Constipation can be caused by a number of factors, ranging from a recent change in diet to stress and medicinal side effects. In this article we explore the most common causes of constipation, and offer practical advice that you can take today to deal with the issue. If you haven't already read it, try our article "What is Constipation?" to find out the medical definition of constipation.
Like other digestive problems, one of the first things you should do when you notice things become a bit slow is to look at the food that you’re eating. Constipation can sometimes be caused by a lack of certain foods. Dietary fibre, for instance, is fundamental to maintaining a regular and comfortable bowel, and not having enough can make things feel sluggish.
Dietary fibre is mostly indigestible, which means that as it travels through the gut it pushes the rest of the food along too. Fibre also tends to soak up water, helping your stools stay soft and bulky. So, a lack of fibre is one of the most common causes of constipation. You might find that simply eating more fibre rich foods, like wholemeal flour, bran cereals, green vegetables and fruit, helps alleviate the problem.
Lack of exercise is another common cause of constipation. Your bowel depends on peristalsis (a series of muscular contractions) to move food along the digestive tract. Exercise is a great and natural way to stimulate your body’s natural rhythm.
A further cause of constipation is a lack of water. The recommended daily allowance of water is 1.5 litres, or up to 2 litres if you’re on a high fibre diet. Not only does water keep your body hydrated, but it lubricates the digestive system. Not drinking enough water makes your bowel movements dry and hard to pass. Usually when food reaches the colon, only a portion of the water is extracted. The main job of the colon is to extract water from faeces; however it doesn’t know when to stop taking water. Usually this isn’t a problem, however when you don’t drink enough water, the colon will dry out the stools more quickly, making them harder to pass.
This cause is more commonly associated with children suffering from constipation, but adults can have it too. Surprisingly, you can sometimes be the cause of your own constipation. Refraining is when you feel that you need to go, but you don’t because it’s an inconvenient time. If you do this once, it’s generally not an issue, but sometimes you might repeatedly put off going to the toilet because you’re at work, visiting a friend or you really don’t want to use a public bathroom. The longer you hold off going to the loo, the longer the stool stays in the colon and the drier it gets. When you do finally decide to go, it can be especially difficult, painful or sometimes impossible. This won’t come as a surprise, but when nature calls, it’s best to answer!
Stress can be a cause of constipation because it tends to suppress normal bowel movements. There is some evidence that stress and emotional strain is related to digestive health issues like constipation, indigestion and diarrhoea. You can manage your stress levels by talking to a friend or relative, avoiding caffeine (which lowers serotonin levels), and exercising more often. Read more about stress and constipation in our blog post.
Your gut, especially the colon, is host to a large number of friendly bacteria which help to break down food, extract vitamins and vital chemicals which your body needs to stay healthy. These friendly bacteria (probiotics) also keep bad bacteria (pathogens) under control. An imbalance of good and bad bacteria in your gut can be a major factor in digestive problems like diarrhoea, bloating, wind and constipation. Topping up your friendly bacteria can help address the imbalance in your gut.
Probiotics can be found in yoghurt and fermented foods like Kefir, Sauerkraut, Miso Soup and Natto. However, the easiest and most effective way to get your probiotics is in the form of a supplement. Our favourite is ‘For maintaining regularity’ by OptiBac Probiotics, which contains prebiotics (that stimulate the growth of your probiotics) and a particularly well studied probiotic strain called Bifidobacterium lactis BB-12.  
Medicinal side effects
Sometimes when you take a prescription or over-the-counter medicine you might suffer from constipation. Some of the biggest contributors are painkillers such as codeine, and antidepressants, like imipramine. Taking an iron supplement can also result in constipation, which could partly explain why pregnant women often suffer with the condition.
If you think that your medicines are making you constipated, try talking to your doctor to see if there as an alternative. If there isn’t, try to compensate with extra exercise, drinking more water, or taking probiotic supplements.
Constipation can of course be a symptom of a pre-existing health condition, like Irritable Bowel Syndrome (IBS). However, the causes of IBS are uncertain and can vary from person to person. If you think your constipation is caused by IBS, you can still try any of the ideas above, but if it’s something you suffer with continuously for a long time it is always advisable to talk to your doctor.
References & Footnotes
Matsumoto M, Imai T, Hironaka T, Kume H, Watanabe M and Benno Y. Effect of Yoghurt with Bifidobacterium lactis LKM512 in Improving Fecal Microflora and Defecation of Healthy Volunteers. Intestine Microbiology Magazine 2001;14:97-102.
Murakami T, Miyahara H, Yukisato S, Nakamura R, Kanno H, Kotakemori M, Kamei T and Kobayashi O. Safety and effect of yoghurt containing Bifidobacterium lactis BB-12 on improvement of defecation and fecal microflora in healthy volunteers. Food, Health and Nutrition Research (Journal of Nutritional Food) 2006;9(1):1-12.
Uchida K, Akashi K, Kusunoki I, Ikeda T, Katano N, Motoshima H and Benno Y. Effect of fermented milk containing Bifidobacterium lactis BB-12 on stool frequency, defecation, fecal microbiota and safety of excessive ingestion in healthy female students -2nd report. Food Health and Nutrition Research (Journal of Nutritional Food) 2005;8(1):39-51.