In recent years, scientists have discovered that many facets of human health — ranging from chronic inflammation to weight gain — are strongly influenced by the ecological health of the vast numbers of microbes that live in and on us, collectively known as our microbiome. This burgeoning field has sparked efforts at UCSF and across biomedical research to better understand how our environments and behavior can improve human health by shaping healthier microbiomes.

近年来，科学家们发现，人类健康的许多方面——从慢性炎症到体重增加——都严重受到大量生活在我们体内外微生物的生态健康的影响，这些微生物统称为我们的微生物群落。这一新兴领域已经在加州大学旧金山分校（ UCSF ）和整个生物医学研究领域引起重视，以便更好地了解如何通过改变我们的环境和行为塑造更健康的微生物群落，从而进一步改善人类健康。

“Our lab and others have studied how different kinds of diet — such as vegetarian versus meat-based diets — impact the microbiome,” said Peter Turnbaugh, Ph.D., an associate professor of microbiology and immunology and a member of the executive leadership of the UCSF Benioff Center for Microbiome Medicine. “We were surprised to discover that no one had studied the fundamental question of how cooking itself alters the composition of the microbial ecosystems in our guts.”

“我们和其他的实验室研究了不同类型饮食对微生物的影响——如素食与肉类饮食”，微生物学&免疫学副教授，加州大学旧金山分校贝尼奥夫微生物组医学中心（the UCSF Benioff Center for Microbiome Medicine）执行领导成员Peter Turnbaugh博士说。“我们惊讶地发现，没有人研究过烹饪本身是如何改变我们肠道内微生物生态系统组成的这个基本问题。”

The new study — published Sept. 30, 2019, in Nature Microbiology — represents a seven-year collaboration between Turnbaugh and Harvard evolutionary biologist Rachel Carmody, Ph.D., which began when Turnbaugh was an independent Bauer fellow and Carmody a graduate student at Harvard.  

这项新研究发表在2019年9月30日的《自然微生物学》杂志上，它代表了Turnbaugh和哈佛大学进化生物学家Rachel Carmody博士之间长达7年的合作。合作初期Turnbaugh还是鲍尔的独立研究员， Carmody也还是哈佛的研究生。

The researchers examined the impact of cooking on the microbiomes of mice by feeding diets of raw meat, cooked meat, raw sweet potatoes, or cooked sweet potatoes to groups of animals — selected because prior data demonstrated that cooking alters the nutrients and other bioactive compounds in both meat and tubers.

研究人员通过喂食老鼠生肉、熟肉、生红薯,或熟红薯来检测烹饪方法对老鼠体内微生物的影响——之所以选择它，是因为之前的数据表明，烹饪改变了肉类和块茎中的营养成分和其他生物活性化合物。

To the researchers’ surprise, raw versus cooked meat had no discernible effect on the animals’ gut microbes. In contrast, raw and cooked sweet potatoes significantly altered the composition of the animals' microbiomes, as well as microbes’ patterns of gene activity and the biologically crucial metabolic products they produced. The researchers confirmed their findings using a more diverse array of vegetables, performing what Turnbaugh called a “mad scientist experiment" — feeding the mice an assortment of raw and cooked sweet potato, white potato, corn, peas, carrots, and beets.

令研究人员惊讶的是，生肉和熟肉对动物的肠道微生物没有明显的影响。但相比之下，生红薯和熟红薯显著改变了动物的微生物群落组成，以及微生物的基因活动模式和它们产生的至关重要的生物代谢产物。研究人员用更多样化的蔬菜证实了他们的发现，进行了Turnbaugh所说的“疯狂的科学家实验”——给老鼠喂各种各样的生的和熟的红薯、白薯、玉米、豌豆、胡萝卜和甜菜。

The group attributed the microbial changes they saw to two key factors: cooked food allows the host to soak up more calories in the small intestine, leaving less for hungry microbes further down the gut; on the other hand, many raw foods contain potent antimicrobial compounds that appear to directly damage certain microbes.

该小组将他们所看到的微生物变化归因于两个关键因素:一方面，熟食让宿主的小肠吸收更多的热量，减少肠道深处饥饿微生物的数量;另一方面，许多生食含有某些有效的抗菌化合物，似乎会直接损害某些微生物。

“We were surprised to see that the differences were not only due to changing carbohydrate metabolism but also may be driven by the chemicals found in plants,” Turnbaugh said. “To me, this really highlights the importance of considering the other components of our diet and how they impact gut bacteria.”

Turnbaugh说:“我们惊讶地发现，这些差异不仅是由于碳水化合物代谢的改变，还可能是由植物中的化学物质造成的。对我来说，这确实强调了我们饮食的其他成分的重要性以及它们是如何影响肠道菌群的。”

In collaboration with colleagues at the U.S. Department of Energy’s Joint Genome Institute in Walnut Creek, Calif., Turnbaugh’s team performed a detailed analysis of the chemical changes that cooking produced in each plant they had fed to their mice, resulting in a short list of compounds that might explain how these diets may have impacted the animals’ microbiomes, a question they are currently analyzing further.

与在美国加州核桃溪市的美国能源部联合基因组研究所的同事们合作，Turnbaugh的团队对他们喂给老鼠的每一种植物所产生的化学变化进行了详细分析，由此产生了一个简短的化合物清单，可以解释这些饮食影响动物微生物群落的可能性，目前他们正在进一步分析这个问题。

Among other observations, the researchers noted that raw diets caused mice to lose weight, and they wondered whether this resulted from the changes to their microbes. But when the team transplanted these altered microbiomes into mice living on a regular diet of mouse chow, normally fed animals instead put on extra fat, a seemingly paradoxical finding the researchers say they are still investigating.

在其他观察结果中，研究人员注意到，生食会导致老鼠体重减轻，他们想知道这是否是因为它们体内的微生物发生了变化。但是，当研究小组将这些改变了的微生物群落移植到正常饮食的老鼠体内时，正常喂养的老鼠反而增加了额外的脂肪。研究人员称，这一看似矛盾的发现仍在研究中。

Finally, to understand whether similar microbiome changes could be triggered in humans eating a raw or cooked diet, the team partnered with a Harvard graduate student who is also a professional chef to prepare appetizing and experimentally comparable raw and cooked menus for a small group of research participants. The participants tried each diet for three days each in random order, then submitted stool samples for researchers to analyze their microbiomes, which showed that these distinct diets significantly altered the research participants’ microbiomes.

最后，为了了解食用生食或熟食是否会引发类似的微生物群变化，研究小组与一名哈佛大学的研究生合作，这名研究生也是一名专业厨师，他为一小群研究参与者准备了可比较的开胃的和实验性的生食和熟食菜单。参与者在三天内随机尝试每种饮食，然后提交粪便样本供研究人员分析他们的微生物群落，结果显示，这些不同的饮食显著改变了参与者的微生物群落。

“It was exciting to see that the impact of cooking we see in rodents is also relevant to humans, although interestingly, the specifics of how the microbiome was affected differed between the two species,” Turnbaugh said. “We’re very interested in doing larger and longer intervention and observational studies in humans to understand the impact of longer-term dietary changes.”

Turnbaugh说，“令人兴奋的是，我们看到的烹饪方式在啮齿动物身上的影响也与人类有关，有趣的是，尽管两种物种的微生物群落受到影响的具体方式不同，但我们很有兴趣对人类进行更大规模、更长期的干预和观察性研究，以了解长期饮食变化带来的影响。”

Understanding how diet impacts the microbiome has important implications for how our gut microbes influence weight gain and other aspects of human health, Turnbaugh said. The study also raises intriguing questions about how human-associated microbes have evolved over the millennia to adapt to our culinary culture, he said, and whether this could have important side effects for modern health.

Turnbaugh说，了解饮食如何影响微生物群对于我们的肠道微生物，如何影响体重增加和人类健康的其他方面具有重要的意义。他说，这项研究还提出了一些有趣的问题，比如人类相关的微生物是如何在数千年的时间里进化来适应我们的饮食文化的，以及这是否会对现代健康产生重要的副作用。