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 Jul 5;7(7):CD012960. doi: 10.1002/14651858.CD012960.pub2.
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 and associations 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the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov for ongoing and unpublished studies (5 June 2017).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 cohort studies if they related baseline total fat intake to weight or body fatness at least 12 months later.
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 body weight and blood lipid levels outcomes at six months, six to 12 months, one to two years, two to five years and more than five years for RCTs; and for cohort studies, at 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 studies 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 to combine.Effects of dietary counselling to reduce total fat intake from RCTsTwo studies recruited children aged between 4 and 11 years and a third recruited children aged 12 to 13 years. Interventions were combinations of individual and group counselling, and education sessions in clinics, schools and homes, delivered by dieticians, nutritionists, behaviourists or trained, supervised teachers. 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.One study of dietary counselling to lower total fat intake found that the intervention may make little or no difference to weight compared with usual diet at 12 months (mean difference (MD) -0.50 kg, 95% confidence interval (CI) -1.78 to 0.78; n = 620; low-quality evidence) and at three years (MD -0.60 kg, 95% CI -2.39 to 1.19; n = 612; low-quality evidence). Education delivered as a classroom curriculum probably decreased BMI in children at 17 months (MD -1.5 kg/m, 95% CI -2.45 to -0.55; 1 RCT; n = 191; moderate-quality evidence). The effects were smaller at longer term follow-up (five years: MD 0 kg/m, 95% CI -0.63 to 0.63; n = 541; seven years; MD -0.10 kg/m, 95% CI -0.75 to 0.55; n = 576; low-quality evidence).Dietary counselling probably slightly reduced total cholesterol at 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. Dietary counselling probably slightly decreased low-density lipoprotein (LDL) cholesterol at 12 months (MD -0.12 mmol/L, 95% CI -0.20 to -0.04; 1 RCT; n = 618, moderate-quality evidence) and at five years (MD -0.09, 95% CI -0.17 to -0.01; 1 RCT; n = 623; moderate-quality evidence), compared to controls. Dietary counselling probably made little or no difference to HDL-C at 12 months (MD -0.03 mmol/L, 95% CI -0.08 to 0.02; 1 RCT; n = 618; moderate-quality evidence), and at five years (MD -0.01 mmol/L, 95% CI -0.06 to 0.04; 1 RCT; n = 522; moderate-quality evidence). Likewise, counselling probably made little or no difference to triglycerides in children at 12 months (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 at seven years (MD -0.60 cm, 95% CI -2.06 to 0.86; 1 RCT; n = 577; low-quality evidence).Associations between total fat intake, weight and body fatness from cohort studiesOver 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 dietary counselling or education to 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. There were no consistent 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. Most 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 to look at both possible benefits and harms.
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体脂之间的关系。
评估总脂肪摄入量对不打算减肥的儿童和青少年体重及体脂测量指标的影响和关联。
本次更新时，我们修订了先前的检索策略，并在考克兰图书馆、MEDLINE（Ovid）、MEDLINE（PubMed）和Embase（Ovid）（截至2017年5月23日）的所有年份中进行检索。未设语言和出版状态限制。我们检索了世界卫生组织国际临床试验注册平台和ClinicalTrials.gov以查找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（占总能量（TE）的30%或更少）与常规或中等脂肪饮食（大于30%TE），且无意减轻体重，并在至少6个月后评估体重或体脂测量指标。如果前瞻性队列研究将基线总脂肪摄入量与至少12个月后的体重或体脂相关联，我们也将其纳入。
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。对于RCT，我们提取了6个月、6至12个月、1至2年、2至5年和超过5年时的体重和血脂水平结局；对于队列研究，提取了基线至1年、1至2年、2至5年、5至10年和超过10年时的结局。我们计划进行相关亚组分析的随机效应荟萃分析，并在数据允许的情况下进行敏感性分析和漏斗图分析。
我们纳入了24项研究，包括3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）。23项研究在高收入国家进行。由于只有一项RCT在每个时间点范围内对所有结局报告了相同的结局，且队列研究异质性太大无法合并，因此无法进行荟萃分析。
来自RCT的降低总脂肪摄入量的饮食咨询效果
两项研究招募了4至11岁的儿童，第三项研究招募了12至13岁的儿童。干预措施包括个体和小组咨询以及在诊所、学校和家庭中由营养师、营养学家、行为学家或经过培训和监督的教师进行的教育课程。对不精确性和报告不佳的担忧限制了我们对研究结果的信心。此外，两项试验中纳入高胆固醇血症儿童引发了对适用性的担忧。
一项降低总脂肪摄入量的饮食咨询研究发现，与常规饮食相比，干预措施在12个月时对体重可能几乎没有影响或没有差异（平均差异（MD）-0.50 kg，95%置信区间（CI）-1.78至0.78；n = 620；低质量证据），在3年时也是如此（MD -0.60 kg，95% CI -2.39至1.19；n = 612；低质量证据）。作为课堂课程进行的教育可能在17个月时降低儿童的BMI（MD -1.5 kg/m，95% CI -2.45至-0.55；1项RCT；n = 191；中等质量证据）。在长期随访中效果较小（5年：MD 0 kg/m，95% CI -0.63至0.63；n = 541；7年：MD -0.10 kg/m，95% CI -0.75至0.55；n = 576；低质量证据）。
与对照组相比，饮食咨询在12个月时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），但在更长时间段内可能几乎没有影响或没有差异。饮食咨询在12个月时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5年时也是如此（MD -0.09，95% CI -0.17至-0.01；1项RCT；n = 623；中等质量证据）。与对照组相比，饮食咨询在12个月时对高密度脂蛋白胆固醇（HDL-C）可能几乎没有影响或没有差异（MD -0.03 mmol/L，95% CI -0.08至0.02；1项RCT；n = 618；中等质量证据），在5年时也是如此（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，咨询在12个月时对儿童甘油三酯可能几乎没有影响或没有差异（MD -0.01 mmol/L，95% CI -0.08至0.06；1项RCT；n = 618；中等质量证据）。与常规或改良脂肪摄入量相比，较低的脂肪摄入量在7岁时对身高可能几乎没有影响或没有差异（MD -0.60 cm，95% CI -2.06至0.86；1项RCT；n = 577；低质量证据）。
来自队列研究的总脂肪摄入量、体重和体脂之间的关联
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，体脂测量指标可能会朝着相同方向变化。然而，队列研究中方法和报告的异质性，以及主要是非常低质量的证据，使得难以得出确凿结论，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饮食咨询或教育以降低总脂肪摄入量（30%或更少TE）与常规或改良脂肪摄入量但无意减轻体重的试验提供的有限证据表明，与对照组相比，较低脂肪摄入量在某些时间点会使体重指数、总胆固醇和LDL胆固醇略有降低。对体重、高密度脂蛋白（HDL）胆固醇或身高没有一致影响。队列研究中总脂肪摄入量与儿童后期体脂测量指标之间的关联不一致，且该证据质量大多非常低。大多数研究在高收入国家进行，可能不适用于低收入和中等收入环境。需要高质量、长期的研究，包括低收入和中等收入环境，以研究可能的益处和危害。
