How to check if fish oil is good? A complete guide to quality

Over 50% of fish oil supplements tested in some markets have failed to meet recommended oxidation standards, highlighting a critical quality control issue. This guide explains how to check if fish oil is good, ensuring you get a fresh, potent, and non-rancid product for maximum health benefits.

Quick Summary

This article details practical and scientific methods for evaluating fish oil quality, covering sensory assessments, reading labels for certifications and EPA/DHA content, and understanding crucial lab test markers like TOTOX values. It also explains proper storage techniques to maintain freshness.

Key Points

• Sensory Checks: Trust your nose and taste buds; a strong, fishy smell or taste indicates rancidity, not freshness.

• Third-Party Certified: Look for independent certifications from programs like IFOS or GOED, which test for purity, potency, and freshness.

• Understand Oxidation: Recognize that fish oil can become rancid due to oxidation, a process accelerated by heat, light, and air.

• Check EPA/DHA Content: Read the label to find the specific amounts of EPA and DHA, as these are the key active ingredients.

• Prioritize Proper Storage: Store fish oil in a cool, dark, and airtight place to prevent it from going bad prematurely.

• Choose the Right Form: The natural triglyceride (TG) form is generally more stable and bioavailable than the ethyl ester (EE) form.

Your Guide to High-Quality Fish Oil

When purchasing fish oil, many consumers assume that all products are created equal. However, the quality of omega-3 supplements can vary dramatically, with freshness being a primary concern. Taking oxidized, or rancid, fish oil can negate the health benefits of EPA and DHA and may even cause harm by contributing to oxidative stress. Knowing how to check if fish oil is good is essential for anyone looking to maximize their supplement's potential.

Performing a Sensory Quality Check

Before even looking at the label, your own senses can provide the first clues about the oil's quality. This is particularly useful for liquid fish oil or for capsules that you can break open for testing.

• The Smell Test: High-quality fish oil should have a mild, slightly oceanic aroma, or no smell at all if it's highly purified. A strong, pungent, or overly 'fishy' odor is a major red flag for rancidity. If the smell makes you recoil, discard the product. Be wary of heavily flavored oils, which can sometimes be used to mask an unpleasant smell.
• The Taste Test: A fresh fish oil should not leave an unpleasant aftertaste. A metallic, bitter, or strongly fishy repeat (burps) after consumption is a sign that the oil is oxidized. Flavored liquids should taste pleasant and fresh, with no hint of underlying rancidity.
• The Appearance Check: While less reliable for capsules, the oil should be clear or light yellow. If you notice any cloudiness or discoloration, it could indicate poor quality. The proper storage environment, however, can sometimes cause harmless cloudiness in the oil when refrigerated.

Deciphering the Label for Proven Purity

The label is a treasure trove of information for determining quality. A trustworthy brand will be transparent about its testing and sourcing.

Key Label Indicators

• EPA and DHA Content: Check the supplement facts panel for the specific amounts of EPA and DHA per serving. A higher concentration means a more potent and effective supplement. Some cheaper products may require you to take more capsules to get an effective dose.
• Triglyceride (TG) Form: Look for fish oil in the natural triglyceride form, which is more stable and better absorbed by the body than the cheaper, less stable ethyl ester (EE) form.
• Third-Party Certifications: The most reliable sign of quality is third-party testing. Look for certifications from reputable organizations that test for purity and freshness. Programs like IFOS (International Fish Oil Standards) and GOED (Global Organization for EPA and DHA Omega-3) are gold standards. A 5-star IFOS rating is a strong indicator of quality.
• Oxidation Values (TOTOX): Some brands are transparent about their oxidation numbers, including the Total Oxidation (TOTOX) value. TOTOX combines peroxide and anisidine values to give an overall measure of freshness. A low TOTOX value (ideally less than 26, or even better, less than 15) indicates very fresh oil.
• Added Antioxidants: Quality brands often add natural antioxidants, like vitamin E or rosemary extract, to their formula to protect the delicate omega-3s from oxidation.

The Importance of Storage

Even the highest quality fish oil can go rancid if not stored correctly. Light, heat, and air are the primary enemies of freshness.

• Store in a Cool, Dark Place: Keep your fish oil in a cupboard or refrigerator, away from direct sunlight and heat sources like the stove. Some liquid fish oils explicitly require refrigeration after opening.
• Ensure the Bottle is Airtight: Always close the lid tightly after each use to minimize exposure to oxygen, which accelerates oxidation.
• Check the Expiration Date: Never ignore the expiration date. Even if a product seems fresh, its potency will degrade over time, and it may become rancid once expired.

Comparison Table: Fresh vs. Rancid Fish Oil

Feature	Fresh, High-Quality Fish Oil	Rancid, Poor-Quality Fish Oil
Taste	Mild, clean, and pleasant; no fishy aftertaste or burps.	Strong, bitter, or metallic aftertaste; causes fishy burps.
Smell	Faint, oceanic, or neutral; not strongly fishy or pungent.	Pungent, sour, or overly fishy; similar to old fish.
Appearance	Clear and light yellow in color; smooth liquid consistency.	Cloudy or discolored; may have a thicker consistency.
Label Certifications	Often IFOS, GOED, or NSF certified with visible testing data.	Lacks third-party certification or fails to provide batch testing results.
Oxidation (TOTOX)	Low TOTOX value, ideally below 15-26.	High TOTOX value, indicating significant oxidation.
Health Impact	Delivers beneficial EPA and DHA; supports cardiovascular and cognitive health.	Negates health benefits; may increase oxidative stress and inflammation.

Conclusion: Making an Informed Choice

Ensuring you are taking a good quality fish oil is a straightforward process that involves both sensory evaluation and careful label reading. By trusting your senses, checking for third-party certifications like IFOS, and understanding key metrics like the TOTOX value, you can confidently select a fresh and potent supplement. Proper storage is also crucial for maintaining the oil's integrity over time. Don't fall for products that use heavy flavoring to mask rancidity. Instead, seek out reputable brands that are transparent about their sourcing, testing, and quality control. Investing a little time in research will ensure you receive the full health benefits that quality fish oil can offer. For further information on industry quality standards, consult the Global Organization for EPA and DHA Omega-3s (GOED) or International Fish Oil Standards (IFOS) organizations. GOED Voluntary Monograph offers detailed quality and safety specifications.

How to check if fish oil is good? Practical steps

1. Check for strong, fishy smells: Break open a softgel or smell a liquid product. A strong, pungent odor is a sign of rancidity and should be avoided.
2. Taste for unpleasant aftertastes: Fresh fish oil should not cause strong, fishy burps or have a metallic flavor. Any off-taste indicates oxidation.
3. Look for third-party certification: Prioritize supplements certified by independent organizations like IFOS or NSF. These certifications guarantee the product has been tested for purity and freshness.
4. Verify EPA/DHA potency on the label: Ensure the supplement facts panel clearly lists the specific amounts of EPA and DHA per serving, not just the total 'fish oil' content.
5. Look for the triglyceride (TG) form: The natural TG form of omega-3 is more stable and bioavailable than the cheaper ethyl ester (EE) form found in many low-quality supplements.
6. Review the TOTOX value: Some transparent brands provide their TOTOX score, a measure of total oxidation. Aim for a low number, preferably under 15-26.
7. Choose dark, opaque bottles: Quality fish oil is sensitive to light. Dark bottles help protect the oil from degradation, and some brands add natural antioxidants like vitamin E.

FAQs about Fish Oil Quality

Q: What does it mean if my fish oil smells and tastes very fishy? A: A strong, pungent smell or taste, along with fishy burps, is a primary indicator that your fish oil has oxidized and gone rancid. Fresh fish oil should have a mild, clean, or nearly neutral odor.

Q: Are fish oil capsules with added flavoring better for masking rancidity? A: Not necessarily. While flavoring can make fish oil more palatable, some companies use strong flavors like lemon to mask the taste and smell of rancid oil. Relying on third-party test results is a more reliable measure of freshness.

Q: Is it dangerous to take rancid fish oil? A: While it is unlikely to cause acute sickness like eating spoiled food, consuming rancid or oxidized fish oil negates the intended health benefits and may increase oxidative stress and inflammation in the body. It's best to discard it.

Q: How can I find the IFOS or TOTOX value for my fish oil? A: Many reputable brands that use IFOS testing will publish the results on their website. You can also search for the product on the IFOS website. Some brands also list their TOTOX value or other oxidation markers on a certificate of analysis.

Q: What is the difference between triglyceride and ethyl ester fish oil? A: The triglyceride (TG) form is the natural fat structure found in fish and is generally more stable and better absorbed by the body. The ethyl ester (EE) form is a cheaper, synthetic version that is more prone to oxidation.

Q: How should I store my fish oil to keep it fresh? A: Store your fish oil in a cool, dark place away from heat and light. Refrigeration is recommended for most liquid oils and some capsules. Always keep the lid tightly sealed to prevent oxidation from air exposure.

Q: Does the expiration date on fish oil guarantee freshness? A: The expiration or 'best by' date indicates the manufacturer's guarantee of potency. However, improper storage can cause the oil to go rancid well before this date. Always use your senses to check for freshness, especially if the product has been open for a while.

Frequently Asked Questions

How can I tell if my fish oil is rancid without opening the capsule?

While the smell and taste test is most effective, another sign of rancidity can be persistently fishy burps after consumption, even if the capsules are flavored. You can also check if the brand provides a TOTOX value, as a high number indicates oxidation.

What is a TOTOX value and what is a good number to look for?

TOTOX stands for Total Oxidation value and measures the overall freshness of the oil. It combines peroxide (current oxidation) and anisidine (past oxidation) values. A low TOTOX value, ideally below 26, indicates a fresher fish oil.

Is fish oil from small fish like anchovies and sardines better than from larger fish?

Yes, oil from smaller fish is often considered purer. Small fish are lower on the food chain and accumulate fewer toxins, such as heavy metals and PCBs, than larger, predatory fish like tuna or swordfish.

What is molecular distillation and why is it important?

Molecular distillation is a process used by manufacturers to remove heavy metals and other contaminants from the fish oil. It is an effective method for ensuring high purity levels in the final product.

Do I need to refrigerate my fish oil capsules?

While it depends on the product and manufacturer's instructions, refrigerating liquid fish oil after opening is generally recommended to slow down oxidation. For capsules, a cool, dark cupboard is often sufficient, but always check the label.

How do flavored fish oils affect the taste test for freshness?

Flavored fish oils can mask the taste and smell of rancid oil, making the sensory test unreliable. If you use flavored oil, rely more heavily on checking for third-party certifications and the product's TOTOX value.

Should I throw away my fish oil if it gets cloudy in the fridge?

Not necessarily. Just like olive oil, fish oil can become cloudy when exposed to cold temperatures. This is usually harmless. It should return to its normal clarity after being left at room temperature for a few minutes.