TOTOX (Total Oxidation) in Fish Oil: Full Guide

TOTOX basics

• TOTOX combines two measures of oxidation in oils.
• Formula: TOTOX = 2 × PV + AV.
• Lower values indicate less oxidation at test time.

PV and AV explained

• Peroxide Value (PV)
  • Represents primary oxidation products (hydroperoxides).
  • Often rises early during exposure to oxygen, heat, or light.
• Anisidine Value (AV)
  • Represents secondary oxidation products (aldehydes formed as peroxides break down).
  • Captures later‑stage changes that PV alone can miss.

Common guidance (finished oils)

• PV ≤ 5 meq O₂/kg (primary oxidation).
• AV ≤ 20 (secondary oxidation).
• TOTOX ≤ 26 (combined index).
• Targets may vary by product type and specification; consult batch reports.

Market surveys

• This study titled “Oxidation levels of North American over‑the‑counter omega‑3 supplements” reported that subsets exceeded voluntary oxidation thresholds².
• This study titled “Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n‑3 PUFA” concluded that many products were highly oxidised and failed to meet labeled n‑3 PUFA content⁴.
• This U.S. dataset titled “Oxidation levels in U.S. omega‑3 products 2014–2020” described oxidation patterns across years, including flavor status reporting³.

Examples: real brands/products

• Nordic Naturals: Ultimate Omega, ProOmega.
• Life Extension: Super Omega‑3 EPA/DHA Fish Oil.
• NOW Foods: Ultra Omega‑3 Fish Oil, DHA‑1000.
• Pure Encapsulations: EPA/DHA Essentials.
• Thorne: Super EPA, Super EPA Pro.

Storage and handling

• Keep containers closed and away from heat and strong light.
• Consider packaging that limits oxygen exposure (e.g., tight seals).
• Refer to the labeled expiration date for product‑specific guidance.

References

1. Shahidi F, Ambigaipalan P. Fishing for answers: oxidation of fish oil supplements. Critical Reviews in Food Science and Nutrition. 2018. PMC
2. Jackowski SA, et al. Oxidation levels of North American over‑the‑counter omega‑3 supplements. Journal of Nutritional Science. 2015. PMC
3. Hedayati M, et al. Oxidation levels in U.S. omega‑3 products 2014–2020. Food Science & Nutrition. 2023. PubMed
4. Albert BB, et al. Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n‑3 PUFA. Scientific Reports. 2015. PubMed
5. NFO. TOTOX A‑Z: The importance of being fresh.

The products listed are not endorsements; they are examples drawn from our database.

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