Functional Foods and Health Effects: A Nutritional Biochemistry Perspective

Background: Increased consumer's interest in health has driven the development of foods that offer specific beneficial effects. The list of foods and ingredients includes essential and non-essential nutrients, plant and marine components, whole foods, microorganisms, microalgae and technological approaches. Traditionally, health outcomes focussed on the prevention of chronic diseases but health targets have expanded to cover areas such as brain health, inflammation, eye health, women's health, healthy ageing and beauty. Objective: This review highlights, from a nutritional biochemistry perspective, differential aspects on designing and interpreting human studies to support the health effects of functional foods. Results: Despite the available evidence from in vitro, animal and observational studies, well-designed human studies are necessary to support the health effects of functional foods. Intervention trials with foods are complex as they imply limitations due to methodological, food-related and host-related factors. The use of responsive, validated and clinically relevant markers becomes essential even though there is a lack of reliable biomarkers of exposure for many bioactives. Furthermore, the effect of modulating factors such as subclinical inflammation, gut microbiota and genetic variability should be taken into account. Multiple indicators may provide a more reliable alternative to assess physiological processes while emerging biomarkers (microRNAs, epigenetic changes) constitute a promising approach. Additionally, the magnitude of the change is critical to support any health effect although interventions may have a limited clinical impact but be epidemiologically relevant. Also, based on the available data, the premise that bioactives-containing foods are safe may be questionable. Conclusion: An integrated approach including multiple biomarkers, genetic variability, effect of gut microbiota and risk/benefit assessment should be used to support the potential health effects of functional foods.