Understanding the Effects of EPA and DHA
Fish oil contains two key long-chain omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). While both are important for overall health, including reducing inflammation, they have slightly different effects on blood lipids.
How EPA and DHA Impact Your Lipid Profile
- Triglycerides: Both EPA and DHA are highly effective at lowering high triglyceride levels in the blood, which is a major risk factor for heart disease. Clinical trials have consistently demonstrated significant reductions in triglycerides with fish oil supplementation.
- HDL (Good) Cholesterol: Some studies suggest that fish oil can modestly increase levels of HDL, the "good" cholesterol that helps remove LDL from the arteries. DHA has shown a greater ability to increase HDL levels than EPA.
- LDL (Bad) Cholesterol: The effect of fish oil on LDL is more complex. Many studies show that fish oil supplementation does not significantly lower LDL cholesterol, and some even indicate it can cause a slight increase, particularly with higher doses of DHA. However, DHA may also increase the size of LDL particles, making them less atherogenic (less likely to cause plaque buildup). EPA, on the other hand, appears to have a more neutral or smaller effect on LDL.
The Importance of the EPA-Only Approach
For individuals with high cardiovascular risk, a prescription-grade, high-EPA formulation called icosapent ethyl has shown significant benefits. This specific form has demonstrated a reduction in major cardiovascular events when used alongside statin therapy in certain patients. Research suggests that EPA and DHA have distinct biochemical properties and, in some contexts, an EPA-only approach may yield different, potentially more beneficial, outcomes for reducing major cardiovascular events.
Fish vs. Supplements for Cholesterol
While supplements are a convenient option, eating fresh, fatty fish is often considered a superior method for obtaining omega-3s for overall cholesterol management. A 2017 study found that people who ate farmed trout twice a week saw a more significant reduction in total cholesterol, LDL, and triglycerides, along with an increase in HDL, compared to those taking fish oil supplements.
Best food sources of EPA and DHA include:
- Salmon
- Mackerel
- Sardines
- Herring
- Trout
Comparison of Different Fish Oil Supplements
When choosing a supplement, the source and concentration matter. Different types of fish oil and marine oils offer varying benefits.
Fish Oil Comparison for Heart Health
| Feature | Standard Fish Oil | High-EPA Fish Oil | Krill Oil | Cod Liver Oil |
|---|---|---|---|---|
| Source | Various fatty fish (e.g., anchovy, sardine) | Concentrated fatty fish oil | Antarctic Krill (crustaceans) | Cod fish liver |
| Omega-3 Ratio | Mixed EPA and DHA | Primarily EPA | EPA and DHA, bound to phospholipids | EPA and DHA, plus Vitamins A & D |
| LDL Effect | May slightly increase LDL with high DHA | Less likely to increase LDL | May have similar LDL effects as fish oil | May have similar LDL effects as fish oil |
| Triglyceride Effect | Very effective | Very effective | Effective, potentially more bioavailable | Effective |
| Best For | General heart health support | High-risk patients (as prescription) | Potentially better absorption, rich in antioxidants | Sourcing extra Vitamins A and D |
| Consideration | Look for third-party testing for purity | Requires medical supervision | May trigger shellfish allergies | High vitamin A content can be toxic in high doses |
What to Look For When Buying Fish Oil
When navigating the supplement aisle, follow these steps to ensure you select a high-quality product:
- Concentration: Check the label for the amount of combined EPA and DHA per serving. A higher concentration means you get more omega-3s without taking a large number of capsules. For very high triglycerides, your doctor may recommend 2,000 to 4,000 mg of EPA and DHA per day.
- Third-Party Testing: Since the supplement industry is not strictly regulated, opt for brands verified by independent organizations like the International Fish Oil Standards (IFOS), USP, or NSF International. These certifications guarantee the product's purity, potency, and freedom from contaminants like mercury.
- Source: Consider fish from sustainable, wild-caught sources, such as sardines and anchovies, which tend to have lower levels of mercury due to their position lower on the food chain.
- Freshness: Ensure the product is not rancid, as oxidized fish oil is less effective and may be harmful. Many brands include a lemon flavor to mask any fishy taste, which can indicate freshness.
Conclusion: Which Fish Oil Is Best to Reduce Cholesterol?
For reducing cholesterol levels, particularly lowering LDL, fish oil is not a primary solution and is not a replacement for prescribed medication like statins. Instead, fish oil is most effective at significantly lowering triglycerides, with a modest benefit to HDL levels. The choice of fish oil depends on individual health goals. For most people seeking general heart health support, a high-quality, third-party tested standard fish oil or whole fish consumption is beneficial. For those with high triglycerides and specific cardiovascular risks, a healthcare provider might recommend a prescription-strength, high-EPA formulation. Always consult a doctor before starting any new supplement, especially if you are already on cholesterol-lowering medication, as high doses can interact with blood thinners and other medicines. Eating a balanced diet rich in fatty fish and soluble fiber, alongside regular exercise, remains the most proven and effective strategy for overall cholesterol management. The American Heart Association recommends eating fish at least twice a week.
