Cancer patients’ survival improves with higher omega-3 intake from fish oil

The number of cancer cases is rising alarmingly, and although treatments have improved, cancer survivors still face an increased risk of premature death for a number of reasons. A higher intake of omega-3 fatty acids, however, appears to be associated with longer life, according to a population-based study published in Nutrition Research Journal. The researchers describe how the omega-3 fatty acids EPA and DHA from fatty fish and fish oil not only affect cancer patients’ long-term survival but may also play a role in cancer prevention through various biological mechanisms.

In 2020, nearly 20 million people were diagnosed with cancer, and 10 million died from the disease. The number of cancer cases continues to rise at an alarming rate, and although early diagnosis and improved treatments have increased overall five-year survival rates, more people are living with a history of cancer. Studies have shown that people with a history of cancer have an increased risk of dying earlier than the general population due to cardiovascular disease, infections, cancer recurrence, and many other causes.
The increased risk of premature death following cancer treatment therefore creates a greater need to improve these patients’ long-term survival. This is particularly important because conventional cancer treatments such as radiation, surgery, and chemotherapy do not sufficiently target the causes of cancer and the underlying mechanisms that have promoted the growth of cancer cells.
Long-term cancer prevention and treatment involve living a healthier lifestyle, but that is a broad concept. When it comes to diet, there has been growing interest in the potential cancer-preventive effects of omega-3 fatty acids. This applies particularly to the active omega-3 forms EPA and DHA, with fatty fish such as herring, mackerel, anchovies, and wild salmon being the best sources. These omega-3 fatty acids are widely lacking in the modern diet, so the new population-based study set out to investigate the relationship between cancer patients’ health and long-term survival.

The more omega-3, the greater the chance of living longer

The researchers obtained relevant data from a large population-based study called NHANES (National Health and Nutrition Examination Survey), and the new study included 4,836 adult participants who had undergone cancer treatment and survived. The participants’ intake of omega-3 fatty acids was assessed using dietary questionnaires. The participants were then divided into four quartiles according to their total intake of omega-3 fatty acids.
During a follow-up period of just under seven years (81 months), 1,776 participants died, corresponding to 37 percent. After adjusting for various confounding factors, the researchers found the following:

• Each one-gram increase in dietary omega-3 fatty acids was associated with a six percent lower risk of death during the follow-up period
• Participants in the quartile with the highest omega-3 intake had a 24 percent lower risk of death during the follow-up period compared with participants in the quartile with the lowest omega-3 intake
• The positive effect of omega-3 fatty acids on health and longevity was greatest among overweight participants

The researchers therefore conclude that patients with a history of cancer who consume more omega-3 fatty acids have a reduced risk of premature death from all causes. This association is particularly evident among overweight individuals.
According to the researchers, new dietary strategies are therefore needed to improve the chances of living longer after cancer treatment over the long term.

The cancer-preventive effects of omega-3 fatty acids

The omega-3 fatty acids EPA and DHA are found in cell membranes, where they have numerous biological functions together with omega-6 fatty acids. In the introduction to the new population-based study, the researchers describe how EPA and DHA affect health and cancer prevention through the following mechanisms:

• Counteract chronic inflammation, which increases the risk of cellular damage and cancer
• Counteract oxidative stress, in which free radicals attack cells and tissues
• Thin the blood and help prevent blood clots
• Have a protective effect on the heart
• May potentially inhibit tumor growth

It is also important to consume omega-3 and omega-6 fatty acids in the proper balance so that their many functions proceed normally. However, the modern diet often contains far too little omega-3 from fatty fish and far too much omega-6 from vegetable oils, margarine, mayonnaise, dressings, French fries, chips, ready-made meals, and other highly processed foods.
The imbalance between omega-3 and omega-6 fatty acids automatically creates favorable conditions for chronic inflammation and other undesirable reactions that increase the risk of rheumatoid arthritis, high blood pressure, cancer, and many other chronic diseases.

• The official recommendations for omega-3 fatty acids are around one gram per day, which can, for example, be obtained by eating a serving of herring
• In cases of inflammation, higher doses corresponding to two to four grams of omega-3 fatty acids per day are recommended
• This can be achieved by eating more fatty fish or by taking a daily supplement containing 2–4 standard capsules of high-quality fish oil.

References:

Wentao Zang et al. Higher dietary omega-3 polyunsaturated fatty acid intake is associated with reduces all-cause mortality survivors: A prospective cohort study. Nutrition Research Journal. 2026