Lactose malabsorption intolerance

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Frequently Asked Questions

Frequently Asked QuestionsWhat is IBS?IBS is a group of symptoms. It is a long-term disorder of gastrointestinal (GI) functioning. It usually involves the large and small bowel/intestine (also called the gut). Learn MoreWhat are the symptoms of IBS?Common IBS symptoms are abdominal pain or discomfort, altered bowel habits (diarrhea and/or constipation), and bloating or a sense of gaseousness. Abdominal pain or discomfort is the key symptom of IBS. It may feel better with a bowel movement. The pain occurs when stool frequency or consistency changes. Symptoms can come and go, and even change, over time. Learn MoreHow is IBS diagnosed?A doctor will diagnosis IBS by asking about your past history and doing a physical examination. In IBS, certain typical symptoms occur. The diagnosis is based on symptoms and in the absence of signs not typical of IBS.The symptom-based Rome diagnostic criteria for IBS emphasize a “positive diagnosis” rather th an exhaustive tests to exclude other diseases. Learn MoreAre there tests to confirm irritable bowel syndrome?There are no tests that confirm the diagnosis of IBS. Laboratory tests, x-rays, and procedures such as colonoscopy are used to rule out other diseases of the bowel. Research is ongoing to find biological markers for IBS. Learn MoreI have been diagnosed with irritable bowel syndrome (IBS), buttests found nothing wrong. Do I need more tests?In IBS, tests are expected to find nothing. In the absence of physical findings, the symptom-based Rome diagnostic criteria have been shown tobe reliable. In addition, a physical exam and limited diagnostic tests help confirm this diagnosis with a high level of confidence. Extensive testing may be reserved for specific situations.What is the Rome Criteria?The Rome Criteria is a classification system that uses specific symptom patterns to identify functional GI disorders, such as IBS. Learn MoreHow common is IBS?Irritable bowel syndrome (IBS) is the most common functional GIdisorder. Worldwide prevalence rates range from 9–23%.What is a “functional” bowel disorder?A functional bowel disorder occurs when there is a problem with the way the bowels work, not their structure. The body's normal activities are impaired involving:• movement of the intestines,• sensitivity of the nerv es of the intestines, or• the way in which the brain controls some of these functions.What does “irritable” mean?Irritable means that the nerve endings in the bowel wall are unusually sensitive.What causes IBS?The cause of IBS is not yet completely understood. In IBS there is an altered pattern of muscle contraction in the colon. There is increased sensitivity within the GI tract. Normal regulation of the communication between the brain and the gut becomes altered. This leads to changes in normal bowel function.Does lactose intolerance cause IBS?Lactose (milk sugar) intolerance can cause similar symptoms to IBS. Lactose intolerance and IBS can occur at the same time in a person. But they are separate conditions which are treated differently. Learn MoreIs IBS a “serious illness”?For many people, IBS causes symptoms that are mild, which do not interfere with daily activities. For others, IBS may severely compromise their quality of life.Is IBS a risk factor for other serious disease?There are no long-term organic complications associated with IBS. People with IBS have no greater need of preventive checkups than other people. Will my IBS symptoms resolve?Each year, approximately 10% of IBS patients get better. This suggests that most people with IBS will eventually get better. But this is not true for every person.Can the menstrual cycle affect irritable bowel symptoms?Gut function does appear to be influenced by changes in the level of female hormones. Symptoms like looser stools and cramping can become worse at certain times of the cycle, particularly at the time of menses. It is reported as more intense in women with IBS, than in healthy women without IBS. Sometimes it's hard to tell whether it's coming from the pelvic organs or from the GI tract. Learn MoreWhat is the relationship of stress to IBS?Stress does not cause IBS. It can influence symptoms. Stress is the body’s normal response to stimuli, or stressors. It has been shown to increase motility and sensation of the colon to a greater degree in IBS patients compared to healthy individuals without IBS.Stress may modify signals between the brain and the intestinal tract. Factors that might normally affect the bowel might then affect it more. The stress factors could be physical, dietary, psychologic, or environmental. A personwith IBS might eat a regular meal and experience a bowel problem. For them, it's an overreaction of the bowel to the stressors. Learn More Doesn’t everyone experience stress in their life?Yes, and stressful events can cause a brief change in bowel habits and even abdominal pain for most people. However, this response in people with IBS is more pronounced on a recurrent or chronic basis.Does diet cause IBS?Diet does not cause IBS. Nevertheless, dietary factors may worsen symptoms in some persons. In IBS the bowel may over-react to stimuli. Even the act of eating, and not a particular food, may aggravate symptomsat times. Learn MoreDo certain foods affect symptoms?This varies from person to person. Certain foods are known to stimulate the gut in general, and in those with IBS eating too much of these might worsen symptoms. Maintaining a food and symptom diary for a minimum of one to two weeks can help identify triggering foods. Learn MoreMy doctor prescribed an antidepressant to treat my IBS. Does that mean I have a psychological disorder?In IBS low-dose antidepressants are useful, not to treat depression, but to reduce pain and also overall symptoms. Doses are much lower than what is used to treat depression. Learn MoreIs IBS a Disability?Depending on the circumstances it is up to each employer, insurer, or governing authority to determine individual disability.The U.S. Social Security Administration (SSA) defines disability as the inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment(s) which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months. (SSA Pub. No. 64-039, May 2002) However, the SSA does not recognize irritable bowel syndrome on its Listing of Impairments -- Adults, Section 5, Digestive System.On August 15, 2011, the Department of Veterans Affairs (VA) implemented a “presumptive service connection” when assessing disability benefits in soldiers affected by functional GI disorders (such as IBS) who served in Southwest Asia during the Persian Gulf War.The Veterans Affairs Dept first recognized IBS in the Veterans Education and Benefits Expansion Act of 2001, Public Law 107-103 signed by President Bush on December 27, 2001. Section 202 -- Payment of Compensation for Persian Gulf War Veterans with Certain Chronic Disabilities -- includes this provision: (2) For purposes of this subsection, the term "qualifying chronic disability" means a chronic disability resulting from any of the following (or any combination of any of the following): (B) A medically unexplained chronic multi-symptom illness (such as chronic fatigue syndrome,fibromyalgia, and irritable bowel syndrome) that is defined by a cluster ofsigns or symptoms. The law authorizes funding to expand and increase educational, housing, burial and disability benefits for chronic multi-symptom illnesses to the list of service-connected conditions for Gulf War veterans.。

乳糖不耐受症

症状, 也不需要特殊的饮食疗法。
临床表现的产生取决于乳糖酶
活力低下的严重程度及在小肠上分布范围的大小, 此外, 结肠对未吸收乳糖的清除力也是一个影响因素。 LI 还可能由于单糖吸收障碍 (例如葡萄糖—半乳糖吸收不良)引起, 而并非乳糖酶本身有缺陷。
1. 测定粪便还原物质和PH: 最简单的方法是用Ames公司的Clinitest试剂测定粪便中的还原物质(>0.5%),
呼气氢气升高20ppm为阳性反应(ppm为百万分密度, 气液色譜仪) 。如果呼气氢气高峰在进食乳糖后 1-3 小时之内出现, 提示小肠内乳糖吸收不良; 如果呼气氢气高峰在进食乳糖后1小时之内出现, 提示小肠内有细菌过度增生。
该方法简单, 可靠准确, 灵敏性及特异性高, 无创伤, 但需一定设备, LHBT结果有假阴性及假阳性。当结肠内没有产氢气的菌株, 如用抗生素治疗或结肠内PH降低等可发生假阴性。而睡眠状态, 吸烟及进食纤维素食品可增加氢气的产生出现假阳性。
2. 口服乳糖耐量试验: 2岁以下小儿禁食4h, 2岁以上小儿禁食8h后口服乳糖 2g/Kg之后每半小时测血糖共4次, 如血糖呈低平曲线, 升高不超过20mg/dl, 应考虑低乳糖酶症。但胃排空延迟, 葡萄糖 --半乳糖吸收和代谢异常均可影响结果。最重要的是观察口服负荷
量后是否出现腹泻,以及粪便中是否出现还原物质。
五．治疗：主要采用限制饮食，即食用不含
乳糖的食物，症状明显改善后，可在食物中逐渐增加乳糖，以能耐受为度，多数于36h左右恢复。饮食选择:（1）无乳糖配方奶，如惠氏的爱儿素，以豆蛋白为主配制；雀巢的无乳糖奶粉，安婴乐，奶味较好，但价格高，国产亦有成品；
（2）乳糖经过预处理的配方，例如用乳糖酶作用过24h的牛奶;（3）较贫困家庭可选用谷类或发酵奶与牛奶混合配方。如有脱水给予相应治疗。单纯肠炎后LI疗程较短，而伴有慢性腹泻及营养不良时，疗程较长。当体重已满意地恢复增长时，即可恢复正常饮食。

益生菌联合乳糖酶治疗婴幼儿乳糖不耐受引起的慢性腹泻的临床效果

中国当代医药2020年8月第27卷第24期CHINA MODERN MEDICINE Vol.27No.24August 2020·妇幼医学·婴幼儿腹泻是临床上一种较为常见的肠道疾病,主要表现为腹泻、呕吐等症状,其中腹泻分为急性腹泻和慢性腹泻。

急性腹泻一般多以感染性为主,慢性腹泻的常见原因为乳糖不耐受。

因为婴幼儿的主要能量来源为乳糖,乳糖酶的缺乏使母乳或奶制品中的乳糖不能被分解吸收,随后引起肠腔渗透压增高导致渗透性腹泻;乳糖不耐受为未水解的乳糖被结肠吸收后经细菌分解产生大量的气体,易引发腹胀、腹泻等症状[1]。

因乳糖不耐受易导致婴幼儿营养不良、能量摄入不足、贫血,从而影响体格发育和智能发育。

因此,婴幼儿慢性腹泻治疗的关键在于解决乳糖不耐受。

但是有部分诊断为乳糖不耐受的婴幼儿,使用乳糖酶后腹益生菌联合乳糖酶治疗婴幼儿乳糖不耐受引起的慢性腹泻的临床效果张莹黄鸣剑张凯真广州市海珠区妇幼保健院儿科,广东广州510000[摘要]目的探讨益生菌联合乳糖酶治疗婴幼儿乳糖不耐受引起的慢性腹泻的临床效果。

方法选取2019年8月~2020年1月我院收治的36例乳糖不耐受引起的慢性腹泻患儿作为研究对象,按照随机数字表法将其分为对照组和观察组,每组各18例。

对照组采用乳糖酶治疗,观察组采用益生菌(酪酸梭菌二联活菌散)+乳糖酶治疗。

比较两组患儿的治疗效果、腹泻次数、吐奶次数、体重变化。

结果观察组患儿的临床治疗总有效率(94.44%)高于对照组(83.33%),差异有统计学意义(P <0.05);治疗后,观察组患儿的腹泻次数、吐奶次数少于对照组,体重高于对照组,差异有统计学意义(P <0.05)。

结论益生菌联合乳糖酶治疗婴幼儿乳糖不耐受引起的慢性腹泻效果显著,可以有效减少患儿的腹泻次数和吐奶次数,增加患儿的体重,值得临床推广应用。

[关键词]益生菌;乳糖酶;乳糖不耐受;婴幼儿;慢性腹泻[中图分类号]R725.7[文献标识码]A[文章编号]1674-4721(2020)8(c)-0151-03Clinical effect of probiotics combined with Lactase in the treatment of chronic diarrhea caused by lactose intolerance in infants and young chil⁃drenZHANG Ying HUANG Ming-Jian ZHANG Kai-Zhen Department of Pediatrics,Haizhu District Maternal and Child Health Hospital,Guangdong Province,Guangzhou 510000,China[Abstract]Objective To explore the clinical effect of probiotics combined with Lactase in the treatment of chronic di⁃arrhea caused by lactose intolerance in infants and young children.Methods A total of 36children with chronic diar⁃rhea caused by lactose intolerance admitted to our hospital from August 2019to January 2020were selected as the re⁃search objects,and they were divided into the control group and the observation group according to the random number table method,with 18cases in each group.The control group was treated with Lactase,and the observation group wastreated with probiotics (Clostridium Caseate Bivalent Viable Powder)combined Lactase.Treatment effect,number of di⁃arrhea,number of vomiting and weight changes were compared between two groups of children.Results The total effec⁃tive rate of treatment of children in the observation group was 94.44%,which was higher than that of the control group of 83.33%,the difference was statistically significant (P <0.05).After treatment,the numbers of diarrhea and milking in the observation group were fewer than those in the control group,and the weight was higher than that in the control group,the differences were statistically significant (P <0.05).Conclusion The combination of probiotics and Lactase is effective in treating chronic diarrhea caused by lactose intolerance in infants and young children.It can effectively re⁃ducing the frequency of diarrhea and vomiting in children,increasing the weight of children,and is worthy of clinical application.[Key words]Probiotics;Lactase;Lactose intolerance;Infants and young children;Chronic diarrhea[基金项目]广东省广州市海珠区科技计划项目(海科工商信计2018-31)151·妇幼医学·中国当代医药2020年8月第27卷第24期CHINA MODERN MEDICINE Vol.27No.24August 2020泻症状改善不明显,因此考虑是否有部分婴幼儿同时存在肠道菌群失调加重其腹泻症状[2]。

慢性肝炎患者乳果糖氢呼气试验结果分析

慢性肝炎患者乳果糖氢呼气试验结果分析作者：刘伟，钟良，钟基大，戎兰，徐章【关键词】慢性乙型肝炎；乳果糖氢呼气试验；小肠细菌过度生长【摘要】目的分析38例慢性乙肝患者的乳果糖氢呼气试验结果，了解慢性乙肝患者小肠细菌过度生长(small intestinal bacterial overgrowth，SIBO) 情况。

方法对38例慢性乙型病毒性肝炎患者及40例正常人以10g乳果糖为基质做氢呼气试验（lactulose hydrogen breath test，LHBT）。

结果 38例慢性肝炎患者中LHBT阳性者12例（31.6％），提示这部分患者存在小肠细菌过度生长，40例正常对照者中无LHBT阳性者；伴小肠细菌过度生长的慢性肝炎患者在服用相同基质的条件下，其在单位时间内产氢量、峰值明显高于或峰值时间明显早于无小肠细菌过度生长者。

结论部分慢性肝炎患者LHBT阳性，提示存在小肠细菌过度生长；乳果糖氢呼气试验检测小肠细菌过度生长具有快速，较准确、患者易于接受等特点，基质易得，易于在临床上应用。

【关键词】慢性乙型肝炎；乳果糖氢呼气试验；小肠细菌过度生长氢呼气试验（hydrogen breath test，HBT）所用基质多为糖类物质，如乳果糖、葡萄糖、乳糖等，当存在小肠细菌过度生长时，口服的糖类物质在进入结肠之前，即被过度生长的细菌发酵产生氢气，故此时测定呼气中氢水平和氢浓度增高的时间可检测小肠内细菌过度生长［1］。

乳果糖为不吸收的糖类物质，可以反映整个小肠的情况，本研究采用乳果糖氢呼吸试验(LHBT)检测慢性肝炎和正常人的小肠细菌过度生长情况。

1 资料与方法1.1 受试者情况符合入选标准的慢性乙型肝炎38例，男28例，女10例，年龄20～74岁，平均（43.1±13.6）岁，其中轻度17例，中度11例，重度10例；LHBT阳性12例，其中肝炎轻度2例，中度4例，重度6例。

正常对照组40例，男24例，女16例，年龄25～67岁，平均（44.3±10.8）岁，无LHBT 阳性者。

新生儿乳糖不耐受_姜毅

DOI ：10.3969/j.issn.1673-6710.2014.06.014作者单位：100034北京大学第一医院儿科通讯作者：姜毅，电子信息：jiangyi122@·讲座·新生儿乳糖不耐受姜毅新生儿乳糖不耐受症是由于乳糖酶缺乏，不能完全消化分解母乳或牛乳中的乳糖所引起的一系列消化系统症状。

乳糖是主要存在于哺乳动物乳汁中的一种双糖，母乳中乳糖含量为7.2g /100ml ，牛乳中乳糖含量为4.7g /100ml 。

乳制品是新生儿主要的能量来源，乳糖为新生儿提供约20%的能量。

在生长发育过程中，乳糖不仅在能量供给方面起重要作用，亦参与大脑的发育进程。

乳糖主要在空肠及回肠吸收，在小肠上皮细胞刷状缘所分泌的乳糖酶（1actose ）作用下水解为葡萄糖和半乳糖，通过细胞的主动转运而吸收。

乳糖酶又称β-半乳糖苷酶（lactase-phlorizin-hydrolase ，LPH ），从十二指肠近端段向远端段其活性逐渐增加，在空肠或近段回肠达高峰，末段回肠乳糖酶水平较低。

如果乳糖吸收的任何一个环节出现障碍，都将会导致肠腔内乳糖浓度异常升高，导致乳糖消化不良［1］。

如果乳类食物进入结肠段，肠道内菌群可将乳糖分解为乳酸、短链脂肪酸等酸性物质，同时释放氢气和甲烷，引起腹胀，刺激肠道蠕动造成含气性腹泻。

一、新生儿乳糖酶发育特点从胎龄12周起就可在肠道中检测到乳糖酶，直到胎龄34周，乳糖酶一直缓慢增加，胎龄34周时乳糖酶活性相当于足月儿的30%，足月儿乳糖酶发育基本成熟［2］，因此早产儿比足月儿对乳糖的耐受性差。

在小肠上皮细胞刷状缘，乳糖由乳糖酶分解成半乳糖和葡萄糖，经小肠上皮细胞吸收后，约50%半乳糖在肝脏细胞内进一步代谢，经半乳糖激酶、半乳糖-1-磷酸尿苷酰转移酶和尿苷二磷酸半乳糖表异构酶转化，生成1-磷酸葡萄糖进入糖酵解路径释放能量。

乳糖亦可作为合成半乳糖苷的原料，组成脑苷脂成分，与婴儿出生后脑的迅速生长密切相关。

牛奶的成分

Nutritional Components in MilkThis page describes the function of nutritional components in milk: Energy, Water, Carbohydrate, Fat, Protein, Vitamins, Minerals, and Minor Biological Proteins & Enzymes. Links are provided to move the reader to pages that present the content of specific nutrients in milk, important background information on the chemistry of milk carbohydrate (lactose), fat, protein, and enzymes, and other topics that are covered in more depth in other sections of this website.EnergyThe energy in milk comes from its protein, carbohydrate and fat content, with the exception of skim milk that has virtually no fat. The energy content of some milk varieties is shown in the Nutrient Content Tables.Food provides energy to the body in the form of calories (kcal). There are many components in food that provide nutritional benefits, but only the macronutrients protein, carbohydrate and fat provide energy. The energy value of a food is calculated based on the calories provided by the amount of protein (4 kcal/gram), carbohydrate (4 kcal/gram), and fat (9 kcal/gram) that is present.WaterMilk is approximately 87% water, so it is a good source of water in the diet. The water content of some milk varieties is shown in the Nutrient Content Tables.Water does not provide a nutritional benefit in the same manner as proteins or vitamins, for example. However, water is extremely important in human metabolism. Water is a major component in the body. Water maintains blood volume, transports nutrients like glucose and oxygen to the tissues and organs, and transports waste products away from tissues and organs for elimination by the body. Water helps to lubricate joints and cushions organs during movement. Water maintains body temperature regulation through sweating. Lack of water (dehydration) results in fatigue, mental impairment, cramping, and decreased athletic performance. Severe dehydration can be life-threatening.CarbohydrateMilk is approximately 4.9% carbohydrate in the form of lactose. The lactose content of some milk varieties is shown in the Nutrient Content Tables.Carbohydrates are the primary source of energy for activity. Glucose is the only form of energy that can be used by the brain. Excess glucose is stored in the form of glycogen in the muscles and liver for later use. Carbohydrates are important in hormonal regulation in the body. Lack of adequate levels of glucose in the blood and carbohydrate stores leads to muscle fatigue and lack of concentration.Lactose is a disaccharide made up of glucose and galactose bonded together. Before it can be used by the body, the bond must be broken by the enzyme lactase in the small intestine. People that have decreased activity of lactase in the small intestine may have problems digesting lactose and this is referred to as lactose intolerance or malabsorption.FatMilk is approximately 3.4% fat. The fat content of some milk varieties is shown in the Nutrient Content Tables.Fats are a structural component of cell membranes and hormones. Fats are a concentrated energy source and are the main energy source used by the body during low intensity activities and prolonged exercise over 90 minutes. Fat is the main storage form of excess energy in the body. Fats cushion organs during movement.There are 2 fatty acids that are considered “essential” that cannot be made by the body and must come from the diet, and these are linoleic (18:2) and linolenic (18:3) acids. These fatty acids are used to synthesize the longer chain fatty acids arachidonic acid (AA, 20:4o-6), docopentaenoic acid (DPA, 22:4o-6), eicosapentaenoic acid (EPA, 20:5o-3) and docohexaenoic acid (DHA, 22:6o-3). These fatty acids are essential for the synthesis of hormones such as prostaglandins, thromboxanes, and leukotrienes that are involved in muscle contraction, blood clotting, and immune response.monounsaturated, The polyunsaturated fatty acids in milk fat include small amounts of the essential fatty acids linoleic and linolenic, and approximately 5% trans fatty acids. An important trans fatty acid in milk fat is conjugated linoleic acid (CLA, 18:2). There are several types (isomers) of CLA in milk that have been shown to inhibit cancer and help maintain lean body mass while promoting thefat. The health benefits of CLA consumption are discussed inHuman Health section.The health concerns associated with fats are often linked to the chemical differences in the fatty acids. Saturated and trans unsaturated fats have been associated with high blood cholesterol and heart disease. However, the relationships are not simple. The length of the fatty acid chain and source of the unsaturated bond (naturally-occurring or man-made through processing) can greatly influence the health consequences of a specific fat in the human diet. In addition, the genetics and health status of an individual greatly influences the impact of consuming different types of fats. The subject of fats and health is complex and constantly being updated in the medical literature. Issues relating to milk fat areThe content of cholesterol in milk is shown in the Nutrient Content Tables. Cholesterol is an important component of cell membranes and as a starting material for the production of bile salts and steroid hormones. The body manufactures cholesterol to ensure that an adequate level of cholesterol is available for body functions. High levels of blood cholesterol arerisk for heart disease and are discussed in thesection. Cholesterol is associated with fat so the8 oz serving of 2% milk contains 8% of the Daily Reference Intake (DRI) for cholesterol.ProteinMilk is approximately 3.3% protein and contains all of the essential amino acids. The protein content of some milk varieties is shown in the Nutrient Content Tables.Proteins are the fundamental building blocks of muscles, skin, hair, and cellular components. Proteins are needed to help muscles contract and relax, and help repair damaged tissues. They play a critical role in manybody functions as enzymes, hormones, and antibodies. Proteins may also be used as an energy source by the body.Nine amino acids must be obtained from the diet and are referred to as the “essential” am ino acids: leucine, isoleucine, valine, phenylalanine, tryptophan, histidine, threonine, methionine, and lysine. Proteins that contain all 9 essential amino acids are often called “complete” proteins. Proteins of animal origin and soy are complete proteins, whereas proteins from grains and legumes are missing 1 or more of the essential amino acids, which means that consumers must eat complementary foods in order to get all of the essential amino acids.casein and whey proteins are present in milk, yogurt, and ice cream. In most cheeses the casein is coagulated to form the curd, and the whey is drained leaving only a small amount of whey proteins in the cheese. During cheese making, the 6-casein is cleaved between specific amino acids and results in a unique protein fragment that is drained with the whey. This fragment, called milk glycomacropeptide, does not have any phenylalanine and can be used as a source of protein for people with phenylketonuria, the inability to digest proteins that contain phenylalanine. Whey proteins have become popular ingredients in foods as an additional source of protein or for functional benefits. Whey proteins are used as a protein source in high protein beverages and energy bars targeted to athletes. Some examples include the use of whey proteins to bind water in meat and sausage products, provide a brown crust in bakery products, and provide whipping properties that replace a portion of egg whites.Whey proteins contain immunoglobulins which are important in the immune responses of the body. Whey proteins contain branched chain amino acids (leucine, isoleucine, and valine) and have been proposed to have some benefits to athletes for muscle recovery and for preventing mental fatigue.VitaminsVitamins have many roles in the body including metabolism co-factors, oxygen transport and antioxidants. They help the body use carbohydrates, protein, and fat. The functions of vitamins are described below in alphabetical order.The content of vitamin A in milk is shown in the Nutrient Content Tables. Vitamin A is a fat soluble vitamin involved in vision, gene expression, reproduction, and immune response. The compounds with vitamin A activity are called retinoids and are found in foods in different forms –typically animal foods provide retinol and retinyl esters, and plant foods provide ß-carotene, a starting molecule (precursor) for vitamin A synthesis. Milk contains retinol, retinyl esters, and ß-carotene. Dairy products are a good source of vitamin A, although the vitamin A content will vary with the fat content of the product. An 8 oz serving of 2% milk contains approximately 15% of the daily reference intake (DRI) for vitamin A.The content of thiamin (vitamin B1) in milk is shown in the Nutrient Content Tables. Thiamin is a water soluble vitamin that is an enzyme cofactor involved in the metabolism of carbohydrates and branched chain amino acids. An 8 oz serving of 2% milk contains approximately 8% of the DRI for thiamin.The content of riboflavin (vitamin B2) in milk is shown in the Nutrient Content Tables. Riboflavin is a water soluble vitamin that is an enzyme cofactor involved in electron transport reactions. Milk is a recommended source of riboflavin and an 8 oz serving of 2% milk provides approximately 35% of the DRI for riboflavin.The content of niacin(vitamin B3) in milk is shown in the Nutrient Content Tables. Niacin is a water soluble vitamin that is an enzyme cofactor involved in electron transport reactions required for energy metabolism. There is a small amount of niacin in milk, an 8 oz serving of 2% milk contains less than 2% of the DRI for niacin.The content of pantothenic acid (vitamin B5) in milk is shown in the Nutrient Content Tables. Pantothenic acid is a water soluble vitamin that is an enzyme cofactor in fatty acid metabolism. Milk is a good source of pantothenic acid and an 8 oz serving of 2% milk contains approximately 17% of the DRI for pantothenic acid.The content of vitamin B6 (pyridoxine) in milk is shown in the Nutrient Content Tables. Vitamin B6 is a water soluble vitamin involved in the metabolism of proteins and glycogen (energy stored in the liver and muscles), and in the metabolism of sphingolipids in the nervous system. An 8 oz serving of 2% milk contains approximately 7% of the DRI for vitamin B6.The content of vitamin B12 (cobalamin) in milk is shown in the Nutrient Content Tables. Vitamin B12 is a water soluble vitamin involved in protein metabolism and blood functions. Milk is a recommended source of vitaminB12. An 8 oz serving of 2% milk contains approximately 47% of the DRI for vitamin B12.The content of vitamin C in milk is shown in the Nutrient Content Tables. Vitamin C is a water soluble vitamin that is an important antioxidant. It has a role in collagen formation in connective tissue and helps in iron absorption and healing of wounds and injuries. There is a negligible amount of vitamin C in milk, and a serving of milk contains less than 1% of the DRI for Vitamin C.The content of vitamin D in milk is shown in the Nutrient Content Tables. Vitamin D is a fat soluble vitamin that is important in maintaining blood calcium and phosphorus balance and assists calcium metabolism. Milk is typically fortified with vitamin D. Fortified milk is a good source of vitamin D, and an 8 oz serving of 2% milk contains over 50% of the DRI for vitamin D.The content of vitamin E in milk is shown in the Nutrient Content Tables. Vitamin E is a fat soluble vitamin that has antioxidant activity. The compounds with vitamin E activity are the tocopherols and tocotrienols. Milk contains a small amount of vitamin E, which increases with increasing fat content of dairy products. An 8 oz serving of whole milk contains 1% vitamin E, and an 8 oz serving of 2% milk contains only 0.5% of the DRI for vitamin E.The content of folate in milk is shown in the Nutrient Content Tables. Folate is one of the water soluble B vitamins. Folate is an enzyme cofactor important in the metabolism of proteins and nucleic acids and blood functions. There is a small amount of folate in milk. An 8 oz serving of 2% milk contains 3% of the DRI for folate.The content of vitamin K in milk is shown in the Nutrient Content Tables. Vitamin K is a fat soluble vitamin involved in blood clotting, bone metabolism, and protein synthesis. Milk contains a small amount of vitamin K, which increases with the fat content in dairy products. An 8 oz serving of milk contains less than 1% of the DRI for vitamin K.MineralsMinerals have many roles in the body including enzyme functions, bone formation, water balance maintenance, and oxygen transport. They help the body use carbohydrates, protein, and fat. The functions of minerals are described below in alphabetical order.Calcium plays an essential role in bone formation and metabolism, muscle contraction, nerve transmission and blood clotting. Dairy products are a significant source of calcium in the diet. Milk is a recommended source of calcium, and an 8 oz serving contains almost 30% of the DRI for calcium.The content of copper in milk is shown in the Nutrient Content Tables. Copper is a component of enzymes used in iron metabolism. Milk contains a small amount of copper. An 8 oz serving of 2% milk contains approximately 3% of the DRI for copper.The content of iron in milk is shown in the Nutrient Content Tables. Iron is a component of blood and many enzymes. It is involved in blood metabolism and oxygen transport. Milk contains a small amount of iron, and an 8 oz serving of milk contains less than 1% of the DRI for iron.The content of magnesium in milk is shown in the Nutrient Content Tables. Magnesium is an enzyme cofactor and is important in bone metabolism. Milk is a recommended source of magnesium, and an 8 oz serving of 2% milk contains approximately 7% of the DRI for magnesium.The content of manganese in milk is shown in the Nutrient Content Tables. Manganese is involved in bone formation, and in enzymes involved in amino acid, cholesterol, and carbohydrate metabolism. There is a small amount of manganese in milk. An 8 oz serving contains less than 1% of the DRI.The content of phosphorus in milk is shown in the Nutrient Content Tables. Phosphorus is involved in maintaining body pH, in storage and transfer of energy, and in nucleotide synthesis. Milk is a recommended source of phosphorus, and an 8 oz serving of milk contains over 30% of the DRI for phosphorus.The content of potassium in milk is shown in the Nutrient Content Tables. Potassium is an electrolyte that is important in the maintenance of water balance, blood volume and blood pressure. Dairy products are a recommended source of potassium, and an 8 oz serving of milk contains approximately 8% of the DRI for potassium.The content of selenium in milk is shown in the Nutrient Content Tables. Selenium is important in oxidative stress response, electron transport, and regulation of thyroid hormone. Milk is a good source of selenium, and an 8 oz serving of 2% milk contains approximately 11% of the DRI for selenium.Sodium is an electrolyte that is important in the maintenance of water balance and blood volume. An 8 oz serving of milk contains approximately 7% of the DRI for sodium.The content of zinc in milk is shown in the Nutrient Content Tables. Zinc is a component of many enzymes and proteins, and is involved in gene regulation. Milk is a good source of zinc, and an 8 oz serving contains approximately 10% of the DRI for zinc.Minor Biological Proteins & EnzymesOther minor proteins and enzymes in milk that are of nutritional interest include lactoferrin and lactoperoxidase. There are many other enzymes in milk but these do not have a role in human nutrition.Lactoferrin is an iron binding protein that plays a role in iron absorption and immune response. Many other functions of lactoferrin have been proposed, but their confirmation is still under study, including protection against bacterial and viral infections, and it's role in inflammatory response and enzyme activity. The use of lactoferrin as an antimicrobial agent is discussed in the section on AntibacterialLactoperoxidase is an enzyme that, in the presence of hydrogen peroxide and thiocyanate, has antibacterial properties. The use of lactoperoxidase as an antimicrobial agent is discussed in the section on Antibacterialantimicrobial protection to fresh milk because hydrogen peroxide is not normally present in milk – it must be added to activate this system.Lipases, a group of enzymes that break down fats, are present in milk but are inactivated by pasteurization, which increases the shelf life of milk.A popular belief among raw milk consumers is that the native lipase in milk plays an important role in the digestion of fat. Fat digestion begins in the stomach with gastric lipase, and the majority of fat digestion occurs in the small intestine, using enzymes secreted by the pancreas. The relative importance of the native milk lipase in digestion compared to the pancreatic lipases is not clear.Lactase (ß-galactosidase) is the enzyme responsible for the breakdown of lactose into glucose and galactose for digestion. There is no lactase present in fresh milk. Any lactase present in milk products comes fromlactic acid bacteria that are either added to milk on purpose, as in the case of yogurt and cheese, or that enter milk from airborne or other contamination. A popular belief is that people with lactose intolerance are able to drink raw milk but not pasteurized milk because the lactase present in raw milk is inactivated during pasteurization. Because there is no lactase present in fresh milk, this concept is a myth. People with lactose intolerance have, themselves, lower levels of lactase which creates problems when it comes to digesting large amounts of lactose in a timely manner. Naturally occurring lactase used to digest milk is normally secreted by the small intestine. Lactase found in any lactic acid bacteria present will minimally help to digest lactose when it is released as the milk is digested in the small intestine.Updated 02/16/07。

酒精在人体内是如何代谢的

酒精在人体内是如何代谢的?摄入体内的酒精（乙醇）除极少量经呼吸和尿排泄外，95％以上在体内分解代谢，而肝脏是乙醇代谢的重要器官。

在周围组织内进一步氧化为二氧化碳和水，其余者在肝内进入糖和（或）脂肪池，或进入三羧酸循环而氧化分解。

乙醇和乙醛都可以使人出现头晕、脸红、心跳过速，甚至神态不清等酒精中毒现象，但乙醛的作用比乙醇更大。

酒精在肝内的代谢带来多种后果：刺激脂肪的合成，消耗大量的氧，给肝脏造成缺氧状态，干扰肝细胞ATP的产生，影响蛋白质的合成，造成直接损伤，出现肝功能障碍。

酒的化学成分是乙醇，在消化道内不需要消化即可吸收，吸收快而且完全。

一般在胃中吸收20%，其余80%被十二指肠和空肠吸收。

胃内有无食物、胃臂的功能状况、饮料含酒精的多少以及饮酒习惯均可影响酒精的吸收。

空腹饮酒时，15分钟吸收50%左右，半小时吸收60%－90%，2－3小时吸收100%。

酒精还能通过皮肤和呼吸道进入体内，人在有酒精的空气中工作，有可能因吸入酒精而中毒。

酒对人体的作用与其浓度和吸收速度成正比，即浓度越高，吸收速度越快，作用也越明显。

进入人体内的酒，约10%由呼吸道、尿液和汗液以原形排出。

因此，饮酒者都是“一身酒气”，也可用呼吸测酒器检测出来。

其余90%经由肝脏代谢。

乙醇首先被氧化成乙醛，脱氢后转化为乙酸，最后氧化成二氧化碳和水排出体外，同时放出大量的热能。

但乙醇的氧化，并不受血液中酒精浓度高低的影响，也不按机体的需要进行，它只按其固定的规律进行，即肝脏以每小时10毫升的速度将酒精分解成水，二氧化碳和糖，直至消化完为止。

对肠胃道的影响许多因素会影响乙醇在肠胃道的吸收，如大家所熟知的，空胃饮酒所引起的酒精毒害最显著。

食物不但可以减慢乙醇的吸收速率，并可延缓血液中酒精高峰期的到达；除此之外，食物的成分及量都会直接影响乙醇在肠胃道的吸收；例如，可溶解的碳水化合物对于延缓乙醇吸收的作用大于蛋白质及脂肪。

其它影响胃及小肠吸收乙醇的因素有：乙醇浓度、黏膜的特性及其表面积、黏膜微血管血流量和胃的蠕动。

肚子不舒服肠鸣声很大英语作文

肚子不舒服肠鸣声很大英语作文The Symphony of Intestinal Discomfort.The symphony of intestinal discomfort, a cacophony of gurgling and rumbling, reverberates within the depths of my abdomen. It's an unwelcome orchestra, a chorus of discontent that announces to the world the turmoil within.Intestinal gas, the culprit behind this sonic assault, is a byproduct of digestion. As our bodies break down food, bacteria in our digestive system feast upon theindigestible remnants, producing gases such as hydrogen, carbon dioxide, and methane. These gases accumulate in the intestines, and when they reach a critical volume, they seek release through the path of least resistance: our rear ends.While flatulence is a normal part of digestion, excessive gas production can be a sign of underlying digestive issues. Certain foods, such as beans, lentils,and cruciferous vegetables, are known to promote gas formation due to their high fiber content, which isdifficult for bacteria to digest. Other potential culprits include lactose intolerance, irritable bowel syndrome (IBS), and celiac disease.Lactose intolerance, a condition that affects about 65% of the world's population, occurs when the body lacks the enzyme lactase, which is necessary to break down lactose, the sugar found in milk and dairy products. When lactose-intolerant individuals consume these products, bacteria in the intestines ferment the undigested lactose, producinggas as a byproduct.Irritable bowel syndrome (IBS) is a common functional bowel disorder that affects the large intestine. It's characterized by abdominal pain, bloating, and alteredbowel habits. While the exact cause of IBS is unknown, it's believed to be related to abnormalities in the gut-brain axis, the communication pathway between thegastrointestinal tract and the brain.Celiac disease is an autoimmune disorder that triggers an immune response when gluten, a protein found in wheat, rye, and barley, is consumed. This immune response damages the lining of the small intestine, impairing its ability to absorb nutrients. Gas is a common symptom of celiac disease due to the malabsorption of food and the subsequent fermentation of undigested carbohydrates by bacteria in the intestines.Excessive intestinal gas can not only be embarrassing but also uncomfortable and disruptive to daily life. It can cause abdominal pain, distension, and a feeling of fullness. In some cases, gas can also lead to nausea and vomiting.Managing intestinal gas requires a multipronged approach that includes dietary modifications, lifestyle changes, and, in some cases, medication. Dietary interventions involve identifying and limiting the intakeof gas-producing foods. This may include reducing the consumption of beans, lentils, cruciferous vegetables, and dairy products for lactose-intolerant individuals.Lifestyle changes that can help reduce gas production include eating smaller meals more frequently, chewing food thoroughly, and avoiding carbonated beverages, which can contribute to swallowed air. Additionally, regular exercise can help promote intestinal motility, reducing the opportunity for gas to build up in the intestines.In some cases, over-the-counter medications, such as simethicone or activated charcoal, may be used to relieve gas symptoms. Simethicone works by breaking down gas bubbles in the intestines, while activated charcoal absorbs and traps gas.If excessive intestinal gas persists despite dietary modifications, lifestyle changes, and over-the-counter medications, it's important to consult a healthcare professional to rule out any underlying medical conditions that may be contributing to the problem.。

分子生物学词汇（L）

分子生物学词汇(L)lac operon 乳糖操纵子laccase 漆酶lacmus 石蕊lactalbumin 乳白蛋白，乳清蛋白lactam 内酰胺lactamase 内酰胺酶lactase 乳糖酶lactate 乳酸；乳酸盐、酯、根lactenin 乳抑菌素lacticifer [植物]乳汁器lacticin 乳链球菌素lactoalbumin 乳白蛋白lactobacillus 乳杆菌属lactobionic acid 乳糖酸lactococcin 乳球菌素lactococcus 乳球菌属lactoferritin 乳铁蛋白[一种金属结合蛋白]lactogen 催乳素lactoglobulin 乳球蛋白lactol 内半缩醛lactone 内酯lactoperoxidase 乳过氧化物酶lactopontin 乳桥蛋白[与骨桥蛋白相关]lactosaminoglycan 乳糖胺聚糖lactose 乳糖lactotransferrin 乳运铁蛋白ladder 梯，（序列）梯[如指dna测序凝胶的放射自显影影像或大小不同的分子量标准参照物的电泳图谱]laemmli buffer system laemmli缓冲液系统[一套用于蛋白质sds-聚丙烯酰胺凝胶电泳的缓冲液系统]laevo isomer 左旋异构体lag phase [细胞生长曲线的]延滞期，滞后期lagging strand 后随链lamiflow 片流[膜][具有流动性的片层膜]lamin 核纤层蛋白lamina [植物]叶片；[真菌]囊盘总层laminaribiose 昆布二糖laminarin 昆布多糖laminarinase 昆布多糖酶laminariose 昆布糖laminin 层粘连蛋白lampbrush chromosome 灯刷染色体landfill gas [废物]掩埋气[含50%～65%的甲烷和30～40%的二氧化碳]lane [电泳]泳道langerhans cell 朗氏细胞[见于皮肤和淋巴器官]langmuir adsorption isotherm 朗缪尔吸附等温式lanosterol 羊毛固醇，羊毛甾醇lanthionine 羊毛硫氨酸lanthiopeptin 羊毛硫肽lantibiotics 羊毛硫抗生素[抗菌活性很高的肽类抗生素，含有羊毛硫氨酸组成的硫桥]lapinization 兔化法[通过兔体使病毒等减毒]lapinized virus 兔化（病）毒lariat 套索[真核mrna剪接过程中形成的分枝状中间体]laser crosslinking 激光交联[通过紫外激光照射使蛋白质与核酸发生交联]lassa virus 拉沙病毒[属沙粒病毒科]late gene 晚期基因[可特指病毒]latency 潜伏状态lateral element [联会复合体]侧成分，侧体[由侧线组成，其两侧与染色质纤维毗联并具有横纹带]latex 乳汁，乳胶[见于植物]laticifer 乳汁器laticotoxin 扁尾蛇毒素lavendulin 淡紫灰菌素lavendustin （灰）薰草菌素lawn 菌苔leader 前导区，前导序列leavening 发酵lecithin 卵磷脂lectin 凝集素legcholeglobin 豆胆绿蛋白leghemoglobin 豆血红蛋白legionella 军团菌属legionella pneumophilia 嗜肺军团菌legumin 豆球蛋白leishmania 利什曼原虫属lens crystalline 晶状体晶体蛋白lentinan 香菇多糖lentivirus 慢病毒属[包括人免疫缺损病毒]lepromin 麻风菌属leptonema 细线期leptospira 钩端螺旋体属leptotene stage 细线期lettuce necrotic yellows virus 莴苣坏死黄化病毒leucine zipper 亮氨酸拉链[亮氨酸出现周期性重复的一种dna结合域，可形成卷曲螺旋结构]leucoagglutinin 白细胞凝集素leucoanthocyanidin 无色花色素，白花色苷元leucoanthocyanin 无色花色苷，白花色苷leucocidin 杀细胞素leucocyan 藻蓝素leucokinin 白细胞激肽leucolysin 白细胞溶素，溶白细胞细胞素leucomycin 柱晶白霉素leuconostoc 嗜柠檬酸明串球菌属leucoplast 白色体leucopyrokinin 白细胞焦激肽[n端为焦谷氨酸] leucoregulin 白细胞调节素leucosialin 白涎素leucosin 硅藻多糖[硅藻中的β-1,3-葡聚糖]；麦清蛋白leucotriene 白（细胞）三烯leucovorin 甲酰四氢叶酸leupeptin 亮抑蛋白酶肽，亮抑酶肽levan 果聚糖levisomer 左旋异构体levivirus 轻小病毒[一类噬菌体]levolose 果糖levorotary 左旋的levorotatory 左旋的levulinate 乙酰丙酸，乙酰丙酸酯、盐、根liberin 释放素[类名，包括促性腺素释放素、促乳素释放素等] library 文库lichen 地衣lichenan 地衣淀粉lichenin 地衣淀粉ligament 韧带ligamenta （复数）韧带ligand 配体ligandin 配体蛋白[见于肝细胞，可结合胆红素及其他阴离子]ligase 连接酶ligase chain reaction lcr,连接酶链式反应[两对互补寡核苷酸的连接产物的指数式积累]ligation 连接反应lignan 木脂体lignanoid 木脂体lignanolide 木脂内酯lignification 木质化（作用）lignin 木（质）素lignocellulose 木（质）素纤维素limonoid 柠檬苦素类化合物limosphere 顶体球[见于植物]limulus test 鲎试验[用于检定内毒素]linear plasmid 线性质粒[可特指以线型分子形式存在于细菌内的质粒]linker 接头linking number 连接数[闭环dna中两条链相互缠绕的总次数] linoleate 亚油酸lipase 脂肪酶lipid 脂类lipoamide 硫辛酰胺lipocortin 脂皮质蛋白[介导糖皮质素的抗炎作用的一组磷脂酶a2抑制蛋白]lipofectamine reagent [商]lipofectamine试剂[由lifetechnologies公司（brl）生产的商品化细胞转染试剂，是合成的阳离子脂类dospa和dope的3:1（w/w）混合物]lipofection 脂（质）转染（法）lipofuscin 脂褐质lipogenesis 脂肪生成lipoid 类脂lipolysis 脂解（作用）lipomodulin 脂调蛋白[一种磷脂酶抑制蛋白]lipopectace reagent [商]lipopectace试剂[由lifetechnologies公司（brl）生产的商品化细胞转染试剂，是合成的阳离子脂类ddab和dope的1:2.5（w/w）混合物]lipopectin reagent [商]lipopectin[由lifetechnologies公司（brl）生产的商品化细胞转染试剂，是dotma和dope的1：1（w/w）混合物]lipopeptide 脂肽lipophilic 亲脂的lipophobic 疏脂的lipophosphoglycan 脂磷（酸）聚糖lipopolysaccharide 脂多糖lipoprotein 脂蛋白liposome 脂质体lipothrixvirus 脂毛病毒[一类噬菌体]lipotropic hormone 促脂解素lipotropin 促脂解素lipovitellin 卵黄脂磷蛋白lipoxygenase 脂（肪）氧合酶liquefaction 液化（作用）liquid culture method 液体培养法[特指小量制备λ噬菌体dna 的一种方法]liquification 液化liquiritigenin 甘草根亭配基liquiritin 甘草根亭liquiritoside 甘草根糖苷lissamine rhodamine 丽丝胺罗丹明listeria 李斯特菌属lithium diiodosalicylate 二碘水杨酸锂[可用作去污剂]lithotroph 无机营养生物，无机营养菌litmus 石蕊litorin 雨滨蛙肽liverwort 苔类（植物）livetin 卵黄蛋白lizard venom 蜥蜴毒loading slot 加样槽lobopodia （复数）叶足lobopodium 叶足loci （复数）基因座locus 基因座locus controlregion 基因座控制区[在转基因实验中，其调控作用可使基因表达对整合位点不敏感，而仅仅取决于转基因的拷贝数，如见于珠蛋白基因]lod 优势对数lodging 倒伏long period interspersion 长周期散布[中度重复序列与非重复序列在基因组中相隔较长距离交替出现]loopout 环，环出序列loricrin 兜甲蛋白luciferase 萤光素酶luciferin 萤光素lucigen 光泽精lucite [商]聚甲基丙烯酸甲酯有机玻璃[杜邦公司商标]luliberin 促黄体素释放素lumen 流明[光通量单位]；腔lumichrome 光色素，二甲异咯嗪lumiflavin 光黄素，三甲异咯嗪luminol 鲁米诺，氨基苯二酰一肼lupeol 羽扇豆醇lupeose 水苏（四）糖lupulin 蛇麻素lupus anticoagulant 狼疮抗凝物luteinization 黄体化luteolysis 黄体溶解luteovirus 黄矮病毒组[一组植物病毒，模式成员是大麦黄矮病毒] lutidine 二甲基吡啶lutropin 促黄体素，黄体生成素lyase 裂合酶lycopene 番茄红素[胡萝卜素生物合成的中间物]lydimycin 利迪霉素lymphoblast 淋巴母细胞，成淋巴细胞，原淋巴细胞lymphogenesis 淋巴生成lymphokine 淋巴因子lymphoma 淋巴瘤lymphophoresis 淋巴去除术lymphopoiesis 淋巴细胞生成lymphotoxin 淋巴毒素[即β-肿瘤坏死因子]lymphotropic 嗜淋巴细胞的lyoenzyme 可溶酶，（细）胞外酶lyophilic 亲液的lyophilization 冷冻干燥lyophilized 冻干的lyophilizer （冷）冻干（燥0机lyophobic 疏液的lyophozyme [商]冻干酶[是由life technologies公司（brl）以冷冻干燥形式供应的工具酶]lysate 裂解物，裂解液lyse 裂解lysine 赖氨酸lysogen 溶源体，溶源菌lysogenesis 溶源现象lysogenic immunity 溶源性免疫[原噬菌体阻碍另一同类噬菌体基因组的建立]lysogenization 溶源化lysogeny 溶源性，溶源状态lysolecithin 溶血卵磷脂lysophosphatidylcholine 溶血卵磷脂lysophospholipase 溶血磷脂酶lysophospholipid 溶血磷脂lysopine 章鱼赖氨酸，赖氨章鱼碱[即n-α-（1-羧乙基）-l-赖氨酸，见于冠瘿瘤]lysosome 溶酶体lysostaphin 溶葡（萄）球菌素lysozyme 溶菌酶lyssavirus 狂犬（病）病毒属lyticase 溶细胞酶lyxose 来苏糖。

Lactose intolerance and the irritable colon

1. Greenbergher NJ, Isselbacher KJ: Disorders of absorption, in Isselbacher KJ, Adams RD, Peterdorf RG, et al (eds): Harrison's Principles of Internal Medicine, ed 9. New York, McGraw-Hill, 1980. 2. Welsh JD: Isolated lactase deficiency in humans: Report on 100 patients. Medicine (Baltimore) 1970; 49:257-277. 3. Fung W, Kho KM: The importance of milk intolerance in patients presenting with chronic (nervous) diarrhea. Aust NZ JMed 1971; 4:374-376. 4. Pena AS, Truelove SC: Hypolactasia and the irritable bowel syndrome. Scand J Gastroenterol 1972; 5:433-438.
substantial modification of their symptoms from a lactose-free diet. The British study4 found lactose intolerance in nine of 73 native Britons and seven of eight non Britons who suffered from irritable bowel syndrome. Of these 16 sufferers, only six obtained remission of symptoms with a lactose-free diet. In each case, some patients had lactose intolerance which contributed little or nothing to their symptoms. Lactose intolerance may be suspected in those who suffer abdominal pain, distension, nausea and diarrhea after drinking milk. Some sufferers may have arrived at the correct conclusion by bitter experience. In a group of physicians attending a postgraduate course in Scotland,7 5% of whites and 34% of non whites beCAN. FAM. PHYSICIAN Vol. 28: NOVEMBER 1982

乳酸代谢英语

Lactate Metabolism: An Insight into its Roleand ProcessesLactate, a key metabolite in biology, plays a crucial role in energy production and cellular metabolism. Also known as lactic acid, it is produced during anaerobic glycolysis, a process that occurs when cells do not have enough oxygen to carry out aerobic respiration. Thisarticle delves into the intricacies of lactate metabolism, exploring its significance, processes, and the role it plays in various physiological and pathological conditions. **The Basics of Lactate Metabolism**Lactate metabolism primarily involves the conversion of pyruvate, a product of glycolysis, into lactate. This conversion is catalyzed by the enzyme lactate dehydrogenase (LDH). Under anaerobic conditions, when cells lack oxygen, pyruvate is reduced to lactate, releasing energy in the form of ATP. Lactate can then be transported to other tissues, where it can be reconverted back to pyruvate and further metabolized.**The Role of Lactate in Physiology**Lactate metabolism is essential for energy production during intense exercise or hypoxic conditions. During exercise, muscles consume oxygen rapidly, and when the supply cannot meet the demand, anaerobic glycolysis occurs, producing lactate. Lactate is then transported to the liver, where it is converted back to glucose through the processof gluconeogenesis. This recycling of lactate allows for continuous energy production during exercise.**Pathological Conditions Associated with Lactate Metabolism**Elevated lactate levels can be indicative of various pathological conditions. High lactate levels in the blood can occur in cases of hypoxia, such as heart failure or stroke, where oxygen supply to tissues is compromised. Lactate acidosis, a condition characterized by a buildup of lactate in the blood, can also occur in conditions like diabetes, sepsis, and cancer. In these cases, lactate production exceeds its removal, leading to acidosis and potentially life-threatening consequences.**Conclusion**Lactate metabolism is a complex process that plays a pivotal role in energy production and cellular metabolism. Understanding the intricacies of lactate metabolism, from its production to its role in physiological and pathological conditions, is crucial for comprehending the fundamental mechanisms of cellular energy production andits dysregulation in disease states. As research in this field continues to evolve, so does our understanding of the role of lactate in health and disease.**乳酸代谢：深入探索其作用与过程**乳酸，生物学中的关键代谢产物，在能量产生和细胞代谢中发挥着至关重要的作用。

氢呼气试验文献整理

（备注：氢呼气试验为金标准基因检测为新方法）
2、小肠菌群过度生长：
1）IBS，正常与IBS对照组进行氢呼气试验，IBS组氢呼气增多，但小肠菌群过度生长是否是IBS的病因仍具争议。
????【11】Ford?AC,?Spiegel?BM,?Talley?NJ,?Moayyedi?P.?Small?intestinal?bacterial?overgrowth?in?irritable?bowel?syndrome:?systematic?review?and?meta-analysis.?Clin?Gastroenterol?Hepatol.?2009?Dec;7(12):1279-86.?Epub?2009?Aug?12.?Review.?PubMed?PMID:?19602448.?IBS中小肠菌群过度生长：荟萃分析。
Fridge?JL,?Conrad?C,?Gerson?L,et?al.?Risk?factors?for?small?bowel?bacterial?overgrowth?in?cystic?fibrosis.?J?Pediatr?Gastroenterol?Nutr.?2007?Feb;44(2):212-8.?PubMed?PMID:?17255834.胆囊纤维化患者小肠菌群过度生长的风险因素。
2）小肠菌群过度生长与药物
????【12】Lombardo?L,?Foti?M,?Ruggia?O,?Chiecchio?A.?Increased?incidence?of?small?intestinal?bacterial?overgrowth?during?proton?pump?inhibitor?therapy.?Clin?Gastroenterol?Hepatol.?2010?Jun;8(6):504-8.?Epub?2010?Jan?6.?PubMed?PMID:20060064.PPI治疗期间小肠菌群过度生长发病率增加。

乳糖酶缺乏综合征

乳糖酶缺乏综合征
单文华
【期刊名称】《江西医药》
【年(卷),期】1992(027)003
【摘要】乳糖酶缺乏综合征(Lactase deficiencysyndrome LDS)系由于小肠粘膜乳糖酶缺乏致使乳糖消化吸收障碍而引起的以腹胀、腹泻、腹痛为主的临状症群。

人群 LDS 一般分为乳糖吸收不良症(Lactose malabsorption LM)和乳糖不耐受症(Lactose intolerance,LI)。

近年来,据我国调查发现,在汉族人群中 LM 占70～80%;LI 在小儿中为20.5%,成人中高达86%。

可见此综合征在我国发病率是颇高的。

随着我国人民生活的改善,饮食结构的改变,饮用牛奶的人群及用量的增多,本综合征的发病率将更会增高。

为此,笔者给予综合介绍,以引起同道们的重视。

【总页数】4页(P181-184)
【作者】单文华
【作者单位】无
【正文语种】中文
【中图分类】R591
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2.住院新生儿乳糖酶缺乏及其体格生长的随访研究 [J], 叶环;饶燕晓;徐琛;俞栋;阮欢
3.婴儿乳糖酶缺乏的相关因素Logistic回归分析 [J], 俞栋; 叶环; 徐琛; 阮欢
4.乳糖酶缺乏与乳糖不耐受症状的临床特点分析 [J], 张宸;郑中文;布小玲;许凌丽;胡裕荣;宁雨露;綦佩妍;赖卓成;沙卫红
5.用双标稳定同位素技术分析乳糖酶缺乏者小肠粘膜乳糖酶活性 [J], 钟燕;黄承钰;阴文娅;Vonk RJ
因版权原因，仅展示原文概要，查看原文内容请购买。

胃肠因素对成人乳糖不耐受的作用

胃肠因素对成人乳糖不耐受的作用钟燕;黄承钰;阴文娅【期刊名称】《世界华人消化杂志》【年(卷),期】2005(13)13【摘要】目的:研究胃肠因素对成人乳糖酶缺乏者出现不同程度乳糖不耐受症状的作用. 方法:乳糖酶缺乏者(呼气H2浓度>20μmol/mol)43例,根据乳糖不耐受症状评分结果分为乳糖吸收不良(lactose malabsorption,LM)组和乳糖不耐受(lactose intolerance,LI) 组;LI组根据有无腹泻症状又分为轻度(LIa)及重度(LIb)乳糖不耐受组.采用双标记稳定同位素13C-乳糖/2H-葡萄糖负荷试验计算受试者的乳糖消化指数、乳糖消化量和胃排空时间,并采用H2呼气试验分析受试者摄入一定量乳糖之后的口-结肠转运时间、累积H2呼出量. 方法:LM组的乳糖消化指数和乳糖消化量(0.47±0.15和11.8±3.9 g)显著高于LI组(0.34±0.14和8.5±3.5 g)(P= 0.008),胃排空时间和口-结肠转运时间(44.0±14.4 min 和105 min,60-120 min)显著长于LI组(33.9±12.2 min和60 min,30-90 min)(P=0.021和P=0.003);乳糖消化指数与口-结肠转运时间之间呈显著正相关(r=0.30,P=0.048). 而LIa组和LIb组之间以上各项指标均无显著性差异. 结论:乳糖消化能力(主要受乳糖酶活性决定)、胃排空时间和口-结肠转运时间是引起乳糖酶缺乏者出现LI症状的主要原因,但不是引起不同严重程度LI症状产生的主要原因,这种症状差异的产生可能与其他因素,如结肠代谢因素的作用有关.【总页数】3页(P1618-1620)【关键词】乳糖不耐受;口-结肠转运时间;成人;胃肠;乳糖酶缺乏;胃排空时间;葡萄糖负荷试验;乳糖消化;乳糖吸收不良;不耐受症状;稳定同位素;显著性差异;不同程度;症状评分;腹泻症状;试验分析;消化能力;严重程度;代谢因素;受试者;指数【作者】钟燕;黄承钰;阴文娅【作者单位】四川大学华西公共卫生学院营养与食品卫生教研室【正文语种】中文【中图分类】R153.2;R574.5【相关文献】1.外源性乳糖酶对健康成人乳糖吸收和乳糖不耐受症状的影响 [J], 何梅;杨月欣;边立华;崔红梅;王竹2.早期新生儿乳糖吸收不良与乳糖不耐受筛查及影响因素探讨 [J], 郑直;虞人杰3.新生儿乳糖吸收不良与乳糖不耐受筛查及影响因素分析 [J], 刘艳霞; 曾慧慧; 王玉双; 李静; 郭蕾蕾; 郑楠4.轮状病毒性肠炎患儿乳糖不耐受与肠炎转归的相关性及影响乳糖不耐受转归的因素分析 [J], 何素平5.轮状病毒性肠炎患儿乳糖不耐受与肠炎转归的相关性及影响乳糖不耐受转归的因素分析 [J], 刘小茹;徐文渊因版权原因，仅展示原文概要，查看原文内容请购买。

甲烷和氢呼气使用手册

甲烷和氢呼气使用手册甲烷和氢呼气试验解决了很多其它试验难以检查的项目以及一些无法完成的检测盲区，譬如胰腺功能检查、小肠细菌过增长、肠道通过时间以及乳糖酶缺乏症，都是其它检查方法都不能完成的“盲区”。

呼气检测方法是一种无创、无痛、准确、环保、快捷技术，具有广泛的临床应用价值。

检测前需要做好准备工作。

∙禁食12小时∙头天晚餐不吃不易消化的食物。

∙晚饭后至测试前不喝含糖的饮料。

∙清晨清洁口腔。

∙不吸烟、不喝酒。

∙避免剧烈运动。

空腹基础值的解释：H2 <10ppm：正常H2 10-20ppm：禁食不充分或晚餐进食不宜消化食物。

H2 >20ppm：考虑小肠细菌过度生长该技术的应用范围涵盖40%-60%的胃肠疾病，消化科、儿科、体检中心、内分泌科、胃肠及肝胆外科等临床科室都可开展。

1填补国内外胰腺功能检查的盲区，诊断胰腺炎后的胰腺损伤程度可评价糖尿病的病因和预后。

2诊断和治疗不明原因的长期腹泻及腹胀、消化不良综合症、儿童和成人的乳糖酶缺乏症、小肠细菌过度生长。

3慢性便秘的病因测定肠道通过时间和回盲瓣功能障碍。

4诊断糖尿病患者自主神经节病变所致的胃肠动力异常。

5对慢性结肠炎合并碳水化合物吸收不良，确定其肠道感染状况及是否有吸收不良暨严重程度。

6评价亚健康状况常伴有小肠细菌过度生长最常用的几种氢呼气试验1、支链淀粉呼气试验(测定胰腺外分泌功能)用一定负荷量的支链淀粉作试验餐，可诊断胰腺损伤程度，这个试验填补目前国内外胰腺功能无法检测的盲区。

评估胰腺炎后胰腺功能损伤和糖尿病患者的病因和预后。

2、乳果糖呼气试验(用于小肠细菌过量增长、口盲通过时间、回盲瓣功能不良)适应症：慢性腹泻或慢性结肠炎功能性肠病，消化不良综合症、慢性肝病或肝硬化糖尿病患者的胃肠动力异常慢性便秘亚健康状态3、乳糖呼气试验(测定乳糖酶缺乏症、小肠细菌过增长、胃肠通过时间)适应症：乳糖酶缺乏症或不耐症各种功能性肠病慢性腹泻或慢性肠炎肠道预激综合症的诊断胃肠或肝胆外科手术后肠道功能恢复的评估。

β-D-半乳糖苷酶壳聚糖固定方法、特性及应用研究

β-D-半乳糖苷酶壳聚糖固定方法、特性及应用研究摘要“乳糖不耐症”是影响我国乳业发展的瓶颈技术之一，而利用固定化β-D-半乳糖苷酶水解奶中的乳糖是解决“乳糖不耐症”的有效方法。

本研究以壳聚糖为载体和戊二醛为交联剂，采用共价交联和吸附交联的方法，优选出不同形态壳聚糖固定化乳糖酶的方法，并进一步研究了固定化乳糖酶的特性和应用的效果。

另外，还比较研究了测定乳糖水解率的方法，优选出了简便、准确和快捷的测定方法。

主要得出以下结论：1. 对碘量法、蒽酮法、费林法、旋光法和酶催法测定乳糖的准确性和精密性进行了比较研究，结果表明酶催法测定乳糖水解率的标准偏差为0.0102，变异系数为2.7935%，其准确性和精密度好，操作简单快速，是一种准确、经济和快捷的乳糖水解率测定方法。

2. 对壳聚糖薄膜、壳聚糖凝胶和壳聚糖珠3种形态固定化乳糖酶的优化方法及其活力回收率进行了比较研究，结果表明壳聚糖珠与戊二醛吸附交联固定化乳糖酶的活力回收率最高达到52.9%，壳聚糖凝胶与戊二醛共价交联固定化乳糖酶的活力回收率最高达到71.1%，壳聚糖薄膜与戊二醛共价交联固定化乳糖酶的活力回收率达到77.8%。

3. 壳聚糖膜与戊二醛共价交联固定化乳糖酶的最佳工艺条件为：戊二醛浓度为2.5%，pH值为6.5，乳糖酶浓度为0.4 mg/mL，交联时间12h，4℃下固定12h。

4. 壳聚糖膜与戊二醛共价交联法固定乳糖酶的特性发生了变化。

与游离酶相比，固定化后酶最适pH由6.8移至6.5，固定化酶的最适温度由40℃升至45℃, 60℃保温1h后仍保留初始活力的50%，而游离酶则几乎完全失活；固定化乳糖酶米氏常数Km与游离酶相比差异不大，说明在对底物的亲和性上，在乳糖酶固定化后能够基本上按游离酶一样进行。

固定化酶重复使用8次后其活力仅损失10%；4～12℃下储存25d后固定化酶活力仍保留50%以上。

5. 研究了壳聚糖膜固定化乳糖酶在不同条件下水解乳糖的特性，结果表明：①随着固定化酶用量的增加，单位时间内对牛奶中的乳糖水解率升高，即在4℃下，达到70%以上水解率所需的酶量和时间为：酶添加量10.0g/25mL，水解18h；酶添加量14.0g/25mL，水解18h。

Lactose intolerance

S10• JAOA • Vol 101 •No 4 • Supplement to April 2001Rusynyk and Still • Lactose intoleranceIt is estimated that 50 million Ameri-cans have trouble digesting lactose.Although this disorder is usually not dangerous, it can lead to distressing symptoms and multiple office visits to the primary care physician.1Lactose intolerance is the inability to digest lac-tose into its constituents, glucose and galactose, owing to low levels of lactase enzyme in the brush border of the duo-denum.2Galactose is then converted to glucose in the liver by a series of reactions leading to uridine diphospho (UDP)-glu-cose.2Multiple etiologies of lactose intoler-ance exist, the most common being that of primary lactose intolerance, a com-mon disorder in which a low level of lactase develops after weaning.3The con-dition appears to parallel the situation in all other land mammals in which there isa physiologic decline in lactase activity coincident with weaning.4,5This decline in lactase activity in the intestinal mucosa is genetically controlled and follows a permanent course. Primary lactose intol-erance may not become clinically evi-dent until puberty or late adolescence.6,7Secondary lactose intolerance is the inability to digest lactose caused by any condition that leads to injury of the intestinal mucosa or to reductions of the functional mucosal surface area. This form of lactose intolerance tends to be transient, depending on the nature of the primary disorder. Causes include diarrhea, inflammatory bowel disease,and the human immunodeficiency virus.Multiple other viral syndromes may lead to secondary lactose intolerance.Congenital lactose intolerance is an extremely rare disorder in which the small intestines produce no lactase.3,8Consumption of any amount of lactose is intolerable and even dangerous for infants whose diarrhea quickly leads to dehydration. This type of lactose intol-erance is usually apparent in the first week of life. The infant must be fed a lac-tose-free diet.8Lactose “malabsorption” is a disorder in which lactose can be broken down,but, because of an anatomic or cofac-tor deficiency, the disaccharides are not absorbed. Although this disorder may have a presentation similar to that of lactose intolerance, it does not necessar-ily parallel it 8(Table 1).There appears to be an equal preva-lence of lactose intolerance among males and females. Interestingly, up to 45%of women who are lactose intolerant will regain the ability to digest lactose during pregnancy.Primary lactose intolerance has a high degree of race dependence. The preva-lence of primary lactose intolerance in the United States is as follows: 95% to 100% of American Indians; 80% to 90% of blacks, Asians, Mediterraneans,and Jews; and 50% of individuals of N orthern and Central European descent 3,8,9(Table 2). Incidence of sec-ondary lactose intolerance is variable,depending on its underlying etiology. Up to 50% of infants with acute diarrhea have transient lactose intolerance during acute viral syndromes. Most commonly implicated are rotavirus and giardiasis.Signs and symptomsThe diagnosis may be suspected when a history of gastrointestinal symptoms fol-lows milk ingestion. Symptoms tend to occur about 30 minutes to 2 hours after consumption of foods that contain lac-tose. Symptoms such as bloating, cramp-ing, diarrhea, flatulence, and borboryg-mi will develop in one third to one fifth of individuals with lactose intolerance.10Undigested lactose becomes thick as it passes through the small intestines. This thickened lactose combines with colonic bacteria to produce excess hydrogen ctose that is not absorbed also causes an intraluminal osmotic effect resulting in flatulence, bloating, and loose stools.Another significant change with lactose intolerance is the decrease in stool pH secondary to production of lactic acid and short-chain fatty acids from the fer-mentation of lactose by colonic bacte-ria. It should be emphasized that varying degrees of symptoms occur in patients,depending on the severity of their lac-tose intolerance and on the lactose loadLactose intolerance affects more than 50 million Americans. It is one of the most common gastrointestinal disorders seen by primary care physicians. When this dis-order is properly diagnosed, the patient is easily treated with education and dietary modifications. Lactose intolerance is commonly misdiagnosed because of its overlapping symptoms of diarrhea and abdominal bloating. This article reviews the etiology, diagnosis, and treatment of lactose intolerance.(Key words: lactose intolerance, lactase, abdominal bloating, diarrhea,hydrogen breath test)From Geisinger Medical Center, Danville, Pa,where Dr Rusynyk is a Gastroenterology and nutrition fellow, and Dr Dr Still is section head of nutrition and associate physician, Department of Gastroenterology and Nutrition.Correspondence to Christopher D. Still, DO,FACN, FACP, Section Head of Nutrition, Depart-ment of Gastroenterology and Nutrition,Geisinger Medical Center, 100 N Academy Ave,Danville, PA 17822-2111.E-mail: cstill@c Lactose intoleranceR. ALEXANDER RUSYNYK, DO CHRISTOPHER D. STILL, DORusynyk and Still • Lactose intolerance JAOA• Vol 101 •No 4 • Supplement to April 2001 • S11S12• JAOA• Vol 101 •No 4 • Supplement to April 2001Rusynyk and Still • Lactose intolerance。

婴幼儿乳糖不耐受研究进展

婴幼儿乳糖不耐受研究进展李洋洋;刘捷;曾超美【摘要】乳糖不耐受(LI)是指因乳糖酶的相对或绝对缺乏而导致的以腹泻为主的相关消化道症状的现象.由于遗传的多态性,不同种族人群发病率不同,中国是LI的高发人群,婴幼儿LI若不引起重视可导致慢性腹泻、营养不良、贫血、骨质疏松等长期危害.LI的临床分型分为4种:发育性乳糖酶缺乏、先天性乳糖酶缺乏、原发性乳糖酶缺乏和继发性乳糖酶缺乏.其中,发育性乳糖酶缺乏主要见于早产儿,原发性乳糖酶缺乏为中国大多数LI的发病类型.LI的临床症状无特异性,以腹泻、腹胀、腹痛等消化道症状为主,诊断方法多样,但是目前国内还没有把乳糖酶缺乏的实验室诊断作为必要的诊断依据.治疗方法根据临床类型和症状的不同而不同,主要包括饮食回避、添加乳糖酶、益生菌等.【期刊名称】《中国生育健康杂志》【年(卷),期】2019(030)002【总页数】4页(P192-195)【关键词】乳糖;乳糖酶;乳糖不耐受【作者】李洋洋;刘捷;曾超美【作者单位】100044北京,北京大学人民医院儿科;100044北京,北京大学人民医院儿科;100044北京,北京大学人民医院儿科【正文语种】中文乳糖(lactose)是人类和哺乳动物乳汁中特有的碳水化合物，是由葡萄糖和半乳糖组成的双糖。

在婴幼儿生长发育过程中，乳糖不仅可以提供能量，还参与大脑的发育进程。

人们摄入乳糖后需要乳糖酶(lactase)将其分解成单糖后才可以被吸收。

如果因各种原因导致摄入的乳糖不能或不能完全被分解吸收而产生的消化道症状称之为乳糖不耐受(lactose intolerance，LI)。

其关键是乳糖酶的相对或绝对缺乏。

LI 在中国婴幼儿中发病率极高，可达46.9%～70.0%，其最常见的症状为腹泻，如若不引起重视可导致慢性腹泻、营养不良、贫血、骨质疏松等长期危害。

故本文就LI的发病机制、临床分型、诊断方法及治疗进展进行综述。

一、LI的发病机制1. 乳糖的消化吸收：乳糖是以单体分子形式存在于乳中的唯一双糖，由葡萄糖和半乳糖通过1，4-糖苷键连接而成，经乳腺内乳糖合成酶作用产生。