The ‘ food as medicine ’ trend is growing fast, with nutritionists and healthcare professionals recognising the potential for diet to prevent illness and promote overall wellbeing.
Now, research into the potential for tropical fruits such as papaya and passion fruit to prevent diseases like cancer, looks set to boost it even further.
Could tropical fruits help prevent cancer?
Researchers from universities and institutions in Brazil and Germany have conducted separate but complementary studies to ascertain the disease-fighting potential of compounds in tropical fruits including papaya, passion fruit and citrus fruits. Their findings were presented at FAPESP Week in Germany.
Medicinal plants and fruits contain a diverse variety of phytochemicals. These naturally occurring chemical compounds can combat bacterial infections, as well as strengthening the body’s immune response. As a result, there is growing interest in using plant extracts to prevent and treat infections such as urinary tract infections (UTIs), which are one of the most common infections globally, and typically require antibiotics to treat.
“Although their anti-inflammatory, antipyretic and analgesic effects are well known, the active compounds of these plants – such as flavonoids, alkaloids and terpenoids – and their mechanisms of action on pathogen cells have yet to be characterised," says Ulrich Dobrindt, a professor at the University of Munich.
What is 'food as medicine'?
Food as medicine is the concept of eating and drinking to promote health and wellbeing.
Foods and beverages consumed can have a profound effect on overall health and wellbeing, with research showing that dietary habits influence risk of certain diseases.
While some foods may lead to chronic health conditions, others can offer therapeutic and protective qualities.
In order to further their understanding, the German research team developed infection models to study the effects of plant extracts on the innate immune response and on the epigenetic regulation of gene expression (biochemical processes that activate and deactivate genes).
In collaboration with researchers at the Federal University of Minas Gerais (UFMG) in Brazil, they found that some aqueous plant extracts (from species such as Solidago gigantea and Equiseti herba) significantly reduced the adhesion and survival of Escherichia coli in human bladder epithelial cells.
“We observed a drastic reduction in the adhesion and proliferation of this bacterium in bladder cells,” says Dobrindt.
In Brazil the researchers focused on the technological prospection and evaluation of the biological effects on humans of non-digestible water-soluble polysaccharides (bioactive polysaccharides), such as pectins.
Pectins, say the researchers, make up a large portion of the fibre in fruits such as papaya, passion fruit, and citrus fruits, and have been linked to a reduction in chronic non-communicable diseases.
However, some of the challenges in extracting these compounds from fruits such as papaya are that they ripen very quickly, resulting in softening of the pulp and chemical modification of the structures of its pectins, which are linked to biological effects such as modulation of the gut microbiota.
“During fruit ripening, enzymes are expressed that modify the structure of the pectins, reducing their beneficial biological effects,” says Professor João Paulo Fabi, coordinator on the project. “Passion fruit and citrus pectins, on the other hand, must be chemically modified in order to present beneficial activities in the intestine.”
To do this, the Brazilian researchers developed techniques to extract pectin from the albedo of oranges and passion fruit – the white part between the peel and the pulp that is normally discarded when the fruit is processed to make juice – and to modify it in the laboratory to reduce its molecular complexity in order to increase its biological activity.
The development resulted in a patent for the process of extracting pectin from fleshy fruits such as papaya and chayote. A second patent covering the modification of pectin from passion fruit by-products is in the process of being filed.
“We already have a prototype for extracting and modifying these pectins on a laboratory scale. The idea is to obtain a product, such as a flour rich in modified pectin, that could be consumed as a supplement or food ingredient,” says Professor Fabi.
In partnership with other groups, the researchers conducted animal studies to demonstrate the correlation between modified pectins and increased biological activity.
“These preclinical studies can serve as a basis for the development of clinical trials,” says Professor Fabi.