Oxidized ß-Carotene Is a Novel Phytochemical Immune Modulator That Supports Animal Health and Performance for Antibiotic-Free Production.

Oxidized ß-carotene (OxBC), a phytochemical that occurs naturally in plants, is formed by the spontaneous reaction of ß-carotene with ambient oxygen. Synthetic OxBC, obtained by full oxidation of ß-carotene with air, shows considerable promise as an in-feed antimicrobial alternative additive that enhances health and performance in livestock. OxBC is predominantly composed of ß-carotene-oxygen copolymers that have beneficial immune-modulating effects that occur within the innate immune system by priming it to face microbial challenges and by mitigating the inflammatory response. OxBC does not have any direct anti-bacterial activity. Further, unlike traditional immune stimulants, OxBC modulates but does not stimulate and utilize the animal's energy stores unless directly stress-challenged. These immune effects occur by mechanisms distinct from the provitamin A or antioxidant pathways commonly proposed as explanations for ß-carotene's actions. Trials in poultry, swine, and dairy cows with low parts-per-million in-feed OxBC supplementation have shown performance benefits over and above those of feeds containing regular vitamin and mineral premixes. Through its ability to enhance immune function, health, and performance, OxBC has demonstrated utility not only as a viable alternative to in-feed antimicrobials but also in its ability to provide tangible health and performance benefits in applications where antimicrobial usage is precluded.

Safety and uptake of fully oxidized ß-carotene.

Spontaneous oxidation of ß-carotene yields a polymer-rich product (OxBC) together with minor amounts of many apocarotenoids. OxBC's activity extends ß-carotene's benefits beyond vitamin A, finding utility in supporting health in livestock, pets, and humans. Although the naturally occurring form of OxBC is consumed in foods and feeds, a direct demonstration of synthetic OxBC's safety provides additional support for its usage. A toxicological study in rats showed a maximum tolerated single oral dose of 5000 mg/kg, an LD50 of more than 10,000 mg/kg, and a NOAEL of 1875 mg/kg body weight. A repeat-dose 90-day oral toxicity study showed no adverse physiological or pathological effects. A study of OxBC uptake by mice over 2-5 days showed OxBC already was naturally present. The highest levels were in liver, lung, and hamstring. Dosing did not increase levels in liver, kidney, lung, and muscle. Increases occurred in urine, intestinal content, plasma, feces, spleen, and cecum with preferential elimination of polymer, consistent with processing of OxBC. Compared to the 4:1 polymer: apocarotenoid ratio of OxBC, polymer was enriched in liver and spleen and depleted in lung, kidney, hamstring, and abdominal muscle. The apparent control of OxBC in major tissues further supports its safety.

ß-Carotene oxidation products - Function and safety.

ß-Carotene oxidation products have newly discovered bioactivity in plants and animals. Synthetic fully oxidized ß-carotene (OxBC) has application in supporting livestock health, with potential human applications. The safety of synthetic OxBC has been evaluated. An Ames test showed weak-to-moderate mutagenicity in only one cell line at high concentrations. A mouse micronucleus assay established a non-toxic dose of 1800 mg/kg body weight, and no bone marrow micronuclei were induced. Plant sources of ß-carotene inevitably contain varying levels of natural OxBC. Vegetable powders and dried forages can be especially rich. Intakes of natural OxBC for humans and livestock alike have been estimated. The exposure range for humans (1-22 mg/serving) is comparable to the safe intake of ß-carotene (<15 mg/d). In livestock, OxBC in alfalfa can contribute ~550-850 mg/head/d for dairy cattle but in forage-deficient poultry feed much less (~1 ppm). Livestock intake of supplemental synthetic OxBC is comparable to OxBC potentially available from traditional plant sources. Human intake of synthetic OxBC in meat from livestock fed OxBC is similar to a single serving of food made with carrot powder. It is concluded that consumption of synthetic OxBC at levels comparable to natural OxBC is safe for humans and animals.

Discovery and Characterization of Carotenoid-Oxygen Copolymers in Fruits and Vegetables with Potential Health Benefits.

We reported previously that the spontaneous oxidation of ß-carotene and other carotenoids proceeds predominantly by formation of carotenoid-oxygen copolymers and that ß-carotene copolymers exhibit immunological activity, including priming innate immune function and limiting inflammatory processes. Oxidative loss of carotenoids in fruits and vegetables occurs during processing. Here we report evidence for the occurrence of associated analogous copolymer compounds. Geronic acid, an indirect, low molecular weight marker of ß-carotene oxidation at ∼2% of ß-carotene copolymers, is found to occur in common fresh or dried foods, including carrots, tomatoes, sweet potatoes, paprika, rosehips, seaweeds, and alfalfa, at levels encompassing an approximately thousand-fold range, from low ng/g in fresh foods to µg/g in dried foods. Copolymers isolated from several dried foods reach mg/g levels: comparable to initial carotenoid levels. In vivo biological activity of supplemental ß-carotene copolymers has been previously documented at µg/g levels, suggesting that some foods could have related activity.

Biologically active polymers from spontaneous carotenoid oxidation: a new frontier in carotenoid activity.

In animals carotenoids show biological activity unrelated to vitamin A that has been considered to arise directly from the behavior of the parent compound, particularly as an antioxidant. However, the very property that confers antioxidant activity on some carotenoids in plants also confers susceptibility to oxidative transformation. As an alternative, it has been suggested that carotenoid oxidative breakdown or metabolic products could be the actual agents of activity in animals. However, an important and neglected aspect of the behavior of the highly unsaturated carotenoids is their potential to undergo addition of oxygen to form copolymers. Recently we reported that spontaneous oxidation of ß-carotene transforms it into a product dominated by ß-carotene-oxygen copolymers. We now report that the polymeric product is biologically active. Results suggest an overall ability to prime innate immune function to more rapidly respond to subsequent microbial challenges. An underlying structural resemblance to sporopollenin, found in the outer shell of spores and pollen, may allow the polymer to modulate innate immune responses through interactions with the pattern recognition receptor system. Oxygen copolymer formation appears common to all carotenoids, is anticipated to be widespread, and the products may contribute to the health benefits of carotenoid-rich fruits and vegetables.