**1. Introduction**

Nutrients are classified into two major groups, including essential and nonessential nutrients. Essential nutrients can be synthesized by the human body, while nonessential nutrients cannot be made in the body. The former provides normal cellular function, and the latter is not required for life yet brings about healthpromoting outcomes for consumers [1]. Our body is not capable of synthesizing nonessential nutrients. Thus, it is crucial to ingest these vital constituents in the form of dietary supplements or foods. In this regard, the foods containing these beneficial substances that are considered bioactive ingredients (BI), are called functional foods. Functional foods confer a broad spectrum of physiological benefits, including the prevention of cardiovascular disorders, obesity, diabetes, cancers, stress, Parkinson's and Alzheimer's diseases, neurological diseases, and pulmonary and respiratory disorder [2].

Generally, functional foods can be available in two forms. One of the forms is those that possess indigenous BI intrinsicality (such as fruits and vegetables), and the other forms are ones that are fortified by BI extracted from available sources (such as snacks fortified by carotenoids) [3]. As the amount of indigenous BI in various sources might not be enough to provide health benefits, the purified BI are incorporated in foods to increase their nutritional values.

Phytochemicals are plant-produced substances that represent unique features, some of which could be utilized in maintaining human health and strengthening the body's defense shield against diseases. Phytochemicals can be classified based on the chemical structure or their properties: flavonoids, carotenoids, polyphenols, curcumin, and phytosterols are the noteworthy groups [4].

WHO defines probiotics as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host". They might be available in different forms of products, from fortified foods to supplements and drugs formulated with colony-forming units per gram (CFU/g) of probiotic strains of bacteria. Prebiotics, on the other hand, are a group of carbohydrates found in food, which the human body enzymes are incapable of digesting. Probiotic bacteria and some strains of gut microflora can break down these molecules and allow the body to gain nutritional benefits. The products that contain both probiotics and prebiotics are referred to as symbiotics [5]. Various functions in the body are carried out by interactions between proteins. Peptides are counted as the builder blocks of the proteins thus they also play a crucial part in the regulation of many functions in the body. Bioactive peptides have shown advantageous qualities such as immune system booster, cardioprotection, and neuroprotection [6]. For decades, the food industry strived to enrich the food with vitamins and minerals. Fortification of margarine with vitamin A, wheat with folic acid, cereals with vitamin B1, B2, and B3, and adding iodine to salt are among the processes that were done to produce more nutritious foods in the past. In recent years, encapsulating fat-soluble vitamins has been employed in order to increase their bioavailability [7].

Bio-mineralization is attributed to the formation of mineral complexes through living organisms, like bacteria. It can happen through two paths: (a) the metal complexes are formed due to electrostatic interactions between the negatively charged functional groups like COOH groups on the surface of the bacteria and positively charged ions, (b) the other path happens inside the bacteria and the microorganism synthesizes mineral biogenic, also called bio-mineral [8].

Among a myriad of BI, which play a substantial role in human health, we seek to address some of the most prominent ones, such as phytochemicals, prebiotics, probiotics, bioactive peptides, vitamins, minerals, and nano-bio mineral. Future trends: probiotics and bioactive.
