What did the sperm say to the walnut?

The media love sexy studies, and what could be sexier than nuts? According to a new study, walnuts help boost quality output from your own huevos.  So should guys run to the store and start stuffing nuts in their mouths?

As many of those affected will tell you, infertility is no laughing matter. The work up and treatment for male and female infertility is expensive, difficult, and often frustrating. Finding ways to boost fertility could help many people fulfill their desire to have children. What causes infertility? Is it insufficient nut consumption?

Definitions of infertility are problematic. The most common definition is the inability of a married woman to conceive after a year of trying. Some agencies differentiate fertility from fecundity, which is the inability of any woman to get pregnant or to carry a baby to term.  This leaves out a host of people who choose to conceive in other ways, but since this paper is about semen, we’ll stick to “fertility” for now.

Infertility in married couples is a “couples” problem. While we often read about women who are infertile, it is actually the couple who is having trouble conceiving (and to be more accurate, conception is an egg from one person fertilized by a sperm from another and successfully implanted in a woman; a problem can occur anywhere in the process.)  About 40% of the time, the health of the male is a causal factor male-female couple infertility. While semen quality (however measured) affects fertility it’s not entirely clear how or to what extent.

With this knowledge we can start to tease apart the semen-nut study. It’s good, but not perfect (not placebo-controlled). It’s an interesting study looking at a difficult medical problem. It’s grounded in scientific plausibility. And it’s relevance is unknown.  The best thing about this study, something often absent from sensationalist headlines is in the final paragraph:

Whether adding walnuts to the diet will go beyond the shifts in sperm parameters as seen in this study to improving birth outcomes for men within fertility clinic
populations or in the general population is not yet known and will require further research.

The authors explicitly acknowledged that their study does not show improved fertility. And while almost all studies conclude “further research is required,” in this case, maybe it truly is.  Now if we could only implement better definitions of fertility.



  1. I think the problem here is the sensationalist media. The networks make money when people watch their programs, and to make people watch their programs they have to broadcast all kinds of nonsense. Science reporting comes out the worst. Do your nuts need nuts? That story sells itself! I could go on a whole screed about how capitalism is the problem, but I’ve learned it annoys people when I do that.

  2. Old Geezer

     /  August 20, 2012

    @camilletixier: With all due respect, in this case, there does not appear to be a sensationalist media at work. The title of the paper states that walnuts improve fertility. It is only when you work your way through the paper itself that you find that the title is not justified by the body of work itself. While I agree with your premise, it really does not apply in this instance. Of greater interest to me is the fact that better sperm quality may well have been demonstrated but without actual pregnancies, the outcomes are just speculative.

  3. Anon.

     /  August 21, 2012

    “The most common definition is the inability of a married woman to conceive after a year of trying….Infertility in married couples is a “couples” problem.”

    I am wondering what effect the social contract that is marriage can possibly have on fertility. Please explicate.

  4. Uncle Glenny

     /  September 1, 2012

    The RDA of zinc, of which a source is nuts, was set in part by estimations of loss of seminal fluid in men. It was assumed that women would have a similar need due to loss from menstruation.

    No, I can’t give any cites. This was from a book on nutritional recommendations (settings of things like RDA and “tolerable upper limit” (TUL) and how they were calculated) from about 6-10 years ago, which I read online. I don’t know if anything from that synthesis ever went into effect (i.e. changes in RDA on anything).

    It was fascinating reading, though.

    n.b. Oysters are also high in zinc, which I assume is the cause of their aphrodisiacal reputation.

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