结论高盐摄入量在世界范围内流行，并导致高血压的产生和维持，这是全球疾病的最大风险因素。现在有令人信服的证据支持减少盐分以降低血压，并且有大量证据支持在一般人群中减少盐分以降低因心血管疾病而死亡的风险。在心力衰竭、糖尿病和 CKD 等特定疾病中，指南支持 WHO 将盐摄入量减少到 5 克/天的目标，尽管证据可能只是现在才赶上指南。来自人口研究的进一步证据将有助于加强当前的指导，但该级别的干预研究不太可能得到行业或政府的支持。与食品行业的合作，

减盐挑战避免盐的饮食行为受多种因素的影响，包括低盐选择的可用性、成本和可及性、低盐食物适口性的感知降低，以及教育限制，例如缺乏感知益处或识别低盐食物的能力。盐类食物。27由于餐桌上仅添加了 15% 的食盐，食品行业添加了 80%，因此需要有动力有效减少盐分​​。来自专家组成的行动小组（盐与健康共识行动）的压力有效地与政府和食品行业合作，同意将盐含量自愿减少 10-15% 的水平，这是无法检测到的水平消费者。1重要的是要让个人放心，随着盐摄入量的减少，味蕾在几个月内对盐变得更加敏感。一旦味蕾得到调整，人们就会发现他们更喜欢含盐量较低的食物。28监测对低盐饮食的依从性也面临着测量 24 小时尿钠排泄量的挑战；确定平均每日盐摄入量的最准确方法（方框 1）。仔细的饮食史可能有助于识别高盐食物。可以在以下位置找到对专业人员和患者有用的资源框 2。

盐与肾肾脏是钠平衡的主要调节器，在长期血压调节中起着核心作用。慢性肾病 (CKD) 很常见，影响多达 13% 的成年人。22绝大多数 CKD 患者不会发展为终末期肾病，CKD 患者的主要风险是心血管疾病，因为它是导致心血管死亡的有效且独立的危险因素。23进行性 CKD 导致高血压患病率增加，这通常需要多种药物治疗才能获得充分控制。由于肾脏钠排泄减少，个体更容易受到高盐摄入的影响。管理高血压是 CKD 管理的基石，旨在降低 CKD 进展和心血管疾病的风险。4,24 有 证据表明，降低盐摄入量将有益于 CKD，减少蛋白尿和尿白蛋白排泄，以及增强肾素 - 血管紧张素系统阻滞剂的抗蛋白尿和抗高血压作用。25,26最近对 CKD 干预研究的回顾得出结论，有证据表明减少盐分降低了 CKD 患者的血压，但承认总体上缺乏对这一患者组的研究。27

限盐和心力衰竭与心力衰竭相关的血流动力学变化导致神经体液活动增加，尽管处于容量超负荷状态，但仍会出现钠和水潴留的恶性循环。虽然限制盐摄入量是心力衰竭管理的既定做法，但证据仍然仅限于观察性研究和限制盐分的小型随机对照试验，通常还有额外的治疗干预。17–20鉴于缺乏有力的证据，尽管目前所有的临床指南都推荐，但对于适当的限盐水平没有达成共识也就不足为奇了。然而，将盐的摄入量限制在 5 克/天，这是世界卫生组织 (WHO) 为一般人群推荐的水平，是一种安全、实用且适度的干预措施，可能有益且无害处。使用高剂量利尿剂的个体在实施低盐饮食时需要明智地监测体液平衡，并且可能需要调整利尿剂治疗以确保他们不会耗尽体液。21

High salt intake is likely to contribute to cardiovascular risk primarily through its effects on blood pressure, as well as through blood pressure independent effects on arterial stiffening and albuminuria.1 The actual effect of lowering population salt intake on cardiovascular outcomes has been more controversial. Available evidence from epidemiological studies is largely supportive. Public health strategy in the UK has successfully achieved a 15% reduction in salt intake from 2003 to 2011. This has been achieved through partnership with industry reducing salt content.12 Several recent cohort studies have found a J-shaped association between urinary sodium excretion and a composite of major cardiovascular events and death.13 While this has led to concern about the effect of lowering population salt intake, a review of available cohort studies found inconsistencies in the relationship between sodium intake, with 13 finding a direct relationship, 8 with an inverse relationship and 2 with a J-shaped relationship. All but 1 had inherent methodological limitations which could change the direction of the relationship, including reverse causality and systematic error, and from this the true relationship remains unclear.14 While there are limited interventional studies of salt reduction and cardiovascular disease, a meta-analysis of available studies found that a modest reduction in salt intake lowered cardiovascular events.15 When individuals who participated in the Trial of Hypertension Prevention I and II were followed up subsequent to the trial completion, those randomised to the low salt arm had a 25% reduction of cardiovascular events, despite receiving no further dietary advice after completing the study.16 It remains appropriate to endorse the current guidelines on salt reduction to prevent cardiovascular events, with the National Institute for Health and Care Excellence endorsing salt reduction as the primary public health strategy for the prevention of cardiovascular disease.3

盐摄入量及其与心血管疾病的关系高盐摄入量可能主要通过其对血压的影响以及通过血压对动脉硬化和蛋白尿的独立影响而导致心血管风险。1降低人群盐摄入量对心血管结局的实际影响更具争议性。流行病学研究的现有证据在很大程度上是支持性的。英国的公共卫生战略已成功实现了从 2003 年到 2011 年减少 15% 的盐摄入量。这是通过与行业合作减少盐含量来实现的。12最近的几项队列研究发现，尿钠排泄与主要心血管事件和死亡的复合之间呈 J 型关联。13虽然这引起了人们对降低人口盐摄入量的影响的担忧，但对现有队列研究的回顾发现钠摄入量之间的关系不一致，13 项发现直接关系，8 项呈负相关，2 项呈 J 型关系. 除 1 外，所有方法都有可能改变关系方向的固有方法学局限性，包括反向因果关系和系统错误，因此真正的关系仍不清楚。14虽然关于减盐和心血管疾病的干预研究有限，但对现有研究的荟萃分析发现，适度减少盐摄入量可降低心血管事件。15当参与高血压预防试验 I 和 II 的个体在试验完成后进行随访时，尽管在完成研究后没有接受进一步的饮食建议，但随机分配到低盐组的患者的心血管事件减少了 25%。16赞同目前关于减盐以预防心血管事件的指导方针仍然是适当的，美国国家卫生与保健卓越研究所支持将减盐作为预防心血管疾病的主要公共卫生战略。3

盐分与高血压高血压是全球疾病的主要危险因素，在所有心血管疾病的危险因素中影响最大，非最佳血压占中风的三分之二和缺血性心脏病的二分之一。5来自遗传、流行病学、迁移和干预研究的证据有助于提供令人信服的证据，即盐摄入量会升高人群血压。1最大的盐和血压流行病学研究，INTERSALT 研究，包括来自不同人群的 10,079 个人，发现钠摄入量和血压之间存在很强的正相关关系，即使排除四个盐摄入量非常低的人群，这种关系仍然存在，增加了估计每天摄入 6 克盐会使收缩压在 30 年内升高 9 mmHg。6最近的研究——EPIC-Norfolk 和 INTERMAP——支持这些发现。7,8降低盐的摄入量可以降低血压。 一项更新的系统回顾研究发现，在至少 4 周内每天减少 4.4 克盐的研究发现，收缩压降低了 4 毫米汞柱，舒张压降低了 2 毫米汞柱。9该研究发现，对血压的影响持续低于国际指南目前建议的水平。这种剂量依赖性关系得到了 2 项独立进行的不同盐摄入量（12、6 和 3 克10和 8、6 和 4 克11）的双盲随机对照研究的支持，其中最低的盐减少将血压降低到最低水平。

几百万年来，人类吃的盐非常少——每天不到 0.25 克。盐被引入作为保存食物的方法，这对文明社会来说是变革性的。1最初，冷藏的出现导致盐摄入量减少；然而，随后盐的摄入量增加了，现在估计在全球大多数国家/地区达到 9 至 12 克/天，明显高于我们的进化祖先。1,2 这种全球食盐习惯引起了人们极大的关注，因为它与高血压和心血管疾病风险增加以及胃癌、肾结石疾病和骨质疏松症有关。1在特定疾病中，减少盐摄入量的证据是令人信服的，至少达到指南建议的水平，如果不是更低的话。1,3,4然而，即使在对有积极性的患者进行的临床试验中，对限盐的依从性也很差。这至少部分是由于食物中的盐分含量很高，特别是烘焙和加工食品，使患者难以达到获得临床益处所需的减少。1在本综述中，我们重点关注降低一般人群以及心血管和肾脏疾病患者盐摄入量的证据。

Many of these issues come to a head with the health apps which have been widely used in Asia and are gradually being introduced in Europe to track an individual’s health status. Germany’s Robert Koch Institut has introduced an app, developed with Berlin digital health group Thryve,which links to fitness bands and smartwatches. It says the app will help it map the spread of Covid-19 by monitoring anonymised data for signs of infection including a user’s resting pulse, sleep and activity levels, which tend to alter significantly in the case of acute respiratory problems.The data drawn from such apps can both track individual sufferers and people they have encountered via contract tracing methods to create a much deeper data set for governments. Editor’s note The Financial Times is making key coronavirus coverage free to read to help everyone stay informed. Find the latest here.In Singapore, the government has asked citizens to opt in to its system and European governments including Germany have stressed that the use of tracking and tracing apps must be done on a voluntary basis.“This is nowhere near the South Korean or Chinese or Israeli model where they have the power to track you, know you have the disease and who you know. We are nowhere near there,” says Enrique Medina, chief policy officer for Telefónica, which is working with the Spanish government.The European Commission is working on guidelines on the use of tracing apps. Vera Jourova, vice-president for values and transparency, says citizens must be able to give informed consent. “There must not be a hidden purpose or something I as a citizen don’t know,” she says. “The main thing is people entering such a system know what they are doing.”  Recommended TechnologyCoronavirus prompts delays and overhaul of EU digital strategy Under pressure from privacy activists, the scientific community has created a body called the Pan-European Privacy-Preserving Proximity Tracing coalition in Switzerland, led by Germany’s Fraunhofer Heinrich Hertz Institute, to create standards for apps being developed that adhere to European laws around privacy. The GSM Association, the mobile telecoms trade body, has also published a blueprint for best practice in how data gathered through apps is handled. Juan Rio, who specialises in analytics at telecoms consultancy Delta Partners, says there will always be a trade-off between the common good and civil liberties in a time of crisis but questioned the efficacy of governments forcing citizens into using apps, as they may rebel and stop using their phones. “With the invasive way, you are affecting the experiment. You change the behaviour of people and you cannot trust the results,” he says.Additional reporting by Edward White in Seoul and Sam Fleming in Brus

Austrian data privacy activist Max Schrems warns citizens should be careful of the rights they are giving away at a time of global panic. “I am worried that we will accept state surveillance during the health crisis but that it will then take years in court to get rid of it.”However, he says there are apps that help citizens choose which data they share, leading to a more efficient tracking of the virus. “If people can decide themselves if they want to participate or not, then we have privacy-friendly alternatives. That’s a game changer.”Some analysts worry that the data sets could be put to other uses in the future. “They need to demand reassurances from governments [that the data] won’t be repurposed. The last thing they want is to wake up after Covid-19 and find that the data is still being used for other purposes. How do you police who is using it?” asks one industry executive. “There has to be a sunset clause.” The telecoms industry has had to tread a fine line on the use of data or face punitive action. In the US, the Federal Communications Commission last month fined the four largest industry players a combined $208m over the historic sale of location data to third parties without the explicit consent of users. Francisco Montalvo, Telefónica’s chief data officer, argues that governments need to combine the need to use the data without endangering privacy rights. “Governments and regulators should find a proper balance between privacy and public interest,” he says.

European telecoms companies remain adamant that the information that has been provided to governments is anonymised and aggregated. That means it cannot be traced to any specific individual or phone. The process of scrubbing the data usually takes between 24 and 48 hours before it is available in data sets that can then be used by governments.The industry insists that data about users is of little use for big data analysis of the contagion: the best way to track the spread of the pandemic is to use heatmaps built on data of multiple phones which, if overlaid with medical data, can predict how the virus will spread and determine whether government measures are working.Telecoms companies say they are frustrated with the confusion between the kind of group data they are providing and the personal data that can be gleaned from apps on mobile phones. In Europe, personal information, such as whether someone has coronavirus and has shared that on social media or searched on Google for symptoms, is not legally accessible under GDPR by a telecoms provider.  Recommended Rachman Review podcast18 min listenCoronavirus and the threat to democracy Still, assurances from officials and industry executives have done little to appease anxiety that privacy rights could be brushed aside as governments seek to use tools of mass surveillance in their efforts to combat the virus. The concerns about political use of data have been aggravated by the fact that the European Commission wants the telecoms companies to provide the actual aggregated data, not just access to insights from that information. Latvia, for example, has exercised its right to be exempted from certain obligations in the European Convention of Human Rights, which grants citizens privacy and data protection rights. Slovakia passed a law last month to use telecoms data to ensure people abide by quarantine laws. Some researchers are not convinced by the claim that such data sets are completely anonymous. A 2019 study by researchers at Imperial College London and Belgium’s Catholic University of Louvain revealed there is a way to re-identify 99.98 per cent of individuals with just 15 demographic characteristics using location data. Other studies have come to similar conclusions that individuals can be identified based on aggregate data sets with relative ease. Spain’s far-right Vox party has urged people to turn off their mobile data, reflecting the anger over government intrusion on their privacy.

The use of location data to track the disease has been applied in Italy, Spain, Norway and Belgium, with the UK, Portugal and Greece set to follow.In cities such as Madrid and Milan, telecoms operators have created heat maps that show how restrictions on movement are working and what effect the presence of police on the streets is having on behaviour. Telecoms companies in Spain were able to show that the movement of people in one city dropped 90 per cent during the first week of the lockdown and a further 60 per cent of the remainder in the second week, while in Italy the lockdown was largely ignored for the first week, with between 800,000 and 1m people still travelling in and out of Milan. In Belgium, the data showed that long distance trips of more than 40km dropped 95 per cent after confinement measures were introduced. Belgians are spending 80 per cent of their time within their home postal area, with mobility down 54 per cent. The data can show if large numbers of people in cities have fled for their second homes, as was the case in France. The insights that telecoms companies can derive from these data sets build on their experience of working with epidemiologists to track infectious diseases in the developing world. Telenor, the Norwegian company, has participated in big data projects to predict the spread of dengue fever in Pakistan and malaria in Bangladesh. Kenth Engo-Monsen, a senior researcher at Telenor, says it was able to show that movement between Norwegian cities dropped 65 per cent after restrictions were applied.  In cities such as Madrid, telecoms operators have created heat maps that show how restrictions on movement are working © Juan Medina/Reuters “Knowledge about a population’s travel pattern is vital to understanding how an epidemic spreads throughout a country,” he says.Telefónica, Spain’s national carrier which owns networks across Latin America, has developed expertise working with companies like Facebook to use data to deal with natural disasters such as earthquakes. It also worked with Unicef and the University of Notre-Dame in 2017 to improve epidemiological models for predicting the spread of the Zika virus in Colombia. Prof Tatem cites coastal areas in Namibia as an example of where heat maps detailing migration into heavily infected areas can be used to prioritise other areas where bed nets and insecticides need to be deployed. Vodafone has a researcher paid for by the Bill & Melinda Gates Foundation embedded in its data team at the company’s London headquarters, to work on data sets providing insights to academics tracking a variety of diseases. Nick Read, chief executive of Vodafone, says the team offers invaluable insights. “We have seen how aggregated data can check the spread of disease in Africa. We’re now using the same insights to understand and combat the spread of Covid-19 in Europe,” he says.

Vittorio Colao, former Vodafone chief executive now at General Atlantic, says people should be willing to allow the use of “pseudo-anonymised” data by health services such as Britain’s National Health Service to respond to the pandemic. Originally from northern Italy, he says citizens understand the need to trust authorities to handle their data. “It is not a question of spying on everyone forever but of saving lives for a time that demands temporary rules,” he says. “We trust Uber to know everywhere we go, we trust Gmail with everything we write. If we don’t trust the NHS with our health data then who do we trust?”Vincent Keunen, founder of app developer Andaman7 in Belgium who works on ways to securely share health data, says citizens have legitimate concerns about vast amounts of data being used to track them individually. But he says it is a tricky balance to strike between using technology to help tackle health crises and safeguarding privacy. “The use of technology should end as soon as the health of the people is guaranteed. We must be vigilant,” he says. “If you go to one extreme, you’ll have super high privacy but then you die and it becomes useless to have privacy. It’s a very delicate balance to reach.”

The debate over the use of location data sets could be a forerunner to a broader discussion about civil liberties and surveillance in Europe and the US as governments put in place plans to lift at least parts of the lockdowns. The strategies for reopening an economy before a vaccine is developed could involve monitoring the contacts of newly infected people, which will raise questions about how much curtailment of privacy societies are prepared to take. In South Korea, which is seen as a benchmark of how to control infectious diseases, the authorities can require telecoms companies to hand over the mobile phone data of people with confirmed infections to track their location. The data has enabled the rapid deployment of a notification system alerting Koreans to the movements of all potentially contagious people in their neighbourhoods or buildings.China and Israel have also used personal telecoms data to trace coronavirus patients and their contacts. Governments around the world are creating apps to gather more personal data, such as who is sick and with whom they have been in contact.Even the EU’s General Data Protection Regulation, which was adopted in 2018, has a clause allowing exceptions for cases that are in the public interest. 

With much of Europe at a standstill as a result of the coronavirus pandemic, politicians want the telecoms operators to provide similar data from smartphones. Thierry Breton, the former chief executive of France Telecom who is now the European commissioner for the internal market, has called on operators to hand over aggregated location data to track how the virus is spreading and to identify spots where help is most needed.Both politicians and the industry insist that the data sets will be “anonymised”, meaning that customers’ individual identities will be scrubbed out. Mr Breton told the Financial Times: “In no way are we going to track individuals. That’s absolutely not the case. We are talking about fully anonymised, aggregated data to anticipate the development of the pandemic.”

When the World Health Organization launched a 2007 initiative to eliminate malaria on Zanzibar, it turned to an unusual source to track the spread of the disease between the island and mainland Africa: mobile phones sold by Tanzania’s telecoms groups including Vodafone, the UK mobile operator.Working together with researchers at Southampton university, Vodafone began compiling sets of location data from mobile phones in the areas where cases of the disease had been recorded. Mapping how populations move between locations has proved invaluable in tracking and responding to epidemics. The Zanzibar project has been replicated by academics across the continent to monitor other deadly diseases, including Ebola in west Africa.“Diseases don’t respect national borders,” says Andy Tatem, an epidemiologist at Southampton who has worked with Vodafone in Africa. “Understanding how diseases and pathogens flow through populations using mobile phone data is vital.”