examined the effect of 20 CBT lifestyle (LS) sessions combined with a healthy diet and physical therapy with or without 9 months additional feedback through Short Message Service (SMS) via mobile phone, compared to care as usual (CAU, involving advice to lose weight). In this secondary analysis, 155 women with PCOS and a BMI above 25 kg/m2 were eligible. Depression scores decreased significantly in the LS programme compared to CAU (P = 0.045). In both the LS programme without SMS (P = 0.036) and the LS programme with SMS (P = 0.011) depression scores decreased while no change was observed in CAU (P = 0.875). Self-esteem scores improved significantly in the LS programme compared to CAU (P = 0.027). No differences in body image scores were observed in LS participants compared to CAU (P = 0.087), although body image improved significantly in both the LS without SMS (P = 0.001) and with SMS (P = 0.008) study arms. We found no significant mediating role by androgens in the relationship between LS participants and emotional well-being. Only weight-loss mediated the relationship between LS and self-esteem. To conclude, a three-component lifestyle intervention programme with or without additional SMS resulted in significant improvements in depression and self-esteem compared to CAU, in women with PCOS, obesity, and a wish to achieve a pregnancy. Testosterone, androstenedione, DHEA, insulin, HOMA-IR, and cortisol did not mediate this effect. Weight loss mediated the effects on self-esteem but not on depression and body-image. This suggests that lifestyle treatment independent of weight loss can reduce depression and body-image, but both lifestyle treatment and weight loss can improve self-esteem. Thus, a three-component lifestyle intervention based on CBT could prove successful in improving mood in women with PCOS who are overweight or obese and attempting to become pregnant.
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Glycemic Index, Glycemic Load and Cancer Risk: An Updated Meta-Analysis.
Turati, F, Galeone, C, Augustin, LSA, La Vecchia, C
Nutrients. 2019;11(10)
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This 2019 meta-analysis is an update of an earlier 2015 study on the relationship between high Glycemic Index (GI) and Glycemic load (GL) diets and cancer risk. Twenty new epidemiological reports were added to the original seventy-five studies covering a total of 169,00 cancer cases. The theory is that elevated insulin levels, triggered by a high GI diet, increase bioactive chemicals which promote cancer development by inhibiting cell apoptosis and stimulating cell proliferation. This study collated cancers into 3 subgroups of hormonal cancers (breast, endometrium, ovary and prostate), digestive tract cancers (cancers, stomach, colorectum and pancreas) and other (lung, bladder and kidney). The combined results showed that the risk ratio for hormonal-related cancers and GI/GL were modestly elevated but not significant except for a possible moderate positive association between GL and endometrial cancer (RR1.12). There was a positive significant association between high GI intake and colorectal cancer risk (RR 1.20) but not with the other digestive-tract cancers. A high GI was associated with small increased risks of bladder (RR 1.25) and kidney (RR 1.16) cancers. The researchers conclude that the high number of studies and cancer types included provide high statistical power. Although the results show only moderate association this may be relevant at population level given the high incidence of cancers.
Abstract
Diets high in glycemic index (GI) and glycemic load (GL) have been related to an increased risk of selected cancers, but additional quantification is required. We updated a systematic review and meta-analysis published in 2015 to May 2019 to provide quantitative information on GI/GL and cancer risk. Relative risks (RR) and the corresponding 95 % confidence intervals (CI) for the highest versus the lowest categories of GI and GL were extracted from selected studies and pooled using random-effects models. Twenty reports (>22,000 cancer cases) have become available after January 2015, and 15 were added to the meta-analyses by cancer sites, which considered a total of 88 investigations. The five additional reports were reviewed, but not included in the meta-analyses, since data were inadequate to be pooled. For hormone-related cancers, summary RRs for the highest versus lowest GI and GL intakes were moderately increased. They ranged from 1.04 (breast) to 1.12 (endometrium) for GI and from 1.03 (prostate) to 1.22 (ovary) for GL, of borderline significance. High GI was associated with small increased risks of colorectal (summary RR for GI: 1.20, 95% CI, 1.07-1.34-GL: 1.09, 95% CI, 0.97-1.22, 19 studies), bladder (GI: 1.25, 95% CI, 1.11-1.41-GL: 1.10, 95% CI, 0.85-1.42, four studies) and kidney cancers (GI: 1.16, 95% CI, 1.02-1.32-GL: 1.14, 95% CI, 0.81-1.60, five studies). GL was not significantly related to those cancer sites. Stomach, prostate and lung cancers were not associated with GI and GL. The present analysis, based on an updated comprehensive evaluation of the epidemiological literature, indicates moderate unfavorable effects of high versus low GI on colorectal, and possibly bladder and kidney cancers, and a possible moderate positive association between GL and endometrial cancer.
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Mechanisms Underlying Metabolic Syndrome-Related Sarcopenia and Possible Therapeutic Measures.
Rubio-Ruiz, ME, Guarner-Lans, V, Pérez-Torres, I, Soto, ME
International journal of molecular sciences. 2019;20(3)
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Sarcopenia is a multifactorial process in which losses occur in both muscle mass and function. Although several studies indicate an association between sarcopenia and metabolic syndrome (MetS), the connection has not been extensively reviewed. The aim of this study is to examine the relationship between sarcopenia and MetS to better understand the mechanisms underlying disease and assess current therapeutic options. According to the existing literature, this study found insulin resistance, inflammation and obesity to be major underlying factors of MetS-related sarcopenia. Based on this information, the authors suggest the best option for managing MetS-related sarcopenia is preventative lifestyle change around diet and exercise until a consensus on a therapeutic treatment can be established.
Abstract
Although there are several reviews that report the interrelationship between sarcopenia and obesity and insulin resistance, the relation between sarcopenia and the other signs that compose the metabolic syndrome (MetS) has not been extensively revised. Here, we review the mechanisms underlying MetS-related sarcopenia and discuss the possible therapeutic measures proposed. A vicious cycle between the loss of muscle and the accumulation of intramuscular fat might be associated with MetS via a complex interplay of factors including nutritional intake, physical activity, body fat, oxidative stress, proinflammatory cytokines, insulin resistance, hormonal changes, and mitochondrial dysfunction. The enormous differences in lipid storage capacities between the two genders and elevated amounts of endogenous fat having lipotoxic effects that lead to the loss of muscle mass are discussed. The important repercussions of MetS-related sarcopenia on other illnesses that lead to increased disability, morbidity, and mortality are also addressed. Additional research is needed to better understand the pathophysiology of MetS-related sarcopenia and its consequences. Although there is currently no consensus on the treatment, lifestyle changes including diet and power exercise seem to be the best options.
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Intermittent Fasting in Cardiovascular Disorders-An Overview.
Malinowski, B, Zalewska, K, Węsierska, A, Sokołowska, MM, Socha, M, Liczner, G, Pawlak-Osińska, K, Wiciński, M
Nutrients. 2019;11(3)
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Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. IF has gained popularity in recent years with people wanting to lose weight, and it may have many long-term health benefits. In this review, the authors looked at human and animal studies using variations of IF including time restricted eating (TRE), where eating is confined within a specific window during the day (for example 8 hours eating and 16 hours fasting), and alternate day fasting (ADF), where a day of eating normally is alternated with a day of either fasting entirely, or significant calorie restriction. The authors found that IF is related to many beneficial effects on the cardiovascular system, involving atherosclerosis progression, benefits for diabetes mellitus type 2 such as improved glucose metabolism and insulin sensitivity, lowering of blood pressure, and other cardiovascular risk factors (such as lipid profile and inflammation). It is currently unclear whether the benefits of IF are solely due to weight loss or other mechanisms. The success of every type of diet depends on compliance, and IF seems to be as easy or easier to follow than more traditional diets for many people. Fasting is not recommended for people with hormonal imbalances, pregnant and breastfeeding women, and diabetics. People with eating disorders and underweight people are also not recommended to use the intermittent fasting diet. In recent years, the IF diet and its varieties have become increasingly popular. This diet not only serves to reduce body weight but seems to have other long-term health benefits. However, individuals’ current health and situation should be considered before commencing the IF diet.
Abstract
Intermittent fasting is a form of time restricted eating (typically 16 h fasting and 8 h eating), which has gained popularity in recent years and shows promise as a possible new paradigm in the approach to weight loss and the reduction of inflammation, and has many potential long term health benefits. In this review, the authors will incorporate many aspects of fasting, mainly focusing on its effects on the cardiovascular system, involving atherosclerosis progression, benefits for diabetes mellitus type 2, lowering of blood pressure, and exploring other cardiovascular risk factors (such as lipid profile and inflammation).
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Combining Short-Term Interval Training with Caloric Restriction Improves ß-Cell Function in Obese Adults.
Francois, ME, Gilbertson, NM, Eichner, NZM, Heiston, EM, Fabris, C, Breton, M, Mehaffey, JH, Hassinger, T, Hallowell, PT, Malin, SK
Nutrients. 2018;10(6)
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The development of type 2 diabetes is characterised by insulin resistance and dysfunction of the pancreas. Over time, loss of function of the ß-cells of the pancreas leads to impaired tolerance of blood sugar and type 2 diabetes. Low-calorie diets have been shown to improve blood sugar regulation, but it is unclear what impact interval exercise has in addition to a low-calorie diet. This study tested the hypothesis that combining interval exercise with a low-calorie diet would enhance pancreatic function compared to a low calorie diet alone in adults with obesity. Twenty-six obese adults were assigned to 2 weeks of a LCD (1200 kcal/day), using meal replacement shakes for breakfast and lunch. Half the group also underwent 60 minutes of interval training a day; after each session they received a 350 kcal shake to compensate for the calories burned during training. A series of blood tests was carried out to measure glucose tolerance and insulin secretion rates. Combining a low calorie diet with interval training reduced glucose and insulin secretion rates, whereas the low calorie diet alone did not. Both interventions improved insulin sensitivity. The authors concluded that the data supports combining low calorie diets with interval training to preserve pancreatic function and prevent type 2 diabetes.
Abstract
Although low-calorie diets (LCD) improve glucose regulation, it is unclear if interval exercise (INT) is additive. We examined the impact of an LCD versus LCD + INT training on ß-cell function in relation to glucose tolerance in obese adults. Twenty-six adults (Age: 46 ± 12 year; BMI 38 ± 6 kg/m²) were randomized to 2-week of LCD (~1200 kcal/day) or energy-matched LCD + INT (60 min/day alternating 3 min at 90 and 50% HRpeak). A 2 h 75 g oral glucose tolerance test (OGTT) was performed. Insulin secretion rates (ISR) were determined by deconvolution modeling to assess glucose-stimulated insulin secretion ([GSIS: ISR/glucose total area under the curve (tAUC)]) and ß-cell function (Disposition Index [DI: GSIS/IR]) relative to skeletal muscle (Matsuda Index), hepatic (HOMA-IR) and adipose (Adipose-IRfasting) insulin resistance (IR). LCD + INT, but not LCD alone, reduced glucose and total-phase ISR tAUC (Interactions: p = 0.04 and p = 0.05, respectively). Both interventions improved skeletal muscle IR by 16% (p = 0.04) and skeletal muscle and hepatic DI (Time: p < 0.05). Improved skeletal muscle DI was associated with lower glucose tAUC (r = -0.57, p < 0.01). Thus, LCD + INT improved glucose tolerance more than LCD in obese adults, and these findings relate to ß-cell function. These data support LCD + INT for preserving pancreatic function for type 2 diabetes prevention.
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Low-carbohydrate diets for type 1 diabetes mellitus: A systematic review.
Turton, JL, Raab, R, Rooney, KB
PloS one. 2018;13(3):e0194987
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Type 1 diabetes is an autoimmune condition that affects the ability to produce insulin, the hormone that regulates blood sugar levels. Patients with Type 1 diabetes manage their condition with daily insulin injections or patches, and the standard dietary advice is to continue to eat a normal diet, and adjust the insulin dose to keep blood sugar under control. This systematic review of 9 studies of varying types, aimed to examine the effects of low-carbohydrate diets on type 1 diabetes management. 8 of the studies reported a change in HbA1c (the blood marker used to assess long-term blood sugar management); 3 of these reported statistically significant reductions. 2 studies reported statistically significant reductions in daily insulin use whilst following a low-carbohydrate diet. The study authors were unable to conclude an overall effect due to the differences in design and methods used in the 9 studies included. They call for more primary research to be conducted.
Abstract
Type 1 diabetes is an autoimmune condition characterised by pancreatic beta cell destruction and absolute insulin deficiency. The strongest predictor of diabetes complications is glycaemic control and achieving HbA1c ≤ 7.0% is the primary management target. However, standard treatment appears to be lacking and adjunctive strategies require consideration. A systematic review was conducted to examine the effect of low-carbohydrate diets on type 1 diabetes management. Four databases were searched from inception until 28 March 2017: MEDLINE; CINAHL; Cochrane Library; and EMBASE. All primary studies containing a methods section (excluding cross-sectional) were included. Reports had to quantitatively measure the effect(s) of a dietary intervention or observed intake over at least two weeks where carbohydrate is below 45% total energy in adults and/or children with type 1 diabetes. The primary outcome was HbA1c and secondary outcomes were severe hypoglycaemia, total daily insulin, BMI, quality of life and mean daily glucose. Seventy-nine full-text articles were assessed for eligibility and nine were included (two randomised controlled trials, four pre-post interventions, two case-series, one case-report). Eight studies reported a mean change in HbA1c with a low-carbohydrate diet. Of these, four reported a non-significant change (P ≥ 0.05) and three reported statistically significant reductions (P < 0.05). Two studies reported severe hypoglycaemia, five reported total insulin, three reported BMI, and one reported blood glucose. Due to the significant heterogeneity of included studies, an overall effect could not be determined. This review presents all available evidence on low-carbohydrate diets for type 1 diabetes and suggests an urgent need for more primary studies.
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Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial.
Gardner, CD, Trepanowski, JF, Del Gobbo, LC, Hauser, ME, Rigdon, J, Ioannidis, JPA, Desai, M, King, AC
JAMA. 2018;319(7):667-679
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Obesity is a major public health challenge and different dietary strategies are employed to lose weight. This randomised clinical trial of 609 obese adults between the age of 18 and 50 aimed to determine the effects of a healthy low-fat diet in comparison to a healthy low-carbohydrate diet on weight change over a 12 month period. The study also assessed whether 3 genetic markers and blood sugar management affected weight loss in the 2 groups. Participants in the study were offered 22 group sessions of health coaching to support adherence to the programme. 481 participants completed the study. The low-carbohydrate group lost on average 6kg and the low-fat group lost on average 5.4kg. The difference between the 2 groups did not achieve significance for weight loss. There was also no significant genetic or blood sugar management effect in relation to dietary pattern and weight loss. The authors of this study conclude that the results of this study do not help in identifying which dietary type is better for whom in relation to 3 genetic markers and blood sugar management.
Abstract
Importance: Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets. Objective: To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss. Design, Setting, and Participants: The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss. Interventions: Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality. Main Outcomes and Measures: Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss. Results: Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was -5.3 kg for the HLF diet vs -6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, -0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups. Conclusions and Relevance: In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom. Trial Registration: clinicaltrials.gov Identifier: NCT01826591.
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Type-4 Resistant Starch in Substitution for Available Carbohydrate Reduces Postprandial Glycemic Response and Hunger in Acute, Randomized, Double-Blind, Controlled Study.
Stewart, ML, Wilcox, ML, Bell, M, Buggia, MA, Maki, KC
Nutrients. 2018;10(2)
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Resistant starch is a combination of dietary fibre and carbohydrate that ‘resists’ digestion in the small intestine and is fermented in the large intestine by gut bacteria. It is associated with a number of health benefits, particularly the management of blood glucose levels. This small double-blind, randomised controlled trail allocated 36 healthy individuals (mostly female, average age 46 and BMI 26) to eat either a low-fibre scone or a scone with added resistant starch in the form of acid-hydrolyzed and heat treated maize starch. The response of blood glucose and blood insulin levels were measured, as well as participants feeling of fullness and intestinal comfort after eating the scones. The scone with the added resistant starch had significantly lower blood glucose (43-45% lower) and blood insulin (35-40% lower) levels after eating the scone, when compared to those eating the low-fibre scone. They also reported feeling fuller for longer and had no particular digestive symptoms. Whilst this is a small study, Nutrition Practitioners may want to investigate dietary sources of resistant starch when working with clients to balance blood glucose and insulin levels.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Based on the findings of the Predict Study, it is highly probable that the same meal will elicit a different glycaemic response in individuals with different gut microbial compositions.
- The gut microbiota, therefore, needs to be taken into consideration when assessing glycaemic responses to a meal.
- Healthcare practitioners may like to consider the use of resistant starches as an additional tool to balance blood sugar responses to a meal.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Dietary modulation of the gut microbiota impacts human health. This paper discusses the effects of a man-made type of resistant starch on the glycaemic response to a meal. Based on the initial findings of the Predict Study, it is highly probably that the same meal will elicit a different glycaemic (and wider metabolic) response in individuals with different gut microbial compositions. So this paper confirms the need to take the gut microbiota into consideration when assessing glycaemic responses to a meal, both in research and in clinical practice.
Clinical practice applications:
Not all fibres are equal, and not all starches are equal. Type 4 resistant starch is a novel addition to the already known types 1, 2, and 3 and provides with clinicians with an additional tool to balance their patient's blood sugar response to a meal based on the effect of resistant starch on the gut microbiota.
Considerations for future research:
Resistant starches are known for their ability to affect gut microbiota composition and short-chain fatty acid concentrations which, in turn, have the ability to modulate immune and metabolic functions in the host, including cholesterol, fasting glucose, glycosylated haemoglobin, and pro-inflammatory markers. Further studies on glycaemic and wider metabolic responses to a meal must take into consideration the effect of resistant starches on gut microbial composition. Not doing so may be skewing scientific findings.
Abstract
Resistant starch (RS) is a type of dietary fiber that has been acknowledged for multiple physiological benefits. Resistant starch type 4 (RS4) is a subcategory of RS that has been more intensively studied as new types of RS4 emerge in the food supply. The primary aim of this randomized, double-blind, controlled study was to characterize the postprandial glucose response in healthy adults after consuming a high fiber scone containing a novel RS4 or a low fiber control scone without RS4. Secondary aims included assessment of postprandial insulin response, postprandial satiety, and gastrointestinal tolerance. The fiber scone significantly reduced postprandial glucose and insulin incremental areas under the curves (43-45% reduction, 35-40% reduction, respectively) and postprandial glucose and insulin maximum concentrations (8-10% and 22% reduction, respectively). The fiber scone significantly reduced hunger and desire to eat during the 180 min following consumption and yielded no gastrointestinal side effects compared with the control scone. The results from this study demonstrate that a ready-to-eat baked-good, such as a scone, can be formulated with RS4 replacing refined wheat flour to yield statistically significant and clinically meaningful reductions in blood glucose and insulin excursions. This is the first study to report increased satiety after short-term RS4 intake, which warrants further investigation in long-term feeding studies.
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Food sources of fructose-containing sugars and glycaemic control: systematic review and meta-analysis of controlled intervention studies.
Choo, VL, Viguiliouk, E, Blanco Mejia, S, Cozma, AI, Khan, TA, Ha, V, Wolever, TMS, Leiter, LA, Vuksan, V, Kendall, CWC, et al
BMJ (Clinical research ed.). 2018;363:k4644
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With increasing evidence linking fructose to metabolic disease, current dietary guidelines recommend a reduction of added free sugars, especially fructose-containing sugars from sugars-sweetened beverages (SSBs). However, it is currently unclear whether the negative impact of fructose on metabolic health is as implicative in the context of an overall dietary consumption pattern. The aim of this study was to assess the effect of different sources of fructose-containing sugars on glycaemic control in people with and without diabetes. This review analysed 155 controlled intervention studies and found that fructose-containing sugars in the form of fruit do not have a harmful effect on glycaemic control when compared to energy-matched macronutrient substitutions. Further, harmful effects on glycaemic control were found when excess energy in the form of fructose-containing sugars from SSBs were added to the diet. The authors conclude the food source of fructose-containing sugars on glycemic control is important in the conversation of metabolic health and glycaemic control. While further research is needed to assess a wider variety of food sources, public health professionals should consider the influence of food sources when developing dietary recommendations for the prevention and management of diabetes and other metabolic conditions.
Abstract
OBJECTIVE To assess the effect of different food sources of fructose-containing sugars on glycaemic control at different levels of energy control. DESIGN Systematic review and meta-analysis of controlled intervention studies. DATA SOURCES Medine, Embase, and the Cochrane Library up to 25 April 2018. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Controlled intervention studies of at least seven days' duration and assessing the effect of different food sources of fructose-containing sugars on glycaemic control in people with and without diabetes were included. Four study designs were prespecified on the basis of energy control: substitution studies (sugars in energy matched comparisons with other macronutrients), addition studies (excess energy from sugars added to diets), subtraction studies (energy from sugars subtracted from diets), and ad libitum studies (sugars freely replaced by other macronutrients without control for energy). Outcomes were glycated haemoglobin (HbA1c), fasting blood glucose, and fasting blood glucose insulin. DATA EXTRACTION AND SYNTHESIS Four independent reviewers extracted relevant data and assessed risk of bias. Data were pooled by random effects models and overall certainty of the evidence assessed by the GRADE approach (grading of recommendations assessment, development, and evaluation). RESULTS 155 study comparisons (n=5086) were included. Total fructose-containing sugars had no harmful effect on any outcome in substitution or subtraction studies, with a decrease seen in HbA1c in substitution studies (mean difference -0.22% (95% confidence interval to -0.35% to -0.08%), -25.9 mmol/mol (-27.3 to -24.4)), but a harmful effect was seen on fasting insulin in addition studies (4.68 pmol/L (1.40 to 7.96)) and ad libitum studies (7.24 pmol/L (0.47 to 14.00)). There was interaction by food source, with specific food sources showing beneficial effects (fruit and fruit juice) or harmful effects (sweetened milk and mixed sources) in substitution studies and harmful effects (sugars-sweetened beverages and fruit juice) in addition studies on at least one outcome. Most of the evidence was low quality. CONCLUSIONS Energy control and food source appear to mediate the effect of fructose-containing sugars on glycaemic control. Although most food sources of these sugars (especially fruit) do not have a harmful effect in energy matched substitutions with other macronutrients, several food sources of fructose-containing sugars (especially sugars-sweetened beverages) adding excess energy to diets have harmful effects. However, certainty in these estimates is low, and more high quality randomised controlled trials are needed. STUDY REGISTRATION Clinicaltrials.gov (NCT02716870).