Fibre is an essential part of a balanced diet, including the benefits of fibre for promoting good digestion, supporting heart health, and aiding in weight management. However, both a lack of fibre and excessive intake can lead to various side effects. According to the British Nutrition Foundation, the recommended daily intake for adults in the UK is 30g, but most people consume significantly less, averaging 18g per day [1].
This article discusses the side effects of both low and high fibre intake and advice for controlling fibre levels for best health.
Key Takeaways
• Fibre is critical for digestive health, but both low and excessive intake can cause side effects like bloating, constipation, and nutrient malabsorption.
• The recommended fibre dosage for adults in the UK is 30g, but many fall short, with an average consumption of around 18g per day.
• To avoid negative side effects, gradually increase your fibre intake, drink plenty of water, and consult a healthcare professional if needed.
What is Fibre?
Fibre, or roughage, is a type of carbohydrate that is not fully digested by the body [8]. It passes through the digestive system, aiding in bowel regularity and overall gut health. There are two types of dietary fibre:
• Soluble fibre: This dissolves in water to form a gel-like substance, helping to lower cholesterol and control blood sugar levels [9]. Sources include oats, barley, and fruits like apples and citrus.
• Insoluble fibre: This adds bulk to the stool and promotes regular bowel movements [10]. It’s found in whole grains, nuts, and vegetables like carrots and potatoes.
Fibre is very important for maintaining a healthy gut, but both too little and too much can have adverse effects.
What Happens When You Consume Too Much Fibre?
Excess fibre intake, especially from fibre supplements or tablets, can lead to various side effects. Let’s look at the most common issues related to consuming too much fibre:
1. Bloating
One of the most common side effects of a high-fibre diet is bloating. When fibre isn’t digested, it can ferment in the gut, leading to gas production and uncomfortable bloating [10]. This can be particularly noticeable if fibre intake is increased too quickly. To minimise bloating, it’s recommended to increase fibre gradually and ensure proper hydration. Including a variety of fibre sources, such as fruits and vegetables, may also help reduce bloating.
2. Gas
As fibre ferments in the intestines, it produces gases such as methane and hydrogen, which can cause flatulence. This is more likely to occur when your fibre intake increases rapidly [10]. Some individuals may be more sensitive to certain types of fibre, such as those found in beans or legumes, which can produce more gas. Slowly increasing fibre intake and drinking plenty of water may reduce these side effects.
3. Stomach Cramps
Excessive fibre can cause cramping and discomfort in the intestines as your digestive system struggles to process the increased bulk [10]. This can happen if there’s a sudden jump in fibre intake or if not enough fluids are consumed. Ensuring a gradual increase in fibre and staying hydrated can help alleviate these cramps. Additionally, incorporating different types of fibre, such as both soluble and insoluble, may ease discomfort.
4. Constipation
While fibre is often recommended to treat constipation, too much insoluble fibre without adequate fluid intake can harden stools and make them difficult to pass [3]. This occurs when the body doesn’t have enough water to help fibre move through the intestines. To prevent this, it is crucial to drink plenty of water alongside a high-fibre diet. Soluble fibre sources, like oats and fruits, can also help soften stools.
5. Diarrhoea
Conversely, too much soluble fibre can lead to diarrhoea. Soluble fibre draws water into the intestines, and when consumed in excess, it can result in loose stools [11]. This is more common when supplements are used or when a drastic change in diet occurs. Moderating soluble fibre intake and pairing it with insoluble fibre can help balance stool consistency.
6. Dehydration
Fibre absorbs water as it moves through the digestive system. Without sufficient fluid intake, excessive fibre can lead to dehydration, further contributing to constipation and bloating [11]. Dehydration can also cause fatigue, headaches, and a general feeling of sluggishness. Drinking at least 6-8 glasses of water a day is essential to keep up with increased fibre intake.
7. Poor Absorption of Some Key Nutrients
Excess fibre can interfere with the absorption of essential minerals, including calcium, iron, magnesium, and zinc [4]. Fibre can bind to these nutrients, reducing their availability to the body. This can be particularly concerning for individuals who rely on a high-fibre diet or those with certain medical conditions requiring a balanced intake of these minerals. To minimise this effect, it’s important to maintain a well-rounded diet and consult a healthcare provider if using fibre supplements.
8. Nausea
A rapid increase in fibre intake can sometimes lead to nausea, particularly when fibre supplements are taken on an empty stomach or with inadequate hydration [12]. Nausea can also be a result of digestive discomfort as the body adjusts to the new fibre levels. To avoid this, it’s best to introduce fibre gradually into your diet and ensure it is consumed with enough fluids and food.
9. Intestinal Blockage
In rare cases, a dramatic increase in fibre intake, especially without sufficient water, can cause an intestinal blockage. This serious condition requires medical intervention and may cause severe pain, vomiting, and an inability to pass stools. Those with pre-existing digestive conditions should be cautious when increasing fibre intake and consult a healthcare professional for guidance [5].
How Much Fibre Should You Eat Daily?
In the UK, adults are advised to intake 30g of fibre per day [1]. However, many people fall short of this recommendation, which can lead to digestive problems and long-term health risks. It’s important to balance fibre intake and gradually increase it if you are not currently meeting the recommended levels.
How to Avoid the Negative Effects of Excess Fibre
To prevent the side effects associated with fibre overconsumption, it’s important to manage your intake carefully. Here are a few tips:
• Gradually Increase Fibre Intake: Start by introducing small amounts of fibre-rich foods to your diet and gradually increase the quantity over time. This allows your digestive system to adjust.
• Stay Hydrated: Since fibre absorbs water, it’s essential to drink plenty of water. This helps move fibre through the digestive tract and prevents dehydration [3].
• Balance Your Diet: Ensure your diet includes a mix of soluble and insoluble fibre from a variety of food sources. This balance will help you avoid the negative effects of consuming too much of either type.
• Consult a Healthcare Expert: If you are unsure how much fibre you should consume or if you’re experiencing persistent symptoms, seek advice from a healthcare professional. They can guide you on how to adjust your fibre intake appropriately.
Conclusion
Fibre is vital to a healthy diet, contributing to everything from digestive health to heart disease prevention. However, both too little and too much fibre can lead to unwanted side effects, like bloating, constipation, and poor nutrient absorption. To avoid these problems, it’s important to consume fibre in moderation, gradually increase your intake, and stay hydrated. If you’re struggling to meet your daily fibre requirements, fibre supplements and tablets can help, but they should be used carefully to prevent side effects.
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FAQs
1. What are the effects of low fibre intake?
Low fibre intake may lead to increased cholesterol levels, constipation and a higher risk of heart disease [6].
2. Can fibre supplements cause side effects?
Yes, fibre supplements may cause bloating, gas, and constipation if taken in excess or without enough water.
3. What are the best natural sources of fibre?
Vegetables, whole grains, fruits and legumes are excellent natural sources of fibre.4.
4. Can excess fibre cause weight loss?
Excess fibre may cause unintentional weight loss due to reduced appetite and lower calorie consumption.
5. How does fibre benefit men’s health?
Fibre for men supports health by aiding digestion, regulating blood sugar levels, and potentially reducing the risk of prostate issues.
6. What are the signs of fibre overconsumption?
Common signs include bloating, gas, stomach cramps, constipation, and diarrhoea.
References
1 – https://www.bda.uk.com/resource/fibre.html
2 – https://continentalhospitals.com/blog/the-role-of-fiber-in-managing-blood-sugar-levels
3 – https://www.healthline.com/health/food-nutrition/too-much-fiber
4 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2681046/
5 – https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/fiber-supplements/faq-20058513
6 – https://www.bhf.org.uk/informationsupport/heart-matters-magazine/nutrition/fibre
7 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3435786/
8 – https://www.healthline.com/nutrition/roughage
9 – https://www.cdc.gov/diabetes/healthy-eating/fiber-helps-diabetes.html
10 – https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983
11 – https://www.medicalnewstoday.com/articles/321286
12 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9572413/
