Have you ever wondered if there’s a natural way to lower your high blood pressure, guard against Alzheimer's, lose weight, and feel better? Well as it turns out there is. Michael Greger, M.D. FACLM, founder of NutritionFacts.org, and author of the instant New York Times bestseller “How Not to Die” celebrates evidence-based nutrition to add years to our life and life to our years.

Erectile Function and Dysfunction

Today, on the NutritionFacts Podcast, we explore foods that enhance male sexuality and fertility.

This episode features audio from Mixed Nuts Put to the Test for Erectile Dysfunction, Pistachio Nuts for Erectile Dysfunction, and Male Fertility & Diet. Visit the video pages for all sources and doctor’s notes related to this podcast.


Today, we look a problem that many men experience from time to time – erectile dysfunction. And we start by looking at the nuts. I’m talking about walnuts, almonds, and hazelnuts. Here’s the story.

In 2013—I can’t believe it’s already been so long, I posted a video based on this study that found that three weeks of pistachios resulted in a significant improvement in erectile function in men. It’s always nice to see a whole food intervention have clinical effects, and I was curious to revisit the topic to see what’s been published since.

Even if you ignore all the lab animal studies on, you know, how much hazelnuts improve the function of rat testicles, you still never know what you’ll find searching the medical literature for nuts and sexual function––like this case of penile strangulation with a metal hex nut. I guess nuts can sometimes make things worse, if you can’t remove them. They used the Dundee Technique, which involves creating 20 puncture holes to relieve the pressure, but that didn’t work; so, a diamond disk cutter was used to saw through it, and they slipped a few times: all’s well that ends well.

Well, that got me curious. Evidently, penile entrapment is so common, there’s an entire grading system that emergency room docs can use. If a drill is not available, these surgeons advise, a hammer and chisel may be used.

A drill? Oh, a dental drill. I like how they brag about the precisely cut edges.

To “preserve the penis from a fatal outcome” (that’s a strange way to put it), urologists should be aware of all the available armamentarium, and if you don’t know how to operate the saw, you can always call in the local blacksmith.

Yeah, but how are you going to remove a barbell or steel sledgehammer head? A heavy-duty air grinder provided by the fire department, requiring six hours of cutting, with the patient protected from the sparks with fire coats—whatever it takes. Hack saw. Cement eater. Or, the silk winding method. Anyway, back to the task at hand.

Consumption of at least one serving of vegetables a day and more than two servings of nuts a week was associated with a more than 50 percent decrease in the probability of erectile dysfunction in a snapshot-in-time cross-sectional study. But such observational studies can’t prove cause and effect. It’s like finding that men who eat healthier are better swimmers. Maybe men who eat nuts, are just health nuts, and the improvement is due to some other factor, like exercise. What we need is an interventional trial and, here we go.

The effect of nut consumption on semen quality and functionality: randomized controlled trial. A Standard American Diet with or without a handful of walnuts, and a half handful of each almonds and hazelnuts. And the nut group experienced significant improvements in their total sperm count, vitality, motility, and shape, perhaps because those in the nut group showed a significant reduction in SDF, sperm DNA fragmentation. The nuts appeared to protect their sperm DNA. Too bad while they were at it, they didn’t measure the guys’ erectile and sexual dysfunction…oh, but they did!

The effect of nut consumption on erectile and sexual function from the same study. The researchers report that those in the nut group saw a significant increase in orgasmic function and sexual desire. But, uh, what about erectile function? Any time you see this kind of selective glass-half-full reporting, you suspect some kind of industry funding, and indeed, that was the case here. Yes, there was a marginal increase in orgasmic function and sexual desire of questionable clinical significance, but no improvement in erectile function, intercourse satisfaction, or overall satisfaction. And with so many comparisons, even the so-called significant findings may not even be statistically significant.

But why did the pistachios I talked about back in 2013 work, while these other nuts didn’t? Well, if you remember in the original study, it was done on men in their 40s and 50s who already had chronic erectile dysfunction, whereas the average age in the new study was 24 years old; so, they may have started out with near-maximum circulation, not leaving much room for the nuts.

In our next story we look at how men eating pistachio nuts experienced a significant improvement in blood flow through the penis accompanied by significantly firmer erections. Here’s the story.

Erectile dysfunction is considered “an important cause of decreased quality of life in men”—in fact, so much so that one early theory suggested that this may explain the link between impotence and heart attacks. Depression is a risk factor for coronary heart disease, and the thought was that men who couldn’t get it up became so depressed that they, like, die of a broken heart.

But, now we know that erectile dysfunction and heart disease can be two different manifestations of the exact same root problem: diseased arteries—inflamed, oxidized, cholesterol-clogged blood vessels. So, no wonder a diet chock-full of anti-inflammatory, antioxidant, cholesterol-lowering plant foods would improve sexual functioning in both men and women, as well as reduce risk of heart disease. But why go low-risk when you can shoot for no risk? A totally plant-based diet can even stop and reverse our #1 killer.

Of all the plant foods individually examined so far, nuts are among those most tied to longevity. Just two handfuls of nuts a week may extend a woman’s life as much as jogging four hours a week. So, if nuts reduce the risk of heart disease, might they also help with sexual function?

Well, men eating three to four handfuls of pistachios a day for just three weeks experienced a significant improvement in blood flow through the penis accompanied by significantly firmer erections. This may not be surprising.

Remember how antioxidant-rich foods have a Viagra-like effect of boosting nitric oxide production? Well, pistachios are certainly “rich sources” of antioxidants. And, remember how the citruline in watermelons helped with erection firmness by boosting arginine, which is what our body makes nitric oxide out of? Well, pistachios have a bunch of arginine, which may help explain the improvement in blood flow.

And, we know that cholesterol is an important predictor of sexual dysfunction in both men and women, and after just three weeks on all those pistachios, there were significant improvements in cholesterol.

And, like other studies that piled on hundreds of calories of nuts a day, there was no weight gain. Conclusion: Just three weeks of pistachios “resulted in a significant improvement in erectile function…with additional improvement in [cholesterol] without any side effects.”

Note the two important differences between diet and drugs. Just taking drugs like Viagra to poison this enzyme, and artificially boost nitric oxide signaling, is just covering up the symptoms of the underlying problem—unhealthy arteries. Whereas eating whole healthy plant foods, like nuts, actually helps attack the root cause—cholesterol, oxidation, and inflammation—and only has good side effects.

This enzyme that Viagra-like drugs muck with is primarily found in two places in the body: the erectile tissue of the penis, and the retina of the eye. That’s why the FDA encourages people to stop taking drugs like Viagra, and call a doctor right away if you “experience sudden loss of vision” (of course, you can still find your phone).

Though the harms tend to be self-limited and reversible, such as cyanopsia (in which your vision suddenly becomes tinted blue), why risk side effects at all, when the problem can reversed, cured in the first place, improving the quality and quantity of our lives?

“Improvement of sexual…function in men [and women] should be added to the growing list of clinical benefits brought about by healthy lifestyles in human beings.”Did you know that dioxins, endocrine disrupting pollutants, heavy metals, saturated fat, and steroids in the meat supply may be affecting sperm counts, semen quality, and the ability of men to conceive? 

Infertility affects 10 to 15% of couples attempting to conceive, and, in about half the cases, a problem is found in the man. A recent Harvard study found that increasing saturated fat intake just 5% was associated with a 38% lower sperm count; but why? I’ve talked about the role of xenoestrogens, endocrine-disrupting industrial pollutants that build up in animal fat (particularly fish). But, male fertility is not just about sperm count—the number of sperm—but about how well the sperms themselves work.

A recent study found that “successful pregnancy and fertilized egg implantation outcomes are decreased in patients reporting a more frequent intake of meat. This finding is consistent with poor semen quality associated with a higher intake of products that may incorporate…[these chemicals and] steroids. The use of these compounds in the food industry results in an increased total level of xenoestrogens and sex steroids in processed foods, such as meat or milk, whose intake contributes significantly to daily exposures. Xenoestrogens are highly lipophilic substances that can accumulate in fat-rich foods, such as meat, and may be suspected as partially responsible for the decline in semen quality. Conclusion: [Couples having trouble conceiving] must be advised about the drastic effect of both the male and female lifestyle[s] on [infertility] treatment success.”

This is consistent with previous findings that “[f]requent intake of [fat-laden] foods like meat products or milk may negatively affect semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.” Vegetable consumption was also found protective in the new study, which may be because of the antioxidant and nutrient content of these plant foods.

The adverse effects of meat could be from other pollutants as well. Exposure even as an infant to low levels of dioxin “can permanently reduce sperm quality.” The “general consensus is that human sperm quality has declined over time in different areas…” We’re still not sure why, but dioxins may be playing a causal role.

The reason why “maternal beef consumption…may alter a man’s testicular development…and adversely affect his future reproductive capacity,” is thought to be due to the anabolic steroids implanted into the animals. But, as the accompanying editorial points out, “the steroids could also be interacting with “other xenobiotic, [meaning industrial] chemicals” present in meat, such as pesticides and dioxin-like pollutants, and even chemicals that may be present in the plastic wrap.

Heavy metals may also play a role. Lead and cadmium exposure, as measured by levels in the bloodstream, was associated with a significantly “longer time to conceive.” Where might exposure be coming from? Well, common types of seafood, right out of fish markets and supermarkets were sampled. The highest cadmium levels were found in tuna; highest lead levels found in scallops and shrimp. The greatest risk from different metals resided in different fish; some of which got really high. “Thus, the risk information given to the public (mainly about mercury) does not present a complete picture.” There are other toxic metals in fish as well.

The largest and oldest fish had some of the highest levels, and we see that with other animals, as well. For example, “[c]ontamination of beef by [cadmium and lead] is clearly dependent on the age of the animal.”

The only beverage associated with infertility in women was soft drinks, though this may be from an indirect route, with soda linked to obesity, and then obesity then linked to reduced fertilization rates—though there has been a study on one really direct route: “The effectiveness of Coca Cola as a spermicidal agent in vaginal douching.” Diet Coke apparently had the strongest effect, Harvard researchers publishing in the New England Journal of Medicine.

What about Coke versus Pepsi? Taxpayer money hard at work for this head-to-head test. And, neither of them really worked—Coke nor Pepsi—though they explain their methods for preparing the sperm-cola mixtures differed from the Harvard group. Bottom line: soda probably isn’t good for you, going into any orifice.

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