Improved nutritional status of cancer patients undergoing chemotherapy may correspond to improved prognosis. What is the role of omega-3s in this association? Can they enhance the effects of treatments? At what dosages? Here's what we know about the topic.

Fish oil, a rich source of Omega 3 fatty acids, could help counteract weight loss during chemotherapy and improve the therapeutic efficacy of the treatment and the nutritional status of patients. 

Scientific literature suggests this: according to the authors of a meta-analysis published in 2023 in Critical Reviews in Food Science and Nutrition, there is evidence that "the consumption of oral food supplements enriched with Omega 3 polyunsaturated fatty acids exert beneficial effects on the nutritional status and clinical effects in patients undergoing chemotherapy (radio) therapy".

Their conclusions reinforce what emerged from previous systematic reviews of publications on the topic; in fact, already in 2015 a review published in the pages of Clinical Nutrition had highlighted the existence of «beneficial effects of Omega 3 fatty acid supplements in patients undergoing chemotherapy», underlining that, of all, the most evident is «the possibility of preserving body composition».

In this regard, it would be eicosapentaenoic acid (EPA, one of the biologically active Omega 3s that marine sources, such as fish oil, are rich in) that helps those struggling with cancer to prevent both the loss of muscle mass and the loss of fat mass. This detail emerged from a study coordinated by Vera Mazurak of the University of Alberta (Canada), published in the journal Cancer in 2011, which also suggests a possible dosage: 2.2 grams per day.

Omega 3 and tumors

Cancer patients often experience increased levels of inflammation; furthermore, chemotherapy further increases the production of inflammation-associated molecules (cytokines and prostaglandins) and reactive oxygen species, promoting a cascade of events that suppress immune function.

Given their anti-inflammatory properties , Omega 3 appear as possible allies against these phenomena. Furthermore, they are nutrients with anti-proliferative, pro-apoptotic and anti-metastatic actions useful against cancer. Finally, they could also perform an anti-tumor action by regulating genes at the epigenetic level (i.e. without modifying their sequence).

Numerous in vitro and in vivo studies suggest that EPA and the other marine Omega 3 (docosahexaenoic acid - DHA) positively regulate the effects of anti-tumor treatments; furthermore, experiments conducted on humans suggest that they can improve the results of therapies by reducing risks and side effects.

Chemotherapy Side Effects: Weight Loss

Among the possible side effects, weight loss is a very common event in cancer patients undergoing chemotherapy; furthermore, for these patients the prognosis is closely associated with body composition.

Finding a remedy for the state of malnutrition that causes this wasting is essential to counteract the sense of fatigue and the decrease in quality of life that accompany treatment and that prevent the patient from undergoing further treatments, with a consequent decrease in life expectancy. 

An interesting aspect is the link between Omega 3 and the loss of lean mass and skeletal muscle, which is greater in cancer patients in whom the levels of these fats are lower.

The study by Muzarak and colleagues, demonstrating that the loss of muscle mass and adipose tissue can be counteracted by taking 2.2 grams per day of EPA, offers a solution to the state of malnutrition associated with chemotherapy. 

The study involved 40 patients, 16 of whom supplemented their diet daily with fish oil containing EPA for the duration of the chemotherapy cycle, for a total of about 10 weeks of treatment. The remaining 24 patients, however, received only traditional treatments. 

During chemotherapy treatment, researchers monitored the health of muscle mass through computed tomography, a technique that allows for precise quantification of skeletal muscles. It turned out that, even though in the 6 months prior to the start of the trial, patients who took Omega 3 had reported an average weight loss of 6.3%, supplementation with fish oil allowed them to maintain their weight. In addition, about 70% of those who combined chemotherapy with EPA maintained their muscle mass intact or even increased it. And the effect was closely related to the presence of the Omega 3 fatty acid, so much so that the higher the increase in EPA in the bloodstream, the greater the gain in muscle mass. 

In contrast, patients who did not supplement their diets with fish oil lost, on average, 5 pounds (2.3 kg) over the course of 10 weeks of chemotherapy. Not only that, less than 30 percent of these patients maintained their muscle mass, and their one-year survival rate was 38.7 percent—far lower than the 60 percent rate among patients who received fish oil supplementation.

Omega-3 against malnutrition

Mazurak emphasized how promising these results were: before this study, no effective treatment for cancer-related malnutrition had been identified. And because fish oil had been shown to prevent weight loss and muscle loss by interfering with some of the metabolic pathways that are disrupted in advanced cancer, the researchers were quick to suggest daily omega-3 supplementation with fish oil containing 2 grams of EPA to help cancer patients maintain weight and muscle mass during chemotherapy. 

The 2023 meta-analysis proved Mazurak and colleagues right. Taking into account 22 studies published in the scientific literature (with a total of 1155 patients involved), its authors found a significant increase in body weight and body mass index following the intake of Omega 3.

Omega 3 against inflammation and toxicity of treatments

The 2015 review also highlighted the anti-inflammatory effects of Omega 3 in cancer patients undergoing chemotherapy. “Lower levels of systemic inflammation, assessed by C-reactive protein levels, were observed in all studies where it was measured,” the authors explained.

The 2023 meta-analysis confirms these effects, finding a reduction not only in C-reactive protein, but also in Tumor Necrosis Factor-α (TNF-α) and interleukin 6 (IL-6), two known pro-inflammatory molecules.

Finally, the 2023 meta-analysis found a significant reduction in the incidence of adverse effects, while the 2015 review also considered studies that evaluated the effect of Omega 3 supplementation on the toxicity of anticancer treatments. One of these highlighted the potential of Omega 3 in the prophylaxis of peripheral neuropathy induced by the chemotherapy paclitaxel.

The authors emphasize that counteracting peripheral neuropathy would significantly improve the quality of life of patients and that, more generally, fish oil supplements are associated with better quality of life scores during chemotherapy.

How much Omega 3 during chemotherapy?

As mentioned, according to the study by Mazurak et al., 2.2 grams of EPA per day are needed to prevent weight loss during chemotherapy – at least in the specific case considered (advanced non-small cell lung cancer).

According to the authors of the review published in Cancer, «taking into account the clinical benefits, the optimal and safe dose for long-chain Omega 3 polyunsaturated fatty acids (EPA and/or DHA) is approximately 2 grams per day».

"In the studies examined, fish oil was effective," the experts specify, adding that "EPA and/or DHA were rapidly incorporated into blood cells." In this regard, it is worth remembering that the levels of Omega 3 in red blood cells (measured by the Omega-3 Index ) are a widely used indicator of the presence of Omega 3 in the body.

Bibliographic references:

de Aguiar Pastore Silva J, Emilia de Souza Fabre M, Waitzberg DL. Omega-3 supplements for patients in chemotherapy and/or radiotherapy: A systematic review. Clin Nutr. 2015 Jun;34(3):359-66. doi: 10.1016/j.clnu.2014.11.005

Murphy RA, Mourtzakis M, Chu QS, Baracos VE, Reiman T, Mazurak VC. Supplementation with fish oil increases first-line chemotherapy efficacy in patients with advanced nonsmall cell lung cancer. Cancer. 2011 Aug 15;117(16):3774-80. doi: 10.1002/cncr.25933

Wang Y, Liu R, Chang M, Wei W, Guo Y, Jin Q, Wang X. Does omega-3 PUFA-enriched oral nutritional intervention benefit cancer patients receiving chemo (radio) therapy? A systematic review and meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. 2023;63(18):3081-3096. doi: 10.1080/10408398.2021.1984199