If you are struggling with constipation, some foods can help by working as natural laxatives. They do this by increasing the number of times you poo and making poo softer, bulkier, and easier to pass.
In this article, we’ll cover the top science-backed natural laxatives and how you can add them in to your everyday diet.
Remember if you’re trialling something new, build up gradually to give your gut time to adjust to the change.
Kiwis
A handful of studies have shown that eating kiwis can reduce straining, shorten gut transit time, and increase poo frequency. This is likely due to a few different components in kiwis.
The fibres in kiwis have a high-water holding capacity. This means the fibres swell up when they reach the gut. This can help bulk out poo and improve poo consistency. Two skin-on green kiwis contain 6g of fibre.
Other components that might contribute to the laxative effects of kiwis include polyphenols which are particularly high in kiwi skin - around 1273 mg per 100g (or 1.5 kiwis). What’s more, an enzyme identified in kiwis called actinidin has been linked to improvements in gut motility.
Try this: Start with 1 skin-on kiwi (green or gold) for the first week, then increase to 2. Trial for 4 weeks.
Prunes
There are a few reasons why studies have shown prunes can increase poo weight and poo frequency.
Prunes are naturally high in sorbitol - around 12g per 100g of prunes (10-12 prunes). Sorbitol is a sugar alcohol that has an osmotic effect. This means that it draws water into the gut and helps to soften poo.
Besides sorbitol, prunes are high in fibre - around 6g per 100g. Prunes contain a mix of different fibres, including hemicellulose, pectin, and cellulose.
Prunes also contain an abundance of plant chemicals, including polyphenols. Around 90-95% of polyphenols are undigested and reach the large intestine where trillions of microbes ferment them. In turn, they release beneficial compounds into the gut such as short chain fatty acids (SCFAs). SCFAs are thought to play a role in gut motility.
Try this: Start with 50g per day (5-6 prunes) for 1 week, then increase to 100g per day (10-12 prunes). Divide the dose and consume half in the morning and half in the afternoon or evening as a snack. Drink alongside a glass of fluid. Trial for 4 weeks.
Flaxseeds
In the plant world, flaxseeds (or linseeds) are recognised as one of the richest sources of omega-3 fatty acids. These healthy fats - alpha linoleic acid (ALA) and docosahexaenoic acid (DHA) - are in the form of oil which makes up around 35-45% of their weight.
Flaxseeds are also rich in fibre -around 26g per 100g. They contain the types of fibre that have a high-water holding capacity.
Combined, flaxseeds are thought to have lubricating effects, as well as poo bulking and softening properties.
One study showed that people with constipation who consumed 50g of flaxseed flour per day for 4 weeks reported an improvement in poo frequency and less difficulty going to the toilet.
Flaxseeds are versatile – you can add them to all sorts of meals, including cereals, salads, soups and yogurt.
Try this: Start with 1/2 -1 tablespoon per day (ground or whole) and build up to 3 tablespoons. Make sure you drink a glass of fluid alongside (it’ll help the fibre to work once it reaches your gut).
Chia Seeds
Other seeds that have been less researched but may also help with constipation are chia seeds.
Chia seeds also contain a lot of fibre – around 35g per 100g. When chia seeds absorb water (think chia pudding), they develop a gel-like consistency. In fact, the fibre part of chia seeds can hold around 15 times their weight when wet.
Chia seeds haven’t been studied in constipation, but due to their characteristics, it’s thought that they may have a laxative effect by increasing poo bulk, poo weight, as well as softening poo.
Try this: Try including more chia seeds by adding to smoothies or when you’re baking. For chia pudding, mix 2 tablespoons of chia seeds and ½ cup of cow’s milk or plant-based milk. Add a topping of your choice (such as fruit, nuts, dark chocolate chips) for some extra plant-based diversity.
Mango
Mango is a fibre-rich fruit containing 1.6g per 100g. One of the main fibres in mango is pectin – a high-water holding capacity fibre that helps to form mango’s characteristic gel-like pulp. It’s this fibre that can help to bulk out poo making it easier to pass. This bulking effect can also help to stimulate gut motility and keep things ‘moving along’.
In fact, one study showed that eating one whole mango every day increased poo frequency, consistency, and shape. What's more, another study showed that eating half a mango every day can improve gut microbiome diversity.
Mango also contains high amounts of antioxidants (such as vitamin C) and polyphenols (such as carotenoids). It’s possible that these beneficial compounds create an anti-inflammatory effect in the gut which might also help to relieve symptoms of constipation.
Try this: Start by adding half a mango (or more if you’d prefer) into your diet every day for 4 weeks.
Figs
Like mango, figs are rich in pectin, especially the skin. As with other fruits, there is more fibre in the skin of figs than the flesh.
One study showed that eating fig paste every day for 8 weeks improved gut transit time in people who pooed 3 or less times per week. Another study in constipation predominant irritable bowel syndrome (IBS-C) found that 90g of dried fig every day for 4 months reduced the frequency of hard poo.
Try this: Start with 1 fig (35g) for the first few days, then increase to 2-3 figs for 4 weeks. You could try fresh figs or soft figs (partially rehydrated).
Rye bread
Rye bread is rich in different fibres including β-glucans, cellulose, lignin, and fructans.
Studies have found that consumption of rye bread for 3 weeks in people with constipation resulted in easier pooing, including increases in poo frequency and improvements in poo consistency. Eating rye bread also increased poo weight and gut transit time compared with white bread.
These studies provided 6-8 slices of rye bread per day, equating to around 30g of fibre in total. One slice of rye bread contains 3.5-4g of fibre.
Try this: Swap out white bread for rye bread instead. Try it toasted with crunchy peanut butter and jam with added chia seeds for an extra fibre boost.
Juices
Pure fruit juices extracted from fruits such as prunes, pears, and cherry might also help with constipation. This is because they contain sorbitol.
In fact, one study found that 54mls of prune juice for 8 weeks decreased hard, lumpy poo and helped to normalise poo consistency. Another study found that drinking 125mls twice a day for 4 weeks was effective for mild constipation.
The key difference between pure fruit juices and whole fruits is that whole fruits retain the dietary fibre portion, unlike pure fruit juices which contain very small amounts. However, both contain an abundance of polyphenols.
Nutritionally, you’re getting far more bang for your buck with whole fruits including prunes, pears and cherries, but give the juice equivalent a go, if you’d prefer.
Try this: Try including a glass (around 150mls) of pure prune fruit juice (or pear or cherry) every day for 4 weeks.
NB: There is no one approach to treating constipation and different approaches will work for different people. It’s often a combination of approaches that can help. For tailored advice, please seek advice from a registered dietitian.
Sources
Consumption of 2 Green Kiwifruits Daily Improves Constipation and Abdominal Comfort-Results of an International Multicenter Randomized Controlled Trial. Pub Med. (2023) Link.
Exploratory Comparative Effectiveness Trial of Green Kiwifruit, Psyllium, or Prunes in US Patients With Chronic Constipation. Pub Med. (2021). Link.
The Effects on Immune Function and Digestive Health of Consuming the Skin and Flesh of Zespri® SunGold Kiwifruit (Actinidia Chinensis var. Chinensis 'Zesy002') in Healthy and IBS-Constipated Individuals. Pub Med. (2020). Link.
The effect of prunes on stool output, gut transit time and gastrointestinal microbiota: A randomised controlled trial. Pub Med. (2019). Link.
Effects of flaxseed supplementation on functional constipation and quality of life in a Chinese population: A randomized trial. Pub Med. (2020). Link.
Polyphenol-rich Mango (Mangifera indica L.) Ameliorate Functional Constipation Symptoms in Humans beyond Equivalent Amount of Fiber. Pub Med. (2018). Link.
The effects of fresh mango consumption on gut health and microbiome – Randomized controlled trial. Pub Med. (2023). Link.
Randomized, double-blind, placebo-controlled trial of Ficus carica paste for the management of functional constipation. Pub Med.. Pub Med. (2016). Link.
Comparison and Assessment of Flixweed and Fig Effects on Irritable Bowel Syndrome with Predominant Constipation: A Single-Blind Randomized Clinical Trial. Science Direct. (2019). Link.
A combination of fibre-rich rye bread and yoghurt containing Lactobacillus GG improves bowel function in women with self-reported constipation. Pub Med. (2006). Link.
Constipation Is Relieved More by Rye Bread Than Wheat Bread or Laxatives without Increased Adverse Gastrointestinal Effects. Science Direct. (2010). Link.
Prune Juice Containing Sorbitol, Pectin, and Polyphenol Ameliorates Subjective Complaints and Hard Feces While Normalizing Stool in Chronic Constipation: A Randomized Placebo-Controlled Trial. The American Journal of Gastroenterology. (2022). Link.
Prune juice has a mild laxative effect in adults with certain gastrointestinal symptoms. Science Direct. (2007). Link.
Fruits and their impact on the gut microbiota, gut motility and constipation. The Royal Society of Medicine. (2021). Link.
Systematic review and meta-analysis: Foods, drinks and diets and their effect on chronic constipation in adults. (2023). Link.
