作者：留美强叫兽
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柳叶刀：膳食纤维或全谷物降低心血管疾病、糖尿病、结直肠癌、超重、高血压风险；建议全谷物代替精制谷物，至少25-29克每天膳食纤维；每多15克每天降低全因死亡6%、心脏病7%、糖尿病12%、结直肠癌3%
美国某知名教育集团做的上海教育市场调查部分内容，为内部资料。是在该集团实习员工发到网上，不同于媒体按赞助费广告费给的评比标准。知名度排名：1.金吉利 2.新东方 3.美勤 4.启德 5.新通；专业度排名：1.美勤 2.棕榈 3.中智 4.再来人 5.学美；录取满意度排名：1.美勤 2.世毕盟 3.中智 4.学美 5.澳际《柳叶刀 The Lancet》：碳水化合物质量
和人类健康：一系列系统评价
和荟萃分析
｜Carbohydrate quality and human health: a series of systematic reviews and meta-analyses
An analysis of previous data covering 135 million person-years reveals the health effects of consuming dietary fiber. It’s good news for people who eat whole grains: A diet high in fiber means less risk of heart disease, certain cancers, diabetes, overweight and high blood pressure.
对之前覆盖 1.35 亿人次的数据的分析揭示了食用膳食纤维对健康的影响。 对于吃全谷物的人来说，这是个好消息：高纤维饮食意味着患心脏病、某些癌症、糖尿病、超重和高血压的风险较低。
January 2019
Background
Previous systematic reviews and meta-analyses explaining the relationship between carbohydrate quality and health have usually examined a single marker and a limited number of clinical outcomes. We aimed to more precisely quantify the predictive potential of several markers, to determine which markers are most useful, and to establish an evidence base for quantitative recommendations for intakes of dietary fibre.
以前解释碳水化合物质量与健康之间关系的系统评价和荟萃分析通常检查单一标志物和有限数量的临床结果。 我们的目的是更精确地量化几种标记物的预测潜力，确定哪些标记物最有用，并为膳食纤维摄入量的定量建议建立证据基础。
Methods
We did a series of systematic reviews and meta-analyses of prospective studies published from database inception to April 30, 2017, and randomised controlled trials published from database inception to Feb 28, 2018, which reported on indicators of carbohydrate quality and non-communicable disease incidence, mortality, and risk factors. Studies were identified by searches in PubMed, Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials, and by hand searching of previous publications. We excluded prospective studies and trials reporting on participants with a chronic disease, and weight loss trials or trials involving supplements. Searches, data extraction, and bias assessment were duplicated independently. Robustness of pooled estimates from random-effects models was considered with sensitivity analyses, meta-regression, dose-response testing, and subgroup analyses. The GRADE approach was used to assess quality of evidence.
我们对从数据库建立到2017年4月30日发表的前瞻性研究以及从数据库建立到2018年2月28日发表的随机对照试验进行了一系列系统评价和荟萃分析，这些研究报告了碳水化合物质量和非传染性疾病的指标 发病率、死亡率和危险因素。 研究是通过在 PubMed、Ovid MEDLINE、Embase 和 Cochrane 对照试验中心注册库中检索以及手动检索以前的出版物来确定的。 我们排除了对患有慢性疾病的参与者进行报告的前瞻性研究和试验，以及减肥试验或涉及补充剂的试验。 搜索、数据提取和偏差评估都是独立重复的。 通过敏感性分析、荟萃回归、剂量反应测试和亚组分析来考虑随机效应模型汇总估计值的稳健性。 GRADE 方法用于评估证据质量。
Findings
Just under 135 million person-years of data from 185 prospective studies and 58 clinical trials with 4635 adult participants were included in the analyses. Observational data suggest a 15–30% decrease in all-cause and cardiovascular related mortality, and incidence of coronary heart disease, stroke incidence and mortality, type 2 diabetes, and colorectal cancer when comparing the highest dietary fibre consumers with the lowest consumers Clinical trials show significantly lower bodyweight, systolic blood pressure, and total cholesterol when comparing higher with lower intakes of dietary fibre. Risk reduction associated with a range of critical outcomes was greatest when daily intake of dietary fibre was between 25 g and 29 g. Dose-response curves suggested that higher intakes of dietary fibre could confer even greater benefit to protect against cardiovascular diseases, type 2 diabetes, and colorectal and breast cancer. Similar findings for whole grain intake were observed. Smaller or no risk reductions were found with the observational data when comparing the effects of diets characterised by low rather than higher glycaemic index or load. The certainty of evidence for relationships between carbohydrate quality and critical outcomes was graded as moderate for dietary fibre, low to moderate for whole grains, and low to very low for dietary glycaemic index and glycaemic load. Data relating to other dietary exposures are scarce.
分析中纳入了来自 185 项前瞻性研究和 58 项临床试验（涉及 4635 名成年参与者）的近 1.35 亿人年数据。 观察数据表明，膳食纤维摄入量最高的人群与膳食纤维摄入量最低的人群进行比较时，全因死亡率和心血管相关死亡率以及冠心病、中风发病率和死亡率、2型糖尿病和结直肠癌的发病率降低了 15-30% 临床试验 与膳食纤维摄入量较高和较低的情况相比，体重、收缩压和总胆固醇显着降低。 当每日膳食纤维摄入量在 25 克至 29 克之间时，与一系列关键结果相关的风险降低幅度最大。 剂量反应曲线表明，摄入更多的膳食纤维可以为预防心血管疾病、2 型糖尿病、结直肠癌和乳腺癌带来更大的好处。 在全谷物摄入量方面也观察到了类似的结果。 当比较低血糖指数或负荷而不是高血糖指数或负荷的饮食效果时，观察数据发现风险降低较小或没有。 碳水化合物质量与关键结果之间关系的证据确定性被评为膳食纤维为中等、全谷物为低至中等、膳食血糖指数和血糖负荷为低至极低。 有关其他饮食暴露的数据很少。
Interpretation
Findings from prospective studies and clinical trials associated with relatively high intakes of dietary fibre and whole grains were complementary, and striking dose-response evidence indicates that the relationships to several non-communicable diseases could be causal. Implementation of recommendations to increase dietary fibre intake and to replace refined grains with whole grains is expected to benefit human health. A major strength of the study was the ability to examine key indicators of carbohydrate quality in relation to a range of non-communicable disease outcomes from cohort studies and randomised trials in a single study. Our findings are limited to risk reduction in the population at large rather than those with chronic disease.
与相对较高的膳食纤维和全谷物摄入量相关的前瞻性研究和临床试验的结果是互补的，并且引人注目的剂量反应证据表明，与几种非传染性疾病的关系可能是因果关系。 实施增加膳食纤维摄入量和用全谷物替代精制谷物的建议预计将有利于人类健康。 该研究的一个主要优势是能够通过一项研究中的队列研究和随机试验来检查与一系列非传染性疾病结果相关的碳水化合物质量的关键指标。 我们的研究结果仅限于降低广大人群的风险，而不是降低慢性病患者的风险。
Figure_1 Dose-response relationships between total dietary fibre and critical clinical outcomes based on data from prospective studies 总膳食纤维
(A) Total fibre and all-cause mortality. 68 183 deaths over 11·3 million person-years. Assuming linearity a risk ratio of 0·93 (95% CI 0·90–0·95) was observed for every 8 g more fibre consumed per day.
(B) Total fibre and incidence of coronary heart disease. 6449 deaths over 2·5 million person-years. Assuming linearity a risk ratio of 0·81 (0·73–0·90) was observed for every 8 g more fibre consumed per day.
(C) Total fibre and incidence of type 2 diabetes. 22 450 cases over 3·2 million person-years. Assuming linearity a risk ratio of 0·85 (0·82–0·89) was observed for every 8 g more fibre consumed per day.
(D) Total fibre and incidence of colorectal cancer. 20 009 cases over 20·9 million person-years. Assuming linearity a risk ratio of 0·92 (0·89–0·95) was observed for every 8 g more fibre consumed per day.
Introduction
Before the mid-20th century, carbohydrates were principally regarded as an energy source, and nutrition recommendations suggested that carbohydrates should contribute to the energy deficit remaining after taking into account recommended intakes of fat and protein. From the mid-1950s, awareness increased of the potential of sugar (principally sucrose) to increase the risk of dental caries, and in the 1960s the view that sugar was a major cause of obesity, type 2 diabetes, and cardiovascular disease was promoted. A substantial body of experimental, epidemiological, and clinical trial data have accumulated since these early observations. On the basis of extensive systematic reviews and meta-analyses, in 2015, WHO issued a recommendation, that individuals reduce intake to less than 10% of total energy. They also issued a conditional recommendation suggesting that even greater benefit could accrue if intakes of sugar are less than 5% of total energy. Similar recommendations have been made by national governments and professional organisations worldwide.
在20世纪中叶之前，碳水化合物主要被视为一种能量来源，营养建议表明，考虑到脂肪和蛋白质的推荐摄入量后，碳水化合物应该有助于弥补剩余的能量不足。 从 20 世纪 50 年代中期开始，人们对糖（主要是蔗糖）增加龋齿风险的认识不断提高，而在 20 世纪 60 年代，糖是肥胖、2 型糖尿病和心血管疾病的主要原因的观点得到推广。 自这些早期观察以来，已经积累了大量的实验、流行病学和临床试验数据。 在广泛的系统评价和荟萃分析的基础上，2015年，世界卫生组织发布建议，个人将摄入量减少到总能量的10%以下。 他们还发布了一项有条件的建议，表明如果糖的摄入量低于总能量的 5%，可能会产生更大的益处。 世界各国政府和专业组织也提出了类似的建议。
Figure_2 Dose-response relationships between whole grain intake and critical clinical outcomes based on data from prospective studies 全谷物
(A) Whole grain intake and all-cause mortality. 88 347 deaths over 8·2 million person-years. Assuming linearity a risk ratio of 0·94 (95% CI 0·92–0·95) was observed for every 15 g more whole grains consumed per day.
(B) Whole grain intake and incidence of coronary heart disease. 6587 cases over 2·4 million person-years. Assuming linearity a risk ratio of 0·93 (0·89–0·98) was observed for every 15 g more whole grains consumed per day.
(C) Whole grain intake and incidence of type 2 diabetes. 13 147 cases over 3·5 million person-years. Assuming linearity a risk ratio of 0·88 (0·81–0·95) was observed for every 15 g more whole grains consumed per day.
(D) Whole grain intake and incidence of colorectal cancer. 6056 cases over 5·7 million person-years. Assuming linearity a risk ratio of 0·97 (0·95–0·99) was observed for every 15 g more whole grains consumed per day.
Research in contextEvidence before this study
Foods containing carbohydrate consisting principally of sugars, starches, and dietary fibre (non-starch polysaccharide) provide the main source of dietary energy for people worldwide. The role of free sugars as a determinant of adverse health outcomes has been clarified, and clear guidelines relating to their restriction issued. Dietary fibre and some starches are associated with health benefits. Dietary guidelines typically encourage regular consumption of vegetables, cereals, pulses, and whole fruit, which are rich sources of dietary fibre and some starches, as well as other health promoting nutrients. However, previous systematic reviews and meta-analyses examining the relationship between starches and dietary fibre and health outcomes have usually examined a single indicator of carbohydrate quality and a limited number of disease outcomes. Thus, it has not been possible to establish the extent to which the predictive potential of these indicators applies across the spectrum of non-communicable disease, nor which are most useful in nutrition guidelines or when recommending food choices. Quantitative recommendations relating to dietary fibre do not have a strong evidence base. We searched PubMed, Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials for prospective studies published from database inception to April 30, 2017, and randomised controlled trials published from database inception to Feb 28, 2018, and by hand searching of previous publications. Prospective studies and trials reporting on participants with a chronic disease, and weight loss trials or trials involving supplements were excluded. Robustness of pooled estimates from random-effects models was considered with sensitivity analyses, meta-regression, dose-response testing, and subgroup analyses.
含有主要由糖、淀粉和膳食纤维（非淀粉多糖）组成的碳水化合物的食物为全世界人民提供了膳食能量的主要来源。 游离糖作为不良健康结果决定因素的作用已得到澄清，并发布了与其限制相关的明确指南。 膳食纤维和一些淀粉对健康有益。 膳食指南通常鼓励定期食用蔬菜、谷物、豆类和整个水果，这些都是膳食纤维和一些淀粉以及其他促进健康的营养素的丰富来源。 然而，之前检查淀粉和膳食纤维与健康结果之间关系的系统评价和荟萃分析通常检查碳水化合物质量的单一指标和有限数量的疾病结果。 因此，尚无法确定这些指标的预测潜力在多大程度上适用于所有非传染性疾病，也无法确定哪些指标在营养指南或推荐食物选择时最有用。 与膳食纤维相关的定量建议没有强有力的证据基础。 我们检索了 PubMed、Ovid MEDLINE、Embase 和 Cochrane 对照试验中央注册库，查找从数据库建立到 2017 年 4 月 30 日发表的前瞻性研究，以及从数据库建立到 2018 年 2 月 28 日发表的随机对照试验，并手动检索了以前的研究 出版物。 对患有慢性疾病的参与者进行前瞻性研究和试验，以及减肥试验或涉及补充剂的试验被排除在外。 通过敏感性分析、荟萃回归、剂量反应测试和亚组分析来考虑随机效应模型汇总估计值的稳健性。
Figure_3 Dose-response relationships between dietary glycaemic index and critical clinical outcomes based on data from prospective studies 膳食血糖指数
(A) Glycaemic index and all-cause mortality. 7699 deaths over 0·6 million person-years. Assuming linearity a risk ratio of 1·16 (0·90– 1·49) was observed for every 10 glycaemic index unit increase per day.
(B) Glycaemic index and incidence of coronary heart disease. 7240 cases over 2·4 million person-years. Assuming linearity a risk ratio of 1·09 (0·94–1·27) was observed for every 10 glycaemic index unit increase per day.
(C) Glycaemic index and incidence of type 2 diabetes. 31 780 cases over 4·9 million person-years. Assuming linearity a risk ratio of 1·10 (1·00–1·20) was observed for every 10 glycaemic index unit increase per day.
(D) Glycaemic index and incidence of colorectal cancer. 10 390 cases over 6·5 million person-years. Assuming linearity a risk ratio of 1·05 (1·00–1·10) was observed for every 10 glycaemic index unit increase per day.
Added value of this study
We did a systematic review and meta-analyses of prospective studies and clinical trials reporting on the relationship between the most widely studied indicators of carbohydrate quality (ie, dietary fibre, whole grains or pulses, dietary glycaemic index, or glycaemic load) and mortality and incidence of a wide range of non-communicable diseases and their risk factors. Parallel consideration of prospective studies and clinical trials has enabled an exploration of the extent to which changes in cardiometabolic risk factors associated with altering intake of dietary carbohydrate align with the effect of carbohydrate quality on disease risk observed in the prospective studies. Dose-response curves were generated and the benefits from different amounts of total dietary fibre were calculated. The approach recommended by the GRADE Working Group has been used to assess the quality of evidence and the importance of the observed associations that influence confidence in nutrition recommendations.
我们对前瞻性研究和临床试验进行了系统回顾和荟萃分析，报告了最广泛研究的碳水化合物质量指标（即膳食纤维、全谷物或豆类、膳食血糖指数或血糖负荷）与死亡率和死亡率之间的关系。 多种非传染性疾病的发病率及其危险因素。 前瞻性研究和临床试验的并行考虑使得我们能够探索与改变膳食碳水化合物摄入量相关的心脏代谢危险因素的变化与前瞻性研究中观察到的碳水化合物质量对疾病风险的影响的程度。 生成剂量反应曲线，并计算不同含量的总膳食纤维的益处。 GRADE 工作组推荐的方法已用于评估证据的质量以及观察到的影响营养建议信心的关联的重要性。
Figure_4 Summary forest plots of key outcomes from clinical trials 临床试验主要结果的森林图摘要
(A) Higher compared with lower total fibre intakes.
(B) Higher compared with lower whole grain intakes.
(C) Comparison of diets characterised by lower compared with higher glycaemic index foods.
Implications of all the available evidence
The complementary findings from prospective studies and clinical trials, which show that higher intakes of dietary fibre or whole grains are associated with a reduction in the risk of mortality and incidence of a wide range of non-communicable diseases and their risk factors, provide convincing evidence for nutrition recommendations to replace refined grains with whole grains and increase dietary fibre to at least 25–29 g per day, with additional benefits likely to accrue with greater intakes. Considering current evidence, dietary glycaemic index or glycaemic load might be less useful as overall measures of carbohydrate quality than dietary fibre and whole grain content.
It is more than half a century since epidemiological observations, largely in Africa, suggested that processing of cereal-based foods (grains) with removal of what came to be called dietary fibre, rather than excessive intakes of sugar, were key determinants of both cardiometabolic and large bowel diseases. Nevertheless, until relatively recently, rather less attention has been given to starches and dietary fibre, the other major components of dietary carbohydrate. Although nutrition guidelines issued by many governments and professional organisations encourage increased consumption of vegetables, fruit, and whole grains, fewer quantitative guidelines for sources and intakes of dietary fibre and starch are available. We report here on indicators of carbohydrate quality and non-communicable disease (NCD) incidence, mortality, and risk factors.
This study is essential at this time of increased interest in the area of nutrition and NCDs, and growing knowledge of the impact of carbohydrate intake on public health. The research was commissioned by WHO to inform the development of updated recommendations regarding carbohydrate intake.
前瞻性研究和临床试验的补充结果表明，膳食纤维或全谷物的摄入量较高与死亡率风险和多种非传染性疾病及其危险因素发病率的降低有关，这提供了令人信服的证据 营养建议用全谷物代替精制谷物，并将膳食纤维增加到每天至少 25-29 克，摄入量增加可能会带来额外的好处。 考虑到目前的证据，膳食血糖指数或血糖负荷作为碳水化合物质量的总体衡量指标可能不如膳食纤维和全谷物含量有用。
半个多世纪以来，流行病学观察（主要是在非洲）表明，加工谷类食品（谷物）并去除所谓的膳食纤维，而不是过量摄入糖，是心脏代谢的关键决定因素。 和大肠疾病。 然而，直到最近，人们对淀粉和膳食纤维（膳食碳水化合物的其他主要成分）的关注还相当少。 尽管许多政府和专业组织发布的营养指南鼓励增加蔬菜、水果和全谷物的消费，但关于膳食纤维和淀粉的来源和摄入量的定量指南却较少。 我们在此报告碳水化合物质量和非传染性疾病 (NCD) 发病率、死亡率和风险因素的指标。
在人们对营养和非传染性疾病领域的兴趣日益浓厚，以及人们对碳水化合物摄入对公共健康影响的认识不断加深的情况下，这项研究至关重要。 这项研究是由世界卫生组织委托进行的，旨在为制定有关碳水化合物摄入量的最新建议提供信息。
Reynolds A, Mann J, Cummings J, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses[J]. The Lancet, 2019, 393(10170): 434-445.
