Krill Oil vs. Fish Oil: What You Need to Know About Health Benefits and Risks

Krill oil, a dietary alternative to fish oil, is derived from tiny shrimp-like crustaceans that serve as a fundamental food source for Antarctic wildlife such as whales and birds. Rich in omega-3 fatty acids, krill oil is believed to provide superior absorption compared to fish oil, offering potential health benefits.

Omega-3s: Krill Oil and Fish Oil  

Both krill oil and fish oil supplements are key sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two types of omega-3 fatty acids shown to promote heart health and reduce inflammation. Despite these benefits, the effectiveness of krill oil for improving cardiovascular health remains uncertain. A recent 2023 meta-analysis revealed that krill oil had no significant impact on blood pressure or heart disease risk factors.  

“We need more studies because even omega-3s have fallen flat on some of the things we thought they could do,” Judy Simon, MS, RD, CD, a clinical dietitian nutritionist at UW Medical Center, told Verywell. “In some studies, eating fish has demonstrated better outcomes than taking fish oil supplements.”  

Unique Benefits of Krill Oil  

Beyond omega-3 absorption, krill oil is lauded for its antioxidant content, particularly Astaxanthin, which gives the oil its distinctive red hue. Astaxanthin, also found in salmon, shrimp, and algae, has been linked to improved eye health and reduced inflammation. A 2017 study suggested krill oil could alleviate dry eye symptoms more effectively than fish oil due to this antioxidant.  

In older research from 2003, krill oil was found to help manage premenstrual syndrome (PMS) symptoms better than fish oil, likely because of its anti-inflammatory properties. However, Sue-Ellen Anderson-Haynes, MS, RDN, CDCES, a registered dietitian from Boston, notes that PMS relief can be achieved by making broader dietary adjustments.  

Cost and Considerations  

Krill oil is significantly pricier than fish oil due to the complex harvesting process. Extracting krill requires specialized vessels capable of navigating perilous environments like the Drake Passage, making Antarctic krill oil three to four times more expensive than its fish-based counterpart.  

“The price is much higher, and I don’t think they’ve proven a cost-benefit for it,” Simon said.  

Additionally, omega-3s in both krill and fish oil supplements may elevate the risk of bleeding, particularly if taken alongside blood-thinning medication. Common side effects of krill oil include gastrointestinal discomfort such as nausea, bloating, diarrhea, gas, or heartburn. Furthermore, individuals allergic to shellfish should avoid krill oil altogether.  

A Food-First Approach  

Experts often recommend prioritizing natural dietary sources of omega-3s over supplements. Anderson-Haynes highlighted seafood and fish, along with plant-based options like seaweed, walnuts, flax seeds, and chia seeds, as excellent sources.  

“You’re getting other nutrients and antioxidant activities from the foods,” she added. “A food-first approach is best.”  

Though krill has yet to find a place on American menus, it is used in Asian cuisine to create fermented shrimp paste and can be purchased canned online. For most, a varied diet rich in omega-3 foods offers a more balanced and cost-effective solution for maintaining health.