The Effects Of Lactose Intake, Stressful Life Events On Irritable Bowel Syndrome

In modern China,with the development of economic,the people are more likely exposed to more stressful life events and the dietary lifestyle changes greatly simultaneously.Irritable bowel syndrome is one of the most common chronic disorders that impairing the sufferer's quality of life and at the same time,IBS patients constitute a great deal of the load for the healthcare system.The pathogenesis and pathophysiology of irritable bowel syndrome is complex and still incompletely known. Rather than being a cause of irritable bowel syndrome or merely affecting fluctuations in the symptom pattern and determining the health care seeking behavior of the patients, psychosocial factors have been looked upon largely as being involved in the etiopathogenesis of irritable bowel syndrome.Dietary lifestyle is highly relevant to the health of the colon and rectum,especially to irritable bowel syndrome.Components of the diet influence function and biology of the bowel both directly and indirectly.Some patients find that certain foods can reproducibly trigger symptoms and almost half of patients suffering IBS can identify a food that triggers symptoms.A significant proportion of irritable bowel syndrome follows the Western type dietary lifestyle.More and more city dwellers take dairy products as one of the essential nutritional resources. However,a status that lactase deficiency is extremely prevalent in China which will cause uncomfortable symptoms when excess lactose intake occurs.Unfortunately,few investigations have been done focusing the relationship between lactose intake,stressful life events and the pathogenesis of irritable bowel syndrome in China.The present study aimed to focus on these two likely factors in the general population and the patients suffering irritable bowel syndrome as well.The main body of the present study consists of three parts detailed below: Part 1:The relationship between lactose,stressful life events and irritable bowel syndrome in general population.Aims:To assess the clinical relevance of dietary lactose,stressful life events and stress as a cause of abdominal symptoms in patients suffering irritable bowel syndrome in an adult Chinese population with a high prevalence of lactase deficiency.Subjects:Individual adults will be invited to participate in this study by health visitors based in their community.Addresses will be selected at random from general population listing of urban Hangzhou.To counteract recruitment bias,subjects will be recruited in strata by gender and age group with margins on the number in each stratum set as 10 percent of the estimate the general population age distribution.Methods:A stratified randomized study by cluster sampling performed via face-to-face interview,the participants fill in the questionnaires with the help of investigators.Main results:Of all the original dwellers enrolled,1063 fully completed the questionnaire.All analyses were limited to the final sample size of 988(92.9%) when subjects who had a history of peptic ulcers or inflammatory bowel disease or major abdominal surgery,which might cause gastrointestinal symptoms,were excluded.The overall prevalence of irritable bowel syndrome in this population is 9.0%,and irritable bowel syndrome with diarrhea is the most prevalent.We found that the prevalence of IBS was higher in women than in men(the ratio of female to male with irritable bowel syndrome was 1.27:1) by the Rome III criteria although the difference not reach the statistical significant level.Irritable bowel syndrome patients have a higher score of stressful life events than the controls(12.3%vs.6.1%,p=0.025,OR=2.139,95%CI: 1.086-4.214) and the score for anxiety is also higher(13.9%vs.8.1%,p=0.022, OR=1.827,95%CI:1.082-3.083).The effect of psychological factors is much more significant in the group with a low dose of lactose intake(17.9%vs.6.4%,p=0.011, OR=3.212,95%CI:1.254～8.228).The average dose of lactose intake is 285g in this population with a large proportion(65.9%) took more lactose than the average level of the Chinese city dwellers.The prevalence of subjective lactose intolerance is 27.1% while the value is 43.8%in irritable bowel syndrome(p<0.001).subjects with subjective lactose intolerance and with more stressful life events are more likely to suffer in irritable bowel syndrome(p<0.001,OR=3.184,95%CI:1.271-7.978).Score from the "B.E.S.T" questionnaire which represents the quality of life correlates with the abdominal symptoms is much higher in irritable bowel syndrome than in controls (37.1±14.3vs.21.8±14.2,p<0.001).Conclusions:Irritable bowel syndrome,especially the subtype of irritable bowel syndrome with diarrhea,is more prevalent in Hangzhou area.The average dose of lactose intake is 285g and is more than the average level of the Chinese city dwellers. Compared with the healthy controls,the quality of life impairment is more significant in irritable bowel syndrome patients.There is a strong correlation between dietary lactose, stressful life events and stress and irritable bowel syndrome.Part 2:The clinical relationship between lactose intolerance,stressful life events and irritable bowel syndrome in patients attending a gastroenterology clinic.Aims:To assess the impact of dietary lactose,stressful life events and stress in patients attending a gastroenterology clinic with irritable bowel syndrome with diarrhea symptoms compared to age and sex matched controls.Also in this population 'enriched' with patients complaining of functional gastrointestinal symptoms,we predict that those individuals that report symptoms even to low amounts of lactose in the diet are those with risk factors for irritable bowel syndrome.In addition to the questionnaire based assessment performed in study 1,this proposition will be tested directly by assessing the response to 10,20 and 40g lactose in terms of H2 breath test(mal-digestion) and symptoms(intolerance).In addition,a dietary intervention will be recommended in IBS patients in the population with high prevalence of lactase deficiency.Subjects:77 new patients of irritable bowel syndrome with diarrhea to the gastroenterology clinic at Sir Run Run Shaw Hospital and 50 healthy volunteers were recruited.The study protocol explained and written consent obtained.Methods:All of the participants involved were asked to fill in the questionnaire used in study 1 and 10,20 and 40g lactose H2 breath test performed in a double-blind way.The test time frame is 180 min and symptoms recorded in 24h after lactose intake. Main results:The patients of irritable bowel syndrome with diarrhea group are much more sensitive to all these three doses of lactose(p10g =0.001;p20g<0.001; p40g=0.002),however,the prevalence of lactose maldigestion is similar in both groups. Most of the healthy volunteers can tolerant 10g lactose(97.4%),while the percentage from patients group is only 71.7%.We also found that the quality of life impaired more in patients' group than in healthy volunteers.What's more,the patients experienced much more stressful life events show a significant sensitivity to even low dose lactose challenge.Conclusions:The patients of irritable bowel syndrome with diarrhea are much more sensitive to lactose challenge than healthy controls,even in the low dose.Recent stressful life events and stress is correlated with the sensitivity as well.In the area where there is a high prevalence of lactase deficiency,we strongly recommend that a lactose tolerate test with the challenge dose based on the average intake level in the daily life preferred before the diagnosis of irritable bowel syndrome with diarrhea be made. Thereafter,a suitable dietary intervention may be recommended and a follow-up be expected.Part 3:Role of visceral sensitivity in patients of irritable bowel syndrome with diarrhea and the study on methodology.Aims:This study will investigate the effects of visceral sensitivity in a Chinese hospital attendee population with irritable bowel syndrome with diarrhea and appropriate controls.In addition,a simple,short-protocol barostat study will be applied in this study to assess if patients with D-IBS have visceral hypersensitivity and whether this is related to their response to diet(as assessed by food diaries or the lactose tolerance test) and reports of life events and psychosocial stress.Subjects:30 patients with irritable bowel syndrome with diarrhea and 50 healthy controls were recruited.The study protocol explained and written consent obtained.Methods:All of the participants complete the foresaid questionnaire,and finish the anorectal manometry via a simple,short-protocol barostat investigation and the traditional manometry as well.Main results:Totally there are 30 patients and 30 healthy controls completed this study.No differences on anorectal motility function found between these two groups (p>0.05).The standardized sensory threshold shows that the discomfort/pain threshold is lower in irritable bowel syndrome patients than in controls(p=0.017).Conclusions:Rectal hypersensitivity has been found in the irritable bowel syndrome with diarrhea patients.Stressful life events,stress and psychological factors affect the sensitivity.The new,simple short-protocol barostat is proved useful in the clinical practice.In conclusion,we found a higher prevalence of irritable bowel syndrome in the general population in Hangzhou area,and a more lactose intake in this population. Compared with the healthy controls,the quality of life impairment is more significant in irritable bowel syndrome patients.There is a strong correlation between dietary lactose, stressful life events and stress and irritable bowel syndrome.The patients of irritable bowel syndrome with diarrhea are much more sensitive to lactose challenge than healthy controls,even in the low dose.Recent stressful life events and stress is correlated with the sensitivity as well.Rectal hypersensitivity has been found in the irritable bowel syndrome with diarrhea patients.Stressful life events,stress and psychological factors affect the sensitivity.These results indicate that lactose intolerance, stressful life events and psychosocial factors may play a important role in the correlation between diet and irritable bowel syndrome.In the area where there is a high prevalence of lactase deficiency,we strongly recommend that a lactose tolerate test with the challenge dose based on the average intake level in the daily life preferred before the diagnosis of irritable bowel syndrome with diarrhea be made.Thereafter,a suitable dietary intervention may be recommended and a follow-up be expected.The new, simple short-protocol barostat applied in this study has been proved useful and effective in clinical practices.