Krill oil is a good source of the omega-3 fatty acids EPA and DHA. It can protect against heart disease, treat depression, and help prevent cancer.
Since krill oil has similar benefits to fish oil and few side effects, it is a good alternative to fish oil. Keep reading to learn more about krill oil’s health benefits and its comparison to fish oil.
What is Krill Oil?
Krill oil is extracted from Antarctic krill (Euphausia superba), a small shellfish similar to shrimp .
Krill can be made into oil, powder, and protein concentrate products. Krill oil is a sustainable source of omega-3s .
It is high in protein and low in saturated fat .
Animal studies of krill oil show it can treat depression, obesity, rheumatoid arthritis, heart disease, and cancer .
Even though krill oil has few human studies, results from animal studies provide valuable information on this supplement .
The fat content of krill oil ranges from 12 to 50% of its total weight. In the spring, krill’s fat content is lower because of the lack of food and is higher in the summer and fall when food is abundant .
The phospholipids (fats with a phosphate group) in krill oil protect membranes from free radicals and prevent cell damage .
Other fatty acids in krill oil include :
- Myristic acid
- Palmitic acid
- Stearic acid
- Behenic acid
Vitamins and Antioxidants
Krill oil also contains choline, which transports fats and reduces homocysteine .
Additionally, krill oil contains astaxanthin, a fat-soluble pigment and powerful antioxidant. However, astaxanthin levels in krill oil may be too low to provide health benefits .
Mechanisms of Action
The Endocannabinoid System
Endocannabinoids stimulate the immune system and play roles in motivation, mood, and memory. Issues with the endocannabinoid system can cause heart, weight, blood sugar problems, anxiety, depression, learning problems, and memory loss .
Omega-3 consumption restores normal endocannabinoid system function .
In rats, krill oil reduces high endocannabinoid levels, endocannabinoid receptor activity, and fat accumulation .
Although reduced endocannabinoid activity in the brain can be harmful, krill oil does not cause any negative cognitive effects .
1) May Prevent Obesity
Krill oil blocks the endocannabinoid (EC) pathway, which controls appetite, promoting weight loss .
Mice with normal omega-3 levels have normal EC levels, while omega-3-deficient mice have higher endocannabinoid levels .
Krill oil raised omega-3 levels and reduced EC levels in rats .
Lowering EC levels reduces the likelihood of overeating, which helps prevent weight gain and obesity.
2) May Lower Cholesterol Levels
3) Reduces Inflammation
Lowering these markers of inflammation helps prevent oxidative damage and excessive inflammation.
4) Combats Arthritis
Omega-3s from krill oil reduced inflammatory cytokine levels, which helps prevent arthritis .
In one study of 90 heart disease and/or arthritis patients, daily krill oil reduced pain, stiffness, and functional impairment .
In another study of 50 patients, krill oil improved mild knee pain and range of motion .
In mice genetically susceptible to arthritis, krill oil reduced arthritis symptoms and development. However, krill oil did not lower inflammatory cytokines .
5) Protects the Brain
Phospholipids from krill oil have antioxidant and anti-inflammatory properties. They reduce oxidative damage in the brain and help prevent brain disorders such as depression, schizophrenia, dementia, epilepsy, and autism [15, 16].
Omega-3s in krill oil also prevent brain function decline in elderly people. In a study of 45 elderly males, krill oil enhanced the function of brain areas that perform calculations and working memory tasks .
6) Improves Depression Symptoms
In rats, krill oil increases brain DHA levels and lowers depression-like behaviors .
7) Protects the Heart
The omega-3s in krill oil lower the rate of heart disease .
Additionally, krill oil:
- Increases HDL (good) cholesterol in patients with high cholesterol .
- Reduces fat and cholesterol levels in patients with high cholesterol and triglycerides .
- Reduces blood pressure in rats with high blood pressure .
- Reduces total blood cholesterol in rats fed high-fat diets .
8) Helps Treat Diabetes
Krill oil helps reduce the risk of a heart attack in diabetic patients by:
- Improving blood tissue function
- Lowering C-reactive protein
- Increasing HDL (good) cholesterol .
In 48 participants with type 2 diabetes, krill oil reduced insulin resistance after four weeks .
9) Stops Cancer Cell Growth
In human cells, fatty acid extracts from krill oil stopped the growth of colorectal cancer cells .
Since krill oil extract kills cancer cells and is well-tolerated, it is a potential anti-cancer therapy .
10) Helps Dry Eyes
Low omega-3 intake was associated with dry eye disease (eye pain and vision loss) in a study of 32,000 women .
In a trial of 54 participants, krill oil reduced dry eye symptoms, inflammation, and eye redness .
11) Reduces PMS Symptoms
EPA and DHA lower PMS symptoms such as mood swings, fatigue, and depression .
12) Reduces Colitis Symptoms
In rats with colitis, krill oil reduced oxidative damage and colon inflammation .
Krill Oil vs. Fish Oil
1) The Body Absorbs More Fatty Acids from Krill than Fish Oil
In contrast to fish oil, krill oil contains free (not bound) DHA and EPA, making them more available for the body to use .
2) Has Stronger Effects than Fish Oil
Krill oil also breaks down more fats in mice by blocking enzymes that promote fat creation .
3) Contains More Nutrients than Fish Oil
The EPA and DHA in krill oil are in the form of phospholipids (fats with a phosphate group), while in fish oil, they are in the form of triglycerides. Phospholipids enhance omega-3 absorption but triglycerides do not .
Additionally, the phospholipids in krill oil protect membranes from free radicals and prevent cell damage .
4) Other Differences
Krill and fish oil affect gene expression differently. In mice, fish oil changed the expression of 192 genes in the liver, while krill oil altered expression of 4,892 genes. This means that krill oil impacts more pathways (glucose and lipid (fat) metabolism and energy production in mitochondria), which increases its potential for health benefits .
People commonly complain about the large size of fish oil capsules. Krill oil capsules are smaller and more suitable for people with difficulty swallowing .
Krill oil is more expensive than fish oil because it must be immediately processed to prevent spoiling .
Given this risk of spoiling, krill oil quality might not be as good as prescription fish oil .
Side Effects & Precautions
Marine-based fatty acids can cause blood thinning and prevent blood from clotting. Although krill oil’s blood-thinning effects have not been tested, it shares similar fatty acids with fish oil. Hence, this side effect could still be possible .
Krill oil might increase the effectiveness of blood thinners and can increase the risk of bleeding. People who are taking blood thinners should not take krill oil supplements at the same time [40, 39].
In mice, krill oil decreases genes responsible for liver glucose production (SLC2A2 and PCK1). However, it did not decrease blood glucose levels .
Krill oil also affects genes involved in body fat production .
Limitations & Caveats
Compared to the large amount of human research on fish oil, there are few krill oil human trials. Additional studies are needed to determine the safety and effectiveness of krill oil on human health.
People who are allergic to crustaceans and shellfish (shrimp/crabs) may experience adverse reactions .
Storage can cause krill shells to increase fluoride levels and their effects on human health are not clear yet .
Food Sources and Supplementation
Currently, there is no recommended dose for krill oil. However, the American Heart Association recommends 250 to 500 mg of EPA + DHA each day. The amount of fatty acids in krill oil depends on the type and brand but typically range between 180 and 250 mg EPA and DHA (combined) per capsule [33, 1].
- “In the past, I have always found that fish oil capsules have given me heartburn and a fishy aftertaste. After switching to Neptune Krill capsules I have not had this problem” .
- “I prefer krill oil to fish oil as it helps immensely with hormone issues, bloating, etc., where fish oil just made the problem worse for me” .
- “Helps me tremendously with joint pain, as well as with PMS. Also, has a great supply of antioxidants” .
- “One of the best because (1) you’re taking fewer capsules (2) krill oil won’t go rancid versus fish oils (3) contains astaxanthin (4) it’s Neptune Krill oil which is toxin-free. I’ve used Krill oil in the past to help me to lose weight” .
- “For a person with heart disease, it is helpful for hypertension and lowering bad cholesterol. Some of the people I know that used it said it help with their memory and vision. One person said it helped their prostate.”
- “I had to stop taking them after 3 days got stomach cramps and became very bloated it has been a week now and still hurting” .
- “Don’t notice anything more than a quality fish oil” .
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