The Battle for Freshness: Why Your Omega-3s Go Rancid and How to Stop It？

Omega-3 fatty acids like DHA and EPA are the superstars of the supplement world, famous for supporting heart, brain, and eye health. However, they have a notorious "Achilles' heel": they are incredibly fragile. If you’ve ever opened a bottle of fish oil and been hit by a pungent "fishy" smell, you’ve encountered oxidative instability.

Maintaining the quality of these oils is a complex game of chemistry. Here are the key factors that determine whether your Omega-3s stay fresh or turn foul.

1. The Vulnerability of "Double Bonds"

The chemical structure of DHA and EPA is their greatest strength and their biggest weakness. They are "polyunsaturated," meaning they contain multiple double bonds. Their oxidative stability is inversely proportional to the number of bis-allylic hydrogens in the molecule. Because DHA and EPA have so many of these points, they are much easier to oxidize in the presence of air than simpler fats.

2. Bulk vs. Aqueous Environments

Surprisingly, where the oil "lives" changes its stability.

• Bulk Oil: When stored as a raw liquid, DHA and EPA are highly prone to oxidation because they have a large surface area exposed to air without protective packing.

• The Liposome Advantage: When encapsulated in liposomes (aqueous systems), the stability of these fats actually increases with higher degrees of unsaturation. This is because the molecules pack more loosely, allowing water molecules to permeate the structure and inhibit the chemical reactions that lead to rancidity.

3. The Manufacturing "Solvent" Trap

How a supplement is made matters. Traditional methods, like the Bangham thin-film hydration method, often use organic solvents (like chloroform) and long evaporation times (up to 6 hours). This extended contact with air during the production phase can jumpstart the oxidation process. Newer, solvent-free methods (like the Mozafari method) provide much higher protection because they use aqueous systems from the very first step.

4. Size Matters: The Power of "Nano"

Research shows a clear link between particle size and shelf life. Nanoliposomes (50–200 nm) exhibit significantly higher oxidative stability than larger liposomes (>200 nm). This is likely due to the tighter "packing degree" of the lipid bilayers in smaller vesicles, which makes it harder for oxygen or free radicals to reach the sensitive double bonds.

5. Pro-oxidants and Temperature

Finally, external "bullies" like iron, ascorbic acid (Vitamin C), and heat can act as pro-oxidants, accelerating the breakdown of marine lipids. This is why most high-quality liposomal Omega-3 products recommend cold storage (4 °C) and protection from light.

About the Author

Le Li, Ph.D., is a scientist dedicated to making nutrition more effective through advanced liposomal technology. With a background in pharmaceutical research and a passion for health, she develops supplements designed for better absorption and real results. At EmerWell, Le combines scientific expertise with a commitment to helping people get the most from their nutrition.

References

1. Ajeeshkumar, K. K.et al. Compr. Rev. Food Sci. Food Saf. 2021, 20 (2), 1280–1306.

2. Rasti, B. et al. Food Chem. 2012, 135 (4), 2761–2770.

3. Panagiotou, T. et al. Funct. Foods Health Dis. 2013, 3 (7), 274–289.

4. Amnuaikit, T. et al. Asian J. Pharm. Sci. 2016, 11 (1), 126–127.