Promoting Digestion With Breadfruit

Overview

The breadfruit is a lesser known, starchy and green cousin to the jackfruit that has various positive potential for your digestive health. It is abundant in dietary fibre and sugars that regulate the rate of digestion and affect stool consistency. Therefore it is helpful for those with diabetes and/or constipation. The presence of vitamin C also has been linked to reducing the risk of ulcerative colitis. Breadfruit contains both vitamin C and minerals that are crucial in maintaining overall intestinal health, preventing constipation

What is breadfruit?

Breadfruit is a plant characterised by its round, green appearance and is related to the jackfruit family. It gets its name from the texture that it has after cooking, but its flavour is more similar to potato.

It is grown all around the world, initially in Austronesian countries such as New Guinea and Tahiti, but has now spread to Africa and the Caribbean.¹

Dietary fibre

Dietary fibre refers to a group of plant-originating compounds that cannot be completely digested by human enzymes. These compounds are typically found within plant cell walls. The presence of dietary fibre influences the cells within the intestinal mucosa (inner lining) which affects their ability to digest and absorb nutrients.² This affects the consistency of stools and fluidity of bowel movements, preventing constipation.

While they are not commonly associated with each other in other foods, dietary fibre is also linked to decreasing cholesterol levels. When fermented, however, dietary fibre combined with lactic acid creates an ideal environment for healthy gut bacteria (probiotics). This makes breadfruit a prebiotic, high-fibre food that benefits our microflora (the range of helpful bacteria that live inside of humans).

Dietary fibre is also known to slow the absorption of glucose into the bloodstream to ensure its transportation throughout the body is consistent. This contrasts with potential spikes in blood glucose concentration that are associated with diabetes mellitus.³

Excess dietary fibre can cause negative effects but this is minimised by the presence of vitamin C which is also in breadfruit (explained below).

Vitamin C

Breadfruit contains a significant amount of vitamin C, in comparison to most fruits. This nutrient is associated with teeth and gum health, but it also has positive implications for digestion.

Vitamin C and the gut microbiome

Within our bodies we have different species of bacteria that inhabit various organs, providing key benefits for us such as producing certain enzymes or ensuring there are no harmful pathogens invading. All the bacterial species within a certain environment are known as a microbiome, which can be affected by our diet, even by vitamin C.

In a 2021 study, gut microbiomes from healthy individuals (18 to 30 years old) were examined for any changes from high intake of vitamin C supplements. After one month, those who followed the supplement regimen showed increases in Lachnospiraceae, Blautia and Roseburia bacterial families, although only the first one was found to be statistically significant to draw conclusions [Figure 1]. Species within these families are known to break down dietary fibre, with species within Roseburia fermenting them to produce short-chain fatty acids (SCFAs), most commonly, butyrate. SCFAs have anti-inflammatory properties that strengthen gut protection against pathogens, antigen tolerance and better control nutrient uptake.⁴

Figure 1: Differences in bacteria family abundance in the presence of a vitamin C-rich diet. Bacterial families found in faecal samples of healthy individuals before (T0) and after (T2) taking vitamin C supplements for two weeks. Error bars indicate interquartile range. * = p ≤ 0.05, ** = p ≤ 0.01.

The vitamin C within breadfruit pairs well with its dietary fibre, essentially “balancing” the effects. This is because too much dietary fibre can lead to constipation. The increase in certain bacteria that vitamin C brings allows for this to be regulated via the breakdown of excess dietary fibre.⁵

Vitamin C and ulcerative colitis

Vitamin C also has a role in maintaining the stability of the intestinal mucosal barrier. This is related to tight junctions, which are protein complexes between cells to prevent fluid from leaking out. Combined with vitamin D3 (known to be found in sunlight), vitamin C prevents tight junctions from rupturing and promotes their repair.⁶

The study that discovered these findings observed that low- or no-vitamin C diets corresponded with higher rates of ulcerative colitis. This condition, as the name suggests, is inflammation of the colon that can cause bloody stools and diarrhoea. While research is limited in this regard, foods like breadfruit have the potential to reduce the likelihood of developing inflammatory bowel disease and improve overall digestive health.

Carbohydrates

Breadfruit contains complex carbohydrates, those which have large chemical compounds that take longer to break down in comparison to smaller carbohydrates. Ultimately this leads to carbohydrate digestion that leads to slower release of glucose (the most basic sugar that we use), leading to a steadier release of energy and maintaining blood-glucose levels which is beneficial for those with diabetes mellitus.⁷

There are 3 main complex carbohydrates that have been identified in breadfruit:

• Starch
• Raffinose
• Stachyose

Starch is the most common storage carbohydrate that can be converted into glucose when energy is required. Starch is broken down and absorbed in the small intestine via an enzyme called amylase.⁸ Breadfruit has a very high starch content, which could explain why its taste is compared to potato.¹

Raffinose is a trisaccharide, meaning that it is composed of three sugars: glucose, fructose and galactose. It can only be broken down by α-galactosidase, an enzyme created by bacteria that are part of the large intestinal microbiome.⁹ This suggests that changes in bacterial species distribution (that could be caused by eating other foods) in the large intestine could affect its ability to digest raffinose.

Stachyose is a tetrasaccharide, a compound of 4 sugars. It can be split into a different combination of sugars depending on which enzyme is present. In terms of chemical structure, stachyose is similar to raffinose but only with an additional galactose subunit.¹⁰ Due to this, we also rely on bacteria within our intestines to break stachyose down in order to access these sugars, which in turn allows for regulated digestion.

Due to how large these molecules are, when raffinose and stachyose are broken down, they produce carbon dioxide, oxygen and methane gas. Together the release of these gases from the digestive system, namely the bowels, leads to flatulence, especially in large quantities.

Minerals

Breadfruit contains two minerals that directly benefit our digestive system, potassium and iron.

Potassium

Potassium deficiency, known also as hyperkalaemia, can lead to slower food movement through the digestive system – this is because potassium ions are required for electric impulses from the brain to signal to intestinal muscles to contract. This forces food through the intestines in a process called peristalsis to direct it towards the bowels as is digested via acidic juices. Hypokalaemia is associated with less efficient peristalsis, and most notably constipation, two issues that foods like breadfruit can reduce the chances of.

Iron

In a similar fashion to vitamin C, the presence of iron can influence the diversity of the gut microbiome, leading to subsequent negative changes in the gut. While the mechanisms for their causes are still under research, dysbiosis (loss of regulation) of the gut microbiome led to cases of intestinal inflammation and colorectal cancer in other patients.¹¹ These findings were from observing babies who received iron-fortified milk, whereby the above conditions did not occur as well as a higher concentration of the Lactobacillus group of bacteria. Lactobacillus is known to be found in yoghurts and its effects can be enhanced with iron, which breadfruit contains.

Summary

Breadfruit is an underrated fruit, mostly due to its lack of presence and knowledge in the Western world. Despite this, it is not extraordinary in the sense that it contains nutrients that you may be familiar with from other foods, such as dietary fibre and starch, but it’s the combination of these nutrients that appears to be unique, especially with its positive implications for digestive health. Minerals, vitamin C, and complex sugars all play important roles in keeping our intestines in good condition – this is in terms of their cellular structure but also their microbial communities that play a role just as vital.