Before you rush to your local drug store or pharmacy, here’s something you should know: krill oil isn’t for everyone. “If you have fish allergies or are taking blood thinners, consult your doctor before taking krill oil supplements,” says Retelny.
Fish oil and krill oil can cause blood thinning in some, so it’s important for people who are taking blood thinners (or who have a bleeding disorder or who are having surgery) to consult their doctor before taking them, notes the Cleveland Clinic. As for those with a fish allergy, the American College of Allergy, Asthma, and Immunity agrees that you should talk to your doctor before taking any seafood supplements.
While doctors may recommend that pregnant women take fish oil (the American Pregnancy Association, for example, notes that omega-3 fatty acids may have a positive impact on pregnancy), you may want to stick with fish oil if you’re pregnant or breastfeeding. “Since there isn’t much research on the effects of krill oil, it’s cautioned that women who are pregnant or breastfeeding shouldn’t take krill oil either,” says Kimberlain.
“In addition, there can be interactions with other drugs that people take,” says Kimberlain. For people with diabetes, for example, some classes of oral medications may not be as effective, so it’s important to discuss your plan with your doctor or nutritionist before beginning, she says.
Also, if you have a sensitive stomach and don’t care for fish, it might not be for you. “I wouldn’t call that a risk, but a lot of people find that krill oil supplements have a fishy taste,” says Kimberlain. Some other symptoms or side effects may also be possible, like diarrhea, heartburn, or an upset stomach, she adds.
And a word of caution about dietary supplements in general: The U.S. Food and Drug Administration (FDA) does not approve any dietary supplement before it is marketed, and dietary supplement companies are not required to provide information to the FDA about why their products are safe, and the organization notes. Therefore, it is important to exercise caution when using any dietary supplement and to consult your doctor before beginning.
For this reason, Kimberlain suggests you try to up your seafood game before considering a supplement. “I always suggest that food comes first,” she says. You can get omega-3 fatty acids by adding cold-water oily fish like salmon, trout, herring, mackerel, and sardines to your weekly meal plan. If you don’t eat seafood, you can also get omega-3s from flaxseed, chia seeds, and walnuts, according to the NIH.
A study published in 2018 in Journal of Nutrition Science had one group of study participants eat fish, while the other group was given krill oil capsules. They found that eating fish increased study participants’ vitamin D levels, but those who were in the krill oil group did not see this benefit (however, both eating fish and taking a krill supplement did positive health effects in their respective groups, the researchers note ).
If you decide to take krill oil, carefully follow the dosage directions on the box or bottle. That’s because taking too much fish oil (or krill oil) can increase your risk of bleeding and potentially affect your immune system’s response, notes the Mayo Clinic.