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Pooping only every 3 or more days linked with cognitive decline, research finds
In the first research to look at constipation’s impact on the aging brain, scientists have found some concerning links.
Being chronically constipated, defined by the authors as having a bowel movement only every three or more days, has been linked with a 73% higher risk of subjective cognitive decline, according to research presented Wednesday at the Alzheimer’s Association International Conference in Amsterdam.
“Our study provided first-of-its-kind evidence that examined a wide spectrum of bowel movement frequency,” said Dr. Chaoran Ma, the research’s first author and assistant professor in the department of nutrition at the University of Massachusetts Amherst, via email. “We were surprised at how strong the associations were, especially for those with very infrequent bowel movements.”
About 16% of the worldwide adult population experiences constipation, but it’s even more common among older adults due to age-related factors such as lack of exercise and dietary fiber, and the use of medicines that can cause constipation as a side effect.
Chronic constipation has been linked with inflammation and mental disorders such as anxiety and depression, but there have been many unanswered questions about the relationship between digestive health and long-term cognitive function, according to a news release.
Cognitive function refers to a person’s mental capacity for learning, thinking, reasoning, problem-solving, decision-making, remembering and paying attention.
To find clues to these queries, the authors assessed more than 112,000 adults who had participated in the Nurses’ Health Study, Nurses’ Health Study II and Health Professionals Follow-Up Study. The first two studies investigated risk factors for major chronic diseases among women in North America, while the latter study is looking into the same topics but for men. The authors of the latest research collected data on participants’ bowel movement frequency from 2012 to 2013, participants’ self-assessments of cognitive function between 2014 and 2017, and details on some participants’ objectively measured cognitive function between 2014 and 2018.
Compared with people who pooped once a day, constipated participants had significantly worse cognition equivalent to three years more of chronological cognitive aging, the authors found. Increased risk was also found among those who pooped more than twice daily, though these higher odds were small.
“The more we learn about the gut-brain access, the more we understand that it’s just so important to ensure that (preventing or addressing cognitive decline) is a system approach,” said Maria C. Carrillo, chief science officer of the Alzheimer’s Association, who wasn’t involved in the research. “The brain is not completely isolated from what’s happening in your blood flow.”
Bowel movements and the brain
This research wasn’t “designed to test the causal relationship between bowel movements, the gut microbiome and cognitive health, so we cannot firmly draw conclusions regarding the precise causal sequence underlying this association,” Ma said.
But bowel movement frequency and subjective cognitive function were also linked with the participants’ gut microbiomes, the authors found. Among those with infrequent bowel movements and worse cognitive function, there was a depletion in good bacteria that produce butyrates, fatty acids which support the gut barrier that prevents bacteria and other microbes from entering your bloodstream, according to the Cleveland Clinic.
Butyrates also significantly aid in digestive health by providing the main energy source for colon cells. Those can be found in high-fiber foods, fiber supplements, prebiotics and full-fat dairy products — eaten in moderation — such as butter, cheese, milk or ghee. Ghee is clarified butter, made by isolating pure butterfat from the milk solids and water in butter.
Those who pooped twice or more per day and had worse cognitive function had a higher amount of species that promote inflammation and are related to dysbiosis, an imbalance in gut microbes associated with disease.
Other research presented at the same conference Wednesday had similar findings. In one abstract of 140 middle-aged adults, having lower levels of neuroprotective gut bacteria Butyricicoccus and Ruminococcus was associated with elevated levels of Alzheimer’s disease biomarkers.
In another, of more than 1,000 adults, those with poor cognition had abnormally high amounts of the bacteria Alistipes and Pseudobutyrivibrio compared with other participants. Alistipes bacteria have previously been linked with anxiety, chronic fatigue syndrome, depression and hypertension.
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“It makes sense that individuals that are having those movements so much less frequently are going to have less of the good bacteria and more of the bad bacteria that’s caused by inflammatory conditions,” Carrillo said.
“Further studies are needed to identify the microbes involved, and their function,” Ma said concerning her research.
Regarding neurological and digestive health, “good food not only feeds our brain, but it also promotes healthy bowel movements,” Carrillo said.
Eating enough fiber from vegetables, fruits, whole grains and nuts can prevent constipation. Total fiber intake should be at least 25 grams per day, according to the US Food and Drug Administration. And being hydrated enough softens stool so you can pass it without straining.
Exercising at least a few times per week and managing stress can also help.
注释：
constipation: n
表示" 便秘"，means "irregular and infrequent or difficult evacuation of the bowels; can be a symptom of intestinal obstruction or diverticulitis"，如：Chronic constipation can also cause depression. 长期便秘也会导致抑郁。
inflammation: n
表示" 发炎；炎症"，means "a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat"，如：Many babies develop a mild inflammation in the eyes a few days after birth. 许多婴孩出生几天以后眼睛会有轻微的发炎。
microbiome: n
表示" 微生物组"，means "A microbial biome, such as the community of microbes within the human gut"，如：Jeremy Nicholson of Imperial College London is exploring both the microbiome and the metabolome. 伦敦帝国理工学院的JeremyNicholson分别对该微生物组和代谢组进行探究。
depletion: n
表示" 消耗；逐渐耗尽"，means "the act of decreasing something markedly"，如：The result, unsurprisingly, is resource depletion. 结果导致了资源的消耗，并不令人意外。
butyrate: n
表示"丁酸盐"，如：Ceric sulfate is an excellent catalyst for synthesis of amyl butyrate. 硫酸铈是合成丁酸戊酯的良好催化剂。
prebiotics: n
表示"益生元"，如：Prebiotics stimulate the growth of beneficial bacteria, which helps support your baby's developing immune system. 益生元刺激有益细菌的生长，帮助您的宝宝免疫系统的发育。
ghee: n
表示" 印度酥油"，means "clarified butter used in Indian cooker"，如：Ghee is vegetable oil, so I think I can put up with it. 酥油是植物油，我应该可以忍受。
dysbiosis: n
表示"生态失调"，如：New investigative technology has recently clarified the role of bacterial species, which may account for intestinal dysbiosis, as a factor for triggering ulcerative colitis. 最近研究结果证实，细菌物种可解释肠内生态失调可能是溃疡性结肠炎的一种促发因素。
neuroprotective: adj
表示" 保护神经"，如：It has powerful neurotrophic and neuroprotective activity. 它具有强大的营养和保护神经作用。
Butyricicoccus: n
表示"丁酸球菌属"
Ruminococcus: n
表示"瘤胃球菌属"，如：Ruminococcus albus 白色瘤胃球菌
Pseudobutyrivibrio: n
表示"假丁酸弧菌属"
opioid: n
表示"类鸦片"，如：Opioid dependence is a chronic,repeated relapsing disease in brain. 类鸦片依赖是一种慢性、反复发作性脑疾病。
中文简要说明：
便秘不只造成肠胃不适，身体其他部位也会跟着出问题，大脑也不例外。根据一项最新研究，科学家们首次发现，长期便秘的人容易出现主观认知下降，发生率比排便顺畅者多了73%。这项研究发表于本周三在阿姆斯特丹举行的2023年阿兹海默症协会国际会议（Alzheimer’s Association International Conference）。
根据美国媒体CNN报导，慢性便秘指的是每隔3天（或以上）才排便一次。全球约16%的成年人有便秘经验，又以老年人较为常见，主要原因和缺乏运动、膳食纤维和服用药物（部分副作用导致便秘）有关。
该研究的作者针对超过11万2千位成年人进行调查，结果发现，与每天大便1次的人相比，便秘者的认知能力明显较差，两者认知上的年龄平均差距3岁。而每天大便超过2次的人，也出现风险增加的情况，不过机率较小。
排便频率和肠道微生物群有关，而肠道健康会影响血液和大脑认知能力。那些不常排便、认知力较差的人，他们体内制造丁酸盐（butyrate）的好菌明显减少。丁酸盐是一种脂肪酸，能加强肠道屏障，防止细菌和其他微生物进入血液；丁酸盐也为结肠细胞提供能量，对促进消化系统健康大有帮助。
丁酸盐出现在高纤食物、纤维补充剂、益生元和全脂奶制品中。蔬菜、水果、全谷物和坚果含有大量纤维素，根据美国食品与药物管理局（FDA）规定，成年人每天应至少摄取25公克纤维。全脂奶制品则包含奶油、奶酪、牛奶或酥油，但必须适量食用。
此外，摄取充足的水分能帮助软化粪便。每星期进行数次运动，加上适度释放压力，也能让排便更加顺畅。
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