Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for COD LIVER OIL are as follows:
Insufficient evidence to rate effectiveness for…
- An eye disease that leads to vision loss in older adults (age-related macular degeneration or AMD). People who eat a lot of fish and take cod liver oil don’t have a lower risk of developing this condition compared to people who just eat a lot of fish.
- Hay fever. Taking cod liver oil during pregnancy or while breastfeeding, or giving it to the infant up to 2 years of age, does not seem to prevent hay fever.
- Irregular heartbeat (arrhythmia). Taking cod liver oil by mouth might reduce a specific type of irregular heartbeat in some people. But it’s not known if this reduces the risk of heart-related death. Taking the oil by mouth does not seem to reduce irregular heartbeat in men with an irregular heartbeat after a heart attack.
- Asthma. Most research shows that taking cod liver oil during pregnancy or breast-feeding, or giving it to an infant up to 2 years of age, doesn’t prevent asthma. But taking it 1-3 times weekly during pregnancy might reduce the risk of asthma in the child at 6 years of age.
- Eczema (atopic dermatitis). Most research shows that taking cod liver oil during pregnancy or breast-feeding, or giving it to an infant up to 2 years of age, doesn’t prevent eczema. But fewer infants have eczema at one year of age if they take it at least four times weekly.
- Depression. Taking cod liver oil has been linked with a 29% lower chance of older adults having depression symptoms.
- Diabetes. Taking cod liver oil may help control blood sugar in people with diabetes during pregnancy. This might help to prevent complications at birth. It may take up to 12 weeks for benefit. Taking it doesn’t seem to help with blood sugar control in people with type 1 diabetes.
- The inherited tendency towards high cholesterol (familial hypercholesterolemia). Early research shows that taking cod liver oil doesn’t seem to lower cholesterol levels in people with familial hypercholesterolemia.
- High cholesterol. Taking oil by mouth doesn’t lower cholesterol levels in people with high cholesterol. But it might increase “good” high-density lipoprotein cholesterol levels in people with type 1 diabetes and high cholesterol. Also, it might lower blood fats called “triglycerides” in men who have had a heart attack.
- High blood pressure. Taking the oil by mouth seems to slightly lower blood pressure in healthy people and those with slightly high blood pressure. But it’s not clear if this reduction is clinically meaningful for people with very high cholesterol.
- Long-term swelling (inflammation) in the digestive tract (inflammatory bowel disease or IBD). Some people with inflammatory bowel disease have joint pain. Taking this oil might reduce joint pain in some people with this condition.
- Osteoarthritis. Taking oil along with an NSAID doesn’t reduce swelling in people with osteoarthritis better than taking an NSAID alone.
- Ear infection (otitis media). Taking cod liver oil and a multivitamin might reduce the need to use medicine to treat ear infections in young children by about 12%.
- Infection of the airways. Giving young children this oil and a multivitamin seems to reduce the number of doctor’s office visits for airway infections.
- Rheumatoid arthritis (RA). Taking this oil might decrease pain, morning stiffness, and swelling in some patients with rheumatoid arthritis. Also, taking cod liver oil and fish oil seems to reduce the need to use medicine to treat joint swelling in people with this condition.
- Vitamin D deficiency. Taking cod liver oil seems to increase blood levels of vitamin D in some people. But it’s not clear if it increases vitamin D to normal levels in people with low levels of vitamin D.
- Wound healing.
- Other conditions.
More evidence is needed to rate it for these uses.
Side Effects Of Cod Liver Oil
- When taken by mouth: Cod liver oil is LIKELY SAFE for most adults when taken by mouth. It can cause side effects including belching, bad breath, heartburn, loose stools, and nausea. Taking it with meals can often decrease these side effects. High doses of cod liver oil are POSSIBLY UNSAFE. They might keep blood from clotting and can increase the chance of bleeding. Vitamin A and vitamin D levels might also become too high with high doses of cod liver oil.
- When applied to the skin: There isn’t enough reliable information to know if cod liver oil is safe or what the side effects might be.
Warnings & Precautions
- Pregnancy and breast-feeding: Cod liver oil is POSSIBLY SAFE when used in amounts that provide no more than the recommended daily intakes of vitamin A and vitamin D. It is POSSIBLY UNSAFE when taken in larger amounts. Women who are pregnant or breast-feeding should not take oil that provides more than about 3000 mcg of vitamin A and 100 mcg of vitamin D.
- Children: It is LIKELY SAFE for most children when taken by mouth in amounts that provide no more than the recommended daily intakes of vitamin A and vitamin D. It is POSSIBLY UNSAFE when taken in larger amounts.
- Diabetes: There has been some concern that cod liver oil or other fish oils might increase blood sugar in people with diabetes. But there is no strong research that supports this concern. But there is some evidence that it may lower blood sugar levels and increase the blood sugar-lowering effects of some antidiabetes drugs. There is a concern that blood sugar could drop too low. If you have diabetes and use it, monitor your blood sugar levels closely.
- High blood pressure: Cod liver oil can lower blood pressure and might cause blood pressure to go too low if used along with medications for high blood pressure. Be careful when using if you are taking high blood pressure drugs.
Dosage Of Cod Liver Oil
The appropriate dose depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.
Consult your doctor or pharmacist.
All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.