Abstract
Background: Pharmaceutical and nutraceutical formulations are commonly evaluated through the lens of their active pharmaceutical ingredient (API), while excipients, process-related impurities, and oxidation markers are treated as toxicologically inconsequential. Accumulating preclinical and clinical evidence challenges this assumption decisively. Specific excipient classes — surfactant emulsifiers such as polysorbate 80 (Tween 80), synthetic colorants including titanium dioxide (TiO₂) E171, and cellulosic disintegrants — exert measurable pharmacodynamic effects on intestinal epithelial barrier integrity, tight junction architecture, gut microbiota composition, and innate immune signaling. In parallel, omega-3 fatty acid preparations with supranormal Total Oxidation (TOTOX) values deliver a spectrum of lipid peroxidation products — primary peroxides and secondary carbonyl aldehydes — that may initiate or amplify systemic oxidative stress cascades rather than attenuate them.
Objectives: This clinical review consolidates current evidence on the non-inert pharmacodynamic activity of three excipient/formulation quality domains: (1) surfactant emulsifiers and their effects on mucosal barrier function; (2) titanium dioxide nanoparticles (TiO₂-NPs) and their role in intestinal inflammasome activation; and (3) oxidized omega-3 supplements and TOTOX-driven lipid peroxidation as a clinical safety hazard.
Methods: Narrative synthesis of peer-reviewed literature retrieved from MEDLINE/Semantic Scholar covering in vitro, ex vivo, animal, and human studies published between 1984 and 2026, with emphasis on mechanistic data and regulatory context.
Conclusions: Clinicians and formulators should adopt a whole-formulation pharmacological perspective, incorporating excipient-level safety evaluation and routine TOTOX-based quality gatekeeping into prescribing judgment and CDMO procurement decisions.
1. Introduction
The classical model of pharmaceutical formulation safety rests on a conceptual separation between pharmacologically active and pharmacologically inert components. Under this paradigm, the active pharmaceutical ingredient (API) bears the full burden of therapeutic and adverse effect attribution, while excipients — binders, disintegrants, emulsifiers, colorants, and stabilizers — occupy the status of chemically neutral scaffolding. Regulatory frameworks from both the FDA and EMA have historically reflected this distinction: excipients designated as "generally recognized as safe" (GRAS) or approved food additives are typically accepted for pharmaceutical use without independent clinical pharmacodynamic evaluation in the context of chronic oral exposure.
This conceptual framework is increasingly untenable. A growing body of preclinical, ex vivo, and mechanistic evidence demonstrates that several excipients exert direct or microbiome-mediated effects on intestinal epithelial barrier integrity, tight junction protein expression, mucosal immune activation, and systemic inflammatory tone. [^1] A landmark 2026 systematic review of excipient–drug interactions identified approximately 180 relevant publications, yet noted that only approximately 10% of these studies involved human pharmacokinetic trials — with the remainder relying on rodent models or Caco-2 in vitro systems. [^2] This evidence gap is clinically consequential: physicians making prescribing decisions or patients selecting over-the-counter nutraceuticals are effectively uninformed about the pharmacodynamic activity embedded in the formulation matrix itself.
The problem is compounded in two distinct directions. First, certain excipients that are simultaneously approved food additives — particularly titanium dioxide (TiO₂, E171) as a whitening agent and polysorbate 80 as an emulsifier — are ingested at aggregate daily doses that substantially exceed single-product API-derived exposures, particularly in Western diets. Second, in the nutraceutical space, omega-3 fatty acid supplements represent a category where the quality of the formulation matrix is itself the therapeutic variable: oxidized preparations do not merely fail to deliver benefit but may actively deliver a pro-oxidant lipid peroxidation cascade.
This review addresses three mechanistic pillars of hidden formulation pharmacodynamics: surfactant excipients and mucosal barrier disruption; TiO₂ nanoparticle-driven intestinal inflammasome activation; and TOTOX-defined omega-3 oxidation as a clinical safety signal. The intended audience is clinicians and clinical researchers who engage daily with drug or supplement prescribing but whose training may not have encompassed formulation science at this mechanistic depth.
2. Pathophysiology and Mechanisms
2.1 The Intestinal Epithelial Barrier: A Pharmacodynamic Target
The intestinal epithelial barrier comprises four interdependent layers: the luminal microbiota, the overlying mucus gel, the single-cell-thick epithelium secured by tight junction (TJ) protein complexes, and the subepithelial mucosal immune system. Tight junctions — assembled from claudin, occludin, and zonula occludens (ZO) protein families — form the rate-limiting paracellular seal that governs intestinal permeability. Disruption of TJ architecture, operationally reflected by increased transepithelial electrical resistance (TEER) loss and elevated serum zonulin, is mechanistically linked to systemic endotoxemia, low-grade chronic inflammation, metabolic syndrome, and inflammatory bowel disease (IBD).
The relevance to excipient pharmacodynamics is direct: several widely used formulation additives have been shown to modulate TJ protein expression, alter mucus layer thickness, and shift microbiota composition toward proinflammatory phenotypes, each independently sufficient to compromise barrier integrity.
2.2 Surfactant Excipients: Polysorbate 80 and Carboxymethylcellulose
Polysorbate 80 (P80, Tween 80, E433) is a nonionic surfactant derived from polyethoxylated sorbitan and oleic acid. It is employed across pharmaceutical solid oral dosage forms, parenteral preparations, and a wide range of processed food products as an emulsifier and solubilizer. Carboxymethylcellulose (CMC, E466) functions similarly as a food and pharmaceutical emulsifier and viscosity modifier.
A 2023 study in Allergy employing transcriptomic profiling and barrier integrity assays in gastrointestinal epithelial cell lines demonstrated that polysorbate 20 and polysorbate 80 disrupt epithelial barrier function with dose-dependent reductions in tight junction protein expression, including occludin and claudin-1, and induce pro-inflammatory transcriptome shifts. At the mucosal level, a Scientific Reports study using rat intestinal tissue and the Ussing chamber ex vivo system showed that P80 exposure increased bacterial translocation by reducing mucus barrier function and increasing E. coli motility through the mucus layer, while CMC altered mucus pore size and reduced bacterial diffusion by a structurally distinct mechanism. [^3] These findings converge on a shared conclusion: barrier disruption is achievable at concentrations relevant to human dietary and pharmaceutical exposure.
The microbiome-mediated pathway is equally or more important. A seminal murine study by Chassaing and Gewirtz (2013) demonstrated that both CMC and P80 at 1% concentrations induced low-grade colitis in susceptible IL-10 knockout mice, with perturbation of mucus layer integrity, erosion of the protective exclusion zone between bacteria and the epithelium, and altered microbiota composition with increased proinflammatory potential. Critically, microbiota transfer from emulsifier-treated mice to germ-free recipients was sufficient to transfer low-grade intestinal inflammation, establishing microbiota alteration as both necessary and sufficient for the observed pathology. [^4] More recent work using a dynamic four-stage gut microbiota model confirmed that increasing concentrations of P80 significantly decreased Bacteroides dorei and Akkermansia — taxa central to anti-inflammatory gut homeostasis — while CMC elevated Ruminococcus torques and Hungatella, taxa associated with mucosal barrier dysfunction. [^5]
From a pharmacological mechanism standpoint, P80 releases lysosomal enzymes (including N-acetyl-β-glucosaminidase) from intestinal mucosal cells and increases intestinal permeability to small molecules in a concentration-dependent fashion, as demonstrated in early rat ligated-gut experiments. [^6] A dedicated receptor-level analysis found that P80 decreases expression of claudin-1, occludin, and mucin-2 (Muc2), the structural glycoprotein backbone of the intestinal mucus layer, with downstream increased bioavailability of concurrently administered xenobiotics including endocrine-disrupting chemicals. [^7]
The clinical implication is not merely that these excipients cause gastrointestinal discomfort. It is that formulations containing P80 or CMC may chronically upregulate intestinal permeability and systemic immune activation in a fashion invisible to API-focused adverse event surveillance.
2.3 Titanium Dioxide (TiO₂, E171): From Colorant to Inflammasome Activator
TiO₂ is a white inorganic pigment approved as food additive E171 and used extensively in pharmaceutical tablet coating, capsule opacification, and hard gelatin capsule manufacture to confer opacity and aesthetic whiteness. It is similarly present in confectionery, chewing gum, dairy products, and toothpaste. Critically, commercial E171 consists of a mixture of micron-sized and nano-sized particles, with the nanofraction reported at up to 36% of total particle content. The European Food Safety Authority (EFSA) concluded in 2021 that TiO₂ can no longer be considered safe as a food additive, leading to a European Union ban on E171 in food applications; pharmaceutical applications remain under separate regulatory scrutiny.
The mechanistic evidence for TiO₂ nanoparticle (TiO₂-NP) intestinal toxicity is substantial. A study using Caco-2 cell monolayers as a validated model of human intestinal mucosa demonstrated that exposure to 42 μg/mL TiO₂-NPs disrupted tight junction permeability barrier integrity detectable within 4 hours and wide-ranging at 24 hours, with nano-sized particles being efficiently internalized, triggering TNF-α and IL-8 production in enterocytes. [^8] Ex vivo and in vivo studies in murine models confirmed that TiO₂-NP agglomerates cross both the regular ileum epithelium and the follicle-associated epithelium (FAE) of Peyer's patches, induce tight junction remodeling consistent with paracellular passage, and persist in gut cells where they may induce chronic damage — particles do not dissolve when sequestered in gut cells for up to 24 hours. [^9]
The most clinically relevant mechanistic pathway identified is NLRP3 inflammasome activation. Research published in Gut demonstrated that oral administration of TiO₂-NPs worsened dextran sodium sulfate (DSS)-induced colitis in wild-type mice through NLRP3-ASC-caspase-1 assembly, caspase-1 cleavage, and release of IL-1β and IL-18. Titanium crystals were found to accumulate in the spleen of administered mice, and elevated titanium levels were measurable in blood samples from patients with active ulcerative colitis, suggesting clinically relevant systemic translocation in the context of mucosal barrier compromise. [^10] These findings were extended in a 2023 study establishing the ROS-TXNIP-NLRP3 cascade as the operative pathway through which TiO₂-NPs exacerbate ulcerative colitis development and inhibit recovery, with the lowest tested dose (30 mg/kg) producing the most significant exacerbation during active disease. [^11]
Of particular concern for longitudinal safety assessment, perinatal TiO₂ exposure in animal models produced epigenetic and microbiotic alterations in offspring that persisted into adulthood, conferring increased susceptibility to DSS-induced colitis years after cessation of exposure. [^12] This transgenerational dimension of an excipient-level exposure is entirely absent from current pharmaceutical risk communication to prescribers.
The gut microbiota dimension is equally alarming. TiO₂-NP exposure was shown to break the microbiotic balance in colitis mouse models, with significant reductions in short-chain fatty acid (SCFA)-producing genera (Muribaculaceae, Ruminococcus, Clostridia) and concurrent enrichment of pathogenic genera including Helicobacter and Escherichia-Shigella, establishing an inflammation-oxidative cascade cycle maintained by the loss of mucosal SCFA signaling. [^13]
2.4 Pharmaceutical Impurities: The Invisible Third Pharmacological Axis
Beyond the intentionally included excipient matrix, pharmaceutical manufacturing introduces process-related impurities that may carry independent biological activity. These include genotoxic impurities from synthetic pathways (e.g., nitrosamines, which have prompted multiple global drug recalls since 2018), residual solvents, catalytic metal contaminants, and degradation products from inadequately validated stability-indicating assays. Regulatory frameworks (ICH Q3A–Q3D) define threshold-based safety limits, but these thresholds are set against carcinogenic risk modeling for individual impurities, not against their cumulative pharmacodynamic interaction with the excipient matrix described above.
The clinical-pharmacological point is that impurities and excipients do not act independently: an excipient that upregulates intestinal permeability may dramatically increase systemic exposure to a co-formulated impurity that would otherwise have negligible absorption. This interaction has not been modeled in regulatory pharmacokinetic safety assessments.
A systematic review noting that excipient effects on drug absorption fall into four mechanistic categories — permeability change, transporter modulation, metabolic enzyme interaction, and gastrointestinal transit alteration — underscores that excipients constitute an implicit pharmacokinetic modifier for any co-administered substance, including impurities. [^2]
3. Clinical Manifestations
The clinical expression of excipient-mediated barrier disruption is diffuse and poorly attributable, which contributes to its underrecognition. Patients chronically consuming medications or supplements containing P80, CMC, or TiO₂ are unlikely to present with a discrete adverse drug reaction; instead, the clinical picture may include low-grade systemic inflammation (elevated hsCRP, fecal calprotectin), worsened metabolic syndrome parameters, exacerbation of pre-existing IBD, increased intestinal permeability measurable by lactulose/mannitol ratio or serum zonulin, and accelerated dysbiosis.
For patients with pre-existing mucosal barrier compromise — IBD, celiac disease, irritable bowel syndrome, or post-infectious gut dysbiosis — exposure to these excipients at standard pharmaceutical dosing represents a clinically meaningful second hit. The Gut study demonstrating that IBD patients have measurably elevated blood titanium levels during active disease implies that pharmaceutical TiO₂ exposure may be an underappreciated disease modifier in this population. [^10]
In the omega-3 nutraceutical domain, the clinical manifestation of TOTOX-driven toxicity is more directly pharmacological but equally unrecognized. Patients initiated on omega-3 therapy for cardiovascular risk reduction, hypertriglyceridemia, or inflammatory conditions may be unknowingly consuming preparations that deliver oxidized lipid byproducts — 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), acrolein, and short-chain aldehydes — that are established inducers of systemic oxidative stress and endothelial dysfunction. The therapeutic intent of anti-inflammatory lipid supplementation is directly inverted by a preparation with excessive TOTOX.
4. Diagnostic Approach
4.1 Assessing Excipient Exposure
Clinicians have no routine tool for quantifying excipient burden, as pharmaceutical labeling in most jurisdictions does not require excipient-level disclosure in a format accessible to prescribers at the point of care. The EMA's "excipients in the label" guideline (EMA/CHMP/302620/2017) mandates warnings for specific excipients in the Summary of Product Characteristics (SmPC), but these are patient-risk-group-specific (e.g., lactose intolerance warnings for lactose) rather than barrier-pharmacodynamic warnings.
A practical diagnostic framework for the informed clinician includes:
- Reviewing the SmPC excipient section for polysorbates, CMC, and titanium dioxide in any chronically used oral formulation
- Considering pharmaceutical TiO₂ burden cumulatively with dietary E171 exposure when assessing IBD patients with unexplained flares
- Using serum zonulin or fecal calprotectin as indirect biomarkers of barrier integrity in patients on chronic poly-pharmacy with excipient-dense formulations
4.2 TOTOX Assessment for Omega-3 Preparations
The Total Oxidation Value (TOTOX) is calculated as:
TOTOX = 2 × PV + p-AV
where PV (Peroxide Value, mEq O₂/kg) reflects primary oxidation products (lipid hydroperoxides) and p-AV (para-Anisidine Value) reflects secondary carbonyl aldehyde oxidation products. The Global Organization for EPA and DHA Omega-3s (GOED) voluntary monograph sets maximum limits of PV ≤ 5 mEq/kg, p-AV ≤ 20, and TOTOX ≤ 26.
Multiple independent market surveys have demonstrated that a substantial proportion of commercially available omega-3 products fail these thresholds at time of consumer purchase. A multi-year analysis of 72 consumer omega-3 supplements in the United States found that 68% of flavored products exceeded the GOED TOTOX limit of 26, and 65% of flavored products exceeded the PV limit of 5 mEq/kg. Even among unflavored preparations, 13% exceeded the TOTOX limit. [^14] A 44-product survey in the UAE found average TOTOX values of 23.8 (95% CI 17.4–30.3), with a mean PV of 6.4 mEq/kg against the GOED maximum of 5 mEq/kg. [^15] A New Zealand survey of 47 products reported that 77% complied with voluntary TOTOX limits, with compliance rates varying substantially by product type and regional market. [^16] A large third-party database analysis of over 1,900 globally sourced fish oil samples reported that 8.8% exceeded TOTOX limits of 26, though the authors noted this compares favorably with other dietary oils — a framing that may not reassure clinicians specifically recommending omega-3 for anti-inflammatory benefit. [^17]
The clinical diagnostic corollary is that TOTOX should be treated as a mandatory quality specification, not a voluntary benchmark, for any omega-3 preparation recommended in a therapeutic context. Clinicians cannot rely on brand reputation alone: flavoring agents used to mask fishy taste can dramatically alter measured oxidation values, and the p-AV assay is unreliable in the presence of aromatic flavoring compounds. [^14]
5. Management and Treatment
5.1 Excipient-Aware Prescribing and CDMO Procurement Standards
The primary intervention available to clinicians is formulation selection. Where clinically equivalent alternatives exist, products without P80, CMC, or TiO₂ should be preferred for patients with IBD, compromised intestinal barrier function, established dysbiosis, or active inflammatory conditions. This requires proactive excipient literacy, as drug equivalence databases do not currently stratify by excipient profile.
For Contract Development and Manufacturing Organizations (CDMOs) and pharmaceutical manufacturers, the evidence supports adopting excipient pharmacodynamic evaluation as a component of the formulation safety package, particularly for chronic-use oral products. A 2026 systematic review concluded that understanding excipient-biological target interactions is essential for rational excipient selection and calls for mechanism-based assessment using appropriate validated models. [^2] The traditional reliance on gross morphological tolerability data is insufficient in light of the molecular evidence for TJ modulation and inflammasome activation at subcytotoxic excipient concentrations.
Specific formulation recommendations emerging from the evidence base include:
- Substitution of P80 with biocompatible alternative emulsifiers (e.g., lecithin-based emulsifiers, which do not show equivalent barrier disruption activity) where pharmacotechnical performance is comparable
- Elimination of TiO₂ from oral solid dosage form coatings in line with EU food additive policy; alternative opacifying agents (e.g., calcium carbonate, carnauba wax) offer adequate whitening without inflammatory particle risk
- Mandatory TOTOX specification (TOTOX ≤ 26, PV ≤ 5, p-AV ≤ 20 per GOED standards) as a release criterion, not merely a voluntary guideline, for all pharmaceutical-grade omega-3 preparations, with testing at point of manufacture and post-distribution
5.2 Antioxidant Co-formulation Strategies for Omega-3 Preparations
The susceptibility of omega-3 polyunsaturated fatty acids to autoxidation is inherent to their chemical structure — the multiple bis-allylic hydrogen positions in EPA (20:5 n-3) and DHA (22:6 n-3) render them among the most peroxidation-vulnerable lipid classes. Effective mitigation requires:
- Primary antioxidant inclusion (tocopherols, specifically mixed-tocopherol preparations with γ- and δ-tocopherol fractions) at adequate concentrations
- Secondary antioxidant or chelating agents (rosemary extract, ascorbyl palmitate) to sequester prooxidant metal ions
- Inert gas blanketing (nitrogen/argon) during encapsulation and packaging
- Light-protective and low-oxygen packaging
- Cold-chain integrity from manufacturer to retailer
Clinicians should preferentially recommend products carrying certification from independent third-party testing organizations (USP, NSF International, IFOS) that include oxidation status assays, and should be aware that expiration date alone does not predict TOTOX compliance: one UAE study found TOTOX inversely correlated with time remaining to expiry (r = −0.50, p = 0.041), meaning newer-to-expiry products may be more oxidized than those at midlife. [^18]
5.3 Clinical Monitoring in High-Risk Populations
For patients in whom excipient pharmacodynamic activity is clinically relevant — those with IBD, metabolic syndrome, chronic use of high-excipient formulations, or who rely on omega-3 supplementation for cardiovascular or neurological indications — a monitoring framework should include periodic assessment of:
- Serum zonulin or urinary lactulose/mannitol ratio as indirect markers of intestinal permeability
- Fecal calprotectin as a non-invasive surrogate of mucosal inflammation
- Plasma malondialdehyde (MDA) or F2-isoprostanes as in vivo lipid peroxidation markers in patients on chronic omega-3 therapy
- Routine review of the full excipient content of all chronically prescribed oral formulations at each medication reconciliation
6. Conclusion
The pharmacological inertness of pharmaceutical excipients is a regulatory convention, not a biological fact. Evidence reviewed here demonstrates that polysorbate 80 and CMC disrupt intestinal tight junction integrity and shift gut microbiota composition toward proinflammatory phenotypes through both direct epithelial and microbiome-mediated pathways. [^3][^4][^5][^6][^7] Titanium dioxide nanoparticles, present in pharmaceutical coatings as food colorant E171 and now banned from the European food supply on safety grounds, activate the NLRP3 inflammasome, increase intestinal permeability, accumulate systemically in susceptible individuals, and induce dysbiosis that worsens the course of inflammatory bowel disease. [^8][^9][^10][^11][^12][^13] Omega-3 preparations with TOTOX values above the GOED threshold deliver a lipid peroxidation byproduct burden — including malondialdehyde, 4-hydroxynonenal, and acrolein — that may actively promote the oxidative and inflammatory pathology they are prescribed to prevent; market surveys consistently show that a meaningful fraction of commercially available products exceed these thresholds. [^14][^15][^16]
Physicians are trained to evaluate the pharmacology of the molecule; the pharmacology of the matrix that delivers it has remained largely outside medical education. As CDMOs and pharmaceutical formulators design next-generation products, and as clinicians face prescribing decisions in patients with inflammatory, metabolic, and gastrointestinal comorbidities, the whole-formulation pharmacological profile demands the same rigor as API selection. The evidence base sufficient to justify this shift already exists. What remains is the clinical will to act on it.
Conflicts of Interest
The author declares no conflicts of interest.
Funding
No external funding was received in support of this work.
1. Maher S, Geoghegan C, Brayden DJ. Safety of surfactant excipients in oral drug formulations. Adv Drug Deliv Rev. 2023;115086. [^1] 2. Morita T, Yoshida H, Tomita N, Sato Y. Pharmaceutical excipients that alter intestinal drug absorption: a systematic review of excipient–drug interactions. J Drug Deliv Sci Technol. 2026;107850. [^2] 3. Ogulur I, Yazici D, Pat Y, et al. Mechanisms of gut epithelial barrier impairment caused by food emulsifiers polysorbate 20 and polysorbate 80. Allergy. 2023;78:1532–1546. 4. Lock J, Carlson T, Wang CM, Chen A, Carrier R. Acute exposure to commonly ingested emulsifiers alters intestinal mucus structure and transport properties. Sci Rep. 2018;8:10008. [^3] 5. Chassaing B, Gewirtz A. Food additives promote intestinal inflammation in susceptible hosts. Inflamm Bowel Dis. 2013;19(S1):P231. [^4] 6. Bellanco A, Requena T, Martínez-Cuesta MC. Polysorbate 80 and carboxymethylcellulose: a different impact on epithelial integrity when interacting with the microbiome. Food Chem Toxicol. 2025;115236. [^5] 7. Tagesson C, Edling C. Influence of surface-active food additives on the integrity and permeability of rat intestinal mucosa. Food Chem Toxicol. 1984;22:573–578. [^6] 8. Zhu YT, Yuan YZ, Feng QP, et al. Food emulsifier polysorbate 80 promotes the intestinal absorption of mono-2-ethylhexyl phthalate by disturbing intestinal barrier. Toxicol Appl Pharmacol. 2021;421:115411. [^7] 9. Pedata P, Ricci G, Malorni L, et al. In vitro intestinal epithelium responses to titanium dioxide nanoparticles. Food Res Int. 2019;122:661–671. [^8] 10. Brun E, Barreau F, Veronesi G, et al. Titanium dioxide nanoparticle impact and translocation through ex vivo, in vivo and in vitro gut epithelia. Part Fibre Toxicol. 2014;11:13. [^9] 11. Ruiz P, Morón B, Becker HM, et al. Titanium dioxide nanoparticles exacerbate DSS-induced colitis: role of the NLRP3 inflammasome. Gut. 2017;66:1216–1224. [^10] 12. Duan S, Wang H, Gao Y, et al. Oral intake of titanium dioxide nanoparticles affects the course and prognosis of ulcerative colitis in mice: involvement of the ROS-TXNIP-NLRP3 inflammasome pathway. Part Fibre Toxicol. 2023;20:21. [^11] 13. Carlé C, Boucher D, Morelli L, et al. Perinatal foodborne titanium dioxide exposure-mediated dysbiosis predisposes mice to develop colitis through life. Part Fibre Toxicol. 2023;20:34. [^12] 14. Feng X, You T, Guo J, Xu H. Titanium dioxide nanoparticles drive the enhanced pro-inflammation response, worsening oxidative injury and gut microbiota dysbiosis in experimental colitis mice. NanoImpact. 2025;100574. [^13] 15. Hands JM, Anderson ML, Cooperman T, Frame LA. A multi-year rancidity analysis of 72 marine and microalgal oil omega-3 supplements. J Diet Suppl. 2023;20:849–869. [^14] 16. Jairoun AA, Shahwan M, Zyoud SH. Fish oil supplements, oxidative status, and compliance behaviour: regulatory challenges and opportunities. PLoS ONE. 2020;15:e0244688. [^15] 17. Bannenberg G, Mallon C, Edwards H, et al. Omega-3 long-chain polyunsaturated fatty acid content and oxidation state of fish oil supplements in New Zealand. Sci Rep. 2017;7:1488. [^16] 18. de Boer AA, Ismail A, Marshall K, et al. Examination of marine and vegetable oil oxidation data from a multi-year, third-party database. Food Chem. 2018;254:390–397. [^17] 19. Alomar M, Al-Tabakha M, Shahwan M, et al. Experimental evaluation of selected fish oil supplements available in the UAE market and factors associated with the extent of their oxidation. Asian J Adv Res Rep. 2026;20:i1265. [^18]
This review was prepared as an initial evidence synthesis. The literature on excipient pharmacodynamics and TOTOX-driven oxidative toxicity is active and rapidly expanding, particularly in the context of emerging EU regulatory actions; a systematic review with extended literature search would provide more complete coverage of human clinical data.
[^1]: Maher et al., 2023. Safety of Surfactant Excipients in Oral Drug Formulations. Advanced Drug Delivery Reviews.
[^2]: Morita et al., 2026. Pharmaceutical excipients that alter intestinal drug Absorption: A systematic review of Excipient–Drug interactions. Journal of Drug Delivery Science and Technology.
[^3]: Lock et al., 2018. Acute Exposure to Commonly Ingested Emulsifiers Alters Intestinal Mucus Structure and Transport Properties. Scientific Reports.
[^4]: Chassaing & Gewirtz, 2013. P-231 YI Food Additives Promote Intestinal Inflammation in Susceptible Hosts. Inflammatory Bowel Diseases.
[^5]: Bellanco et al., 2025. POLYSORBATE 80 AND CARBOXYMETHYLCELLULOSE: A DIFFERENT IMPACT ON EPITHELIAL INTEGRITY WHEN INTERACTING WITH THE MICROBIOME. Food and Chemical Toxicology.
[^6]: Tagesson & Edling, 1984. Influence of surface-active food additives on the integrity and permeability of rat intestinal mucosa. Food and Chemical Toxicology.
[^7]: Zhu et al., 2021. Food emulsifier polysorbate 80 promotes the intestinal absorption of mono-2-ethylhexyl phthalate by disturbing intestinal barrier. Toxicology and Applied Pharmacology.
[^8]: Pedata et al., 2019. In vitro intestinal epithelium responses to titanium dioxide nanoparticles. Food Research International.
[^9]: Brun et al., 2014. Titanium dioxide nanoparticle impact and translocation through ex vivo, in vivo and in vitro gut epithelia. Particle and Fibre Toxicology.
[^10]: Ruiz et al., 2016. Titanium dioxide nanoparticles exacerbate DSS-induced colitis: role of the NLRP3 inflammasome. Gut.
[^11]: Duan et al., 2023. Oral intake of titanium dioxide nanoparticles affect the course and prognosis of ulcerative colitis in mice: involvement of the ROS-TXNIP-NLRP3 inflammasome pathway. Particle and Fibre Toxicology.
[^12]: Carlé et al., 2023. Perinatal foodborne titanium dioxide exposure-mediated dysbiosis predisposes mice to develop colitis through life. Particle and Fibre Toxicology.
[^13]: Feng et al., 2025. Titanium dioxide nanoparticles drive the enhanced pro-inflammation response, worsening oxidative injure and gut microbiota dysbiosis in experimental colitis mice. NanoImpact.
[^14]: Hands et al., 2023. A Multi-Year Rancidity Analysis of 72 Marine and Microalgal Oil Omega-3 Supplements. Journal of Dietary Supplements.
[^15]: Jairoun et al., 2020. Fish oil supplements, oxidative status, and compliance behaviour: Regulatory challenges and opportunities. PLoS ONE.
[^16]: Bannenberg et al., 2017. Omega-3 Long-Chain Polyunsaturated Fatty Acid Content and Oxidation State of Fish Oil Supplements in New Zealand. Scientific Reports.
[^17]: Boer et al., 2018. Examination of marine and vegetable oil oxidation data from a multi-year, third-party database. Food Chemistry.
[^18]: Alomar et al., 2026. Experimental Evaluation of Selected Fish Oil Supplements Available in the UAE Market and Factors Associated with the Extent of Their Oxidation. Asian Journal of Advanced Research and Reports.
