This review delves into the concept of nutrition by design, exploring the relationship between poultry production, the utilization of dietary by-products to create functional foods, and their impact on human health. Functional foods are defined as products that extend beyond their basic nutritional value, offering potential benefits in disease prevention and management. Various methods, including extraction, fermentation, enrichment, biotechnology, and nanotechnology, are employed to obtain bioactive compounds for these functional foods. This review also examines the innovative approach of enhancing livestock diets to create functional foods through animal-based methods. Bioactive compounds found in these functional foods, such as essential fatty acids, antioxidants, carotenoids, minerals, vitamins, and bioactive peptides, are highlighted for their potential in promoting well-being and mitigating chronic diseases. Additionally, the review explores the functionality of food components within these products, emphasizing the critical roles of bioaccessibility, bioactivity, and bioavailability in promoting health. The importance of considering key aspects in the design of enhanced poultry diets for functional food production is thoroughly reviewed. The safety of these foods through the establishment of regulations and guidelines was reviewed. It is concluded that the integration of nutrition by design principles empowers individuals to make informed choices that can prioritize their health and well-being. By incorporating functional foods rich in bioactive compounds, consumers can proactively take steps to prevent and manage health issues, ultimately contributing to a healthier society and lifestyle.

The purpose of this study was to examine the effects of dietary inclusion of walnut and bilberry leaves (WL and BL), as sources of natural antioxidants in poultry diets, on the enrichment of antioxidant nutrients in the egg yolk and on the susceptibility of the yolk to lipid peroxidation during storage. The experiment was conducted on 32-week-old TETRA SL LL laying hens, which were assigned to three dietary treatments with 30 birds each. Each treatment was replicated 10 times with three chicks per replicate pen. Experimental dietary treatments differed from control diet (C) by addition of 0.5% BL supplement or 1% WL supplement. The phytoadditives were not significant contributors to the productive parameters. The addition of BL and WL in laying hens’ diets significantly increased the total polyphenol content, and the zinc, lutein and zeaxanthin concentrations in the egg yolks. In regards to the oxidative stability parameters, a significant decrease in the concentrations of primary oxidation products formed in the egg yolk of experimental groups was seen, proving an efficient inhibition effect of the phytoadditives on peroxyl radical formation. A significant correlation was observed between primary oxidation products and total polyphenol content of the egg yolks, where zinc, lutein and zeaxanthin are the bioactive compounds that inhibit the formation of secondary oxidation products.

The study aims to compare the nutrient composition, antioxidant potential, and polyphenol bioaccessibility of the fruit, leaves, and pomace of black chokeberry. Phytochemical characterization, antioxidant activity, and the effect of in vitro gastrointestinal digestion on the individual phenolic compounds of fruit, leaves, and pomace of black chokeberry were assessed. Results showed that leaves had a higher content of polyphenols (61.06 mg GAE/g dw), flavonoids (8.47 mg QE/g), and tocopherols (1172.20 mg/kg) than fruit (27.99 mg GAE/g dw polyphenols, 5.23 mg QE/g flavonoids, 38.48 mg/kg tocopherols) and pomace (22.94 mg GAE/g dw polyphenols, 1.89 mg QE/g flavonoids and 157.19 mg/kg tocopherols), with superior in vitro antioxidant activity. Chlorogenic acids were the dominant phenolic compounds in black chokeberry undigested samples (2.713 mg/g in fruit, 17.954 mg/g in leaves, and 1.415 mg/g in pomace) but are poorly absorbed (bioaccessibility index in intestinal phase of 28.84% for fruit, 8.81% for leaves, and 31.90% for pomace). Hydroxybenzoic acids were highly stable in leaves and fruit during simulated digestion and had high bioaccessibility. In conclusion, residues from black chokeberry processing are also valuable sources of bioactive compounds, but the pomace had higher polyphenol bioaccessibility than leaves and might be a promising supplement for the food industry.

Blackcurrant (Ribes nigrum L.) is a berry bush widely cultivated in Europe for producing juices, jams, jellies, and syrups. In addition to berries, blackcurrant leaves and pomace, as byproducts, have also been shown to have health-promoting effects. Static digestion, simulating oral, gastric, and small intestinal digestion, was applied, and blackcurrant leaves, fruits, and pomace and the polyphenol bioaccessibility were evaluated in terms of recovery index. The results were related to sample type, and the recovery index presented higher values in the case of fruits, indicating this morphological part of blackcurrant as the most bioaccessible. The antioxidant potential of blackcurrant was evaluated using four different methods, with the leaves proving to be a significant and powerful antioxidant compared to fruits and pomace. The counteracting potential of inhibiting the oxidation process was evaluated using in vitro-induced lipid peroxidation and the inhibition potential of superoxide and hydroxyl anions. The antioxidant evaluation and the inhibition of biological and non-biological radicals indicate the leaf extract is the most powerful antioxidant studied. Also, the results proved that not only fruits but also the blackcurrant byproducts (pomace and leaves) are promising sources of bioaccessible antioxidants with potential benefits in animal nutrition.

The goal of this research was nutritional evaluation through the phytochemical analysis of blackberry and raspberry leaves, the screening of their biological activity (antioxidant capacity and inhibition of lipid peroxidation), and the investigation of the effect of in vitro gastrointestinal digestion (GID) of blackberry and raspberry leaves on the bioaccessibility of polyphenol subclasses. The concentrations of the analyzed liposoluble antioxidants were higher (p < 0.05) in blackberry leaves compared to raspberry leaves, while a significant (p < 0.05) higher content of water-soluble antioxidants was registered in raspberry leaves (with a total polyphenol content of 26.2 mg GAE/g DW of which flavonoids accounted for 10.6 mg/g DW). Blackberry leaves had the highest antioxidant capacity inhibition of the superoxide radicals (O₂^•−), while raspberry leaves registered the highest inhibition of hydroxyl radicals (^•OH), suggesting a high biological potency in scavenging-free radicals under in vitro systems. The maximum inhibition percentage of lipid peroxidation was obtained for blackberry leaves (24.86% compared to 4.37% in raspberry leaves), suggesting its potential to limit oxidative reactions. Simulated in vitro digestion showed that hydroxybenzoic acids registered the highest bioaccessibility index in the intestinal phase of both types of leaves, with gallic acid being one of the most bioaccessible phenolics. The outcomes of this investigation reveal that the most significant release of phenolic compounds from blackberry and raspberry leaves occurs either during or after the gastric phase. Knowledge about the bioaccessibility and stability of polyphenol compounds during digestion can provide significant insights into the bioavailability of these molecules and the possible effectiveness of plant metabolites for human health.

Dietary sources of bioactive compounds in animal diets, are the natural way to produce animal food products with improved nutritional quality. The present study aimed to test the hypothesis of a synergistic effect of bioactive compounds of cranberry leaf powder and walnut meal on the nutritional quality and antioxidant compounds of broiler meat. An experiment was conducted on 160 COBB 500 broiler chickens, housed in an experimental hall with permanent wood shave litter in boxes of 3 m². The six dietary treatments were based on corn and soybean meal; three experimental groups were fed diets supplemented with cranberry leaves (CLs) with three inclusion rates (0% in the control group and CL 1% and CL 2%); two experimental groups were fed diets supplemented with walnut meal (WM) with two inclusion rates (0% and WM 6%); and two groups were fed diets with a combination of the selected supplements (CL 1% WM 6% and CL 2% WM 6%). The results show that the experimental groups registered higher concentrations of copper and iron compared with the control group. An antagonist effect was noticed on lipophilic compounds, and the lutein and zeaxanthin concentrations presented a dose-dependent increasing effect under CL influence, while vitamin E concentrations decreased in the same manner. The dietary WM positively influenced vitamin E deposits on breast tissue. The dietary supplements did not produce any effect on the primary oxidation products, but the secondary products were influenced, and the maximum effect on the TBARS values were recorded for the dietary combination of CL 1% and WM 6%.