OxC-beta: Improving Health by Enhancing Immune Defences

Overview

It has long-been suspected that β-carotene has benefits that go beyond the micronutrient simply being a source of vitamin A. However, these non-vitamin A benefits have been difficult to reproduce. By probing β-carotene’s natural tendency to oxidize in air, Avivagen discovered the key to unlocking β-carotene’s additional benefits. In air, β-carotene combines with oxygen to form copolymers that partially break down into many small molecule compounds with various flavor and aroma characteristics. The breakdown compounds together with their parent polymers are found in forages and plant-based foods. Avivagen’s commercially produced fully oxidized β-carotene product, OxBC, absent β-carotene and vitamin A, closely reflects the product formed naturally in plant sources. The OxC-beta™ Livestock premix formulation of the OxBC product reliably delivers the suite of β-carotene oxidation compounds that provide flavour, aroma and immune function support that once was available in natural feed stocks, but now largely l are acking in most modern livestock feeds.

Background

TThis journey began at the National Research Council of Canada (NRC) in the 1990s with a study by Avivagen’s founding scientists into the origin of β-carotene’s apparent non-vitamin A activity. Subsequently, at Avivagen Inc., work continued exploring the spontaneous oxidation of β-carotene as a key insight rather than as an antioxidant. Allowing β-carotene to spontaneously oxidize with oxygen led to the discovery in the complex product mixture of a previously unrecognized, readily-formed substance composed of β-carotene-oxygen copolymers. The copolymers form when oxygen molecules add to β-carotene molecules, regardless of environment. As the oxidation reaction progresses the growing polymers release small breakdown compounds, several of which are known to contribute aromas and flavours to various foods and beverages. The combination of the breakdown compounds and their parent polymers occurs in abundance in Nature and the mixture is readily prepared in the laboratory. Commercially produced, fully oxidized β-carotene (OxBC) is the key ingredient in OxC-beta™ products. The benefits of OxBC in animals seen in both OxC-beta™ Livestock and canine supplements, and the absence of both β-carotene and vitamin A in OxBC, provide compelling evidence that benefits of β-carotene beyond being a source of vitamin A in fact originate from its oxidation products. Recognition of the widespread occurrence of carotenoid copolymer compounds and their breakdown products in plant-based foods contributes to a fuller understanding of the potential of carotenoids and of β-carotene in particular,. The oxidation products also provide a plausible explanation, at least in part, for the human health benefits associated with dietary fruit and vegetable consumption.

β-Carotene and the more than 600 other members of the carotenoid family are characterized by an extended system of conjugated carbon-carbon double bonds that not only is the source of their intense colours but also makes the compounds highly susceptible to reaction with oxygen in air.

There’s More to β-Carotene than Vitamin A

Although β-carotene is best known as an excellent source of vitamin A, there is another facet of β-carotene chemistry that Avivagen discovered has important implications. Oxygen plays a critical role in unlocking the full potential of β-carotene. Vitamin A is produced when oxygen, guided by a highly specific enzyme resident in the gut, splits the β-carotene molecule in half. However, in the absence of the enzyme, oxygen in air can spontaneously and indiscriminately attack the β-carotene molecule. This occurs regardless of environment, whether in a plant or in a laboratory.

Spontaneous uptake of oxygen by solid β- carotene standing in air. Up to 6-8 oxygen molecules can add to the β-Carotene molecule .

In the spontaneous, non-enzymatic reaction, oxygen strongly prefers to add to β-carotene to form copolymers, rather than directly cut the β-carotene molecule into smaller pieces. The main product turns out to be β-carotene-oxygen polymers containing upwards of 6-8 molecules of O2 per β- carotene. This substance had not been reported before [1]. The copolymers can partially breakdown into individual compounds called norisoprenoids. Some of these compounds are approved as GRAS (Generally Recognized As Safe) flavoring agents for human use. [1].

Non-Vitamin A Immune-Supporting Effects?

The reported beneficial non-vitamin A effects of β-carotene itself appear to be associated with support of immune function. A summary of literature results for supplementation with β-carotene has been provided in a European Food Safety Authority (EFSA) panel report on the safety and efficacy of β-carotene as a feed additive [2]:

“The positive effects in cows or pigs reported in the literature include decreased service per conception, increased number of viable embryos/reduced embryonic mortality, improved embryo quality, improved immunity with reduced incidence of retained placenta and metritis, increased pregnancy rate, increased percentage of milk fat (with unaffected milk yield), improved protection of the mammary gland against infection as a result of increased intracellular killing of microbes by phagocytes, and higher plasma progesterone and oestradiol levels in the cat…”. “Chew and co-workers reported that beta-carotene improves the immune status and decreases the incidence of reproductive disorders in peripartum cows by increasing lymphocyte and phagocyte function…”.

However, the EFSA panel further states:

“The data on the effects of supplemented beta-carotene on immunity and reproduction remain inconsistent and no conclusions can be drawn”. This comment underscores the lack of reproducibility of data when β-carotene itself is used as the supplement. Also, the possible inadvertent involvement of vitamin A is cited as a confounding factor.

Non-Vitamin A Immune Supporting Effects are Real: β-Carotene Oxidation is the Key

Avivagen manufactures OxBC (Oxidized β- Carotene) by allowing pure β-carotene dissolved in a solvent to react fully with oxygen from air. OxBC is composed entirely of oxidation products comprised of β-carotene-oxygen copolymers and their breakdown products (norisoprenoids). No β-carotene remains. No vitamin A is formed and there is no vitamin A activity. The immune-supporting activity of OxBC demonstrates that β-carotene’s non-vitamin A effects arise directly from β-carotene’s oxidation products [3].

The clear and consistent benefits observed when OxBC is provided orally to livestock and canines are consistent with immune support and confirm that the effects previously associated with β-carotene itself are real. Furthermore, this discovery explains why β-carotene itself is unable to fulfil this function reproducibly unless it first has undergone some amount of spontaneous oxidation to form OxBC. In poultry and swine benefits are obtained at just low parts-per-million levels of OxBC in finished feed, well within the limits of levels of β-carotene were it available from plant sources, and quite apart from and complementary to the effects of supplemental vitamin A.

Real Products. OxC-beta™ Commercial Formulations Support Immune Function

For commercial purposes OxBC is produced synthetically by a global β-carotene manufacturer. The substance is formulated into a premix, known commercially as OxC-beta™ Livestock for livestock feeds and also is incorporated into Vivamune™, Oximunol™ and Dr Tobias All-in-One Dog Chews supplements for companion animals.

Natural Occurrence of OxBC in Plant Materials

The β-carotene copolymer compound, as well as other carotenoid copolymer compounds, and their norisoprenoid breakdown products are ubiquitous, being formed naturally in variable and often significant quantities in carotenoid-containing plant materials, especially during processing, such as dehydration, and during storage. This is simply the result of exposure to air. Naturally occurring examples relevant to livestock feeds include alfalfa, grass and seaweed products, and in human nutrition, carrot and tomato powders [4].

Illustration of the effect of dehydration and storage on β-carotene oxidation in carrots. The formation in dehydrated, powdered carrot of geronic acid, a marker of β- carotene oxidation and the associated copolymer products, can be seen to be closely linked to the concomitant loss of β-carotene. Note: carrots contain crystalline β-carotene.

Corroboration of the natural occurrence of OxBC has been provided independently by Schaub, Beyer and co- workers [5]. In accounting for the loss of β-carotene in an extensive variety of provitamin A (i.e., β-carotene) plant crop foods during storage, this group reported that spontaneous, non-enzymatic oxidation of β-carotene leads to the concurrent formation of β-carotene copolymer compounds as the major product.

Something’s Missing in Livestock Feeds

In animal nutrition β-carotene has been primarily regarded as a source of vitamin A. Originally, vitamin A was provided by adding certain β- carotene-rich plant materials or forages to livestock feeds. Sometimes β-carotene is referred to as provitamin A, reflecting the importance of this precursor function. However, significant losses of β-carotene occur in plant materials during processing and storage, with associated losses of vitamin A activity. Consequently, plant material sources of β-carotene included for vitamin A function have been replaced in modern livestock feeds with supplements that include synthetic vitamin A instead, along with other vitamins, micronutrients and minerals. Consequently, most modern livestock feeds lack or are deficient in forages containing β-carotene and β-carotene-oxygen copolymer compounds, and possibly other phytonutrients. Although oxidative loss of β-carotene means there is some inevitable loss of vitamin A activity from a plant source, the associated appearance of β-carotene copolymer compound potentially provides complementary non-vitamin A activity.

Meeting an Unfilled Food Animal Need for β-carotene Non-Vitamin A Function with OxC-beta™ Livestock

Feeding trials in multiple animal species have demonstrated the clear and reproducible benefits of providing supplemental OxBC in the form of OxC-beta™ Livestock, over and above supplemental vitamin A. As there is no vitamin A or β-carotene present in OxC-beta™ Livestock and it is without vitamin A activity, any benefits observed with OxBC supplementation therefore must be independent of both vitamin A and intact β-carotene itself. Trial results, together with supporting in vitro studies, clearly point to the β-carotene oxidation products in OxBC being the actual source of the observed benefits. When added to livestock feed the mixture of small molecule and copolymer compounds in OxBC uniquely allows the substance to enhance flavour and support immune function, respectively. Benefits can include increased feed consumption from enhanced flavour and a variety of beneficial effects flowing from sustained support and maintenance of immune function.

The OxBC active present in OxC-beta™ Livestock premix has demonstrated benefits in trials with thousands of animals in different countries and under a variety of conditions. These outcomes are consistent with this naturally occurring oxidized form of β-carotene contributing to a better-balanced feed ration by compensating for the lack or deficiency of what is a previously unrecognized dietary forage component.

Companion Animals Also Benefit from OxC-beta™ Products

Oximunol™ tablets, Vivamune™ chews and, most recently, Dr Tobias All-in-One Dog Chews have been available for canines for more than 8 years, With over 1 million administrations, clearly observed benefits include supporting or promoting healthy skin and coat, healthy joint function, normal mobility and normal intestinal function.

Oxidation of β-carotene is a unifying concept that explains both the micronutrient’s vitamin A and non-vitamin A activities. The extended system of double bonds common to all carotenoids means these other naturally occurring compounds also are potentially capable of related non-vitamin A activities.


References

  1. Burton, G. W.; Daroszewski, J.; Nickerson, J. G.; Johnston, J. B.; Mogg, T. J.; Nikiforov, G. B. ß-Carotene autoxidation: oxygen copolymerization, non-vitamin A products and immunological activity. J. Chem. 2014, 92, 305-316. DOI: 10.1139/cjc-2013-0494 (Open Access).
  2. EFSA Scientific Opinion on the safety and efficacy of beta‐carotene as a feed additive for all animal species and categories. EFSA Journal 2012, 10, 2737 (Open Access).
  3. Johnston, J. B.; Nickerson, J. G.; Daroszewski, J.; Mogg, T. J.; Burton, G. W. Biologically active polymers from spontaneous carotenoid oxidation. A new frontier in carotenoid activity. PLoS ONE 2014, 9, e111346 (Open Access).
  4. Burton, G. W.; Daroszewski, J.; Mogg, T. J.; Nikiforov, G. B.; Nickerson, J. G. Discovery and Characterization of Carotenoid-Oxygen Copolymers in Fruits and Vegetables with Potential Health Benefits. J Agric Food Chem 2016, 64, 3767-3777 (Open Access).
  5. Schaub, P.; Wust, F.; Koschmieder, J.; Yu, Q.; Virk, P.; Tohme, J.; Beyer, P. Nonenzymatic beta-Carotene Degradation in Provitamin A-Biofortified Crop Plants. J Agric Food Chem 2017, 65, 6588-6598 (an abstract of the article is available at: https://pubs.acs.org/doi/abs/10.1021/acs.jafc.7b01693).