Hover over a term you want explained. If you need more details, then click on the term and a new tab will open with a full details page.
Cod liver oil is a natural supplement made from the liver of cod fish. It is known for being rich in fat-soluble vitamins—mainly vitamins A, D, E, and K. These vitamins dissolve in fats and oils and are stored in the body’s fatty tissues and liver for later use. Each vitamin plays a unique role: vitamin A supports vision and the immune system; vitamin D helps keep bones and muscles strong; vitamin E protects cells as an antioxidant; and vitamin K is important for blood clotting and bone health. People usually get these vitamins through their diet, including fish oils like cod liver oil, as well as fruits, vegetables, nuts, and animal products.
Nutrition is an important part of cancer care. Some patients may have trouble absorbing nutrients because of digestive problems, surgery, or side effects from treatments like chemotherapy. In these cases, doctors might consider supplements such as cod liver oil to help prevent or treat deficiencies in fat-soluble vitamins. Deficiencies can cause symptoms like vision problems, weak bones, muscle weakness, or bleeding issues, depending on which vitamin is low. However, it is important to balance vitamin intake carefully because too much of these vitamins can also cause health problems. For example, excess vitamin A can be toxic, and too much vitamin D can affect calcium levels. Cod liver oil may also increase bleeding risk, especially if you take blood-thinning medications.
You might hear about cod liver oil during discussions about diet, supplements, or supportive care in cancer treatment. It may be mentioned as a way to support nutrition, improve treatment tolerance, or help recovery after surgery or chemotherapy. However, cod liver oil is not a treatment for cancer itself. It is a nutritional supplement that may be helpful in certain situations but is not necessary or recommended for everyone. Your healthcare team can help decide if cod liver oil or other vitamin supplements are appropriate for you based on your health, treatments, and lab tests.
If you are considering cod liver oil or fat-soluble vitamin supplements, it is important to talk openly with your healthcare providers. You might ask: Do I need to take cod liver oil or other vitamin supplements? How can I tell if I have a vitamin deficiency? Are there risks to taking cod liver oil with my current treatments or medications? What foods can help me get these vitamins naturally? These questions can help guide safe and effective use of supplements as part of your overall care.
Cod liver oil is part of a broader group of fat-soluble vitamins that are important for health. While it may be discussed in cancer care, it should not be seen as a cure or direct treatment for cancer. Instead, it is one option among many to support nutrition and manage side effects. Doctors consider your overall health, diet, medications, and cancer treatments when advising on these vitamins. Blood tests may be used to check vitamin levels if a deficiency is suspected. Because cod liver oil can affect blood clotting and vitamin levels, your care team will carefully weigh the benefits and risks before recommending it.
This information is educational and does not replace personalized medical advice. Each person’s situation is unique, so decisions about supplements like cod liver oil should be made with a healthcare provider who knows your full medical history and treatment plan. Never start or stop supplements without discussing it with your care team. If you are interested in cod liver oil or fat-soluble vitamin supplements, the best next step is to talk with your doctor or a registered dietitian. They can help determine if these supplements fit your individual needs and guide safe use to support your health during cancer care.
Public source information used for this glossary entry includes: