Prediction of lactose malabsorption in referral patients

Two hundred forty-two patients referred for various gastrointestinal complaints were evaluated for clinical parameters that would predict findings of lactose malabsorption. Breath hydrogen and blood glucose lactose tests were performed after ingestion of 50 g lactose. Presenting complaints, duration of symptoms, and patient demographics such as age, sex, and ethnic heritage were not different between lactose malabsorbers and absorbers as defined by the breath hydrogen lactose test. Foodrelated symptoms in general and after specific foods such as milk, ice cream, cheese, and yogurt were also similar between groups. Prior to testing, 30% of malabsorbers (N=161) and 36% of absorbers (N=81) reported lactoserelated symptoms (P=NS). The blood glucose response to lactose was abnormal in 60% of malabsorbers and 15% of absorbers. This study confirmed our impression that it is difficult to predict lactose absorption status by clinical parameters. The majority of our lactose malabsorber patients were unaware of lactose-associated symptoms. Furthermore, symptom assessment, demographics, food history, and blood glucose testing did not predict abnormal hydrogen responses to lactose.The opinions and assertations expressed herein are those of the authors and are not to be construed as reflecting opinions of the United States Air Force or the Department of Defense.This work has been presented in part at the Annual Scientific Session of the American Gastroenterological Association, San Francisco, California, May 19, 1986, and published as an abstract (Gastroenterology 90:1562, 1986).     

呼出气氢测定试验对飞行人员乳糖酶缺乏症的研究

对66名汉族飞行人员进行乳糖呼出气氢测定试验,乳糖吸收不良的发生率为83.3％,其中乳糖不耐受者占34.6％;与一般汉族人群无明显差别。对10名确定为中度以上乳糖吸收不良的飞行人员进行250ml鲜牛奶的试验结果,有50％呼出气氢含量在正常范围,并无一例出现胃肠道症状。提示较长期食用牛奶未能使乳糖酶缺乏状态发生改变,但每日食用适量牛奶属合理营养。     

Investigation of function of the lactose operon of escherichia coli K-12 under the influence of nonspecific regulators

The possible role of cyclic AMP in the stimulating action of ACTH and hydrocortisone on the lactose operon ofEscherichia coli K-12 was investigated. It was shown that ACTH had no effect on strainsE. coli WZ-78/F'lac (cya₈₅₅) andE. coli CA 8001 (L₁), in which the system of regulation of the function of the lactose operon by cyclic AMP is disturbed. Meanwhile this hormone stimulates the lactose operon in wild-type strains:E. coli 200 PS/F'lac andE. coli 3000. Hydrocortisone stimulates the function of the lactose operon both in the wild-type strainE. coli 3000 and in the mutantE. coli CA 8001 (L₁). It is considered that the stimulating action of ACTH on the lactose operon is mediated through cyclic AMP and that hydrocortisone stimulates the function of the lactose operon independently of cyclic AMP.Research Laboratory of Experimental Immunobiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 33, No. 6, pp. 744–746, June, 1977.     

Milk and Dairy Products: Good or Bad for Human Bone? Practical Dietary Recommendations for the Prevention and Management of Osteoporosis

Osteoporosis affects women twice as often as men. Additionally, it is estimated that 0.3 million and 1.7 million people have hip fractures in the USA and Europe, respectively. Having a proper peak bone mass and keeping it as long as possible is especially important for osteoporosis prevention. One of the most important calcium sources is milk and dairy products. Breast milk is the best infant food, but milk should not be avoided later in life to prevent losing bone mass. On the other hand, more and more people limit their milk consumption and consume other dairy or non-dairy products. For example, they are usually replaced with plant beverages, which should be consumed carefully in several age groups. Additionally, an important element of milk and dairy products, as well as plant beverages, are probiotics and prebiotics, which may modulate bone turnover. Dietary recommendations focused on milk, and dairy products are an important element for the prevention of osteoporosis.     

中药配方颗粒辅料麦芽糊精的HPLC定量检测与中红外光谱半定量检测

目的 建立中药配方颗粒辅料麦芽糊精的检测方法,为中药配方颗粒质量评价提供分析技术支持。方法 建立配方颗粒中果糖、葡萄糖、蔗糖、麦芽糖、乳糖的HPLC定量检测方法,根据样品经糖化酶水解后的葡萄糖增加量换算出麦芽糊精含量。基于中药浸膏与麦芽糊精不同比例混合物的中红外光谱（mid-infrared spectroscopy,MIRS）特征峰差异,建立配方颗粒中麦芽糊精的半定量检测方法。结果 所建立的HPLC方法可以准确定量检测配方颗粒中果糖、葡萄糖、蔗糖、麦芽糖、乳糖。如果中药浸膏自身含有较多可经糖化酶水解产生葡萄糖的成分（淀粉、蔗糖等）,HPLC检测配方颗粒中麦芽糊精时存在系统性正误差,可通过中药浸膏酶解后葡萄糖增加量、待测样品酶解后蔗糖减小量等部分修正正误差。如果中药浸膏自身少含或不含淀粉、蔗糖等可经糖化酶水解产生葡萄糖的成分,HPLC检测配方颗粒中麦芽糊精时存在系统性负误差,换算公式偏差、麦芽糊精纯度、样品处理损失等导致根据样品酶解后葡萄糖增加量计算的麦芽糊精“检测含量”预期低于根据生产投料计算的麦芽糊精“名义含量”。麦芽糊精含量越高,配方颗粒MIRS中1200～900 cm-1区域的...     

The prevalence of lactase deficiency and lactose intolerance in Chinese children of different ages

Objective To determine lactose metabolism and lactase activity in Chinese children of diff erent ages, prevalence of lactase deficiency (LD), and lactose intoleran ce (LI).
Methods All 1168 healthy subjects between 3 and 13 years were recruited from schools in four large cities in China. They were screened by a 25 g lactose tolerance tes t. Some subjects were challenged with 50 g milk powder on different days. Bot h indicators, the expiratory H₂ concentration and intolerance symptoms, were a nalyzed.
Results LD occurred in 38.5% of children in the 3-5 year age group, and 87% of the 7-8 year and 11-13 year old groups. The age of occurrence for LD may be at 7-8 years among Chinese children. The prevalence of LI among Chinese children w as 12.2% at age 3-5 years, 33.1% at age 7-8 years, and 30.5% at age 11-13 yea rs, respectively.
Conclusion The results demonstrate that LD is very common in Chinese children from these fo ur cities. LD and LI have a dose dependent response: lactose absorption and sym ptoms are based on lactase activity. The relationship between breast feeding hi story (or the history of cow milk intake) and lactase activity among Chinese chi ldren has not been established.      

有关乳糖不耐受的研究进展

乳糖不耐受与人类尤其是婴儿期的营养和健康密切相关,影响人类对乳及其制品的摄入。了解乳糖不耐受的分型、临床症状及诊断,对维持人体健康、降低老年人群骨质疏松的危险性有着重要意义。对乳糖酶基因多态性的研究为人类了解、预防和控制该症提供了广阔的前景。乳糖酶分型的检测有可能成为对骨质疏松症患者进行早期基因筛查的一种行之有效的手段,而如何对乳糖不耐受进行改善和控制,尚需从多方面加以深入研究。     

Persistence of lactase activity among Northern Europeans: A weighing of evidence for the calcium absorption hypothesis

Considered in this paper is a broad range of evidence bearing on the calcium absorption hypothesis that has been advanced to explain high frequencies of the gene for persistence of lactase activity (PLA) among adults in northern Europe. According to that hypothesis, lactase‐sufficient individuals in early northern Europe enjoyed a selective advantage over lactase‐deficient ones that led to high incidences of PLA in adults of the region. Northern Europeans, the hypothesis goes, suffered from a dietary shortage of vitamin D and, in addition, were unable to synthesize adequate vitamin D from the sun's ultraviolet radiation because of northern Europe's cloudiness and its location in higher latitudes. This led to chronic vitamin D deficiency along with a reduced ability to absorb calcium from milk and lactose‐rich dairy products. As a result, the deficiency diseases rickets—which affects infants and children and can leave a child with bowlegs and other bone defects—and osteomalacia—which weakens and deforms the bones of adults—were common in early northern Europe, and represented powerful selective forces that contributed to development of the highly depigmented skin that is typical of the region's peoples. In addition, the hypothesis goes, calcium absorption was enhanced by a process independent of vitamin D. Such enhancement, found especially or solely among lactase‐sufficient individuals, was brought on by ingestion of lactose in milk and milk products. Thus, persons who enjoyed high lactase activity through life were favored in the struggle for survival, which ultimately led northern European peoples to have among the highest incidences of PLA in the world.

In this article, evidence, much of it recent, is presented to show that lactase‐deficient humans are able to absorb calcium from milk as readily, or nearly as readily, as lactase‐sufficient humans. Evidence is also presented that rickets and osteomalacia occur in parts of the world that have an abundance of sunshine, whether originating from customs that limit exposure to sunshine or otherwise; that heavy cloud cover and high latitude need not result in vitamin D deficiency, rickets, and osteomalacia; that, indeed, osteological evidence from archeological sites in northern Europe indicates that rickets and osteomalacia were quite rare in antiquity; that those conditions appear to have become common in northern Europe only with the advent of the Industrial Revolution, too short a time to have been a significant factor in bringing on the high incidences of PLA that prevail today; and that, indeed, the calcium absorption hypothesis is not confirmed by historical, osteoarcheological, or bio‐medical evidence.     

Contribution of Colonic Fermentation and Fecal Water Toxicity to the Pathophysiology of Lactose-Intolerance

Whether or not abdominal symptoms occur in subjects with small intestinal lactose malabsorption might depend on differences in colonic fermentation. To evaluate this hypothesis, we collected fecal samples from subjects with lactose malabsorption with abdominal complaints (LM-IT, n = 11) and without abdominal complaints (LM-T, n = 8) and subjects with normal lactose digestion (NLD, n = 15). Lactose malabsorption was diagnosed using a ¹³C-lactose breath test. Colonic fermentation was characterized in fecal samples at baseline and after incubation with lactose for 3 h, 6 h and 24 h through a metabolomics approach using gas chromatography-mass spectrometry (GC-MS). Fecal water cytotoxicity was analyzed using a colorimetric assay. Fecal water cytotoxicity was not different between the three groups (Kruskall-Wallis p = 0.164). Cluster analysis of the metabolite patterns revealed separate clusters for NLD, LM-T and LM-IT samples at baseline and after 24 h incubation with lactose. Levels of 5-methyl-2-furancarboxaldehyde were significantly higher in LM-IT and LM-T compared to NLD whereas those of an unidentified aldehyde were significantly higher in LM-IT compared to LM-T and NLD. Incubation with lactose increased short chain fatty acid (SCFA) concentrations more in LM-IT and LM-T compared to NLD. In conclusion, fermentation patterns were clearly different in NLD, LM-IT and LM-T, but not related to differences in fecal water cytotoxicity.     

Coincidental Malabsorption of Lactose, Fructose, and Sorbitol Ingested at Low Doses Is Not Common in Normal Adults

Normal subjects may incompletely absorb either lactose, fructose, or sorbitol and may therefore have abdominal symptoms. The frequency of coincidental malabsorption of these sugars is not known. This is clinically important, since we often ingest them during the same day and malabsorption may cause abdominal symptoms. To shed light on this issue we studied 32 normal subjects. Volunteers drank in random order the following solutions: 20 g lactulose, 50 g sucrose, 50 and 25 g lactose, 50 and 25 g fructose, 20 and 10 g sorbitol. Semiquantitative carbohydrate malabsorption was estimated with lactulose standards. Frequency of 50-g lactose (69%), 50-g fructose (81%), and 20-g sorbitol (84%) malabsorption was not significantly different (P = 0.3). The estimated median fraction of the ingested high dose malabsorbed was 42, 19, and 68% for lactose, fructose, and sorbitol, respectively. At low challenging doses, 63% of the volunteers absorbed two of three or all three sugars, and 88% were asymptomatic to two or all three sugars. In conclusion, the frequency of coincidental malabsorption of lactose, fructose, and sorbitol and intolerance to these sugars is not common, when normal adults ingest them at low doses.