The omega-3 fatty acid DHA is toxic to cancer cells

- and could potentially be used for prevention and treatment

It is commonly known that omega-3 fatty acids are involved in a number of essential functions in the body. One of the fatty acids, DHA, may even have a toxic effect on cancer cells because they are unable to store the fatty acid correctly. In a new Belgian study published in Cell Metabolism, scientists explain the exact mechanisms. They also suggest that omega-3 supplements may be useful in cancer therapy, especially because the average omega-3 intake from the diet is far too limited and because there is a risk of becoming resistant to medical cancer drugs. The new study puts omega-3 fatty acids and their anti-cancer effects in a whole new light.

Omega-3 fatty acids are a group of essential, polyunsaturated fatty acids. The two kinds called EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are found in cell membranes where they take part in a large number of biochemical processes. It is commonly known that DHA is of particular importance to the brain, eyes, vision, and inflammatory control. Now, it even appears that DHA is associated with a reduced risk of developing cancer.
A team of scientists from Université catholique de Louvain in Belgium recently identified the biochemical mechanisms that are responsible for DHA’s ability to block the development of cancer cells and tumors. The scientists are specialized in oncology and in 2016, they discovered that cancer cells in an acidic micro environment (acidosis) replace glucose with fats as an energy source when they divide. In 2020, the scientists demonstrated that the same cells are the most aggressive when it comes to abandoning the original tumor and metastasizing in other sites. This discovery led to a more extensive collaboration with another team of scientists from the same university. The other team was affiliated with the faculty for bioengineering that worked with developing better food sources with fats. The whole purpose with this collaboration was to clarify how cancer cells in tumors behave when exposed to different types of fatty acids.

The DHA in cancer cells makes them vulnerable to free radical attacks

The scientists soon discovered that cancer cells in an acidic micro environment reacted in different ways, depending on which fatty acid they absorbed. In a matter of a few weeks, the found that certain fatty acids stimulated tumor cell growth, while others killed them. DHA was the fatty acid that destroyed cancer cells by poisoning them.
DHA poisons cancer cells by means of a phenomenon called ferroptosis, which is a type of programmed cell destruction that depends on the presence of iron and is caused by free radicals. In addition, the antioxidant defense of the cancer cells is flawed.
Once free radicals attack the polyunsaturated fatty acids in the cell membrane, dangerous chain reactions are triggered and spread to the rest of the cell. This is known as lipid peroxidation or rancidification. It is the same that happens when butter turns rancid if you leave it out on the kitchen table for too long. The new study shows that the higher the concentration of polyunsaturated fatty acids in a cancer cell is, the greater the risk is that the cancer cell oxidizes and becomes damaged.
Normally, cancer cells in tumors store polyunsaturated fatty acids in small droplets that protect them against free radicals and oxidation, but if the cell is flooded by DHA it is no longer able to store the fatty acids in these protective droplets. This results in lipid peroxidation inside the cancer cells and the onset of different chain reactions that eventually cause the cancer cell to die. In other words, what causes the cell to perish is that it is unable to handle the increased DHA uptake and ends up becoming a target for free radical attack.
The scientists also discovered that the development of cancer tumors in mice was delayed significantly when they were given a diet with plenty of omega-3. The new data indicates that increased intake of omega-3 fatty acids from diet or supplements may be useful as part of the cancer therapy. The new study is published in Cell Metabolism.

How do we make sure to get enough omega-3 and DHA in particular?

For millions of years, our ancestors consumed large quantities of omega-3 fatty acids from oily fish, shellfish, and other marine sources that contain EPA and DHA. However, the intake of omega-3 fatty acids has decreased drastically in recent times due to altered eating habits and unnatural animal fodder. This is reflected in the omega-3 content in fish, meat, and eggs.
According to the scientists behind the new study, an average intake of around 50-100 mg of DHA each day is far too little. They recommend a minimum of 250 mg of DHA daily, an amount you can get by eating a serving of mackerel or herring, 50 grams of farmed salmon, or 125 grams of boiled shrimp. People who do not like fish or shellfish or simply eat very little can take a high-quality fish oil supplement, instead. Check the label to see how much EPA and DHA is in each capsule.

Omega-3 can prevent breast cancer cells from growing and spreading

One in nine Danish women is affected by breast cancer and diet is believed to play a major role. According to an American study, omega-3 fatty acids are able to suppress the growth and spreading of breast cancer cells. Saraswoti Khadge, a scientist affiliated with University of Nebraska Medical Center and also the lead investigator of the study, explains that omega-3 fatty acids support the body’s immune defense and anti-inflammatory response. Getting plenty of omega-3 is therefore vital for the prevention and treatment of breast cancer.

EPA protects against prostate cancer

The difference in prostate cancer rates around the world reveal that this is a lifestyle-associated disease. For instance, Inuit men have a very low prostate cancer rate and that is believed to be linked to their high intake of omega-3 from seal, salmon, and other marine sources. Also, the EPA content in prostate cells is a determining factor for how the disease develops, according to a study that is published in Nutrients. The scientists also mention that EPA inhibits chronic inflammation that plays a key role in cancer.

References

Will Chu. Mechanism could explain why Omega-3 fatty acid is toxic to tumor cells. NUTRAingredients.com

Emeline Dierge et al. Peroxidation of n-3 and n-6 polyunsaturated acids into acidic tumor environment leads to ferroptosis-mediated anticancer effects. Cell Metabolism 2021

Saraswoti Khadge et al. Long-chain omega-3 polysaturated fatty acids decrease mammary tumor growth, multi organ metastasis and enhance survival. 2018

Hanane Moussa et al. Omega-3 Fatty Acids Survey in Men under Active Surveillance for Prostate Cancer: from Intake to Prostate Tissue Level. Nutrients 2019

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