**6. Conclusions**

The importance of balanced nutrition containing important nutrients, for example, vitamins or antioxidants, in sufficient amount needed for health of humans and animals is indisputable. Moreover, recently, physicians attribute an increasing significance to the consumption of food products containing special effective ingredients to prevent and improve the health of people suffering from certain diseases (e.g., cancer, diabetes, hyperlipidemia, mental disorders, osteoporosis, various malabsorption, etc.). The fortification of food products with such dietary supplements/nutraceuticals can be easily used in practice when an appropriate stability of the active ingredient in the formulation could be guaranteed at least until the date of consumption (expiration date). For these purposes, nanoformulations of active compounds prepared using biodegradable nature- or semisynthetic-based nanocarriers, such as polymeric matrices, micelles, liposomes, nanoemulsions, solid lipid NPs, nanostructured lipid carriers, or appropriate inorganic matrices are especially favorable, securing not only enhanced stability but also frequently controlled release of nutrients. Definitely, based on previous thorough experiments, for supplementation of food products (e.g., bread, butter, yogurt, cake, biscuit) or beverages (e.g., milk, juice) with individual healthy ingredients, the most convenient nanoformulation could be selected and used. Unlike nutraceuticals that are available for sale in pharmacy and could be overused by some careless consumers resulting in possible harmful side effects, at fortification of food products with dietary supplements/nutraceuticals, the excessive consumption of these compounds is excluded. However, even though nanoformulations enhance the bioavailability and increase the stability of individual active ingredients, all nanoscale materials applied in food industry should be used advisedly and only after in-depth investigation of cytotoxicity due to possible increased nanosize-based toxicity effects (e.g., surface reactivity of NPs), which could result in unspecified toxic effects also in humans or animals. Therefore, an increased attention should be paid to the influence of risk factors associated with their applications and possible adverse/hazardous effects to humans and animals, observing the relevant guidelines, regulations, and directives issued by the European Commission and the EFSA.

**Author Contributions:** J.J., J.K. and K.K. composition and writing.

**Funding:** This study was supported by the Slovak Research and Development Agency (projects APVV-17-0373 and APVV-14-0547), and by the Ministry of Education of the Czech Republic (LO1305).

**Conflicts of Interest:** The authors declare no conflicts of interest.
