Causes of constipation, dietary care, and timing of seeking medical attention

Constipation is a common problem for modern people, and it is mostly related to daily routines and diet. Insufficient intake of vegetables, fruits, and whole grains, drinking too little water, a sedentary lifestyle, or suppressing the urge to defecate can all make bowel movements increasingly difficult. Since the causes are mostly related to lifestyle habits, diet is often the first step in making adjustments.

But "eating more fiber" is only half the story. This article will explain three things separately: how constipation is defined medically, how to adjust your diet correctly, and in what situations you should no longer try to treat it yourself.

1. What constitutes constipation? How to interpret the Rome IV criteria?

Many people believe that "not having a bowel movement for a day means constipation," but the medical diagnosis is not based on the number of days in a single day. The internationally accepted method is...Rome IV StandardFunctional constipation is defined as: symptoms that have been present for at least six months prior to diagnosis, and which meet the following criteria in the most recent three months.At least two：

• More than a quarter of bowel movements require straining.Difficulty defecating）
• More than a quarter of bowel movements are...Dry or granular(Types 1 and 2 of the Bristol fecal classification)
• More than a quarter of them haveFeeling of incomplete bowel movement
• More than a quarter of them haveAnal and rectal obstruction
• More than a quarter of them need manual assistance to defecate.
• Less than three spontaneous bowel movements per week

In addition, the patient must meet the following criteria: loose stools are rare when not using laxatives, and the symptoms are insufficient to diagnose irritable bowel syndrome (IBS).

It is worth noting that:Less than three times a week is just one criterion, not the only one.Some people have bowel movements every day, but experience persistent straining, hard stools, and a feeling of incomplete evacuation—this also qualifies as constipation. Conversely, having bowel movements every two or three days but with a smooth process and no discomfort does not necessarily warrant treatment as an illness.

II. Common causes of constipation: Not just insufficient fiber

"Not eating enough fiber" is the most frequently cited reason, but constipation is actually usually caused by a combination of factors:

It is of practical significance to examine the causes separately:If constipation is mainly caused by medication or a physical condition, simply eating more fiber may not be enough to solve the problem.If the underlying cause is not clear, a doctor needs to address it. Conversely, if it's caused by diet and lifestyle habits, there's much more room for adjustment—which will be the focus of the following sections.

Another important thing to be mindful of is "holding back the urge to defecate." Frequently delaying the urge will gradually decrease the rectum's sensitivity to fullness, making the urge less noticeable over time. This is an easily overlooked but common factor that contributes to habitual constipation.

III. Dietary Fiber: Soluble and Insoluble Fibers Have Different Functions

Dietary fiber comes from plant-based foods and cannot be digested and absorbed by the human body, but it plays a crucial role in the gut. Based on its solubility in water, it can be divided into two main categories, each with different functions:

For constipation, both types of treatments have their benefits:Insoluble fibers are responsible for "propulsion," while soluble fibers are responsible for "softening."Therefore, it is generally more practical to diversify your sources of nutrition among vegetables, fruits, whole grains, and legumes than to focus on a single food.

The Hong Kong Centre for Health Protection recommends that,Adults and adolescents should consume 25 grams or more per day.Dietary fiber; the recommended amount for children is approximately "age plus 5 grams" (for example, an 8-year-old child needs about 13 grams). The Department of Health also recommends eating at least two servings of fruit and three servings of vegetables daily, i.e., "two plus three every day".

Here's a rough guide to the fiber content of some common foods: a medium bowl of brown rice contains about 4.5 grams, a medium apple with the peel on contains about 4.4 grams, half a bowl of cooked red beans contains about 8.4 grams, 50 grams of whole wheat bread contains about 3.4 grams, and half a bowl of broccoli contains about 2.6 grams. From this perspective, reaching 25 grams isn't difficult, but it requires deliberate planning, rather than relying solely on one or two foods.

IV. Three prerequisites for consuming fiber: water, proper timing, and variety.

This section is the most practical part of the whole article, becauseEating the wrong type of fiber can actually worsen constipation.。

First, the moisture content must be increased simultaneously.The function of insoluble fiber is to absorb water and swell, increasing its volume. If there is insufficient water, the fiber cannot absorb enough water in the intestines, and the stool may become drier and harder. Therefore, "eating more fiber" and "drinking more water" are two sides of the same coin, and you can't do only half of it.

Second, we must proceed step by step.The Hong Kong Centre for Health Protection explicitly warns that a sudden and significant increase in dietary fiber may cause bloating, abdominal distension, or even abdominal cramps. This is because the gut microbiota needs time to adapt, and a sudden influx of fiber can lead to fermentation and gas production.It is recommended to gradually increase the dosage over two to four weeks.Allow your body to gradually adapt, rather than doubling your fiber intake in one day.

Third, the sources should be diverse.Vegetables, fruits, whole grains, legumes, nuts, and seeds each have different types of fiber and other nutrients. Instead of just adding one "high-fiber food," try adding a little to both your main meals and snacks: switch to cereal or whole-grain bread for breakfast, mix white rice with red rice or brown rice, add lettuce and tomatoes to your sandwiches, or make soup with vegetables or legumes and eat the solids as well.

5. Water: 6 to 8 cups per day, how to distribute it?

Water has a direct impact on constipation. The Hong Kong Centre for Health Protection recommends increasing fiber intake while...Drink at least 6 to 8 cups of liquid beverages daily.Otherwise, the body may experience bloating, flatulence, or other discomfort due to the body's inability to adapt.

Instead of worrying about "how many milliliters to drink in the morning", a more practical approach is toSpread your drinking water throughout the dayOne cup after waking up, one cup between each of the three meals, and a moderate amount before bed. Regular supplementation is easier to maintain than consuming large amounts at one or two concentrated periods, and it is less likely to cause bloating.

It's important to note that the choice of beverages also matters. Plain water, clear soup, and light tea are all good for hydration; sugary drinks and alcohol are not recommended as primary sources of hydration—alcohol has a diuretic effect, while the extra calories from sugary drinks are another issue.

Normally, thirst is your body's way of signaling that you need to hydrate. However, in hot weather, after exercise, or when intentionally increasing your fiber intake, it's recommended to drink water proactively, rather than waiting until you feel thirsty. If you have heart, kidney, or liver-related conditions, your water intake needs to be adjusted individually; please follow your doctor's instructions.

VI. Probiotics and Fermented Foods: Their Role in Constipation Care

The relationship between gut microbiota and bowel movements is an area of ongoing research. Fermented foods such as cheese, cheese drinks, kimchi, natto, and miso contain lactic acid bacteria and other microorganisms, making them a type of food that is easily incorporated into the daily diet.

Some small studies have observed improved bowel movements after consistent consumption of cheese containing specific strains of bacteria. These studies typically involve small sample sizes and vary in strains and dosages, so the results should not be directly applied to all products or all individuals; however, incorporating fermented foods into one's daily diet is a direction worth exploring.

Here is a common misconception that needs to be clarified:The statement that "two tablespoons of homemade kimchi contain the same number of probiotics as one probiotic supplement" is inaccurate.Studies have shown that, after actual counting, two tablespoons of homemade sauerkraut contain approximately [missing information - likely a number of lactic acid bacteria]. 1.5 × 10⁶ CFUThe control group of probiotic capsules was approximately [missing information]. 4.3 × 10⁷ CFU-- Difference approximately 28 timesThe study only concluded that "kimchi meets the recommended bacterial count range," not that it is "comparable to supplements." This is a common exaggeration in this type of popular science reporting.

Two additional practical tips:In fermented foods that are heated or subjected to high-temperature sterilization, most of the live bacteria are destroyed.When purchasing, pay attention to whether refrigeration is required and whether it is labeled "unsterilized"; people with weak immune systems, undergoing chemotherapy, or seriously ill should consult their doctor before using probiotic products.

Information regarding strains, timing of consumption, intervals with antibiotics, and product selection principles has been detailed in another article and will not be repeated here. Further reading is available there.<Probiotics and Gut Health>。

VII. Oils and Others: Olive oil, flaxseed oil, prunes

Besides fiber and water, there are several other types of food that are frequently mentioned, and it's worth clarifying the evidence for them.

Prunes (dried prunes)This is the one with the clearest empirical evidence among these. A randomized crossover trial recruited forty adults with chronic constipation, comparing the intake of 50 grams of prunes twice a day (approximately 100 grams daily) with that of 11 grams of plantain seeds twice a day (both have the same fiber content, 6 grams daily). The results showed...The number of completely spontaneous defecations and the consistency of feces were both better in the prune group than in the plantain group.Therefore, the study authors suggest that prunes can be classified as a cause of mild to moderate constipation.First-line dietary optionsResearchers speculate that its effect comes from a combination of dietary fiber, sorbitol, and polyphenols, rather than just fiber alone.

Vegetable oils (olive oil, flaxseed oil)In this part, the scope of evidence needs to be narrowed. A double-blind randomized controlled trial with fifty participants...hemodialysis patientsThe subjects were given 4 ml of olive oil or flaxseed oil daily, compared with mineral oil (a laxative). The results showed improvement in constipation scores in all three groups, with olive oil and flaxseed oil showing the best performance.As effective as mineral oilTwo points to note: This isSmall-scale studies of specific ethnic groupsThis cannot be directly extrapolated to the general population; moreover, its comparison is with drugs, not placebos. Replacing some saturated fat with a moderate amount of vegetable oil in one's daily diet is a reasonable practice, but it should not be used as a substitute for laxatives.

Broccoli sproutsThis is another study that needs clarification. One study had 48 people with high constipation scores consume 20 grams daily.raw broccoli sprouts(Not mature broccoli), after four weeks, the constipation score decreased from approximately 7.25 to 5.17. This result is noteworthy, but several points need to be noted: the study was conducted on...Semi-open label design(Subjects knew what they were eating), the study was funded by a farm selling sprouts, and the study observed...The proportion of Bifidobacteria actually decreasedTherefore, a more balanced interpretation is that "broccoli sprouts may help improve bowel habits, but more independent studies are needed to confirm this," rather than "eating broccoli can solve constipation." Mature broccoli is still a good vegetable, but its main role is to provide dietary fiber.

8. List of foods that promote bowel movements: divided into four categories according to their effects.

The following is a list of common foods categorized by their effects, making it easier to choose according to your individual needs. It is important to emphasize that:These are all part of a regular diet, not "laxatives".The effects vary from person to person, and it usually takes several days to several weeks to feel the changes.

As for fruits, kiwifruit contains about 2 to 3 grams of fiber per 100 grams; blackberries, raspberries, and other berries are good with both fiber and water; apples and pears are eaten with the peel on, as the combination of fiber and sorbitol is more complete. These are all easy choices to incorporate into your daily diet.

As for legumes, cooked soybeans provide about 6 grams of dietary fiber per 100 grams, and also contain potassium, folic acid, zinc, and various B vitamins, making them a good source of fiber and other nutrients. If you don't usually eat legumes, it's recommended to start with small amounts to allow your digestive system to adjust.

9. Besides eating, there are three other things worth doing.

Besides food, there are a few other low-cost but often overlooked things:

1. Adjust your toilet posture.Elevating your feet with a small footstool so that your knees are slightly higher than your hips can help straighten the anus and rectum, reducing the amount of strain required. This is a practical suggestion listed in the UK's NICE constipation guidelines; it's free and has no side effects.

Second, make good use of the urge to defecate after breakfast.After eating, intestinal peristalsis reflexively increases (gastrocolic reflex), especially after breakfast. Scheduling your toilet visit after breakfast, allowing five to ten minutes to sit comfortably, is more likely to be successful than rushing through it while busy.

3. Maintain regular physical activity and do not suppress the urge to defecate.Daily activities like walking help with bowel movements; conversely, suppressing the urge to defecate for a long time will make the urge less and less noticeable. Neither of these things is difficult, but they require consistency.

10. When is it necessary to seek medical attention?

Most cases of constipation caused by diet and habits can improve within a few weeks with adjustments. However, the following situations should not be treated on your own; it is recommended to seek medical attention as soon as possible:

• Blood in stoolOr there is fresh blood on the toilet paper.
• Unexplained weight loss
• Bowel habitsSudden and continuous change(For example, a person who previously had regular bowel movements suddenly experiences prolonged constipation or alternating diarrhea.)
• Persistent abdominal pain, bloating, and vomitingor completely unable to pass gas or stool
• AccompaniedFever, significant fatigue, anemiaSystemic symptoms
• Persistent constipationmore than several weeksAnd dietary adjustments were ineffective.
• A family history of colorectal cancer, or having reached the recommended age for colorectal cancer screening but never having been screened.

Additionally, if you are experiencing constipation while taking medications that may cause constipation (such as some painkillers, antidepressants, iron supplements, etc.), you should discuss it with your doctor rather than stopping the medication or increasing your fiber intake to counteract it.Food and lifestyle changes can improve symptoms, but they cannot replace diagnosis.Finding the underlying cause of constipation is the first step in addressing it.

XI. Frequently Asked Questions (FAQ)

Does not having a bowel movement for a day mean you are constipated?

Not necessarily. Constipation is not determined by the number of days. The Rome IV criteria consider whether at least two of the following criteria are met for a sustained period of time: difficulty in defecation, hard stools, feeling of incomplete evacuation, feeling of obstruction, need for manual assistance, and less than three spontaneous bowel movements per week. Bowel frequency is only one of these criteria.

Will eating more vegetables definitely improve the condition?

Fiber is an important component, but it needs to be combined with sufficient water and increased gradually. If there is insufficient water, fiber may actually make stools drier and harder; if it is added too quickly at once, it can easily cause bloating and gas. In addition, if constipation is caused by medication or other physical conditions, diet alone may not be enough.

Which is more effective, plums or dragon fruit?

Prunes are currently the most well-documented, with randomized crossover trials showing they are more effective than plantain seeds in improving bowel movements. Dragon fruit, containing dietary fiber and water, is also a good choice, but there are fewer targeted clinical studies. The key is to find one that your gut can tolerate and that you're willing to eat consistently.

Can drinking olive oil relieve constipation?

A small study of hemodialysis patients showed that 4 ml of olive oil or flaxseed oil daily was as effective as mineral oil. However, this was a study of a specific population and should not be applied directly to the general population, nor should it be used as a laxative. In moderation in the daily diet, it is reasonable to use vegetable oils, but if constipation persists, one should consult a doctor rather than increasing the dosage on their own.

How long does it take for probiotics to be effective?

Different strains, dosages, and individual gut conditions vary greatly, so there is currently no single answer. If you intend to try it, it is recommended that you choose one under the guidance of a professional, observe for several weeks, record your bowel movements, and then determine whether it is suitable for you. People with weakened immune systems should consult a doctor before use.

Can enzyme drinks or laxative teas be used long-term to relieve constipation?

Long-term self-use is not recommended. Stimulant laxatives (such as senna leaves and bisacodyl) are suitable for short-term use, and long-term dependence is different from occasional consumption of foods like prunes. If you need to rely on laxatives for bowel movements in the long term, you should consult a doctor to find the cause, rather than continuously increasing the dosage.

Source of information

1. Hong Kong Centre for Health Protection – Healthy Diet High in Fiber (Dietary Fiber Recommendations and Benefits). Centre for Health Protection
2. Hong Kong Department of Health's "Living a Healthy New Direction"—Dietary Fiber (Fiber Classification, Recommended Amount and Food Content). Department of Health
3. Lacy BE, Mearin F, Chang L, et al. Bowel Disorders (Rome IV diagnostic criteria for functional constipation). Gastroenterology 2016;150(6):1393-1407. See standard compilation. Constipation: Evaluation and Management
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5. Yagishita Y, et al. Daily intake of broccoli sprouts normalizes bowel habits in human healthy subjects. Journal of Clinical Biochemistry and Nutrition 2018;62(1):75-82. full text
6. Ramos CI, Andrade de Lima AF, Grilli DG, Cuppari L. The short-term effects of olive oil and flaxseed oil for the treatment of constipation in hemodialysis patients. Journal of Renal Nutrition 2015;25(1):50-56. PubMed
7. Orgeron R, Corbin A, Scott B. Sauerkraut: A Probiotic Superfood. Functional Foods in Health and Disease 2016;6(8):536-543. Journal Records
8. NHS. Constipation (Symptoms and Self-Care for Constipation). NHS
9. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Constipation. NIDDK
10. National Institute for Health and Care Excellence (NICE). Constipation in children and young people: diagnosis and management (including toileting posture and lifestyle adjustment recommendations). NICE
11. USDA FoodData Central — A database of food nutrients (dietary fiber content lookup). USDA

Note: The dietary fiber content mentioned in this article is approximate and may vary depending on the variety, ripeness, and cooking method. Most of the cited studies are specific to particular populations or small-scale experimental designs; results should not be directly extrapolated to the entire population. Please adjust your dietary plans according to your individual circumstances.