热狗、香肠和……痴呆症？哈佛大学和麻省理工学院的研究将超加工肉类与新的健康问题联系起来

【中美创新时报2025 年 1 月 16 日编译讯】（记者温友平编译）波士顿科学家的新研究发现，每周食用两份或两份以上加工红肉（如热狗、培根和博洛尼亚香肠）的人患痴呆症的风险增加。《波士顿环球报》记者Kay Lazar 对此作了下述报道。

经常吃红肉与心脏病、糖尿病和几种癌症有关。现在有新证据表明一些流行的红肉类型与另一个健康问题有关：它可能对你的大脑有害。

波士顿研究人员的一项新研究发现，长期食用加工红肉（如热狗、香肠和培根）与痴呆症风险增加有关。这一发现是在周一发表的另一组科学家的一项令人警醒的研究之后得出的，该研究估计，到 2060 年，每年患痴呆症的美国人数量将翻一番，达到每年约 100 万例，这主要是由于人口老龄化。

随着科学家和政策制定者寻找保护美国人健康和预防慢性病的方法，人们越来越关注改革美国人的饮食习惯。

在周三在线发表于《神经病学》杂志上的肉类研究中，哈佛大学陈曾熙公共卫生学院和麻省理工学院和哈佛大学布罗德研究所的研究人员表示，他们专注于加工红肉，希望他们的研究结果能为联邦政府正在制定并预计将于今年晚些时候发布的新饮食指南提供参考。去年 12 月，科学家就更新后的美国饮食指南向联邦卫生和农业机构提供建议，建议他们强调替代蛋白质来源，如豆类、豌豆和扁豆，而不是红肉和加工肉类。

对于红肉爱好者来说，哈佛大学的最新研究带来了一些令人欣慰的消息：研究发现，食用“未加工”肉类（如碎牛肉或牛里脊肉）不会显著增加患痴呆症的风险。但科学家发现，每周食用约两份加工红肉（包括一些冷盘）的人患痴呆症的风险比每月食用不到三份的人高出 13%。

该研究还得出结论，每天用一份坚果或豆类代替一份加工红肉（相当于 3 盎司）可能会将患痴呆症的风险降低 19%，如果用鱼代替，则可以降低高达 28% 的风险。

“我们希望为公众提供所有这些更健康的替代品，因为我们不想只是说‘请少吃红肉’，”主要作者、哈佛医学院和布莱根妇女医院助理教授 Daniel Wang 博士说。 “我们希望传递积极的信息，而不仅仅是限制人们的摄入量。”

研究人员分析了两项长期健康研究的数据，这两项研究涉及超过 13 万名参与者，并对他们进行了长达 43 年的跟踪，使用常规食物频率问卷来评估红肉与痴呆症之间的关联。

其他未参与这项研究的研究人员表示，参与者数量众多且跟踪时间较长正是监管机构在制定食品政策时需要考虑的证据。但他们警告说，这项研究与许多其他食物跟踪研究一样，依赖于参与者对他们吃过的食物的记忆，而这些记忆有时会很模糊。

在《自然医学》杂志上发表的第二项关于痴呆症的研究结果中，研究人员得出了惊人的结论：大约 40% 的 55 岁以上的人将在其一生中患上痴呆症。这一估计是基于另一项长期研究的数据，该研究涉及四个州的 15,000 多人。

“我们的大脑是一个复杂的器官，”阿尔茨海默病协会负责医疗和科学关系的高级副总裁 Heather Snyder 说道，她没有参与这两项痴呆症研究。“可能导致一个人患 [痴呆症] 风险的因素可能有很多，包括我们可能吃的食物以及确保我们饮食均衡。”

该协会正在开展一项为期两年的研究，研究痴呆症、饮食和生活方式之间的联系，这项名为 US POINTER 的研究在美国五个地点有 2,000 多名参与者。结果预计将于 7 月公布。

与此同时，该协会基于大量其他研究，建议更健康的人食物——蔬菜、瘦肉和蛋白质，以及加工程度较低、脂肪含量较低的食物——可以降低认知能力下降的风险。

自从当选总统唐纳德·特朗普表示将提名直言不讳的加工食品批评者罗伯特·F·肯尼迪二世担任卫生与公众服务部部长以来，公众对“加工”和“超加工”食品的兴趣激增。但研究人员和监管机构也对这些术语的确切含义以及这些食品对健康的影响有很多疑问。

为联邦政府就下一版具有影响力的美国膳食指南提供建议的小组在其建议中没有区分未加工和加工的红肉，并得出结论，在对这一类别做出进一步指导之前，需要对所谓的超加工食品对健康的影响进行更多的研究。预计这将推迟对此类加工食品的重大改变，直到 2030 年的下一次更新。

超加工食品是一个不精确的术语，通常指添加了许多成分的食品，如糖、油、脂肪和人工色素或防腐剂。

许多组织都引用了一种名为 NOVA 的分类系统，该系统根据食品的加工程度将食品分为四类。新鲜或冷冻的蔬菜、谷物、豆类和其他经过最低限度加工的食品被认为是最健康的，而那些处于最底层的“超加工”类别的食品，如调味酸奶、早餐麦片、加糖果汁、冰淇淋、饼干等，则是最不健康的。

但明尼苏达大学食品科学与营养学教授、2010 年美国膳食指南咨询委员会成员乔安妮·斯拉文表示，一些看似健康的食物经常被归入不健康类别。

“全麦面包是超加工的。任何含有四种或更多成分的食物都是超加工的，”斯拉文说。“所以几乎所有东西都被归入第四类，你知道，这不是故意的，但这就是它的最终归宿。”

达特茅斯学院盖泽尔医学院研究高级主任苏珊·罗伯茨（Susan Roberts）也长期研究营养学，她表示，需要对加工食品分类系统进行更多审查，以便更好地帮助公众了解他们应该如何吃以及应该吃什么。

她说，最近关于更新美国饮食指南的咨询委员会报告“很好地表明，超加工食品，其中许多，可能有害，但目前还没有证据证明这一类别是有害的。”

与此同时，斯拉文表示，她提醒消费者注意将所有超加工食品归入有害类别的信息。

“这就像‘永远不要吃超加工食品’，而我们甚至还没有定义超加工食品到底是什么，这让我们在食品和营养咨询领域名声不好，”她说。“我不会责怪消费者说，‘嘿，你们为什么不弄清楚呢？’”

题图：波士顿科学家的新研究发现，每周食用两份或两份以上加工红肉（如热狗、培根和博洛尼亚香肠）的人患痴呆症的风险增加。美联社照片/Mark Lennihan、美联社照片/Richard Drew 和 Joe Raedle/Getty Images

附原英文报道：

Hot dogs, sausage, and . . . dementia? Harvard and MIT research links ultra-processed meat with new health concerns.

By Kay Lazar Globe Staff,Updated January 15, 2025  

New research from Boston scientists finds an increased risk of dementia among those who ate two or more servings a week of processed red meat, such as hot dogs, bacon, and bologna.AP Photo/Mark Lennihan, AP Photo/Richard Drew, and Joe Raedle/Getty Images

Regularly eating red meat has been linked with heart disease, diabetes, and several types of cancer. Now there’s fresh evidence tying some popular types of red meat to yet another health concern: it could be bad for your brain.

A new study by Boston researchers finds that long-term consumption of processed red meat, such as hot dogs, sausage, and bacon, is linked to an elevated risk of dementia. The findings come on the heels of sobering research published on Monday from a separate team of scientists that estimates the number of Americans who develop dementia each year will double by 2060, to roughly 1 million new cases a year, largely because of the aging population.

As scientists and policy makers search for ways to protect Americans’ health — and stave off chronic illnesses— attention is increasingly turning to reforming the American diet.

In the meat study, published online Wednesday in the journal Neurology,researchers at Harvard’s T.H. Chan School of Public Health and the Broad Institute of MIT and Harvard said they focused on processed red meat in hopes their findings would inform new dietary guidelines the federal government is developing and is expected to release later this year. In December, scientists advising federal health and agriculture agencies on the updated US Dietary Guidelines recommended they emphasize alternative sources of protein, such as beans, peas, and lentils, over red and processed meats.

For red meat lovers, the latest Harvard study had some reassuring news: it did not find a significant increased risk of dementia from consuming “unprocessed” meat, such as ground beef or sirloin. But the scientists found that eating about two servings per week of processed red meat, which includes some cold cuts, correlated with a 13 percent higher risk of dementia compared to those who ate less than roughly three servings a month.

The study also concluded that replacing a serving of processed red meat, equal to 3 ounces, with a serving of nuts or legumes per day might lower the risk of dementia by 19 percent, and by as much as 28 percent if the serving is replaced with fish.

“We want to provide all these healthier alternatives for the general public, because we don’t want to just say, ‘Please eat less red meat,’ ” said lead author Dr. Daniel Wang, an assistant professor at Harvard Medical School and Brigham and Women’s Hospital. “We want to give a positive message, not just limiting people’s intake.”

The researchers analyzed data from two long-running health studies that included more than 130,000 participants and tracked them for up to 43 years, using regular food-frequency questionnaires to assess the association between red meat and dementia.

Other researchers not involved in the study said the large number of participants and the lengthy time they were tracked is just the evidence regulators need to consider when setting food policies. But they cautioned that the study, like many other food tracking studies, relies on participants’ memories about what they ate, which can be fuzzy at times.

In the second finding on dementia, which was published in Nature Medicine, researchers made the startling conclusion that roughly 40 (percent of people over age 55 will develop dementia in their lifetime. The estimate was based on data from another long-running study of more than 15,000 people across four states.

“Our brain is a complex organ,” said Heather Snyder,the Alzheimer’s Association’s senior vice president of medical and scientific relations, who was not involved in either dementia study. “What may be contributing to a person’s [dementia] risk is likely a number of things, including the food that we may eat and ensuring that we have a balanced diet.”

The association is conducting its own research on the links between dementia, diet, and lifestyle in a two-year effort called the US POINTER Study, with more than 2,000 participants in five sites across the United States. Results are expected to be reported in July.

In the meantime, the association, based on a multitude of other research, advises that healthier foods — vegetables and leaner meats and proteins, along with foods that are less processed and lower in fat — can reduce risk of cognitive decline.

The public’s interest in “processed” and “ultra-processed” foods has surged since President-elect Donald Trump said he would nominate Robert F. Kennedy Jr., an outspoken critic of processed foods, to be health and human services secretary. But researchers and regulators also have many questions over exactly what these terms should mean and how those foods effect health.

The panel advising the federal government on the next edition of the influential US Dietary Guidelines did not distinguish between unprocessed and processed red meat in its recommendations and concluded that more research was needed on health impacts from so-called ultra-processed food in general before further guidance in this category can be made. That is expected to delay substantial changes regarding such processed foods until the next update, in 2030.

Ultra-processed foods is an imprecise term that generally means foods with many added ingredients like sugar, oils, fats, and artificial colors or preservatives.

Many organizations reference a classification system called NOVA that breaks food into four categories based on how much they are processed. Fresh or frozen vegetables, grains, beans, and other minimally processed foods are considered the healthiest, while those in the bottom “ultra-processed” category, such as flavored yogurts, breakfast cereals, sweetened juices, ice cream, cookies, and more, the most unhealthy.

But Joanne Slavin, a professor of food science and nutrition at the University of Minnesota and a member of the 2010 advisory committee for the US Dietary Guidelines, said several seemingly healthy foods often get swept into an unhealthy category.

“Whole grain breads are ultra-processed. Anything with four ingredients or more is ultra-processed,” Slavin said. “So then pretty much everything gets put into that fourth category, which, you know, wasn’t intentional, but that’s kind of where it ends up.”

Susan Roberts, senior dean of research at the Geisel School of Medicine, Dartmouth College, who has also long studied nutrition, said there needs to be more scrutiny of the processed food classification system to better help the public make sense of how and what they should be eating.

She said the recent advisory committee report on updating US dietary guidelines “did a good job of saying that ultra-processed foods, many of them, are likely to be bad, but the evidence for that as a category isn’t there yet.”

Meanwhile, Slavin said she cautions consumers about information that lumps all ultra-processed food into the bad basket.

“It’s like, ‘Never eat an ultra-processed food,’ when we haven’t even defined what an ultra-processed food really is, and that makes us look bad in the food and nutrition advice place,” she said. “And I don’t blame consumers for saying, ‘Hey, why don’t you guys get it figured out?’ ”