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What are phytochemicals ?

Phytochemicals are secondary metabolites synthesized by plants primarily for their defense against pathogens and stress. They can be specific to a given species or widely distributed in plants, and their final concentration in food products is affected by agronomic factors, as well as industrial and home processing.

So far, more than 1200 phytochemicals belonging to various families (polyphenols, carotenoids, glucosinolates, phytosterols, monoterpenes, alkaloids,…) are identified in commonly consumed plant foods and their total intake often exceeds 1g/day.

Why do phytochemicals matter for cardiometabolic health?

Cardiometabolic diseases are the number-one cause of death in the world. They include cardiovascular disease, diabetes mellitus, and chronic renal failure.

In the last decade, there has been an explosion of research demonstrating the beneficial effects of plant foods and food phytochemicals to prevent obesity and cardiometabolic diseases. Extensive intervention studies have shown the benefits of switching to plant food-rich dietary patterns, including the Mediterranean and New Nordic diets. In parallel, many randomized controlled trials (RCTs) and meta-analyses have provided clear evidence of improvement by particular plant foods or food phytochemicals of risk factors and pathways relevant to weight control and cardiometabolic diseases, such as glucose and lipid metabolism, insulin resistance, inflammation, blood pressure, and endothelial dysfunction.

What are the challenges in research on food phytochemicals?

Food phytochemicals represent a complex chemical space, with a high diversity of structures (n>1200) belonging to different families such as polyphenols, lignans, glucosinolates, alkaloids, phytosterols, carotenoids, and other terpenoids.

They undergo extensive and compound-specific metabolism by phase I or phase II enzymes, and by the gut microbiota. A high interindividual variation exists for the production of some bioactive metabolites and this has to be taken into account for a good understanding of their health effects.

Accurate assessment of the individuals’ exposure to the diverse food phytochemicals is challenging. Dietary questionnaire methods are imprecise, food composition tables are incomplete, and the extensive metabolism affects the internal exposure.

Most food phytochemicals display pleiotropic and compound-specific biological activities, that may vary with the dose. Their mechanisms of action have often been studied in non-physiological conditions, with supra-nutritional doses. Their important interaction with the microbiome is only beginning to be studied.

Finally, data on the metabolism and the cardiometabolic health effects of food phytochemicals are scattered across the literature and difficult to critically evaluate for a non-expert.

What is PhytoHub ?

Phytohub is a freely accessible database dedicated to food phytochemicals and their metabolites. Launched by INRAE in 2014, it has been continuously updated with the collaboration of invited experts.

PhytoHub contains detailed information about chemical structures, nomenclature, machine readable identifiers, classifications, physico-chemical properties, occurrence in food, known metabolites in humans and animals, analytical features for use in metabolomics, links to complementary online databases and will soon integrate health data.

Online databases have proven to boost research and derived applications in many fields. The upgrade of PhytoHub in the framework of the FoodPhyt project, will introduce more contents and advanced search possibilities. We hope that this will contribute to raise awareness of the importance of dietary phytochemicals and plant foods to prevent cardiometabolic diseases as well as to guide the development of new products or nutritional strategies to gain more benefit from their protective effects.