Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Researchers do not understand what causes ovarian cancer. Some studies find galactose to be toxic to oocytes which renders ovaries susceptible to cancer. 1 hypothesis is that high levels of lactose consumption and retained ability to digest lactose (lactase persistence) lead to high levels of galactose exposure which increases the ovarian cancer risk. Denmark, Sweden, and Switzerland have the highest risk of ovarian cancer in the world. They also have the highest levels of lactase persistence and among the highest levels of milk supply for the population. Conversely, Hong Kong, Japan, Shanghai, and Singapore have low ovarian cancer risk, low consumption of milk, and low levels of lactase persistence. yet other researchers using the same data did not find per capita availability of milk to be significant independent of nondairy animal fat. Lactase persistence did have an independent association, however, but data was not standardized across populations. In a case control study, researchers took the dietary history of 11 dairy products to measure lactose consumption. A significant increase in ovarian cancer risk only existed with frequent intake of yogurt and cottage cheese. Researchers hypothesized that the prehydrolyzed lactose in both foods was the main contributor. Using the case control data, others found an increased risk for total lactose intake in women who never used oral contraceptives (OCs). The strongest predictor to date is the lactose/transferase ratio, yet those who found this association did not define this index based on an earlier study or examination. 1 problem with these studies is that dietary fat confounds the association. 2 studies showed that low fat milk was associated with decreased risk, even though both milks have the same lactose content. Another problem is that the subsets of exposure or subgroups of the population are unpredictable. Further research in nutritional epidemiology of ovarian cancer is needed.
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PMID:Invited commentary: progress in the nutritional epidemiology of ovary cancer. 189

Using published data, largely from the 1970s, the author compared ovarian cancer incidence, per capita milk consumption, and population estimates of lactase persistence (the ability to digest lactose after infancy) in 27 countries. Significant positive correlations were noted between ovarian cancer incidence, per capita milk consumption, and lactase persistence. Lactase persistence showed a stronger association than milk consumption or animal fat consumption in multiple regression models. The author speculates that toxicity from the lactose component of milk and, more specifically, galactose, the digestion of which is facilitated by lactase persistence, may provide a biologic basis for the correlation.
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PMID:Lactase persistence and milk consumption as determinants of ovarian cancer risk. 251 Apr 99

It has been suggested that aspects of lactose consumption and metabolism favoring a relatively high tissue level of galactose-1-phosphate may predispose women to ovarian cancer. The authors sought to examine this hypothesis in a study of 108 18- to 74-year-old Caucasian residents of a three-county area of western Washington who were diagnosed with stage I ovarian cancer during 1989-1991, and 108 age- and race-matched controls. Lactose and galactose intake, measured using a food frequency questionnaire, had been hypothesized to increase risk, but were somewhat lower among the cases than among the controls (75th percentile of lactose intake vs. 25th: odds ratio (OR) = 0.80, 95% confidence interval (Cl) 0.52-1.2; of galactose intake: OR = 0.71, 95% Cl 0.48-1.1). Intestinal lactase activity, also hypothesized to have a positive relation with ovarian cancer occurrence, was measured with an oral lactose challenge followed by determination of urinary galactose; no evidence that it was related to the disease was found (75th percentile of excreted galactose vs. 25th: OR = 0.87, 95% Cl 0.62-1.2). Galactose-1-phosphate uridyltransferase (transferase), the enzyme responsible for the metabolism of galactose-1-phosphate, was measured in erythrocytes; no deficit in cases was observed (75th percentile of transferase activity vs. 25th: OR = 1.3, 95% Cl 0.80-2.1). There was also no excess of cases carrying low-activity genetic variants of the transferase enzyme (lower-activity variants vs. higher-activity variants: OR = 0.61, 95% Cl 0.21-1.7). These results do not support the hypothesis that aspects of lactose and galactose intake and metabolism have a bearing on the etiology of ovarian cancer.
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PMID:Lactose and galactose intake and metabolism in relation to the risk of epithelial ovarian cancer. 787 85

To determine whether lactase persistence might be related to ovarian cancer risk, in 1994-1995 the authors assessed the capacity to digest lactose by measuring breath hydrogen production after oral administration of lactose in 50 women with ovarian cancer and 100 healthy controls. All of the women came from Sassari (Sardinia), Italy, an area where the population has a high frequency of lactose malabsorption. Thirty percent of cases were lactose absorbers, as compared with 15% of controls. The odds ratio for ovarian cancer among lactose absorbers was 2.51 (95% confidence interval 1.10-5.68). These results provide some support for a role of lactose ingestion and galactose cytotoxicity in the pathogenesis of ovarian cancer.
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PMID:Lactose absorption in patients with ovarian cancer. 1041 63

Geographic patterns of diseases depend on multilayered causes. However, the division of the world's population into two phenotypes regarding lactose digestion and sunshine exposure to fixed areas of the globe are two relatively slow changing variables. It is hypothesized that it is a vectorial interaction between these two variables that provide a backbone to risk modification of many diseases. Lactase non persistence status tends to follow sunshine exposure particularly in Europe but Lactase persistence status is also been shown to be related to pastoral life styles in spotty regions of Africa, Middle East and China. Current emphasis of research favours the modifying role of vitamin D and sunshine. Nevertheless it was demonstrated that national digester/nondigester status has mathematical relationships to geographic distribution of some diseases. These relationships are also similar to that described for the effects of latitude through sunshine and vitamin D. This observation raises a question as to how each one affects disease outcome. In this paper lactose/lactase interactions are first reviewed for eight exemplary diseases. Based on population findings and corroborative meta-analyses gleaned from the literature 6 types of interactions may be classified. Then in a preliminary fashion lactose digester and maldigester status are related to relative annual sunshine exposure. Further the relative national annual sunshine exposure is evaluated to outcomes of the same exemplary diseases. The patterns related to sunshine reflect that obtained with national lactase status proportions and also corroborate a literature review. However, correlations are weak to moderate and only ovarian cancer reached conventional statistical significance. Because these comparisons are based on modest number of national data firm conclusions cannot be made. However, it is argued that evolutionary pressures exerted by regional sunshine exposure may have had influence on a number of relevant genetic polymorphisms in parallel with lactase status. Furthermore influences of ancestral herding and dairy food consumption also may have exerted independent influences on either lactose phenotype. As such both discussed variables are postulated to exert parallel as well as independent effects on modifying geographic disease patterns. These could partly explain both north to south and west to east directional changes.
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PMID:Determinants of geographic patterns of diseases: interaction of lactose/lactase status and sunshine exposure. 2045 95