Blackberries And Improved Digestion

Introduction

A brief overview of blackberries

Blackberries, known scientifically as Rubus spp., are a group of fruit well known for their diverse health properties. These beneficial properties are due to their rich phytochemical (a plant-based bioactive compound used by plants for protection against infection) and micronutrient composition.¹ 

Phenols (a group of bioactive compounds) are primarily responsible for the properties associated with blackberries, due to their capacity to prevent several disorders including cardiovascular disease and inflammation. They have also been shown to improve neurological function and aid the immune system.²

The importance of digestion for overall health

Digestion is the process by which consumed foods are broken down and the nutrients from these foods are absorbed into the bloodstream, where they circulate throughout the body to supply cells’ needs. Food initially enters the gastrointestinal (GI) tract, which extends from the mouth all the way to the anus. The food we ingest undergoes mastication (chewing) followed by mixing with saliva (aqueous solution), which forms a bolus (a cohesive mass of food).

It’s at this stage that the food can travel via the oesophagus and into the stomach, where it is broken down. Nutrients from the food can pass through the GI lining and enter the bloodstream whereby they can supply the needs of cells, and unwanted material is excreted as faeces. The process of digestion is critically important for the functioning of the whole body, as the nutrients fuel cells and maintain their optimum functioning. 

The nutritional benefits of blackberries

• Rich in fibre: Blackberries contain a high fibre content, with approximately 5g of fibre per 100g.¹ Fibre is a type of carbohydrate found in plants that cannot be broken down by the body nor absorbed
• Vitamins and minerals: Blackberries are packed with vitamins (A, B, C, E, K) and also minerals such as calcium, magnesium and potassium¹
• Antioxidant properties: In addition to high fibre content, blackberries also have antioxidant potential. This antioxidant potential comes from their phenolic bioactive content. Antioxidants are substances that protect against damage from free radicals

How fibre supports digestive health 

There are two types of fibres – soluble and insoluble. Blackberries contain both soluble and insoluble fibre. 

Soluble fibre

Soluble fibre dissolves in water, forming a gel-like substance. This formulation results in a slower digestive process, which enables efficient breakdown of food and nutrient absorption due to the increased transit time (time taken for food to pass through the GI tract). Soluble fibres can help lower blood cholesterol and blood glucose levels.³

Insoluble fibre

Insoluble fibre is not soluble in water. It bulks up the stool (faecal mass/’poo’)and moves food more quickly through the GI tract. This can help maintain digestive regularity.³

The role of antioxidants in digestive health 

Overview of antioxidants in blackberries

Antioxidants protect cells against free radicals – highly reactive molecules that are by-products of metabolism. At high concentrations, free radicals can negatively affect numerous sites in the body. It is important to note that free radicals at low concentrations are actually highly beneficial for the body, aiding in several physiological processes including cell differentiation, apoptosis (removal of unwanted cells) and cell immunity (protection against infection). 

Excessive free radicals, on the other hand, can damage and disrupt cells targeting DNA, proteins and lipids.⁴ Excessive free radical production can be caused by factors such as environmental stress stimuli and infection.

The phenol compounds present in blackberries, particularly anthocyanins and ellagitannins, are responsible for their antioxidant properties. Mounting research has implicated their antioxidant effect in reducing the risk of diseases such as cancer, cardiovascular disease and several other disorders.^5,6

Reduction of oxidative stress in the digestive system

Oxidative stress is the process whereby excess free radicals gradually induce cellular damage over time. This process occurs when there is an imbalance between the levels of free radicals and antioxidants – high free radical levels and low antioxidant levels.^7,8 Oxidative stress can be combated by introducing antioxidant-rich foods such as blackberries to your diet. The GI tract is particularly susceptible to the effects of oxidative stress due to its exposure on a regular basis to food and microbial pathogens.⁸

The connection between antioxidants and a healthy gut lining

Oxidative stress can be a cause of inflammation of the gut lining.⁸ Therefore, it is important that an equilibrium between antioxidants and free radicals is established and maintained for the gut lining to remain healthy. 

Blackberries and gut microbiota 

Introduction to gut microbiota

There are around 30 trillion human cells in the body, however, did you know that there are even more microorganisms? It has been estimated that there are around 38 trillion microorganisms (bacteria, fungi and viruses) in the body and they are known collectively as the ‘microbiome’. The microbiome and human cells form a mutualistic symbiotic relationship which benefits both.^9,10 

The collection of microorganisms in the gut makes up what is known as the ‘gut microbiota’. The gut microbiota accounts for 70% of the entire microbiome and therefore plays a highly important role in health. This mutualistic relationship between the gut microbiota and human cells benefits numerous physiological functions, including gut maintenance, energy production, protection against pathogens (infectious microorganisms) and regulation of host immunity.¹⁰

The prebiotic effects of blackberries

The term ‘prebiotic’ refers to substances that promote the growth of the microbiota and support its activity. Research suggests that blackberries may act as prebiotics as they contain polyphenol compounds. Much research has established polyphenols as being beneficial to the gut microbiota, through positively modulating the gut microbiome and also inhibiting the growth of pathogens. 

A study conducted by Marques et al (2018) found that anthocyanins (a type of polyphenol found in blackberries) administered to rodents promoted the growth of healthy microorganisms in the gut microbiota such as Pseudoflavonifractor and Oscillobacter, whilst inhibiting the growth of Ruminococcus (a bacterial pathogen). 

Another study by Overall et al (2017) in mice, found that anthocyanins in berries promoted the growth of the gut-friendly bacteria Bacteroidetes and Actinobacteria in the gut microbiota.^12,13

Potential considerations and precautions

Allergies and sensitivities

Like any food, it is important to be aware of the allergies and sensitivities associated with blackberries. Although uncommon, these should be taken into consideration when they are being introduced to your diet. Symptoms of a blackberry allergy include:

• Headaches
• Nasal congestion
• Itching
• Stomach discomfort

Summary

Blackberries are a highly nutritious fruit which can be enjoyed as part of a balanced diet. Its high fibre content, vitamins, minerals and antioxidant properties make it a ‘superfood’. Through supporting digestion and providing the body with key nutrients, blackberries are an excellent choice to introduce to your diet and can help lower the risk of several diseases including cardiovascular disease and IBD. It's important however that they are consumed in moderation.