Battling cancer is hard enough, but many cancer survivors also find that fatigue still plagues them…even years after their diagnosis and often after treatment, too.

And this isn’t always just the “I’m a little droopy today” kind of fatigue—some cancer survivors have so little energy that they lose their jobs and stop doing the things that they love.

The fatigue could be due to the cancer, the treatment, the stress of dealing with the disease—or some combination of all three.

What a pity, after having faced up to cancer and defeated it!

So I’m happy to tell you about some progress on this front.

Nobody knows for sure why fatigue lasts so long after getting diagnosed with cancer, but one theory suggests that all that systemic inflammation in the body causes an imbalance in the nervous system, making the “fight or flight” sympathetic nerves overactive and the “resting” parasympathetic nerves underactive—which may lead to fatigue.

We’ve known from past studies that eating certain foods and taking certain supplements can reduce inflammation. So a group of researchers recently studied whether particular foods would help cancer survivors experience less fatigue. They looked at women who had had breast cancer—but there’s no reason to think that survivors of other types of cancer wouldn’t fall into the same boat.

And the results are very promising!


All the cancer survivors in the study had been treated surgically, and some had also had chemotherapy and/or radiation.

Researchers found an interesting connection between their levels of fatigue and their consumption of two sorts of fatty acids—omega-3 and omega-6.

  • The women whose diets had the highest ratios of omega-6s to omega-3s and who did not take fish oil, cod-liver oil or flaxseed oil supplements (which contain omega-3s) had the most inflammation…and almost half of them were experiencing chronic fatigue.
  • The women whose diets had the lowest ratios of omega-6s to omega-3s and who had been taking at least one of the supplements listed above had the least inflammation…and only about one-quarter of them were experiencing chronic fatigue.
  • In between these two extremes, the less omega-6s and the more omega-3s a woman consumed either in her food or from supplements, the less likely she was to have high inflammation and suffer from fatigue.


This result seems unambiguous to me. For these cancer survivors, consuming a small amount of omega-6s relative to omega-3s helped them avoid fatigue—the exact amounts they ate weren’t as important as the ratio. Researchers aren’t sure whether getting omega-3 fatty acids from food versus getting them from supplements made any difference, so for now, “I’d advise cancer survivors to concentrate on increasing their omega-3 fatty acids and decreasing their omega-6 fatty acids through food,” said Catherine Alfano, PhD, the study’s lead author and deputy director of the office of cancer survivorship at the National Cancer Institute in Bethesda, Maryland. “Future research will have to test whether taking a supplement that contains omega-3s can help.”

Dr. Alfano pointed out that in our bodies, omega-3s are partly responsible for reducing inflammation, and that that function can be overwhelmed by an abundance of omega-6s. If you maintain a favorable omega-3-to-omega-6 ratio, the anti-inflammatory properties of omega-3s can prevail.

Omega-6s are found in abundance in margarine and vegetable oils (including corn oil, canola oil, sunflower oil, safflower oil and soybean oil) and are therefore plentiful in processed food and commercially baked products. If you are a cancer survivor, then these oils and foods containing them should become part of your “eat only a little” list.

Meanwhile, omega-3s, with which you should fill your plate, are found mostly in seafood such as salmon, sardines, halibut, scallops, shrimp and tuna, and in other foods such as flaxseed, walnuts, tofu and soybeans. These are all smart dietary choices in general—and if they can also help you break out of post-cancer fatigue, how terrific is that?