Effect of Tree Nuts on Glycemic Control and Features of the Metabolic Syndrome: A Systematic Review and Meta-analysis of Controlled Dietary Trials to Provide Evidence-based Guidance for Nutrition Guidelines Development
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 1
- 试验地点
- 1
- 主要终点
- Metabolic syndrome measures
研究概览
简要总结
Tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios and walnuts) are an important source of unsaturated fatty acids, vegetable protein, and fibre, as well as minerals, vitamins, and phytonutrients. Although heart disease risk reduction claims for nuts have been permitted in the U.S. and general dietary guidelines and recommendations from heart associations recommend the consumption of nuts for heart protection, diabetes associations have not addressed nuts in their most recent recommendations. This omission is despite heart disease being a major cause of death in diabetes. There remains insufficient information on the usefulness of these foods in diabetes. To improve evidence-based guidance for tree nut recommendations, the investigators propose to conduct a systematic review of the effect of tree nuts on diabetes control and features of the metabolic syndrome. The systematic review process allows the combining of the results from many small studies in order to arrive at a pooled estimate, similar to a weighted average, of the true effect. The investigators will be able to explore whether eating tree nuts has different effects between men and women, in different age groups and background disease states, and whether or not the effect of tree nuts depends on the dose and background diet. The findings of this proposed knowledge synthesis will help improve the health of Canadians through informing diabetes association recommendations and heart association recommendations where they relate to diabetes.
详细描述
Background: Tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios and walnuts)are an important source of unsaturated fatty acids, vegetable protein, and fibre, as well as minerals, vitamins, and phytonutrients. Although the dietary guidelines for Americans and American Heart Association (AHA) recommend the consumption of nuts for cardiovascular risk reduction and the US Food and Drug Administration (FDA) issued a qualified coronary heart disease (CHD) risk reduction claim for nuts, none of the diabetes associations have addressed nuts in their most recent recommendations. This omission is despite CHD being a major cause of death in diabetes. Several trials have been undertaken in diabetes, some of which, including the largest to date by our group, have demonstrated advantages in glycemic control. Although the remaining trials have failed to show a significant improvement in glycemic control, the direction of the effect has favored nuts, along with improvements in complementary markers of metabolic control.
Need for a review: The lack of high quality data in this area to support diabetes recommendations represents an urgent call for stronger evidence. A systematic review and meta-analysis of controlled feeding trials remains the "Gold Standard" of evidence for nutrition guidelines development.
Objective: To provide evidence-based guidance for diabetes guidelines, we will conduct two systematic reviews and meta-analyses of controlled feeding trials to assess the effect of tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios and walnuts) on cardiometabolic control: (1) "Tree nuts and glycemic control" and (2) "Tree nuts and features of the metabolic syndrome".
Design: The planning and conduct of the proposed meta-analyses will follow the Cochrane handbook for systematic reviews of interventions. The reporting will follow the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines.
Data sources: MEDLINE, EMBASE, CINAHL and The Cochrane Central Register of Controlled Trials will be searched using appropriate search terms.
研究设计
- 研究类型
- Observational
- 时间视角
- Prospective
入排标准
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Dietary trials in humans
- •Randomized treatment allocation
- •>=3-weeks
- •Suitable control (i.e. isocaloric exchange of other dietary components for tree nuts)
- •viable endpoint data
排除标准
- •Non-human studies
- •Nonrandomized treatment allocation
- •Lack of a suitable control (non-isocaloric)
- •no viable endpoint data
结局指标
主要结局
Metabolic syndrome measures
时间窗: Up to 1.5-years
Harmonized metabolic syndrome diagnostic measures (waist circumference, TG, HDL-C, blood pressure, fasting glucose)
Glycemic control measures
时间窗: Up to 1.5-years
Glycated blood proteins (HbA1c, total glycated hemoglobin, fructosamine, glycated albumin), fasting glucose, fasting insulin, and the homeostasis model assessment of insulin resistance (HOMA-IR)
次要结局
未报告次要终点
研究者
John Sievenpiper
Knowledge Synthesis Lead
University of Toronto