Naude Celeste E, Visser Marianne E, Nguyen Kim A, Durao Solange, Schoonees Anel
Centre for Evidence-based Health Care, Division of Epidemiology and Biostatistics, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Drive, Cape Town, South Africa.
Cochrane Database Syst Rev. 2018 Feb 15;2(2):CD012960. doi: 10.1002/14651858.CD012960.
As part of efforts to prevent childhood overweight and obesity, we need to understand the relationship between total fat intake and body fatness in generally healthy children.
To assess the effects of total fat intake on measures of weight and body fatness in children and young people not aiming to lose weight.
For this update we revised the previous search strategy and ran it over all years in the Cochrane Library, MEDLINE (Ovid), MEDLINE (PubMed), and Embase (Ovid) (current to 23 May 2017). No language and publication status limits were applied. We searched the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov for ongoing and unpublished studies (5 June 2017).
We included randomised controlled trials (RCTs) in children aged 24 months to 18 years, with or without risk factors for cardiovascular disease, randomised to a lower fat (30% or less of total energy (TE)) versus usual or moderate-fat diet (greater than 30%TE), without the intention to reduce weight, and assessed a measure of weight or body fatness after at least six months. We included prospective analytical cohort studies in these children if they related baseline total fat intake to weight or body fatness at least 12 months later. We duplicated inclusion decisions and resolved disagreement by discussion with other authors.
We extracted data on participants, interventions or exposures, controls and outcomes, and trial or cohort quality characteristics, as well as data on potential effect modifiers, and assessed risk of bias for all included studies. We extracted outcome data using the following time point ranges, when available: RCTs: baseline to six months, six to 12 months, one to two years, two to five years and more than five years; cohort studies: baseline to one year, one to two years, two to five years, five to 10 years and more than 10 years. We planned to perform random-effects meta-analyses with relevant subgrouping, and sensitivity and funnel plot analyses where data allowed.
We included 24 studies comprising three parallel-group RCTs (n = 1054 randomised) and 21 prospective analytical cohort studies (about 25,059 children completed). Twenty-three were conducted in high-income countries. No meta-analyses were possible, since only one RCT reported the same outcome at each time point range for all outcomes, and cohort studies were too heterogeneous.For the RCTs, concerns about imprecision and poor reporting limited our confidence in our findings. In addition, the inclusion of hypercholesteraemic children in two trials raised concerns about applicability. Lower versus usual or modified total fat intake may have made little or no difference to weight over a six- to twelve month period (mean difference (MD) -0.50 kg, 95% confidence interval (CI) -1.78 to 0.78; 1 RCT; n = 620; low-quality evidence), nor a two- to five-year period (MD -0.60 kg, 95% CI -2.39 to 1.19; 1 RCT; n = 612; low-quality evidence). Compared to controls, lower total fat intake (30% or less TE) probably decreased BMI in children over a one- to two-year period (MD -1.5 kg/m, 95% CI -2.45 to -0.55; 1 RCT; n = 191; moderate-quality evidence), with no other differences evident across the other time points (two to five years: MD 0.00 kg/m, 95% CI -0.63 to 0.63; 1 RCT; n = 541; greater than five years; MD -0.10 kg/m, 95% CI -0.75 to 0.55; 1 RCT; n = 576; low-quality evidence). Lower fat intake probably slightly reduced total cholesterol over six to 12 months compared to controls (MD -0.15 mmol/L, 95% CI -0.24 to -0.06; 1 RCT; n = 618; moderate-quality evidence), but may make little or no difference over longer time periods. Lower fat intake probably slightly decreased low-density lipoprotein (LDL) cholesterol over six to 12 months (MD -0.12 mmol/L, 95% CI -0.20 to -0.04; 1 RCT; n = 618, moderate-quality evidence) and over two to five years (MD -0.09, 95% CI -0.17 to -0.01; 1 RCT; n = 623; moderate-quality evidence), compared to controls. However, lower total fat intake probably made little or no difference to HDL-C over a six- to 12-month period (MD -0.03 mmol/L, 95% CI -0.08 to 0.02; 1 RCT; n = 618; moderate-quality evidence), nor a two- to five-year period (MD -0.01 mmol/L, 95% CI -0.06 to 0.04; 1 RCT; n = 522; moderate-quality evidence). Likewise, lower total fat intake probably made little or no difference to triglycerides in children over a six- to 12-month period (MD -0.01 mmol/L, 95% CI -0.08 to 0.06; 1 RCT; n = 618; moderate-quality evidence). Lower versus usual or modified fat intake may make little or no difference to height over more than five years (MD -0.60 cm, 95% CI -2.06 to 0.86; 1 RCT; n = 577; low-quality evidence).Over half the cohort analyses that reported on primary outcomes suggested that as total fat intake increases, body fatness measures may move in the same direction. However, heterogeneous methods and reporting across cohort studies, and predominantly very low-quality evidence, made it difficult to draw firm conclusions and true relationships may be substantially different.
AUTHORS' CONCLUSIONS: We were unable to reach firm conclusions. Limited evidence from three trials that randomised children to a lower total fat intake (30% or less TE) versus usual or modified fat intake, but with no intention to reduce weight, showed small reductions in body mass index, total- and LDL-cholesterol at some time points with lower fat intake compared to controls, and no consistent differences in effects on weight, high-density lipoprotein (HDL) cholesterol or height. Associations in cohort studies that related total fat intake to later measures of body fatness in children were inconsistent and the quality of this evidence was mostly very low. Twenty-three out of 24 included studies were conducted in high-income countries, and may not be applicable in low- and middle-income settings. High-quality, longer-term studies are needed, that include low- and middle-income settings and look at both possible benefits and risks.
作为预防儿童超重和肥胖工作的一部分，我们需要了解一般健康儿童的总脂肪摄入量与身体脂肪含量之间的关系。
评估总脂肪摄入量对未打算减肥的儿童和青少年体重及身体脂肪含量指标的影响。
为更新本综述，我们修订了之前的检索策略，并在Cochrane图书馆、MEDLINE（Ovid）、MEDLINE（PubMed）和Embase（Ovid）（截至2017年5月23日）中检索了所有年份的文献。未设置语言和发表状态限制。我们检索了世界卫生组织国际临床试验注册平台和ClinicalTrials.gov以获取正在进行和未发表的研究（2017年6月5日）。
我们纳入了年龄在24个月至18岁之间、有或无心血管疾病风险因素的儿童的随机对照试验（RCT），随机分为低脂肪饮食（占总能量（TE）的30%或更少）与常规或中等脂肪饮食（大于30%TE），且无减重意图，并在至少六个月后评估体重或身体脂肪含量指标。如果前瞻性分析队列研究将基线总脂肪摄入量与至少12个月后的体重或身体脂肪含量相关联，我们也将其纳入这些儿童的研究。我们重复入选决策，并通过与其他作者讨论解决分歧。
我们提取了关于参与者、干预措施或暴露因素、对照和结局的数据，以及试验或队列的质量特征，以及潜在效应修饰因素的数据，并评估了所有纳入研究的偏倚风险。我们在可行时使用以下时间点范围提取结局数据：RCT：基线至六个月、六至十二个月、一至两年、两至五年以及五年以上；队列研究：基线至一年、一至两年、两至五年、五至十年以及十年以上。我们计划在数据允许的情况下进行随机效应荟萃分析，并进行相关亚组分析、敏感性分析和漏斗图分析。
我们纳入了24项研究，包括三项平行组RCT（n = 1054例随机分组）和21项前瞻性分析队列研究（约25,059名儿童完成研究）。其中23项研究在高收入国家进行。由于只有一项RCT在每个时间点范围针对所有结局报告了相同的结果，且队列研究异质性过大，因此无法进行荟萃分析。对于RCT，由于存在不精确性和报告质量差的问题，我们对研究结果的信心有限。此外，两项试验纳入了高胆固醇血症儿童，这引发了对研究适用性的担忧。在六至十二个月期间，低脂肪摄入量与常规或改良的总脂肪摄入量相比，对体重可能几乎没有影响（平均差值（MD）-0.50 kg，95%置信区间（CI）-1.78至0.78；1项RCT；n = 620；低质量证据），在两至五年期间也是如此（MD -0.60 kg，95%CI -2.39至1.19；1项RCT；n = 612；低质量证据）。与对照组相比，在一至两年期间，较低的总脂肪摄入量（30%TE或更低）可能会降低儿童的BMI（MD -1.5 kg/m²，95%CI -2.45至-0.55；1项RCT；n = 191；中等质量证据），在其他时间点没有明显差异（两至五年：MD 0.00 kg/m²，95%CI -0.63至0.63；1项RCT；n = 541；五年以上：MD -0.10 kg/m²，95%CI -0.75至0..55；1项RCT；n = 576；低质量证据）。与对照组相比，在六至十二个月期间，较低的脂肪摄入量可能会使总胆固醇略有降低（MD -0.15 mmol/L，95%CI -0.24至-0.06；1项RCT；n = 618；中等质量证据），但在更长时间内可能几乎没有影响。与对照组相比，在六至十二个月期间，较低的脂肪摄入量可能会使低密度脂蛋白（LDL）胆固醇略有降低（MD -0.12 mmol/L，95%CI -0.20至-0.04；1项RCT；n = 618，中等质量证据），在两至五年期间也是如此（MD -0.09，95%CI -0.17至-0.01；1项RCT；n = 623；中等质量证据）。然而，在六至十二个月期间，较低的总脂肪摄入量对高密度脂蛋白胆固醇（HDL-C）可能几乎没有影响（MD -0.03 mmol/L，95%CI -0.08至0.02；1项RCT；n = 618；中等质量证据）即在两至五年期间也是如此（MD -0.01 mmol/L，95%CI -0.06至0.04；1项RCT；n = 522；中等质量证据）。同样，在六至十二个月期间，较低的总脂肪摄入量对儿童甘油三酯可能几乎没有影响（MD -0.01 mmol/L，95%CI -0.08至0.06；1项RCT；n = 618；中等质量证据）。在五年以上的时间里，较低的脂肪摄入量与常规或改良脂肪摄入量相比，对身高可能几乎没有影响（MD -0.60 cm，95%CI -2.06至0.86；1项RCT；n = 577；低质量证据）。超过一半报告主要结局的队列分析表明，随着总脂肪摄入量的增加，身体脂肪含量指标可能会朝着相同方向变化。然而，队列研究的方法和报告存在异质性，且主要是非常低质量的证据，因此难以得出确凿结论，真实关系可能有很大不同。
我们无法得出确凿结论。三项将儿童随机分为低总脂肪摄入量（30%TE或更低）与常规或改良脂肪摄入量但无减重意图的试验提供的证据有限，结果显示与对照组相比，低脂肪摄入量在某些时间点会使体重指数、总胆固醇和低密度脂蛋白胆固醇略有降低，对体重、高密度脂蛋白（HDL）胆固醇或身高的影响没有一致差异。队列研究中总脂肪摄入量与儿童后期身体脂肪含量指标之间的关联不一致，且该证据质量大多非常低。24项纳入研究中有23项在高收入国家进行，可能不适用于低收入和中等收入环境。需要开展高质量、长期的研究，包括低收入和中等收入环境，并兼顾可能的益处和风险。
