Parameters and pitfalls to consider in the conduct of food additive research, Carrageenan as a case study

Abstract

This paper provides guidance on the conduct of new in vivo and in vitro studies on high molecular weight food additives, with carrageenan, the widely used food additive, as a case study. It is important to understand the physical/chemical properties and to verify the identity/purity, molecular weight and homogeneity/stability of the additive in the vehicle for oral delivery. The strong binding of CGN to protein in rodent chow or infant formula results in no gastrointestinal tract exposure to free CGN. It is recommended that doses of high Mw non-caloric, non-nutritive additives not exceed 5% by weight of total solid diet to avoid potential nutritional effects. Addition of some high Mw additives at high concentrations to liquid nutritional supplements increases viscosity and may affect palatability, caloric intake and body weight gain. In in vitro studies, the use of well-characterized, relevant cell types and the appropriate composition of the culture media are necessary for proper conduct and interpretation. CGN is bound to media protein and not freely accessible to cells in vitro. Interpretation of new studies on food additives should consider the interaction of food additives with the vehicle components and the appropriateness of the animal or cell model and dose-response.

Clarifying the confusion between poligeenan, degraded carrageenan, and carrageenan: A review of the chemistry, nomenclature, andin vivotoxicology by the oral route

“…In fact, many studies published today still use the term CGN when describing the use of d-CGN, which continues to confuse both the scientific community and consumers. Over the past several years several groups have attempted to set the record straight regarding issues of size and nomenclature (Weiner, McKim, and Blakemore 2017;Weiner 2016;McKim 2014;Beattie et al 2015). This confusion has resulted not only in some innocent, but incorrect conclusions in research papers and reviews (Weiner, McKim, and Blakemore 2017;Weiner 2016), but has also fueled misinterpretations of toxicological data by research groups (Tobacman 2001;Tobacman 2015) and by consumer groups (Cornucopia Institute Report 2013; Cornucopia Institute Report 2016).…”

An integrated approach to the safety assessment of food additives in early life

“…113 As described elsewhere in this document, doses above 5%, which is the regulatory top level unless appropriate controls are included, can result in confounding results due to nutritional deficiencies. 109 Carcinogenicity studies in rats and hamsters of food grade CGN at 5% in the diet did not show evidence of carcinogenicity, tumor promotion, or ulceration. 111,112,114 Teratogenicity was not observed in mice, rats, rabbits, or hamsters, no developmental or reproductive toxicity was observed in a three generational study in rats, and no genotoxicity was identified.…”

“…Such a staining had actually been included in the previous long-term studies in baboons (feeding at 500 mg/kg bw/d over 7.5 years), with negative results. 109 No adverse events had been identified from the commercial use of CGN-containing infant formulas; however, it was considered that the retrospective observations on associations of CGN-containing formula with respiratory tract infections did not address possible effects on the GI tract and that the statistical power was not sufficient to have identified any immune-suppressive effect. In addition, when considering LOAELs based on inflammatory effects from rodent studies fed with CGN in the drinking water (1100-1300 mg/kg bw/d) compared to the highest expected exposure to infants from the use of 0.1% CGN in formula (160 mg/kg bw/d), the margin of exposure of about 7 was not considered sufficient to protect the health of young infants, 104 even though this study is not representative of the intended food uses.…”

“…There are limitations to testing doses high enough in animal studies to obtain large margins over infant exposure due the viscosity of the material at high doses, leading to feeding, nutritional, and palatability problems. 109 …”

“…108 Feeding rodents with CGN in the drinking water did result in inflammatory effects, with an LOAEL of 1100-1300 mg/kg bw/d (1% in the diet). However, when not bound to protein in food, CGN is in a random, openstructured molecular conformation, allowing increased exposure to the intestinal mucosa, 107,109 and is not representative of the conditions of use of the material. This also helps to explain the observations when direct exposure of various forms of CGN in the in vitro cell culture systems suggested the potential for inflammation.…”