Dr. Sabina Lachowicz-Wisniewska 

Behind the colour, flavour and aroma of foods such as red wine, coffee, olive oil, dark chocolate and berries lies a family of naturally occurring compounds known as polyphenols.

Beyond their sensory appeal, polyphenols play multiple roles in human health. On the one hand, they neutralise free radicals, molecules in our bodies that, in excess, can cause cellular damage, thereby reducing oxidative stress. They also help to alleviate chronic inflammation and support a balanced gut microbiota, which in turn improves immune, metabolic and cognitive functions.

Because of this wide range of benefits, polyphenols are being studied as key dietary components for the prevention of chronic diseases and the promotion of healthy ageing.

However, there is a major obstacle: a considerable proportion of these compounds reaches the colon in forms that the small intestine cannot absorb and, once there, they undergo microbial transformation that diminishes their beneficial effects.

Therefore, the mere presence of polyphenols in the diet does not, by itself, guarantee effective biological utilisation. This means that the main challenge is not so much increasing the amount we consume, but rather modulating how efficiently our bodies can absorb and use them once ingested.

How does our body process polyphenols? 

Many polyphenols are chemically unstable, meaning they degrade during food processing and storage when exposed to external factors such as oxygen, heat, light or changes in pH, among others.

Once ingested, they undergo further transformations as they move through the digestive system. For example, anthocyanins, responsible for the red, blue and purple colours of many fruits and vegetables, and which are stable and intensely coloured in acidic environments, shift to duller tones as the pH of the intestine increases.

These changes are followed by additional metabolic processes, such as glucuronidation, sulfation and methylation, as well as microbial degradation into low-molecular-weight phenolic acids and aldehydes. All of these processes chemically modify polyphenols, facilitating their elimination and reducing their original activity.

To make matters worse, interactions with other food components: including proteins, dietary fibre and lipids, together with the influence of bile salts and digestive enzymes, can further reduce their activity.

All of this highlights the need for protective and controlled-release systems that limit degradation, prolong exposure, and direct the action of polyphenols to the appropriate site within the gastrointestinal tract.

 
Improving the passage of polyphenols through the body
 

One possible approach is the use of food encapsulation systems based on biopolymers, which act as “protective vehicles” by encapsulating sensitive compounds to prevent them from degrading before the body can absorb them.

In particular, layer-by-layer (LbL) multilayer films, composed of polysaccharides and proteins, make it possible to enhance the resistance of polyphenols to environmental degradation (for example, changes in pH, temperature or exposure to light) and to prolong their gastrointestinal retention.

Further engineering of this pioneering encapsulation system improves retention and bioactivity during digestion even more, demonstrating high encapsulation efficiency, preservation of antioxidant activity, and greater mechanical and thermal resistance. In this way, it becomes possible to control how and when polyphenols are released, at least for now, under laboratory conditions.

The idea behind this initiative, which forms part of the Marie Skłodowska-Curie BIOCOMAT project, is to create delivery systems for polyphenols that naturally occur in chocolate or wine, in much the same way that we take a vitamin C supplement without eating an orange, or an iron supplement without eating liver, while obtaining the same health benefits.

The great challenge: an optimal delivery system

The next challenge in this process is to design smart materials capable of knowing where and when to release their payload. The goal is to ensure that polyphenols remain protected from heat, processing and digestion, and are released only once they reach the appropriate section of the intestine.

The difference between a conventional supplement and what our team is developing lies in the fact that, through the materials and techniques employed, it is possible to control how these delivery systems degrade within the body and the time they take to do so. As a result, instead of releasing polyphenols before passing through regions where they would not be effectively absorbed, they are released where they can exert the greatest effect.

Achieving this will require precise fine-tuning of the release rate under conditions that mimic the human digestive system, while simultaneously employing computational modelling, such as simulations and predictive models, alongside experimental design.

At the same time, advances in process automation, from dosing and coating to real-time measurements, will ensure that the technology can be efficiently scaled up.

Ultimately, the ambitious goal of our laboratory is to develop an easy-to-consume product that truly delivers on its promise: providing the health benefits of polyphenols at the moment and in the place where they matter most.