Research indicates that the relationship between omega-3 fish oil supplements and cancer risk is complex. While some extensive clinical studies suggest that these supplements may reduce cancer risk, others have shown no significant benefits or even a potential increase in cancer cases.
Gene's Role in Colon Cancer Defense
A collaborative study by the University of Michigan and the University of Texas MD Anderson Cancer Center aimed to clarify these contradictory findings. Their research, published in Cellular and Molecular Gastroenterology and Hepatology, pinpointed a gene named 15-lipoxygenase-1, or ALOX15, as a vital component in determining whether EPA and DHA can effectively inhibit colorectal cancer.
The results indicate that assessing ALOX15 levels in cancer patients may be crucial for developing prevention strategies that involve omega-3 supplementation.
Unexpected Outcomes in Mice Studies
To investigate the impact of fish oil on tumor development, researchers compared mice on a fish oil-enriched diet with those on a standard diet. Surprisingly, the mice consuming fish oil exhibited a higher incidence of colon tumors when exposed to inflammation-inducing chemicals.
Typically, when EPA and DHA are ingested, the body transforms them into resolvins, which are essential for mitigating chronic inflammation--a significant factor in cancer progression. This transformation heavily depends on the enzyme ALOX15, which is often inactive in various cancer types.
The study further explored the effects of fish oil on mice that lacked ALOX15. In these subjects, the absence of ALOX15 resulted in an increase in colorectal tumors, with variations depending on the type of omega-3 fatty acid consumed.
Comparing EPA and DHA Forms
Mice that were fed diets high in EPA developed fewer tumors compared to those that received DHA. Both EPA and DHA are available in multiple forms, including free fatty acids, ethyl esters, and triglycerides.
Lovaza, a prescription medication containing ethyl esters of EPA and DHA, is approved for managing elevated triglyceride levels by the Food and Drug Administration.
This study found that Lovaza, along with the ethyl ester and free fatty acid forms of EPA, significantly reduced both the number and size of tumors, particularly in mice with active ALOX15. Conversely, DHA forms did not inhibit tumor growth in mice lacking ALOX15; however, when ALOX15 was active, tumor growth was diminished.
"Not all fish oil supplements are identical," noted Imad Shureiqi, a professor of internal medicine at the University of Michigan and a member of the Rogel Cancer Center.
"It's crucial to consider whether individuals taking these supplements possess the necessary enzymes to metabolize them effectively, thereby preventing chronic inflammation and cancer progression."
Implications for Patients
While the majority of the data stem from animal research, these findings prompt significant inquiries. They imply that individuals with colon polyps who lack active ALOX15 may not experience the same protective effects from EPA and DHA, potentially rendering the supplements less effective in inhibiting tumor growth.
Shureiqi recommends that patients consult their healthcare providers before initiating fish oil supplementation.
In the meantime, the research team is working on developing treatments aimed at enhancing ALOX15 levels in cancer cells, with the objective of improving the body's capacity to utilize EPA and DHA, thereby bolstering colon cancer prevention efforts.
