There are lots of good reasons to try and follow a healthier diet–you lose weight, you feel good, but the main reason–to live a longer, happy, productive life. Sounds good, right? And though it may sound deceptively easy, the devil is in the details. Welcome to the Nutrition Facts podcast. I’m your host, Dr. Michael Greger.
Today, we count sperm. Not literally of course. That might take all day. Our job today is to consider sperm health, and fertility. And all you guys out there with cell phones in your pockets may want to pay close attention. Because our first story is a close look at the effect of cell phone radiation on sperm motility and the possibility of DNA damage.
“Are men talking their reproductive health away?” There have been “unexplained declines in semen quality reported in several countries.” Might cell phones be playing a role, as “[r]adio-frequency electromagnetic radiation from these devices could potentially affect sperm development and function”? The cell phone industry bristles at the “r-word,” radiation, preferring the more innocuous sounding “RF-EMFs”. They do have a point, though, about it being used by snake-oil hucksters of “radiation protection” gadgets. Radiation need not be atomic-bomb gamma rays, but just the warm glow of sunshine on your face; that’s radiation, too. The question is: does the specific type of radiation emitted by cell phones affect male fertility?
After the “World Health Organization…declared that cell phones [could possibly] cause brain cancer,” many folks were like, no problem, I’ll just keep it in my pants and use Bluetooth or something. Away from the brain, but “close to the gonads.” Put all the studies together, including nearly 1,500 semen samples and: “Exposure to mobile phones was associated with reduced sperm motility…and viability…,” though not necessarily sperm concentration.”
How much less could they swim? Sperm motility only appeared to be about 8% less, and so that alone may not actually translate into reduced fertility—unless you’re starting out with a marginal sperm count in the first place. So, especially for men who already have fertility problems, it might be better to avoid keeping an active cell phone next to your crotch for long periods of time. Cell phones may just be one of a bunch of things that could potentially add up. For example, Wi-Fi may be an issue. So, researchers got semen samples from more than a thousand guys, and the total number of swimmers? “[M]otile sperm were decreased in a group who used a wireless internet.”
Okay, but these were all just observational studies. Maybe men who use Wi-Fi just tend to smoke more, or do more horseback riding, or something—and that’s the reason for the apparent link. You don’t know, until you put it to the test.
Unfortunately, many of the studies are on rats. So, while the microwaves emitted from a cell phone do not appear to affect rat testicles, it can be argued that you can’t necessarily extrapolate from these animal models, since, for example, their scrotums are “nonpendulous”—meaning their testicles are more inside their bodies rather than out swinging around.
So, at least “[u]ntil proven otherwise, it is recommended that [men] with…fertility issues” may not want to keep their cell phones in their front pants pocket, “in close proximity to the[ir] testicles.” Even when not in use, cell phones emit radiation—to keep pinging their location, though the main exposure is during talk mode, where it may still remain in the pocket, thanks to headsets these days.
And then, what happens when you have it in proximity to other common metal objects? You may have a metal zipper, key ring in your pocket. “When all three objects were added, the SAR [the amount of radiation absorbed into]…the testicles, was generally increased…[even] approximately doubled.”
But, that’s only a problem if the radiation does actually damage sperm. How hard is it to just design a study where you just wave a cell phone over some human sperm in a Petri dish to see if it’s an issue? Significantly more DNA fragmentation in sperm exposed to cell phone radiation, starting within an hour of exposure. Such a dramatic effect that they suggest women might not want to pocket their cell phones for a few days after trying to get pregnant, so as to not put the sperm at further risk.
In our next story we ask, should laptops not be on laps? And what is the effect of Wi-Fi exposure on general sperm health and wellbeing?
“It is impossible to imagine a modern socially-active man who does not use [cell phones] and…Wi-Fi…” Might that be “harmful for male fertility…?” We don’t really know if Wi-Fi actually damages sperm until you put it to the test.
Yeah, Wi-Fi exposure may decrease human sperm motility, and increase sperm DNA fragmentation, but the effect is minor. I mean, is having 10% fewer good swimmers really going to make a difference? Fertile men release hundreds of millions. What has yet to be done is a study looking at bouncing baby endpoints—do men randomized to a certain exposure have a tougher time having children? It’s actually a harder study to perform than one might think. You can’t just have men avoid cell phones and laptops for a day. Yes, we make millions of new sperm a day, but they take months to mature. The sperm with which you conceive today started as a preconceived notion months before. So, you can imagine why such a study has yet to be done: you’d have to randomize men to essentially avoid wireless communications completely, or maybe come up with some kind of Faraday-cage underwear.
Another reason why one may not want to use a laptop computer on your lap is just the heat generated by the laptop itself—Wi-Fi or not—[can warm men’s scrotums], undermining the whole point of scrotum possession in the first place. This all dates back to a famous series of experiments back in 1968. It was an illuminating study, one might say. Sometimes, they’d add a reflector to boost the heat, “though the bulb alone was just as effective,” but they had to move it closer to the skin. Much simpler, but more likely to result in a Jerry Lee Lewis song. (“Great Balls of Fire!”)
But now, we have nice cool fluorescents. But, heated car seats remain a “testicular heat stress factor.” Saunas aren’t a good idea for men trying to conceive. Sperm counts before, and after—apparently cutting sperm production in half—and still down, three months later. But apparent full recovery by six months. But, that’s why boxers, not briefs—or, go all commando. Do not, I repeat, do not put an ice pack on your scrotum. A few frozen peas and carrots, and you can frostbite yourself. See, sometimes, even vegetables can be bad for you. Then, there’s the schvitzer that keeps the scrotum damp, and finally, attached with a belt, achievement of scrotal cooling with “a continuous air stream.” With so many options to choose from, do laptop users really need protection from scrotal hyperthermia? You don’t know, until you put it to the test. And indeed, an “[i]ncrease in scrotal temperature [was] found in laptop computer users”—scrotal temperatures up a feverish five degrees Fahrenheit.
A little scrotal warmth doesn’t sound that bad, though. Then, I read this case report: “a previously healthy 50-year-old scientist,” typing out a report one evening. “Sitting comfortably in [his favorite] …chair,…laptop [in] lap,” but woke up the next day with blisters—penile and scrotal blisters that then broke, and “developed into infected wounds that caused extensive [oozing pus].”
Even third-degree burns have been reported, requiring surgical intervention with skin grafts. The guy drank 12 units of vodka, and passed out while watching a film on his lap, and the laptop burned through his leg. The surgeons call for “a public education campaign” to educate the public “against the risks of using a laptop in its most literal sense.” Uh, how about instead educating the public against drinking 12 units of vodka?
In our last story, we look at how the ongoing global drop in male fertility may be associated with saturated fat intake and lack of sufficient fruits and vegetables.
In 1992 a controversial paper was published, suggesting sperm counts have been dropping around the world over the last 50 years. However, this remains a matter of debate. It’s notoriously difficult to determine sperm counts in the general population for an obvious reason. If you go ask men for samples, less than 1 in 3 tend to agree to participate.
Finally though, a study of tens of thousands of men studied over a 17-year period and they did indeed find a significant decline in sperm concentration, about a 30% drop, as well as a drop in the percentage of normal-looking sperm. Most looked normal in the 90’s but more recently that has dropped to less than half. This may constitute a serious public health warning. Semen quality may actually be related to life expectancy. In a study of more than 40,000 men visiting a sperm lab during a 40-year period, they found a decrease in mortality was associated with increasing semen quality, suggesting that semen quality may therefore be a fundamental biomarker of overall male health. So, declining sperm counts could be like the canary in the coal mine, for us, and future generations. Even when defective sperm are capable of fertilizing an egg, creating a child with abnormal sperm may have serious implications for that child’s future health.
What role may diet play? In a previous video I profiled a first-of-its-kind Harvard study suggesting that a small increase in saturated fat intake was associated with a substantially lower sperm count, but not all fat was bad, higher intakes of omega-3s was associated with a more favorable sperm shape. This may help explain why researchers at UCLA were able to improve sperm vitality, movement, and shape by giving men about 18 walnuts a day for 12 weeks, though walnuts, as a whole food, have more than just omega-3s but lots of other important micronutrients. In a study of men aged 22 through 80, older men who ate diets containing lots of antioxidants and micronutrients, for example vitamin C, had the genetic integrity of sperm from much younger men.
The antioxidants we eat not only end up in our semen, but are concentrated there. The amount of vitamin C ends up nearly 10 times more concentrated in our testicles than the rest of our bodies. Why? Because sperm are highly susceptible to damage induced by free radicals, and accumulating evidence suggests that this oxidative stress plays an important role in male infertility. So, we should eat lots of antioxidants, which is to say eat lots of fruits and vegetables. Why not just take antioxidant pills? Because in pill form antioxidants may have unexpected adverse effects. So, more fruits and vegetables and perhaps less meat and dairy, which is where most saturated fat is found. But, the Harvard data were considered preliminary. They studied fewer than 100 men, but it was the best we had until now. The higher the saturated fat intake the lower the sperm count, up to a 65% reduction in total sperm count. These findings are of potential great public interest, because changes in diet over the past decades may be part of the explanation for the recently reported high frequency of subnormal human sperm counts. In any case, the current findings suggest that adapting dietary intake toward eating less saturated fat may be beneficial for both general and reproductive health.
To see any graphs, charts, graphics, images or studies mentioned here, please go to the Nutrition Facts podcast landing page. There, you’ll find all the detailed information you need, plus links to all of the sources we cite for each of these topics.
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Thanks for listening to Nutrition Facts. I’m Dr. Michael Greger.
This is just an approximation of the audio content, contributed by Allyson Burnett.