Precipitating factors of Irritable Bowel Syndrome (IBS)

The causes of IBS can be divided into precipitating and aggravating factors. For most patients, it is very difficult to pinpoint the precipitating event because it happened a long time ago. The following may precede the onset of IBS.

• Food poisoning or gastroenteritis is the most obvious risk factor for IBS. About 20% to 30% of IBS cases may start this way. Depending on the severity, 10% to 30% of people who have food poisoning may develop IBS, usually diarrhoea-predominant IBS.
• Surgery in the abdomen, such as a hysterectomy or cholecystectomy. A hysterectomy is an operation to remove the uterus or womb. The risk is probably low (less than 10%) and affected women usually develop constipation-predominant IBS. A cholecystectomy is an operation to remove the gallbladder. Some patients develop frequent diarrhoea after this type of operation.
• Severe stress in the form of a major life event, such as loss, separation or trauma, can in some cases precede the development of IBS.
• Other possible causes of IBS include inflammatory bowel disease, a change in diet and the use of antibiotics. Contrary to popular belief, lack of fibre intake does NOT cause IBS.

Aggravating factors of Irritable Bowel Syndrome (IBS)

Aggravating factors for IBS include sleep disturbances, chronic stress, menstruation, antibiotics and certain foods.

The findings of a survey of 118 female nurses working at a major hospital in Singapore, the National University Hospital, illustrate how a combination of factors such as a stressful job and sleep deprivation could make a person more prone to IBS.

Overall, about 30% of these nurses had IBS, which is higher than what was observed in the general population. The rate was higher among nurses working night shifts (38%) compared with nurses working regular hours (20%). Other studies also show that sleep deprivation gives rise to bowel disturbance.

In the West, foods that have been implicated in the worsening of IBS symptoms are milk and dairy products, cereals (e.g., bran, muesli), grains (e.g., wheat, rye, oats) and certain sugars (e.g., lactose, fructose, sorbitol). In the past, it was thought that increasing fibre intake by eating more cereals was advisable for patients with IBS. However, new studies have emerged showing the opposite, i.e., most patients with IBS actually feel worse (55%) on a bran diet and only 10% benefit from it. In Singapore, curry, chili and coffee were the foods that most patients felt worsened their IBS pain.

IBS 的起因

IBS的起因可分成两大因素：急性的和逐渐恶化的，后者因为事情发生太远了，多数病人不能指出使病情恶化的因素，以下几点可能导致IBS的发起：

食物中毒或肠胃炎是最明显的诱发因素，约有20%或30%的IBS个案是由此而引起的。根据个别病情的严重性，10%到30%的病人得了食物中毒后引发IBS，通常为腹泻型IBS。

腹部手术如子宫切除术或胆囊切除术后。子宫切除术后得的IBS风险低（少于10%），但病人通常会引发便秘型的IBS。胆囊切除术后，有些病人会引发腹泻。

生命中发生重大事件，例如亲友的失散，精神或心里的创伤，都会引发IBS。其他可能引起IBS的因素有肠炎性的疾病，饮食的改变，以及服用抗生素等。许多人认为，缺少纤维会引起IBS，其实却不尽然。

使病情恶化的因素IBS 恶化的因素还包括睡眠被干扰，延续性的压力，经期，抗生素，某些食物等等。

曾经对新加坡一所主要医院即国大医院的118名女护士作过考察，发现综合各种因 素如工作压力和睡眠被剥夺等，有较高倾向患IBS，约有30%被考察的护士患上IBS，这比普通人为高。而必须轮夜班的护士的比例，高于做日班者。两者分 别为38%至20%。曾作过的多个研究包括先前对国大医院的考察，都发现被剥夺睡眠会引起肠胃不适。

西方国家里，会激引病情恶化的食物包括牛奶，奶制品， 榖物（如糠，麦，黑麦，燕麦等）以及某些糖类（如乳糖，果糖，山梨糖醇）。过去认为，增加摄取富含纤维的食物，会对IBS病者有助。但根据最新的研究，发 现刚好相反。IBS病患食用含高纤维的饭食，多数病情恶化（55%），只有10%的病患受益。在新加坡，病患由于咖厘，辣椒和咖啡等食物而使病情加剧。