Vegetarian vs. conventional diabetic diet - A 1-year follow-up

The impact of food-based dietary strategies on achieving type 2 diabetes remission: A systematic review

OBJECTIVE

Conventional wisdom once asserted that diabetes was irreversible. However, contemporary research indicates that dietary changes may contribute to achieving diabetes remission in persons with type 2 diabetes (T2D). We aimed to determine the effectiveness of food-based dietary approaches for T2D remission.

METHODS

We systematically searched Medline, EMBASE, and Web of Science, along with exploring grey literature, to identify longitudinal studies. Data extraction and quality assessment adhered to predetermined criteria, and the results of the included studies were analyzed using a narrative synthesis and graphical display.

RESULTS

We included 52 original studies-40 % were rated as low-risk of bias. Overall, studies showed the low-carbohydrate Mediterranean diet (LCMD), compared to a low-fat diet, was more effective for achieving T2D remission in newly diagnosed patients who also had a weight loss of up to 6 kg. Compared to both the traditional Mediterranean diet and the American Diabetic Association diet, the LCMD was also more effective at diabetes remission for persons with T2D with any duration of diabetes; however, more substantial weight loss of 8 kg was required. Other diets that appeared effective for T2D remission included low-calorie diets and diets high in plant protein sources. Less weight loss was needed to achieve remission on plant-based diets than a low-calorie diet and low-carbohydrate diet.

CONCLUSIONS

Diets high in plant protein sources may support T2D remission, particularly among newly diagnosed patients. For patients with a duration of over 2 years, the combination of plant-based diets with greater weight loss should be considered to induce remission.

Effects of Plant-Based Diets on Markers of Insulin Sensitivity: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

The aim of this systematic review and meta-analysis was to examine the effects of plant-based diets on markers of insulin sensitivity in people with overweight/obesity, prediabetes, or type 2 diabetes (T2D). A systematic literature search in MEDLINE, Embase, CINAHL, and CENTRAL was conducted, and randomised controlled trials (RCTs) investigating the effect of plant-based diets (vegan, ovo-vegetarian, lacto-vegetarian, and lacto-ovo-vegetarian) for ≥14 d on markers of insulin sensitivity in adults (≥18 years) with BMI ≥ 25 kg/m2, prediabetes, or T2D were eligible. We identified eight RCTs, including 716 participants. In comparison with control diets, plant-based diets improved Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (-0.97, 95% confidence interval (CI) (-1.67, -0.27), p = 0.007) and fasting insulin (-4.13 µU/mL, 95% CI (-7.22, -1.04), p = 0.009) in people with overweight/obesity. In people with prediabetes, one study compared vegan and vegetarian diets and found no difference in HOMA-IR, or fasting insulin. One study of people with T2D reported no difference in immunoreactive insulin and metabolic glucose clearance compared with a conventional diabetes diet. In conclusion, adhering to plant-based diets for ≥14 d improved HOMA-IR and fasting insulin in people with overweight/obesity. Long-term RCTs are needed to determine whether plant-based diets can result in prolonged improvements in insulin sensitivity in people at risk of or with T2D.

Onset of Ulcerative Colitis in a Patient with Type 2 Diabetes: Efficacy of a Plant-Based Diet for Both Diseases

No case has been reported in which ulcerative colitis occurred in a patient with type 2 diabetes mellitus and the patient was treated with a plant-based diet. A 56-year-old man with a 3-year history of diabetes noticed bloody stool about 2 months after his worst glycated hemoglobin A1c test. Endoscopy revealed diffuse inflammation in the rectum. He was diagnosed with ulcerative colitis (proctitis, mild severity). He underwent educational hospitalization. A plant-based diet (1400 kcal/day) was provided. The same dosage of metformin was continued, but no medication was prescribed for ulcerative colitis. At the end of hospitalization, fecal occult blood 271 ng/mL became negative. Glycated hemoglobin A1c 6.9% had decreased to 6.6%. Two months after discharge, glycated hemoglobin A1c decreased to normal for the first time in 3.5 years. Ulcerative colitis had been in remission without medication for one and a half years after the educational hospitalization. Thereafter, however, he experienced two flareups. Deterioration in glycated hemoglobin A1c preceded the flareups. We described a scarcely reported case in which ulcerative colitis occurred in a patient with diabetes and the patient was treated with a plant-based diet. The plant-based diet was effective for both diseases. It seemed that the status of diabetes influenced the onset and relapse of ulcerative colitis.

Does weight management research for adults with severe obesity represent them? Analysis of systematic review data

OBJECTIVE

Our objective was to determine the extent to which current evidence from long-term randomised controlled trials (RCTs) of weight management is generalisable and applicable to underserved adult groups with obesity (body mass index (BMI) ≥35 kg/m²).

METHODS

Descriptive analysis of 131 RCTs, published after 1990-May 2017 with ≥1 year of follow-up, included in a systematic review of long-term weight management interventions for adults with BMI ≥35 kg/m² (the REBALANCE Project). Studies were identified from MEDLINE, EMBASE, PsychINFO, SCI, CENTRAL and from hand searching. Reporting of trial inclusion and exclusion criteria, trial recruitment strategies, baseline characteristics and outcomes were analysed using a predefined list of characteristics informed by the PROGRESS (Place of residence, Race/ethnicity/culture/language, Occupation, Gender/sex, Religion, Education, Socioeconomic status, Social capital)-Plus framework and the UK Equality Act 2010.

RESULTS

Few (6.1%) trials reported adapting recruitment to appeal to underserved groups. 10.0% reported culturally adapting their trial materials. Only 6.1% of trials gave any justification for their exclusion criteria, yet over half excluded participation for age or mental health reasons. Just over half (58%) of the trials reported participants' race or ethnicity, and one-fifth reported socioeconomic status. Where outcomes were reported for underserved groups, the most common analysis was by sex (47.3%), followed by race or ethnicity (16.8%). 3.1% of trials reported outcomes according to socioeconomic status.

DISCUSSION

Although we were limited by poor trial reporting, our results indicate inadequate representation of people most at risk of obesity. Guidance for considering underserved groups may improve the appropriateness of research and inform greater engagement with health and social care services.

FUNDING

National Institute for Health Research Health Technology Assessment Programme (project number: 15/09/04).

PROSPERO REGISTRATION NUMBER

CRD42016040190.

Optimal Dietary Strategies for Prevention of Atherosclerotic Cardiovascular Disease in Diabetes: Evidence and Recommendations

PURPOSE OF REVIEW

This review presents the current available evidence of the effects of several dietary patterns on atherosclerotic cardiovascular disease (ASCVD) risk in patients with type 2 diabetes (T2D).

RECENT FINDINGS

Evidence demonstrates improvements in cardiovascular risk factors with some dietary patterns in the general population. However, evidence is limited for glycemic control and cardiovascular benefit in patients with T2D for Dietary Approaches to Stop Hypertension and plant-based dietary patterns. Evidence suggests that carbohydrate-restricted dietary patterns improve glycemic control and decrease the use of anti-hyperglycemic medications. The Mediterranean dietary pattern has the most evidence for glycemic control and decreased ASCVD risk in patients with T2D. There is no evidence on ASCVD outcomes in patients with T2D for any other dietary pattern. The Mediterranean dietary pattern has the most evidence for cardiovascular benefit in patients with T2D. Future research should examine the effect of dietary patterns on ASCVD outcomes.

The effects of plant-based diets on the body and the brain: a systematic review

Western societies notice an increasing interest in plant-based eating patterns such as vegetarian and vegan, yet potential effects on the body and brain are a matter of debate. Therefore, we systematically reviewed existing human interventional studies on putative effects of a plant-based diet on the metabolism and cognition, and what is known about the underlying mechanisms. Using the search terms "plant-based OR vegan OR vegetarian AND diet AND intervention" in PubMed filtered for clinical trials in humans retrieved 205 studies out of which 27, plus an additional search extending the selection to another five studies, were eligible for inclusion based on three independent ratings. We found robust evidence for short- to moderate-term beneficial effects of plant-based diets versus conventional diets (duration ≤ 24 months) on weight status, energy metabolism and systemic inflammation in healthy participants, obese and type-2 diabetes patients. Initial experimental studies proposed novel microbiome-related pathways, by which plant-based diets modulate the gut microbiome towards a favorable diversity of bacteria species, yet a functional "bottom up" signaling of plant-based diet-induced microbial changes remains highly speculative. In addition, little is known, based on interventional studies about cognitive effects linked to plant-based diets. Thus, a causal impact of plant-based diets on cognitive functions, mental and neurological health and respective underlying mechanisms has yet to be demonstrated. In sum, the increasing interest for plant-based diets raises the opportunity for developing novel preventive and therapeutic strategies against obesity, eating disorders and related comorbidities. Still, putative effects of plant-based diets on brain health and cognitive functions as well as the underlying mechanisms remain largely unexplored and new studies need to address these questions.

Improving the scientific rigour of nutritional recommendations for adults with type 2 diabetes: A comprehensive review of the American Diabetes Association guideline-recommended eating patterns

AIMS

The global rate of type 2 diabetes (T2D) continues to rise. Guidelines that influence the worldwide treatment of this disease are central to changing this trajectory. We sought in this review to evaluate the appropriateness of sources cited in the American Diabetes Association's (ADA) guidelines on eating patterns for T2D management, identify additional relevant sources, and evaluate the evidence.

MATERIALS AND METHODS

We reviewed the evidence behind the ADA's recommendations on eating patterns in the 2018 and 2019 ADA Standards of Care and the 2014 ADA Nutrition Therapy Recommendations for Adults with Diabetes. Additionally, we conducted a comprehensive search to identify any additional studies not included in the cited evidence. To determine appropriateness of inclusion in the guidelines, the following criteria were applied: 1) it was a clinical trial or systematic review/meta-analysis of clinical trials; 2) it involved persons with T2D; 3) one of the study arms followed one of the eating patterns currently recommended; 4) its reported outcomes included glycaemic control; 5) outcomes were reported separately for persons with T2D.

RESULTS

We found a wide variation in the evidence for each eating pattern. Issues that have hampered the guideline process include: lack of a rigorous literature review, resulting in the omission of pertinent studies; an overreliance on prospective cohort studies; inconsistent standards for evidence; inclusion of studies not on persons with T2D; and bias.

CONCLUSIONS

The ADA Guidelines recommended eating patterns fall short of rigorous standards of scientific review according to state-of-the-art systematic review and guideline creation practices.

A whole-food, plant-based nutrition program: Evaluation of cardiovascular outcomes and exploration of food choices determinants

OBJECTIVES

An ideal diet to prevent cardiovascular diseases contains an unlimited intake of various plant foods and a reduced intake of animal and highly processed foods. Researchers have reported that nutrition education programs that prioritize whole-plant foods effectively contribute to the prevention of unhealthy cardiovascular outcomes. We examined whether a 12-wk nutrition education program in adults from Montreal (Quebec, Canada) with at least one risk factor of cardiovascular disease was effective in modifying their eating patterns toward including more whole-plant foods. We further evaluated the effects of this program on participants' cardiovascular outcomes and explored determinants influencing food choices toward whole-food, plant-based diets.

METHODS

A sequential, explanatory, mixed-methods, research design was used. A quantitative step (i.e., single-arm, quasi-experimental trial) preceded participant recruitment for a qualitative phase (i.e., phenomenological study; semistructured interview; thematic analysis). The examined outcomes were changes in cardiovascular risk factors (paired t tests) and determinants of food choice (thematic analysis).

RESULTS

Weight (-10.5 lbs; 95% confidence interval [CI]: -9.0 to -12.0), waist circumference (-7.4 cm; 95% CI: -6.5 to -8.4), total cholesterol (-0.87 mmol/L; 95% CI: -0.57 to -1.17), and low-density lipoprotein cholesterol (-29.7% or -0.84 mmol/L; 95% CI: -0.55 to -1.13) all improved significantly (P ˂ 0.001). Encouraging ad libitum intake of various whole-food plant-based items appealed more to participants than traditional strategies. Altruistic and societal motives, in addition to health, were identified as key determinants of an increased adoption of whole-food plant-based diets.

CONCLUSIONS

The whole-food, plant-based nutrition program improves cardiovascular health in adults and features characteristics that may inform future nutrition programs and public health interventions.

Bariatric surgery, lifestyle interventions and orlistat for severe obesity: the REBALANCE mixed-methods systematic review and economic evaluation

BACKGROUND

Adults with severe obesity [body mass index (BMI) of ≥ 35 kg/m2] have an increased risk of comorbidities and psychological, social and economic consequences.

OBJECTIVES

Systematically review bariatric surgery, weight-management programmes (WMPs) and orlistat pharmacotherapy for adults with severe obesity, and evaluate the feasibility, acceptability, clinical effectiveness and cost-effectiveness of treatment.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, PsycINFO, the Cochrane Central Register of Controlled Trials and the NHS Economic Evaluation Database were searched (last searched in May 2017).

REVIEW METHODS

Four systematic reviews evaluated clinical effectiveness, cost-effectiveness and qualitative evidence for adults with a BMI of ≥ 35 kg/m2. Data from meta-analyses populated a microsimulation model predicting costs, outcomes and cost-effectiveness of Roux-en-Y gastric bypass (RYGB) surgery and the most effective lifestyle WMPs over a 30-year time horizon from a NHS perspective, compared with current UK population obesity trends. Interventions were cost-effective if the additional cost of achieving a quality-adjusted life-year is < £20,000-30,000.

RESULTS

A total of 131 randomised controlled trials (RCTs), 26 UK studies, 33 qualitative studies and 46 cost-effectiveness studies were included. From RCTs, RYGB produced the greatest long-term weight change [-20.23 kg, 95% confidence interval (CI) -23.75 to -16.71 kg, at 60 months]. WMPs with very low-calorie diets (VLCDs) produced the greatest weight loss at 12 months compared with no WMPs. Adding a VLCD to a WMP gave an additional mean weight change of -4.41 kg (95% CI -5.93 to -2.88 kg) at 12 months. The intensive Look AHEAD WMP produced mean long-term weight loss of 6% in people with type 2 diabetes mellitus (at a median of 9.6 years). The microsimulation model found that WMPs were generally cost-effective compared with population obesity trends. Long-term WMP weight regain was very uncertain, apart from Look AHEAD. The addition of a VLCD to a WMP was not cost-effective compared with a WMP alone. RYGB was cost-effective compared with no surgery and WMPs, but the model did not replicate long-term cost savings found in previous studies. Qualitative data suggested that participants could be attracted to take part in WMPs through endorsement by their health-care provider or through perceiving innovative activities, with WMPs being delivered to groups. Features improving long-term weight loss included having group support, additional behavioural support, a physical activity programme to attend, a prescribed calorie diet or a calorie deficit.

LIMITATIONS

Reviewed studies often lacked generalisability to UK settings in terms of participants and resources for implementation, and usually lacked long-term follow-up (particularly for complications for surgery), leading to unrealistic weight regain assumptions. The views of potential and actual users of services were rarely reported to contribute to service design. This study may have failed to identify unpublished UK evaluations. Dual, blinded numerical data extraction was not undertaken.

CONCLUSIONS

Roux-en-Y gastric bypass was costly to deliver, but it was the most cost-effective intervention. Adding a VLCD to a WMP was not cost-effective compared with a WMP alone. Most WMPs were cost-effective compared with current population obesity trends.

FUTURE WORK

Improved reporting of WMPs is needed to allow replication, translation and further research. Qualitative research is needed with adults who are potential users of, or who fail to engage with or drop out from, WMPs. RCTs and economic evaluations in UK settings (e.g. Tier 3, commercial programmes or primary care) should evaluate VLCDs with long-term follow-up (≥ 5 years). Decision models should incorporate relevant costs, disease states and evidence-based weight regain assumptions.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016040190.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit and Health Economics Research Unit are core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.

Cardio-Metabolic Benefits of Plant-Based Diets

Cardio-metabolic disease, namely ischemic heart disease, stroke, obesity, and type 2 diabetes, represent substantial health and economic burdens. Almost one half of cardio-metabolic deaths in the U.S. might be prevented through proper nutrition. Plant-based (vegetarian and vegan) diets are an effective strategy for improving nutrient intake. At the same time, they are associated with decreased all-cause mortality and decreased risk of obesity, type 2 diabetes, and coronary heart disease. Evidence suggests that plant-based diets may reduce the risk of coronary heart disease events by an estimated 40% and the risk of cerebral vascular disease events by 29%. These diets also reduce the risk of developing metabolic syndrome and type 2 diabetes by about one half. Properly planned vegetarian diets are healthful, effective for weight and glycemic control, and provide metabolic and cardiovascular benefits, including reversing atherosclerosis and decreasing blood lipids and blood pressure. The use of plant-based diets as a means of prevention and treatment of cardio-metabolic disease should be promoted through dietary guidelines and recommendations.