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Walnuts May Improve Sperm Quality in Healthy Men


4 Star

Walnuts May Improve Sperm Quality in Healthy Men

Our Review Summary

The story didn’t hype the findings excessively, and it did a reasonable job of communicating the results as interpreted by the researchers. But it needed to ask a few more pointed questions to make the results meaningful for readers. Specifically:

  • What were the changes in sperm quality reported by the researchers and were they clinically meaningful?
  • Can the results tell us anything about men who are known to have fertility problems (i.e. the people most likely to be interested in this research)?


Why This Matters

As the story points out, male reproductive issues contribute to fertility problems in many couples. Dietary changes – if proven effective – would be a convenient and inexpensive way to address these issues.


Does the story adequately discuss the costs of the intervention?

Not Applicable

Costs aren’t mentioned, but the price of walnuts isn’t a major concern.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The story doesn’t make over-the-top claims about the benefits of walnuts, but it also doesn’t provide enough info to allow readers to judge the signficance of the research. The story says that eating walnuts “improved sperm quality,” but it doesn’t say by how much. A look at the original paper shows that sperm vitality and motility increased by about 5%, while the percentage of sperm with normal size and shape increased by 1%. We’re not expert enough to know if these are clinically meaningful changes, but the point is that news consumers shouldn’t have to be. The story should have clued them in to what these changes mean, perhaps by including some more pointed feedback from an independent source.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

Eating walnuts isn’t harmful per se, but they are packed with fat and protein, and so they should be eaten in moderation. The amount participants in this study were eating (2.5 oz per day) provides about 450 calories and is more than the amount of nuts that is generally recommended for daily consumption (1.5 oz). It could lead to weight gain if not counterbalanced by decreased intake of other foods. The story should have mentioned this.  Of course the California Walnut Commission, which partially funded this study, would love to see people eat as many walnuts as possible.  Why was the studied designed with this level of walnut consumption?

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The story hints at the fact that this was a study of surrogate outcomes when it quotes a researcher who says, “Whether adding walnuts to the diet will improve men’s chances of fathering children remains to be seen, but it couldn’t hurt.” But it would have been helpful if the study had more explicitly addressed the fact that this was a study of healthy men, not men with fertility problems. It’s the latter group that’s going to be most concerned about increasing their fertility, and the study doesn’t tell us much about what, if anything, walnuts can do for them.

Does the story commit disease-mongering?


There was no disease-mongering of male fertility problems – if you can get past the lead line that suggests that any man aspiring to fatherhood should think about eating nuts to improve sperm quality.

Does the story use independent sources and identify conflicts of interest?


The story mentions that the study was partially funded by the California Walnut Commission, and it solicits a comment from an independent fertility expert. However, the expert’s comments don’t really add anything in the way of critical evaluation of the research or its implications. His quote is generally supportive of the idea that diet plays a role in fertility, but offers nothing specific about the study. He could have been tapped, for example, to evaluate the clinical importance of the results. Tough call, but since he also offers advice suggesting that we’re still a ways away from concrete recommendations regarding walnuts (“For now, the idea is to eat healthy with a varied diet.”), we’ll call it good enough for a satisfactory.

Does the story compare the new approach with existing alternatives?


The story mentions that fish oil is also a source of omega-3 fats that are thought to be beneficial for fertility. It could have mentioned that the major omega-3 found in walnuts is alpha-linolenic acid (ALA), which is a precursor to the two long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), that are most consistently associated with health benefits. Only a small amount of ALA gets converted by the human body to these beneficial forms, whereas fatty fish is naturally rich in the active long-chain fatty acids. Therefore, eating fish might theoretically be as good or a better choice for improving fertility.

Does the story establish the availability of the treatment/test/product/procedure?

Not Applicable

The availability of walnuts is not in question.

Does the story establish the true novelty of the approach?


The story mentions previous research on the use of omega-3 fatty acids in men with fertility problems.

Does the story appear to rely solely or largely on a news release?


There is no evidence that the story was based on a press release.

Total Score: 5 of 8 Satisfactory


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