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Intake and adequacy of the vegan diet. A systematic review of the evidence.
Bakaloudi, DR, Halloran, A, Rippin, HL, Oikonomidou, AC, Dardavesis, TI, Williams, J, Wickramasinghe, K, Breda, J, Chourdakis, M
Clinical nutrition (Edinburgh, Scotland). 2021;40(5):3503-3521
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This systematic review investigated vegan diets in the European populations and their adequacy of macro-and micronutrient intake, compared to the recommendations of the World Health Organization. Included were 48 studies and their outcomes regarding protein, carbohydrates, fats and micronutrients summarized. The overall results and their impact on health are discussed in the later sections of the paper. Adequate intake amongst vegans was seen with carbohydrates, fats, Vitamin A, B1, В6, C, E, iron, phosphorus, magnesium, copper and folate. Sodium exceeded recommended intake, whilst protein, Vitamin B2, B3, B12, D, iodine, zinc, calcium, potassium, selenium was of low consumption in a vegan diet. The bioavailability of some nutrients was also acknowledged. In summary, following a vegan diet appears to have positive and negative aspects. A vegan diet profile can contribute to disease prevention with lower incidence rates of obesity, Type 2 diabetes, and cardiovascular disease. Yet veganism appears to increase the risk for mental health conditions, bone fractures, immune system impairments, anaemias and deficiencies from low nutrient intake. This review yields a comprehensive overview of the positive and negative health consequences of a vegan diet. It may be a useful reference for those looking to support vegans or individuals considering adopting a vegan diet pattern.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Vegan diets in European populations tend to be lower in protein intake, particularly amino acids lysine, methionine and tryptophan.
- Other micronutrients that tend to lower in vegan diets are Vitamin B12, zinc, calcium and selenium.
- Healthcare practitioners should be aware of these potential deficiencies when working with vegan clients.
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:
Vegan diets have become increasingly popular in the last ten years. This systematic review of 48 studies investigated the adequacy of vegan diets in European populations. It compared their macro- and micronutrient intakes compared to World Health Organization recommendations. It found that vegan diets tend to be lower in protein and in essential amino acids (lysine, methionine and tryptophan). They can also be lower in micronutrients especially vitamin B12, zinc, calcium and selenium. However, the lower intakes are not always associated with health impairments.
Clinical practice applications:
Practitioners should be aware of the potential deficiencies in a vegan diet.
Considerations for future research:
More research is needed to determine whether lower nutrient intakes in vegans correlated with poor health outcomes.
Abstract
BACKGROUND Vegan diets, where animal- and all their by-products are excluded from the diet, have gained popularity, especially in the last decade. However, the evaluation of this type of diet has not been well addressed in the scientific literature. This study aimed to investigate the adequacy of vegan diets in European populations and of their macro- and micronutrient intakes compared to World Health Organization recommendations. METHODS A systematic search in PubMed, Web of Science, IBSS, Cochrane library and Google Scholar was conducted and 48 studies (12 cohorts and 36 cross-sectional) were included. RESULTS Regarding macronutrients, vegan diets are lower in protein intake compared with all other diet types. Veganism is also associated with low intake of vitamins B2, Niacin (B3), B12, D, iodine, zinc, calcium, potassium, selenium. Vitamin B12 intake among vegans is significantly lower (0.24-0.49 μg, recommendations are 2.4 μg) and calcium intake in the majority of vegans was below recommendations (750 mg/d). No significant differences in fat intake were observed. Vegan diets are not related to deficiencies in vitamins A, B1, Β6, C, E, iron, phosphorus, magnesium, copper and folate and have a low glycemic load. CONCLUSIONS Following a vegan diet may result in deficiencies in micronutrients (vitamin B12, zinc, calcium and selenium) which should not be disregarded. However, low micro- and macronutrient intakes are not always associated with health impairments. Individuals who consume a vegan diet should be aware of the risk of potential dietary deficiencies.
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Vegan Diet Health Benefits in Metabolic Syndrome.
Marrone, G, Guerriero, C, Palazzetti, D, Lido, P, Marolla, A, Di Daniele, F, Noce, A
Nutrients. 2021;13(3)
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Plant-based diets (PBD) have grown in popularity in recent years and have been associated with better health outcomes especially with heart disease, however poorly planned PBD’s can result in nutrient deficiencies like vitamin B12. This review aimed to summarise the health benefits of PBD’s, especially vegan diets, compared to omnivorous diets when looking at risk factors associated with heart disease. The authors started by summarising three PBD’s obvious in the literature; vegan diet with no animal products, lacto-ovo-vegetarian (LOV) with dairy products and eggs, and fish-vegetarian including fish and seafoods. The study then highlighted the strengths and weaknesses of the vegan diet, highlighting that although the vegan diet represents a healthy way of eating rich in carbohydrates, omega-6 fats, fibre, vitamin C, vitamin E and magnesium it can be low in protein, omega-3 fats, vitamin B12, vitamin D, calcium, iron, zinc and iodine if not properly planned. Heart disease incidence was reported to be lower in individuals on a PBD, especially vegans, when compared to omnivorous diets possibly due to their improvement on risk factors associated with the disease. Metabolic syndrome, blood pressure, fat production, and blood sugar balance were all shown to be improved and reasons such as their high fibre content reducing energy intake and causing feelings of satiety and their low saturated fat content impacting cholesterol production were listed as possible mechanisms behind the improvements. It was concluded that a nutritionist led, vegan diet can improve risk factors for heart disease resulting in better health outcomes. This study could be used by healthcare practitioners to understand where vegan diets may lack certain nutrients and the Importance of a well-planned vegan diet in the prevention of heart disease in those at an increased risk.
Abstract
Plant-based diets (PBDs) are increasingly consumed by the Italian population and around the world. In particular, among PBDs, the vegan diet is a food pattern characterized by the exclusion of all animal-origin foods. What drives people to adopt this model are mainly ethical, health and environmental reasons. A vegan diet, if well-balanced and varied, can help in achieving and maintaining an optimal state of health. However, this nutritional approach, if not well-balanced, can cause deficiencies in proteins, ω-3 fatty acids, iron, vitamin D and calcium, zinc, iodine and, above all, vitamin B12. Oral food supplements especially fortified foods are recommended in these cases to restore the nutritional deficiencies. A vegan diet generally reduces the risk of developing chronic non-communicable degenerative diseases, such as metabolic syndrome (MetS) and, in addition, requires fewer natural resources for food production than an omnivorous diet. The aim of this review is to analyze the possible impact of the vegan diet on MetS onset and its treatment.
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Association of prior metabolic and bariatric surgery with severity of coronavirus disease 2019 (COVID-19) in patients with obesity.
Aminian, A, Fathalizadeh, A, Tu, C, Butsch, WS, Pantalone, KM, Griebeler, ML, Kashyap, SR, Rosenthal, RJ, Burguera, B, Nissen, SE
Surgery for obesity and related diseases : official journal of the American Society for Bariatric Surgery. 2021;17(1):208-214
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A growing body of evidence indicates that patients with obesity are disproportionately affected with a severe form of SARS-CoV-2 infection and may experience resultant higher mortality. The aim of this study was to determine the association of prior metabolic surgery with severity of SARSCoV-2 infection in patients with severe obesity. This study is a retrospective, matched-cohort analysis of a prospective, observational, institutional review board–approved clinical registry of all patients tested for SARS-CoV-2 infection. The study population included a total of 363 patients, including 33 individuals who had metabolic surgery and 330 matched patients who tested positive. Results indicate that a history of metabolic surgery is associated with lower severity of SARSCoV-2 infection in patients with severe obesity, as manifested by lower risks of hospital and ICU admission. Authors conclude that prior metabolic surgery with subsequent weight loss and improvement of metabolic abnormalities could potentially reduce morbidity from SARS-CoV-2 infection.
Abstract
BACKGROUND Obesity is a risk factor for poor clinical outcomes in patients with coronavirus disease 2019 (COVID-19). OBJECTIVES To investigate the relationship between prior metabolic surgery and the severity of COVID-19 in patients with severe obesity. SETTING Cleveland Clinic Health System in the United States. METHODS Among 4365 patients who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between March 8, 2020 and July 22, 2020 in the Cleveland Clinic Health System, 33 patients were identified who had a prior history of metabolic surgery. The surgical patients were propensity matched 1:10 to nonsurgical patients to assemble a cohort of control patients (n = 330) with a body mass index (BMI) ≥ 40 kg/m2 at the time of SARS-CoV-2 testing. The primary endpoint was the rate of hospital admission. The exploratory endpoints included admission to the intensive care unit (ICU), need for mechanical ventilation and dialysis during index hospitalization, and mortality. After propensity score matching, outcomes were compared in univariate and multivariate regression models. RESULTS The average BMI of the surgical group was 49.1 ± 8.8 kg/m2 before metabolic surgery and was down to 37.2 ± 7.1 at the time of SARS-CoV-2 testing, compared with the control group's BMI of 46.7 ± 6.4 kg/m2. In the univariate analysis, 6 (18.2%) patients in the metabolic surgery group and 139 (42.1%) patients in the control group were admitted to the hospital (P = .013). In the multivariate analysis, a prior history of metabolic surgery was associated with a lower hospital admission rate compared with control patients with obesity (odds ratio, 0.31; 95% confidence interval, 0.11-0.88; P = .028). While none of the 4 exploratory outcomes occurred in the metabolic surgery group, 43 (13.0%) patients in the control group required ICU admission (P = .021), 22 (6.7%) required mechanical ventilation, 5 (1.5%) required dialysis, and 8 (2.4%) patients died. CONCLUSION Prior metabolic surgery with subsequent weight loss and improvement of metabolic abnormalities was associated with lower rates of hospital and ICU admission in patients with obesity who became infected with SARS-CoV-2. Confirmation of these findings will require larger studies.
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Safety and efficacy of alpha-lipoic acid oral supplementation in the reduction of pain with unknown etiology: A monocentric, randomized, double-blind, placebo-controlled clinical trial.
Esposito, C, Ugo Garzarella, E, Santarcangelo, C, Di Minno, A, Dacrema, M, Sacchi, R, Piccinocchi, G, Piccinocchi, R, Daglia, M
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie. 2021;144:112308
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The management of pain with no apparent cause, or idiopathic pain, is a real challenge. In the absence of any underlying disease that is treatable, idiopathic pain is usually addressed by relieving symptomatic pain with medication. Whereby these medications can be fast and effective, they can have limited benefits and, in some cases, considerable side effects. Alpha-lipoic acid (ALA) is a food supplement and naturally occurring compound in humans, animals and plants. Previous research suggested that it is effective in managing diabetic nerve pain. As reactive oxygen species and antioxidants appear to play a role in pain regulation, the antioxidant and anti-inflammatory activities of ALA are of interest here. In addition, ALA has a strong safety record. This study sought to investigate the safety and effectiveness of ALA in non-diabetic individuals who were diagnosed with idiopathic pain. 210 male and female subjects, from age 18-75, who were non-diabetic and on no pain medication were randomly assigned to receive either a placebo or 400 mg/day or 800 mg/day of ALA over a course of two months. The pain was tracked with two pain scoring questionnaires, whilst blood samples were monitored for adverse effects, including blood sugar, kidney and liver markers. The ALA intervention group showed a significant reduction in both pain scores compared to placebo. Treated subjects showed a marginal decrease in blood sugars of no clinical significance and no other adverse effects were reported. The authors concluded that ALA as a food supplement has suitable potential for the management of idiopathic pain. And given its safety and efficacy compared to commonly used pain medication it could be of interest in clinical application.
Abstract
INTRODUCTION Extensive evidence suggests that alpha-lipoic acid (ALA) is effective in diabetic neuropathy pain management. However, little is known on its safety and efficacy in reducing idiopathic pain in normoglycemic subjects. The aim of this study was to evaluate ALA food supplement safety and efficacy in the reduction of different forms of idiopathic pain. METHODS Two-hundred and ten normoglycemic adults suffering from idiopathic pain (i.e. 57 subjects with primitive neuropathic pain, 141 subjects with arthralgia with unknown etiology, and 12 subjects with idiopathic myalgia) were randomized to receive placebo, 400 mg/day, or 800 mg/day of ALA. Participants underwent two visits (at baseline = t0, and after 2 months = t1) in which two validated questionaries for pain (numerical rating scale [NRS] and visual analogue scale [VAS]) were collected; fasting blood glucose assessment, adverse effects, and renal and hepatic toxicity were also monitored. RESULTS At t1, none of subjects treated with ALA reported a decreased glycemia or adverse effects. The treated subjects showed a significant reduction in NRS (p < 0.001) while the placebo group did not show any NRS reduction (p = 0.86). Similar results were also obtained for VAS. Statistical analysis aimed at detecting possible differences in NRS and VAS scores among treatment groups based on the source of pain did not reveal any significant effect. CONCLUSIONS Since the management of idiopathic pain is challenging for physicians, the use of ALA food supplements could be a feasible option, based on its safety and efficacy compared to commonly-used analgesic drugs.
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Effects of Low-Carbohydrate versus Mediterranean Diets on Weight Loss, Glucose Metabolism, Insulin Kinetics and β-Cell Function in Morbidly Obese Individuals.
Tricò, D, Moriconi, D, Berta, R, Baldi, S, Quinones-Galvan, A, Guiducci, L, Taddei, S, Mari, A, Nannipieri, M
Nutrients. 2021;13(4)
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Both low-carbohydrate and Mediterranean style diets are used to prevent lifestyle associated diseases such as obesity and type 2 diabetes. However, which diet is more effective is unclear. The aim of this randomised control trial of 36 morbidly obese individuals was to compare the effectiveness of Mediterranean diets and low-carbohydrate diets to improve metabolic measures such as blood sugar levels, pre-diabetes, and the body’s ability to use sugar. The results showed that in the short-term both diets were equally effective at improving biochemical dysfunctions that contribute to type 2 diabetes. The low-carbohydrate diet did result in higher weight loss than the Mediterranean diet. Studies on long-term effects are warranted. It was concluded that a low-carbohydrate diet is in the short-term a feasible alternative to the Mediterranean diet for improved weight loss and biological contributors to type 2 diabetes. This study could be used by healthcare professionals to understand that the Mediterranean diet and low-carbohydrate diet are both effective in the short-term for improvements to contributors to type 2 diabetes, however the low-carbohydrate diet may be superior if weight loss is required.
Abstract
Low-calorie Mediterranean-style or low-carbohydrate dietary regimens are widely used nutritional strategies against obesity and associated metabolic diseases, including type 2 diabetes. The aim of this study was to compare the effectiveness of a balanced Mediterranean diet with a low-carbohydrate diet on weight loss and glucose homeostasis in morbidly obese individuals at high risk to develop diabetes. Insulin secretion, insulin clearance, and different β-cell function components were estimated by modeling plasma glucose, insulin and C-peptide profiles during 75-g oral glucose tolerance tests (OGTTs) performed at baseline and after 4 weeks of each dietary intervention. The average weight loss was 5%, being 58% greater in the low-carbohydrate-group than Mediterranean-group. Fasting plasma glucose and glucose tolerance were not affected by the diets. The two dietary regimens proved similarly effective in improving insulin resistance and fasting hyperinsulinemia, while enhancing endogenous insulin clearance and β-cell glucose sensitivity. In summary, we demonstrated that a low-carbohydrate diet is a successful short-term approach for weight loss in morbidly obese patients and a feasible alternative to the Mediterranean diet for its glucometabolic benefits, including improvements in insulin resistance, insulin clearance and β-cell function. Further studies are needed to compare the long-term efficacy and safety of the two diets.
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Type 2 diabetes preventive effects with a 12-months sardine-enriched diet in elderly population with prediabetes: An interventional, randomized and controlled trial.
Díaz-Rizzolo, DA, Serra, A, Colungo, C, Sala-Vila, A, Sisó-Almirall, A, Gomis, R
Clinical nutrition (Edinburgh, Scotland). 2021;40(5):2587-2598
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Older people have a higher risk of developing Type 2 diabetes (T2D) due to the possibility of β-cell dysfunction due to ageing. Sardines are believed to be protective against the development of T2D. Therefore, this randomised controlled trial evaluated the preventative effects of a sardine-rich diet in elderly prediabetic patients. For one year, both the sardine group (SG) and control group (CG) followed a T2D prevention diet, with the SG consuming 200 g of sardines each week. Both groups improved body weight, BMI, waist and hip circumference, and body composition. Taurine, EPA, DHA, omega-3 fatty acid, calcium, iodine, zinc, phosphorous and fluoride, vitamin B12 and D, and lycopene and tocopherols were found to be higher in the SG than the CG, indicating the sardines were protective against T2D. In SG, HDL cholesterol and adiponectin levels were significantly increased, and blood pressure and triglycerides were decreased, signalling a reduced risk of T2D and cardiovascular disease. In addition, SG showed a reduction in HOMA-IR and an Omega-3 fatty acid was substituted for Omega-6 fatty acids in the erythrocyte membrane, suggesting a reduced risk of T2D. Further robust research is required to confirm the protective effect of a sardine-enriched diet against T2D. It may be useful to healthcare providers to comprehend how a sardine-enriched diet could improve obesity, T2D and CVD markers in pre-diabetic elderly patients.
Abstract
BACKGROUND Fish could play a role in preventing type 2 diabetes (T2D) but there has been little specification about the type of fish and the preventive mechanism involved in its health claim. The sardine is a source of omega-3 and taurine that, in isolation or in synergy, would produce T2D-delaying through different molecular mechanism. HYPOTHESIS The consumption of twice a week of sardine, during one year would reduce T2D-developing risk in a population with prediabetes (preDM) and old age. DESIGN 152 subjects with fasting glucose between 100-124 mg/dL aged ≥65 yo were recruited from three primary care centers in Barcelona and were randomly distributed among two interventional groups: control group (CG) and sardine group (SG). Both groups received same T2D-prevention nutritional during a year but only SG had to add 200 g of sardine per week. All variables were collected before to start and at the end of the diet. (ClinicalTrials.gov: NCT03557541). RESULTS 152 people were randomized into CG (n=77) and SG (n=75) with 18 and 12 drop outs respectively. Subjects in SG, significantly compared to CG, decreased percentage classified-individuals in a very high risk group to develop T2D according to FINDRISC (p=0.035). In addition to increasing HDL-cholesterol and adiponectin and decreasing triglycerides (p<0.05) and blood pressure (<0.05), SG showed a lower HOMA-IR (p=0.032). The consumption of sardine characteristics nutrients as omega-3, EPA and DHA, vitamin D, fluorine and taurine were higher for SG (p<0.05). These results agreed with the increased of taurine, fatty acid (FA) omega-3 and bile acids circulating metabolites (p<0.05). Changes erythrocyte membrane FA were detected only in SG with a decrease of 5 omega-6 FA (p<0.001) and an increase of 3 omega-3 FA types (p<0.001). CONCLUSION We conclude that a year T2D-prevention diet with sardine supplementation has a greater protective effect against developing T2D and CV events.
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Effectiveness of Health Coaching in Diabetes Control and Lifestyle Improvement: A Randomized-Controlled Trial.
Lin, CL, Huang, LC, Chang, YT, Chen, RY, Yang, SH
Nutrients. 2021;13(11)
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World Health Organization statistics indicate that over 400 million people worldwide have Type 2 Diabetes. Health coaching is an approach to diabetes management that empowers patients to make healthier choices by changing their behaviours. This two-arm randomised controlled trial evaluated the effectiveness of health coaching in reducing blood sugar levels and following a healthy diet among Type 2 diabetic patients. Patients with diabetes improved their HbA1c by 0.62% after six months of health coaching. Through health coaching, patients were also able to reduce their calorie intake significantly by reducing their consumption of whole grains, meat, proteins, fats and oils and increasing their intake of vegetables. In the intervention group, diet modifications were also associated with a decrease in HbA1c. The benefits of health coaching in Type 2 diabetes management needs to be confirmed in more robust studies. However, healthcare professionals can use the results of this study to understand how behaviour change in diabetic patients contributes to blood sugar management and healthy eating.
Abstract
BACKGROUND The study aimed to look into the effectiveness of a 6-month health coaching intervention for HbA1c and healthy diet in the treatment of patients with type 2 diabetes. METHODS The study was carried out via a two-armed, randomized controlled trial that included 114 diabetic patients at a medical center in Taiwan. During the 6-month period, the intervention group had health coaching and usual care for 6 months, and the control group had usual care only. The outcome variables were HbA1c level and healthy diet for follow-up measurement in the third and sixth month. RESULTS The study discovered a significant decrease in HbA1c and health diet improvement after the 6-month health coaching. Patients in the intervention group decreased their daily intake of whole grains, fruits, meats and protein, and fats and oils while increasing their vegetables intake. CONCLUSIONS Health coaching may be conducive to the blood sugar control and healthy diet of patients with type 2 diabetes. Further study on health coaching with higher-quality evidence is needed.
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Effectiveness of a Multicomponent Intervention in Primary Care That Addresses Patients with Diabetes Mellitus with Two or More Unhealthy Habits, Such as Diet, Physical Activity or Smoking: Multicenter Randomized Cluster Trial (EIRA Study).
Represas-Carrera, F, Couso-Viana, S, Méndez-López, F, Masluk, B, Magallón-Botaya, R, Recio-Rodríguez, JI, Pombo, H, Leiva-Rus, A, Gil-Girbau, M, Motrico, E, et al
International journal of environmental research and public health. 2021;18(11)
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Life habits such as smoking, physical activity, and diet affect glycaemic control. The objective of this multicentre randomised cluster trial (EIRA study) was to evaluate the effectiveness of multicomponent educational interventions on glycaemic control in Type 2 diabetic patients. Interventions in multicomponent individual, group and community settings included smoking cessation, the Mediterranean diet and physical activity, as well as an assessment of the quality of life. Participants had unhealthy lifestyles prior to the intervention. The study was conducted in 26 primary healthcare centres in seven health departments in Spain over a period of 12 months. A brief intervention aimed to change the habits of the participants, including increasing physical activity, quitting smoking and adhering to the Mediterranean diet. After 12 months of intervention, there were no statistically significant improvements in glycaemic control, physical activity, sedentary lifestyle, smoking, or quality of life. However, adherence to the Mediterranean diet was statistically significant. Further research is needed to determine the effectiveness of multicomponent interventions in improving glycaemic control. The clinical applicability of multicomponent interventions to tackle type 2 diabetes, obesity, and unhealthy lifestyles should be considered by healthcare providers.
Abstract
Introduction: We evaluated the effectiveness of an individual, group and community intervention to improve the glycemic control of patients with diabetes mellitus aged 45-75 years with two or three unhealthy life habits. As secondary endpoints, we evaluated the inverventions' effectiveness on adhering to Mediterranean diet, physical activity, sedentary lifestyle, smoking and quality of life. Method: A randomized clinical cluster (health centers) trial with two parallel groups in Spain from January 2016 to December 2019 was used. Patients with diabetes mellitus aged 45-75 years with two unhealthy life habits or more (smoking, not adhering to Mediterranean diet or little physical activity) participated. Centers were randomly assigned. The sample size was estimated to be 420 people for the main outcome variable. Educational intervention was done to improve adherence to Mediterranean diet, physical activity and smoking cessation by individual, group and community interventions for 12 months. Controls received the usual health care. The outcome variables were: HbA1c (main), the Mediterranean diet adherence score (MEDAS), the international diet quality index (DQI-I), the international physical activity questionnaire (IPAQ), sedentary lifestyle, smoking ≥1 cigarette/day and the EuroQuol questionnaire (EVA-EuroQol5D5L). Results: In total, 13 control centers (n = 356) and 12 intervention centers (n = 338) were included with similar baseline conditions. An analysis for intention-to-treat was done by applying multilevel mixed models fitted by basal values and the health center: the HbA1c adjusted mean difference = -0.09 (95% CI: -0.29-0.10), the DQI-I adjusted mean difference = 0.25 (95% CI: -0.32-0.82), the MEDAS adjusted mean difference = 0.45 (95% CI: 0.01-0.89), moderate/high physical activity OR = 1.09 (95% CI: 0.64-1.86), not living a sedentary lifestyle OR = 0.97 (95% CI: 0.55-1.73), no smoking OR = 0.61 (95% CI: 0.54-1.06), EVA adjusted mean difference = -1.26 (95% CI: -4.98-2.45). Conclusions: No statistically significant changes were found for either glycemic control or physical activity, sedentary lifestyle, smoking and quality of life. The multicomponent individual, group and community interventions only showed a statistically significant improvement in adhering to Mediterranean diet. Such innovative interventions need further research to demonstrate their effectiveness in patients with poor glycemic control.
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Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data.
Goldenberg, JZ, Day, A, Brinkworth, GD, Sato, J, Yamada, S, Jönsson, T, Beardsley, J, Johnson, JA, Thabane, L, Johnston, BC
BMJ (Clinical research ed.). 2021;372:m4743
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Diet modification has long been recognised as a component for the treatment of diabetes. Diets low in carbohydrates have been extensively researched, as a diet for those with Type 2 Diabetes (T2D). This systematic review and meta-analysis aimed to determine the effect of low carbohydrate diets on T2D. The systematic review found 23 studies, including 1357 individuals, investigating the role of low carbohydrate diets on T2D outcomes. Low carbohydrate diet was defined as less than 130g of carbohydrate (less than 26% of calories from carbohydrate) for at least 12 weeks. Results reported at 6 months, found low carbohydrate diets were more effective than a normal diet at achieving diabetes remission. However, this effect diminished at 12 months, although longer term improvements were seen in blood lipids, weight loss and measures of prediabetes. It was concluded that individuals with T2D, eating a low carbohydrate diet for 6 months may reverse the disease. This study could be used by healthcare professionals to recommend a short-term low carbohydrate diet to individuals with T2D, to improve their chance of going into remission.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Type 2 diabetes remains a significant and worsening problem worldwide, despite many pharmaceutical developments and a global emphasis on glycemic control.
- This review highlights structured LCDs as a worthwhile option for the management and treatment of diabetes, providing an opportunity for Nutritional Therapy Practitioners to support clients in adopting evidence-informed, modifiable dietary and lifestyle changes for Type Two Diabetes.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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X
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:
- Type 2 diabetes is the most common form of diabetes, accounting for 90-95% of cases.
- Previous randomised trials assessed low carbohydrate diets (LCDs) (<26-45% of daily calories from carbohydrate) as encouraging to improve blood glucose control and outcomes of type 2 diabetes but did not systematically assessed remission of diabetes using low carbohydrate diets (LCDs) and very low carbohydrate diets (VLCDs) for people with type 2 diabetes.
- Systematic reviews (SR) and meta-analyses represent the most valuable, reliable, and objective tool to summarise evidence from primary studies.
- This SR assessed 23 randomised controlled trials comparing LCDs with mostly low fat control diets in individuals / subjects / participants with type 2 diabetes. LCDs were defined as diets with less than 130 g/day or less than 26% of calories from carbohydrates, based on 2000 kcal/day. The authors used the Cochrane Risk of Bias tool 2.0 (RoB 2) to assess methodological quality of evidence, GRADE to assess the certainty of evidence
- On the basis of assessment of moderate to low certainty evidence, individuals / subjects / participants adhering to a LCD for six months may experience remission of type 2 diabetes without adverse consequences.
- Primary outcomes of interest were remission of type 2 diabetes (dichotomously defined as HbA1c <6.5% or fasting glucose <7.0 mmol/L), with or without the use of diabetes medication.
- Eight studies reported on remission of diabetes at six months. Pooled analysis showed that when remission was defined by an HbA1c level below 6.5% independent of medication use, LCDs increased remissions by an additional 32 per 100 patients followed (risk difference 0.32, 95% confidence interval 0.17 to 0.47; 8 studies, n=264; GRADE=moderate)
- When remission was defined by an HbA1c level below 6.5% and the absence of diabetes medication, LCDs increased remissions at a lower rate (risk difference 0.05, –0.05 to 0.14; 5 studies, n=199; GRADE=low)
- Additional primary outcomes were weight loss, HbA1c:
- 18 studies reported on Weight loss results (mean difference –3.46, 95% confidence interval –5.25 to –1.67; n=882 (note that positive results not sustained at 12 mo)
- Seventeen studies reported on HbA1c levels at six months, LCDs achieved greater reductions in HbA1c than did control diets (mean difference –0.47%, –0.60 to –0.34; n=747
- Limitations of study: 1) the definition of remission of diabetes, 2) Self-reported dietary intake data are prone to measurement error, particularly in dietary trials in which participants are not blinded
- This SR was funded in part by Texas A&M University.
- The authors declared no conflicts of interest.
Clinical practice applications:
The Authors highlight LCD diets incorporating carbohydrate of less than 130 g/day or less than 26% of calories (based on 2000 kcal/day) may be a safe strategy to help individuals with type 2 diabetes achieve weight loss and better blood glucose control over a six-month period. Results may not be sustained at 12 months.
Considerations for future research:
- The definition of diabetes remission needs clarification, especially with regard to threshold concentrations of Hb1Ac or fasting glucose and the use of diabetes medication.
- Safety concerns have been raised with LCDs. Although no significant or clinically important increase in total or serious adverse events was identified in this SR, these outcomes should be reported in future trials to confirm the certainty of evidence for safety.
- The Authors suggest long term, well designed, calorie controlled randomised trials are needed to determine the effects of LCD on sustained weight loss and remission of diabetes.
- Larger treatment effects for LCDs in shorter term trials (3 to <6 months), may be trialed as an effect modifier
Abstract
OBJECTIVE To determine the efficacy and safety of low carbohydrate diets (LCDs) and very low carbohydrate diets (VLCDs) for people with type 2 diabetes. DESIGN Systematic review and meta-analysis. DATA SOURCES Searches of CENTRAL, Medline, Embase, CINAHL, CAB, and grey literature sources from inception to 25 August 2020. STUDY SELECTION Randomized clinical trials evaluating LCDs (<130 g/day or <26% of a 2000 kcal/day diet) and VLCDs (<10% calories from carbohydrates) for at least 12 weeks in adults with type 2 diabetes were eligible. DATA EXTRACTION Primary outcomes were remission of diabetes (HbA1c <6.5% or fasting glucose <7.0 mmol/L, with or without the use of diabetes medication), weight loss, HbA1c, fasting glucose, and adverse events. Secondary outcomes included health related quality of life and biochemical laboratory data. All articles and outcomes were independently screened, extracted, and assessed for risk of bias and GRADE certainty of evidence at six and 12 month follow-up. Risk estimates and 95% confidence intervals were calculated using random effects meta-analysis. Outcomes were assessed according to a priori determined minimal important differences to determine clinical importance, and heterogeneity was investigated on the basis of risk of bias and seven a priori subgroups. Any subgroup effects with a statistically significant test of interaction were subjected to a five point credibility checklist. RESULTS Searches identified 14 759 citations yielding 23 trials (1357 participants), and 40.6% of outcomes were judged to be at low risk of bias. At six months, compared with control diets, LCDs achieved higher rates of diabetes remission (defined as HbA1c <6.5%) (76/133 (57%) v 41/131 (31%); risk difference 0.32, 95% confidence interval 0.17 to 0.47; 8 studies, n=264, I2=58%). Conversely, smaller, non-significant effect sizes occurred when a remission definition of HbA1c <6.5% without medication was used. Subgroup assessments determined as meeting credibility criteria indicated that remission with LCDs markedly decreased in studies that included patients using insulin. At 12 months, data on remission were sparse, ranging from a small effect to a trivial increased risk of diabetes. Large clinically important improvements were seen in weight loss, triglycerides, and insulin sensitivity at six months, which diminished at 12 months. On the basis of subgroup assessments deemed credible, VLCDs were less effective than less restrictive LCDs for weight loss at six months. However, this effect was explained by diet adherence. That is, among highly adherent patients on VLCDs, a clinically important reduction in weight was seen compared with studies with less adherent patients on VLCDs. Participants experienced no significant difference in quality of life at six months but did experience clinically important, but not statistically significant, worsening of quality of life and low density lipoprotein cholesterol at 12 months. Otherwise, no significant or clinically important between group differences were found in terms of adverse events or blood lipids at six and 12 months. CONCLUSIONS On the basis of moderate to low certainty evidence, patients adhering to an LCD for six months may experience remission of diabetes without adverse consequences. Limitations include continued debate around what constitutes remission of diabetes, as well as the efficacy, safety, and dietary satisfaction of longer term LCDs. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42020161795.
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The Role of Diet Quality in Mediating the Association between Ultra-Processed Food Intake, Obesity and Health-Related Outcomes: A Review of Prospective Cohort Studies.
Dicken, SJ, Batterham, RL
Nutrients. 2021;14(1)
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Plain language summary
Diet has long been a cornerstone of weight management, with dietary policies being a core feature of government and health organisation strategies to reduce obesity worldwide. Indeed, poor diets are a leading cause of preventable obesity-related death and non-communicable diseases, including cancer, cardiovascular disease and type 2 diabetes. The aim of this study was to provide novel insights into the relative impact of nutrient content and dietary patterns vs. ultra-processing on obesity and adverse health-related outcomes. This study is a review of prospective cohort studies. Findings show that adjustment for fat, sugar and sodium intake, or adjustment for adherence to a range of healthy or unhealthy dietary patterns has a minimal impact on the adverse associations between UPF intake and a diverse range of health-related outcomes. Authors conclude that their findings raise important questions regarding current policy and future research needs, suggesting that the nature and extent of processing is an important dietary dimension.
Abstract
Prospective cohort studies show that higher intakes of ultra-processed food (UPF) increase the risk of obesity and obesity-related outcomes, including cardiovascular disease, cancer and type 2 diabetes. Whether ultra-processing itself is detrimental, or whether UPFs just have a lower nutritional quality, is debated. Higher UPF intakes are inversely associated with fruit, vegetables, legumes and seafood consumption. Therefore, the association between UPFs and poor health could simply be from excess nutrient intake or from a less healthful dietary pattern. If so, adjustment for dietary quality or pattern should explain or greatly reduce the size of the significant associations between UPFs and health-related outcomes. Here, we provide an overview of the literature and by using a novel approach, review the relative impact of adjusting for diet quality/patterns on the reported associations between UPF intake and health-related outcomes in prospective cohort studies. We find that the majority of the associations between UPFs, obesity and health-related outcomes remain significant and unchanged in magnitude after adjustment for diet quality or pattern. Our findings suggest that the adverse consequences of UPFs are independent of dietary quality or pattern, questioning the utility of reformulation to mitigate against the obesity pandemic and wider negative health outcomes of UPFs.