Flack About Flaxseed – Irreproducible Research

Throwing in some flaxseed seems like a good way to paint a health halo. Right now, our pantry has an open box of multigrain crackers with whole wheat and flaxseed. Sounds healthy, tastes good. But on the other hand, we’ve noted that not all of the research about the marvelous health benefits of flaxseed stands up to close scrutiny.

Just last week, Yasaman Jamshidi-Naeini and colleagues from the IU School of Public Health in Bloomington raised a second round of concerns about a meta-analysis of flaxseed research. The original study lacks transparency about methods and data, say Jamshidi-Naeini et al. Thus, the results are irreproducible and the conclusions about the benefits of flaxseed for reducing certain markers of inflammation remain unproven.

Fantastic Claims

One doesn’t have to look very hard to find fantastic claims for the health benefits of flaxseed. Flaxseed is “a powerful cancer fighting food,” says Verywell Health. The claims are based mostly on plausible rationalizations and substances that might be found in flaxseed.

But rationalization is not a great way to improve a person’s health, because we’ve learned that people can rationalize just about anything. It helps to have real data to show that doing something will actually yield better health outcomes.

When applying this standard, the health halo of flaxseed becomes a bit dimmer.

A Study of Inflammation Indicators

The flaxseed research in which Jamshidi-Naeini found issues was a systematic review and meta-analysis published in May 2019. The authors, Mehran Rahimlou and colleagues, concluded that “flaxseed significantly reduced circulating concentrations of hs-CRP and TNFα” – two biomarkers for inflammation.

But then Mojgan Amiri and colleagues raised concerns with inadequate methods and the potential for biased results from this study. “The conclusions are likely to be erroneous,” they wrote. Rahimlou et al disagreed. They thanked Amiri and expressed anticipation for more research ”on this exciting topic.”

Because Rahimlou’s response didn’t provide clarity about unit-of-analysis errors, Jamshidi-Naeini dug deeper and concluded the findings in the original paper were simply irreproducible.

What Is It About Flaxseed Studies?

This is hardly the first time issues have surfaced in research about flaxseed. Notably, Roberta Soares Lara Cassani and colleagues published a paper purporting to show that flaxseed “could be an important nutritional strategy to reduce inflammation markers such as CRP and TNF-α.” Of course, these are some of the same markers Rahimlou et al studied. But as was the case with the Rahimlou paper, Rositsa Dimova and David Allison found issues with the Cassini study. So the journal eventually retracted it.

None of this suggests that flaxseed isn’t a fine ingredient for foods. It has properties that might contribute in some small way to a person’s health. But no, we don’t have compelling evidence that it is “powerful” for fighting cancer or any other health problem.

Flaxseed is simply a useful food ingredient that also seems to be useful to food marketers.

Click here for the Rahimlou study, here for the issues Amiri raised, here for the reply to those issues, and here for the concerns of Jamshidi-Naeini. For further perspective on superfood hype, click here.

Breton Women Scutching Flax, painting by Meijer de Haan / WikiArt

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February 7, 2022