Eating sugar while taking antibiotics might harm gut bacteria

Sugary foods combined with antibiotic treatment can damage the gut microbiome in ways that could leave people vulnerable to dangerous infections, a new study shows.

The new research, published Wednesday in the journal Nature , took advantage of a natural experiment: It looked at what happened to gut bacteria in cancer patients who were hospitalized and treated with sustained antibiotics before receiving stem cell transplants. Because the patients only ate food prepared by the hospital, researchers knew exactly what and how much food they ate – a rarity in nutrition studies, which typically rely on participants to recall what they ate hours or days earlier, something people are notoriously bad at.

The gut microbiome consists of trillions of bacteria, viruses and other microbes that populate human intestines. These tiny organisms perform a host of functions including helping with digestion, making essential vitamins, and playing a role in immune function. Science has shown the microbiome also communicates with the brain to produce neurotransmitters like serotonin, which are important for sleep, mood and stress levels.

Studies have shown that the numbers and variety of bacteria that live in the gut depend largely on diet. People who eat varied, plant-based, fiber-rich diets tend to have higher diversity of organisms in the intestines compared with those who eat diets with more highly processed foods. In general, the more diverse a person’s microbiome is, the healthier it is. A dense, diverse community of bugs in the gut is able to prevent bad actors – called pathobionts – from taking over and causing illness.

“One of the things that that differentiates this study from other ones that have been previously published is that the patients are having their microbiome pummeled, and they’re also having their nutritional state disrupted by the cancer treatment,” said study author Dr. Jonathan Peled, a physician scientist at Memorial Sloan Kettering.

The research, which was led by scientists at Memorial Sloan Kettering Cancer Center and NYU’s Langone Health in New York, and City of Hope Cancer Center in Los Angeles, looked at what happened after antibiotics and hospital food destabilized and disrupted normal gut flora. They used this state of disruption as a window to see the effects of certain types of foods on the composition of the gut microbiome.

“We sliced and diced the data in different ways,” Peled said.

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The late-night eating habit that may throw your gut health into chaos

They looked at the relationship between broad categories of macronutrients like fat, carbohydrates and fiber, and different types of gut bacteria. They also looked at the effects of specific foods like chicken, apples and chocolate cake.

“And the theme that kept popping up over and over again was the more sugary foods you eat, no matter what type of sugar it is – with particularly noxious effects from added sugars – it seemed that really seemed to synergize with antibiotics in terms of damaging the microbiome,” Peled said.

The study drew its data from more than 1,000 stool samples, collected from 173 patients, who ate more than 9,400 hospital prepared meals.

Across the board, the more intense a patient’s antibiotic regimen was, the greater the loss of diversity in their microbiome.

They found most types of foods were not associated with changes to the diversity of bacteria found the in the gut. Sweets, however – which the researchers defined as sugars, and sweetened foods and beverages – were a different story. For every 3.5-ounce increase in consumption of sweets while on antibiotic treatment, the diversity of a patient’s microbiome measured in their stool sample decreased by about 24%, the study showed.

The decrease in gut bacteria diversity was tied to expansions in populations of certain bad actors, such as the bacteria Enterococcus faecium.

Enterococcus is an opportunistic organism. It hangs around harmlessly in the gut and is kept in check by other types of bacteria that outcompete it. But when there’s a disruption, such as antibiotic treatment that wipes out the other bacteria, it can start to overgrow. In some cases, it may slip through the gut wall and into the bloodstream, where it can cause sepsis.

“In bone marrow transplant specifically, we found that Enterococcus can make certain complications of transplant worse, something called graft versus host disease,” Peled said.

In graft versus host disease, donated stem cells recognize a recipient’s body as foreign and begin to attack their healthy tissues.

A healthier gut may be key to cancer care

The team also tested to see if they could recreate the microbiome shifts they saw in human cancer patients in mice. They gave mice a single injection of a broad spectrum antibiotic and saw a small increase in Enterococcus bacteria. When they also fed the mice added sugar after the antibiotic shot, the amount of Enterococci bacteria increased 16-fold by day three and 33-fold by day six.

This increase may have real consequences, too.

Overall, patients who ate more sugar than average had about a 12% higher risk of dying after their transplants compared with those who didn’t consume as much. It’s a small but significant increase in risk.

“It’s a modest change in their risk profile,” Peled said.

The expansion of Enterococcus bacteria lasted about eight days after antibiotic treatment.

“It’s a pretty neat study,” said Dr. Anthony Maresso, professor of virology and microbiology at the Baylor College of Medicine in Houston. “I suspect it’s going to make some waves,” added Maresso, who was not involved in the research.

“This has significance for these transplant recipients because that’s the number one thing hospitals are worried about is that they’re going to get infections in the clinical care setting,” Maresso said. “Makes me wonder about whether we should change the diet of hospitals.”

The next question, he said, is whether this study has significance for people who take antibiotics outside a hospital setting. Does a high-sugar diet on antibiotics for, say, an ear infection, set you up for other infections down the road, for example?

Peled said while thee study is provocative, it’s not a randomized, controlled clinical trial where researchers are able to test different diets to see which one might be most protective for people taking antibiotics.

Because it’s generally a good idea to avoid eating too much sugar, he said, it’s not unreasonable to considering limiting sugar during antibiotic treatment.

“What our study suggests might work is not to avoid sugar or sugary foods during your entire time, but specifically when you’re on antibiotics,” Peled said.

一项新研究表明，含糖食物与抗生素治疗相结合会损害肠道微生物群，使人们容易感染危险的疾病。

这项周三发表在《自然》杂志上的新研究利用了一项天然实验：它观察了癌症患者在接受干细胞移植前，住院并长期服用抗生素治疗期间肠道菌群的变化。由于患者只食用医院提供的食物，研究人员可以精确掌握他们摄入的食物种类和数量——这在营养研究中实属罕见，因为营养研究通常依赖于参与者回忆数小时或数天前的饮食，而人们在这方面的记忆力往往很差。

肠道微生物群由数万亿细菌、病毒和其他微生物组成，它们栖息于人类肠道内。这些微小的生物体发挥着多种功能，包括帮助消化、合成必需维生素以及参与免疫功能。科学研究​​表明，肠道微生物群还能与大脑沟通，产生血清素等神经递质，这些神经递质对睡眠、情绪和压力水平至关重要。

研究表明，肠道内细菌的数量和种类很大程度上取决于饮食。与食用大量加工食品的人相比，食用多样化、以植物性食物为主、富含膳食纤维的饮食的人，其肠道菌群的多样性往往更高。一般来说，人体微生物群的多样性越高，身体就越健康。肠道内密集且多样化的菌群能够有效抑制有害菌（称为致病菌）的过度繁殖，防止​​疾病的发生。

“这项研究与其他已发表的研究的不同之处在于，患者的微生物群受到了严重破坏，而且他们的营养状况也因癌症治疗而受到干扰，”该研究的作者、纪念斯隆-凯特琳癌症中心的医生科学家乔纳森·佩莱德博士说。

这项由纽约纪念斯隆-凯特琳癌症中心、纽约大学朗格尼医学中心以及洛杉矶希望之城癌症中心的科学家共同领导的研究，着眼于抗生素和医院食物破坏肠道正常菌群后发生的情况。他们利用这种菌群紊乱状态，观察某些食物对肠道微生物组组成的影响。

“我们用不同的方式对数据进行了切片和分析，”佩莱德说。

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深夜进食的习惯可能会扰乱你的肠道健康

他们研究了脂肪、碳水化合物和纤维等主要营养素类别与不同类型肠道菌群之间的关系，还研究了鸡肉、苹果和巧克力蛋糕等特定食物的影响。

“反复出现的主题是，你吃的含糖食物越多，无论是什么类型的糖——尤其是添加糖的有害影响——似乎都会与抗生素产生协同作用，从而破坏微生物群，”佩莱德说。

该研究的数据来自 173 名患者收集的 1000 多份粪便样本，这些患者食用了 9400 多份医院准备的饭菜。

总体而言，患者的抗生素治疗方案越强，其微生物群多样性的丧失就越大。

研究发现，大多数食物类型与肠道菌群多样性的变化无关。然而，甜食——研究人员将其定义为糖类以及含糖食品和饮料——则情况有所不同。研究表明，在接受抗生素治疗期间，每增加3.5盎司（约100克）甜食的摄入量，患者粪便样本中测得的微生物群多样性就会下降约24%。

肠道细菌多样性的减少与某些有害细菌（如粪肠球菌）数量的增加有关。

肠球菌是一种机会性致病菌。它通常无害地存在于肠道中，并受到其他细菌的抑制。但当肠道菌群平衡被打破时，例如抗生素治疗导致其他细菌被清除，肠球菌就会开始过度繁殖。在某些情况下，它甚至可能穿过肠壁进入血液，从而引发败血症。

“具体到骨髓移植，我们发现肠球菌会使某些移植并发症恶化，这种情况被称为移植物抗宿主病，”佩莱德说。

在移植物抗宿主病中，捐赠的干细胞会将受者的身体识别为异物，并开始攻击其健康组织。

健康的肠道可能是癌症治疗的关键

研究团队还测试了能否在小鼠身上重现他们在人类癌症患者身上观察到的微生物群变化。他们给小鼠注射了一次广谱抗生素，发现肠球菌数量略有增加。当在注射抗生素后给小鼠喂食添加糖时，到第三天肠球菌的数量增加了16倍，到第六天增加了33倍。

这种增长也可能带来实际后果。

总体而言，与糖摄入量较低的患者相比，糖摄入量高于平均水平的患者在移植手术后死亡风险高出约12%。虽然风险增加幅度不大，但意义重大。

“这只是他们风险状况的一个微小变化，”佩莱德说。

抗生素治疗后，肠球菌的增殖持续了约八天。

“这是一项相当不错的研究，”休斯顿贝勒医学院病毒学和微生物学教授安东尼·马雷索博士说。“我估计它会引起一些轰动，”马雷索补充道，他本人并未参与这项研究。

“这对移植患者来说意义重大，因为医院最担心的就是他们在临床护理环境中感染疾病，”马雷索说。“这让我不禁思考，我们是否应该改变医院的饮食习惯。”

他说，下一个问题是，这项研究对于在医院外服用抗生素的人是否具有意义。例如，如果因为耳部感染而服用抗生素，同时又摄入大量糖分，是否会增加日后感染其他疾病的风险？

佩莱德表示，虽然这项研究具有启发性，但它并非随机对照临床试验，研究人员无法测试不同的饮食方案，以了解哪种方案对服用抗生素的人最有保护作用。

他说，由于避免摄入过多糖分通常是个好主意，因此在接受抗生素治疗期间考虑限制糖分摄入也并非不合理。

佩莱德说：“我们的研究表明，可能有效的办法不是在整个疗程期间避免糖或含糖食物，而是在服用抗生​​素期间特别避免糖或含糖食物。”