Krill is a small shellfish about the size of a shrimp, and it's used to make commercial krill oil supplements. Like fish oil, krill oil provides the two main essential omega-3 fatty acids: eicosapentaenoic acid and docosahexaenoic acid, or EPA and DHA. Your body needs these fats but is unable to produce them, meaning that intake from diet or supplements is crucial. Despite both oils providing omega-3 fats, researchers are uncovering some differences that may give krill oil a slight advantage. It's critical that you talk to your doctor before taking either of these oils.
Krill Offers Benefits at Lower Dose
When too much fat circulates in your blood, it increases your risk for heart disease. One of the main benefits of fish oil is its positive influence on blood fats and inflammation. Fish oil is well-documented to lower triglycerides and raise a form of "good" cholesterol called high-density lipoprotein. When compared to fish oil, krill oil exerted similar effects on blood fats and inflammation but at a lower dose, according to a study published in the January 2011 issue of the journal "Lipids." It took less EPA and DHA from krill oil to have essentially the same results as that of fish oil, which suggests omega-3s from the krill oil may have a higher bioavailability, according to the authors.
Raises EPA and DHA Efficiently
The omega-3 index refers to the level of EPA and DHA -- the most biologically active types of omega-3 -- in your blood. Having low levels of these two fats in your blood is linked to an increased risk for heart disease. While oil from both krill and fish raises the level of EPA and DHA in your blood, krill appears to be more effective, according to a study published "Lipids in Health and Disease" in December 2013. The authors hypothesize that this effect may be due to structural differences in the EPA and DHA found in krill oil that may make it easier for your body to absorb.
Improves Fatty Acid Ratio
The typical diet contains too much omega-6 fat and not enough omega-3 fat. Because certain omega-6 fats may promote inflammation, it's crucial to have a healthy balance of omega-6 to omega-3. In the "Lipids in Health and Disease" study, researchers also examined the effect of krill and fish oil on the omega-6 ratio. They found that compared to fish oil, krill oil is more effective at bringing your ratio of omega-6 to omega-3 fat into a healthier range.
Has Lower Risk for Contamination
It's no secret that larger fish accumulate more contaminants because they're higher up on the food chain and as a result live longer. The longer fish live, the more toxins they accumulate. Fish oil typically comes from large fish, such as mackerel and salmon, though some manufacturers use small fish like sardines. Because krill is a small shellfish and much lower on the food chain, it may have less of a risk for contaminants such as PCBs and mercury.
However, this is not to say that fish oil is dangerously contaminated. Most manufacturers have measures to keep contaminants within a safe limit.
Warnings About Marine Oils
Some people may have allergic reactions to fish oil or krill oil. People with allergies to fish or soybeans should not take fish oil. Anyone who is allergic to shrimp, fish or any other seafood should avoid krill oil.
Marine oils can affect numerous medications and medical conditions, so check with your doctor before beginning supplements. If you're pregnant or breast-feeding or plan on becoming pregnant, talk with your obstetrician about whether fish oil or krill oil is okay for you and your baby.