EBCH：低盐摄入或并不有助健康

通常观点都认为，高盐分的摄入容易导致一些健康问题的发生，但最近有一项研究却宣称，少吃盐并不能有助于防止心脏病，中风等疾病。

据国外媒体报道，这项研究结果的观点与之前医学界普遍敦促民众减少盐摄入量的观点截然相反，该研究对近6500人进行的调查研究，发现“没有确凿的证据表明在日常饮食中较少的盐分摄入量能够减少心脏病及过早死亡的几率。”实际上研究甚至还发现对有些人来讲减少盐分摄入反倒会提高心脏出问题的概率。

最近有研究宣称，少吃盐并不能有助于防止心脏病，中风等疾病

进行此项研究的埃克赛特大学的研究人员表示之前人们可能是“高估了”盐分摄入对于健康的影响，很多其他重要的生活方式因素都会对个人的健康有很大影响，例如吃水果、运动，低脂饮食和不吸烟等，这项研究完全颠覆了之前普遍认为降低盐分摄入能够保护心脏的观点。

研究显示并没有证据能证明减少盐分能够防止心脏病发作，可能是由于人们通常减少摄入量只有短暂的一段时间。之前的观点认为大量的盐分摄入能够增加高血压的风险，从而导致心脏病和中风。所以一般推荐的成人单日摄入量不超过6克。许多政府已经开始试图让食品生产厂家，快餐公司和餐馆减少在他们的产品中加入大量的盐分。

该项研究已发表在《考科蓝回顾》杂志(Cochrane Review)中，研究人员对6489名志愿者进行了跟踪调查，他们其中一些患有高血压，另一些人则血压正常。结果发现，没有证据显示盐分摄入减少能够降低心脏病的发生，此外还发现，一些心力衰竭的患者如果减少盐分摄入反倒面临更大的死亡风险。

不过研究人员也坚持认为，这项研究并不意味着之前政府对于减少食盐摄入的努力是浪费时间。领导此项研究的罗德-泰勒(Rod Taylor)表示，研究人员没有找到任何减少盐分摄入能够显著降低死亡或心血管病例的证据。如果希望以此受益公众需要长期坚持削减盐分的摄入。包括在快餐店，餐馆和办公室等地点。

对此研究结果，包括英国“盐与健康共同行动”组织(Consensus Action on Salt and Health)的凯瑟琳(Katharine Jenner)和英国利物浦大学的临床流行病学教授西蒙(Simon Capewell)在内的一些专家也表示，这项研究结果令人失望，但其并非是一项全面确定的研究，仍旧有强有力的证据表明，盐分的过多摄入会导致高血压，从而提高心血管疾病的几率。（生物谷Bioon.com）

生物谷推荐原文出处：

Evidence-Based Child Health: A Cochrane Review Journal

Cochrane review: School-based secondary prevention programmes for preventing violence

J Mytton Specialist Registrar in Public Health, C DiGuiseppi, D Gough, R Taylor, S Logan

Background

Early aggressive behaviour is a risk factor for later violence and criminal behaviour. Despite over 20 years of violence prevention interventions being delivered in the school setting, questions remain regarding the effectiveness of different interventions for children exhibiting aggressive behaviour.

Objectives

To examine the effect of school based violence prevention programmes for children identified as aggressive or at risk of being aggressive.

Search strategy

We searched CENTRAL, Cochrane Injuries Group specialised register, MEDLINE, EMBASE, other specialised databases and reference lists of articles. We also contacted authors and organisations to identify any further studies.

Selection criteria

We included trials meeting the following criteria; 1) participants were randomly assigned to intervention and control groups; 2) outcome data were collected concurrently; 3) participants comprised children in mandatory education identified as exhibiting, or at risk of, aggressive behaviour; 4) interventions designed to reduce aggression, violence, bullying, conflict or anger; 5) school based interventions; 6) outcomes included aggressive behaviour, school and agency responses to acts of aggression, or violent injuries.

Data collection and analysis

Data were collected on design, participants, interventions, outcomes and indicators of study quality. Results of any intervention to no intervention were compared immediately post-intervention and at 12 months using meta-analysis where appropriate.

Main results

Of 56 trials identified, none reported data on violent injuries. Aggressive behaviour was significantly reduced in intervention groups compared to no intervention groups immediately post intervention in 34 trials with data, (Standardised Mean Difference (SMD) =-0.41; 95% confidence interval (CI) -0.56 to -0.26). This effect was maintained in the seven studies reporting 12 month follow-up (SMD =-0.40, (95% CI -0.73 to -0.06)). School or agency disciplinary actions in response to aggressive behaviour were reduced in intervention groups for nine trials with data, SMD =-0.48; 95% CI -1.16 to 0.19, although this difference may have been due to chance and was not maintained, based on two studies reporting follow-up to two to four months (SMD =0.03; 95% CI -0.42 to 0.47). Subgroup analyses suggested that interventions designed to improve relationship or social skills may be more effective than interventions designed to teach skills of non-response to provocative situations, but that benefits were similar when delivered to children in primary versus secondary school, and to groups of mixed sex versus boys alone.

Authors' conclusions

School-based secondary prevention programmes to reduce aggressive behaviour appear to produce improvements in behaviour greater than would have been expected by chance. Benefits can be achieved in both primary and secondary school age groups and in both mixed sex groups and boys-only groups. Further research is required to establish whether such programmes reduce the incidence of violent injuries or if the benefits identified can be maintained beyond 12 months.

Plain language summary

Are school-based programmes aimed at children who are considered at risk of aggressive behaviour, effective in reducing violence?

Violence is recognised as a major global public health problem, thus there has been much attention placed on interventions aimed at preventing aggressive and violent behaviour. As aggressive behaviour in childhood is considered to be a risk factor for violence and criminal behaviour in adulthood, violence prevention strategies targeted at children and adolescents, such as school-based programmes, are considered to be promising interventions.

Some school-based prevention programmes target all children attending a school or class, whilst others confine the intervention to those children who have already been identified as exhibiting, or threatening, behaviour considered to be aggressive, such an approach is known as 'secondary prevention'. A wide variety of school-based violence prevention programmes have been implemented over the last 20 years, yet we are still without a full understanding of their effectiveness.

The objective of this systematic review was to determine the effectiveness of school-based secondary prevention programmes to prevent violence (that is those interventions targeted at children identified as aggressive or at risk of being aggressive) .

The authors examined all trials investigating the effectiveness of secondary violence prevention programmes targeted at children in mandatory education compared to no intervention or a placebo intervention.

The authors found 56 studies; the overall findings show that school-based secondary prevention programmes aimed at reducing aggressive behaviour do appear to produce improvements in behaviour. The improvements can be achieved in both primary and secondary school age groups and in both mixed sex groups and boy-only groups.

Further research is needed to investigate if the apparent beneficial programmes effects can be realised outside the experimental setting and in settings other than schools. None of the studies collected data on violent injury, so we can not be certain of the extent to which an improvement in behaviour translates to an actual injury reduction. In addition, more research is needed to determine if the beneficial effects can be maintained over time, and if the benefits can be justified against the costs of implementing such programmes.