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This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
By Dr. Mercola
Boxers for baby making? A new study led by Harvard School of Public Health suggests male infertility may be helped simply by your choice of underwear. Based on self-reported data, scientists found men who wear boxers to have significantly higher total sperm counts and greater sperm concentrations than their brief-wearing counterparts.
Because research suggests tighter underwear can inhibit sperm production, if boosting your fertility is important, it may be worth your time to switch to boxers. While other factors influence your sperm quality, it's possible changing your style of underwear may turn out to be the most cost-effective fertility treatment of all.
Your Choice of Underwear May Affect Your Sperm Count
Research led by Harvard School of Public Health and conducted at Massachusetts General Hospital's fertility clinic suggests your choice of underwear may be one of the factors inhibiting your body's production of sperm.1
As reported in the journal Human Reproduction,2 men who self-reported more frequently wearing boxers had significantly higher sperm counts than men who indicated they regularly wore other styles of underwear.
"Beyond providing additional evidence that underwear choices may impact fertility, our study provides evidence, for the first time, that a seemingly random lifestyle choice could have profound impacts on hormone production in men at both the level of the testis and the brain," said senior study author Jorge Chavarro, associate professor of nutrition and epidemiology at Harvard School of Public Health.3
The cross-sectional study involved 656 male partners — ages 32 to 39 — of couples who sought infertility treatment at the hospital's clinic from 2000 to 2017. In addition to take-home questionnaires, semen specimens were analyzed to evaluate the association between the type of underwear worn and testicular function.
Options included bikinis, boxers, briefs, jockeys and "other." As compared to the participants wearing other styles, the 345 men who reported usually wearing boxers had a:4
- 25 percent higher sperm concentration
- 17 percent higher total sperm count
- 14 percent lower serum follicle stimulating hormone (FSH) level, a hormone released by your pituitary gland that stimulates testicle growth and aids in sperm creation
- Men who most often wore boxers also had a higher percentage of motile sperm, the type that is more adept at moving through the female reproductive system and fertilizing an egg5
"These results point to a relatively easy change men can make when they and their partners are seeking to become pregnant," said lead study author Lidia Mínguez-Alarcón, a research scientist at Harvard School of Public Health.6
Limitations of the Harvard Research
While the results are helpful, the scientists are quick to note three limitations in their work that may prevent this study from being generalized to the broader male population:7
- Given the use of a take-home questionnaire, it is possible some participants may have misclassified the type of underwear worn and the frequency it was worn
- Other factors, not considered in this study, such as the type of underwear fabric and the type of clothing worn over the underwear, also may affect sperm counts
- Blood sampling occurred throughout the day, which means researchers may have "missed associations with testosterone or other hormones with significant circadian variation"8
Sperm Counts on a 40-Year Decline in Western Countries
A 2017 systematic review and meta-analysis involving thousands of men in dozens of industrialized countries found sperm counts to have plummeted during the past four decades. The study, published in the journal Human Reproduction Update,9 is said to be the largest and most comprehensive to date.
In preparing the analysis, Shanna Swan, a reproductive epidemiologist at the Icahn School of Medicine at Mount Sinai in New York, and her colleagues screened more than 7,000 studies examining sperm counts and sperm concentrations.
The group then analyzed data from 185 studies involving 42,935 men who provided semen samples between 1973 and 2011 in Australia, Europe, New Zealand and North America.10 To provide a broad sampling, researchers analyzed sperm counts from college students and soldiers as well as men undergoing fertility treatments. During the 39-year observation period, researchers found:11
- A 52.4 percent decline in sperm concentration
- A 59.3 percent decline in total sperm count
"I think these are extremely concerning findings," Swan said. "I think we should take this very seriously … it's a wake-up call."12 As to possible reasons for the dramatic decline, Swan believes chemical exposures while in the womb may be negatively impacting the normal development of the male reproductive system.
"The mother's exposure to a number of chemicals can alter the reproductive tract of baby boys significantly," she said.13 Lead study author Dr. Hagai Levine, lead researcher and head of the environmental health track at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine, told the New York Post:
"While the study did not examine causes of the decline, lower sperm counts have long been associated with conditions such as diabetes, cancer, varicose veins on the testicles and sexually transmitted diseases such as gonorrhea or HIV."14
Lifestyle Factors That May Affect Your Sperm Count
Experts suggest your environment and lifestyle play an important role in your sperm count. According to the New York Post, here are some areas that may be affecting your fertility:15
Being a couch potato — A sedentary lifestyle can have a negative effect on your fertility. "Lifestyle in 2017 is not the same as it was in 1967," says reproductive endocrinologist and infertility specialist Dr. Brian Levine, practice director at CCRM New York. "We're a lot more sedentary."16 To achieve healthy sperm counts, you must exercise regularly.
I recommend high-intensity interval training (such as the Nitric Oxide Dump), strength training, stretching, walking and yoga. A 2012 meta-analysis17 involving 4,779 obese men found 32 percent had a low sperm count and nearly 7 percent had no viable sperm. |
Eating a poor diet — "Sperm is losing its quality based on what we're eating," states urologist Dr. David Shusterman of Advanced New York Urology.18 Of particular concern are farmed fish, genetically modified and hormone-laden meats, especially animal products originating from concentrated animal feeding operations (CAFOs).
Sadly, many Americans are still eating diets containing high amounts of fast food and junk food, including ridiculous amounts of sugar. Diets high in sugar and damaged omega-6 fats lead to men (and women) becoming increasingly overweight, which, as noted above, leads to decreased sperm counts. |
Exposing yourself to too many toxic chemicals — Toxic chemicals in your personal care and household products are another factor that may negatively affect your sperm. "The hot topic in the male reproductive community right now is the role of phthalates, which are mainly used as plasticizers in stuff like hair gel," says Levine. "We know with near-certainty these phthalates interfere with the endocrine system in rats, monkeys and, of course, humans."19 |
Letting job stress get to you — "Men who feel stressed are more likely to have lower concentrations of sperm … and the sperm they have are more likely to be misshapen or have impaired motility," states Pam Factor-Litvak, Ph.D., associate professor of epidemiology at the Mailman School of Public Health at Columbia University, in a 2014 study published in the journal Fertility and Sterility.20 "These deficits could be associated with fertility problems."21
Stressors outside the job are also a factor, including health issues, relationship problems, commuting/transportation and other areas. If you need help managing stress, you might consider meditation, prayer or the Emotional Freedom Techniques, as demonstrated in the following video.
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Producing too much testosterone — Even though you may think higher levels of testosterone production might be a good thing to improve your sperm count, Dr. Cappy Rothman, cofounder of California Cryobank, a leading U.S. sperm bank, suggests testosterone supplements and performance enhancers may actually diminish sperm counts.
"Anabolic steroids interfere with the hormone signals that are needed to produce sperm," says Rothman. "If a man takes them for an extended length of time, he'll wind up with no sperm."22 |
Smoking, drinking and recreational drug use — "Tobacco affects motility and shape of the sperm," asserts reproductive endocrinologist Dr. Kenan Omurtag, assistant professor of reproductive endocrinology and infertility at the Washington University St. Louis School of Medicine.23 A 2016 study published in the journal BJU International showed the DNA and sperm of smokers were damaged in ways that reduce the possibility of fertilization.24
About marijuana and opioid use, Omurtag notes their effect on sperm production. "They effectively disrupt how the brain talks to the testicles," he says.25 With respect to alcohol, a study published in the journal BMJ Open26 involving 1,221 Danish young men ages 18 to 28 found consuming five alcoholic drinks a week could affect sperm quality. Even stronger associations were seen in men who consumed more than 25 drinks per week. |
Spinning too often — "Exercise is a good way to boost fertility but extreme exercise is not," states Levine. If you enjoy spinning, keep in mind it may affect your sperm count. "You are on a bicycle seat and you are compressing the testicles," notes Levine.27
Your sperm production may also be influenced by temperatures, such as those generated during tough workouts — particularly workouts in a crowded, heated room. "The optimum temperature for the testicles to produce sperm is two to 3 degrees below body heat, which explains why the male reproductive organs are found outside of the body," comments Levine.28 |
Wearing tight-fitting clothing — Another factor working against your sperm is your choice of clothing. Certain types of pants, especially skinny jeans, and underwear such as bikinis and briefs hold your scrotum close to your body, which promotes heat. According to professor Allan Pacey, Ph.D., an expert in sperm science at the U.K.'s University of Sheffield, a 2012 study29 involving 2,249 British men suggests wearing tight underwear is a risk factor for infertility.
About the outcomes, he stated, "the single biggest risk factor for how many swimming sperm [a participant] produced each day was whether he is wearing tight pants or loose pants."30 If you want to help procreate a child, it just might be time to take a break from tight-fitting pants and underwear. |
Why Sleeping Naked Is Good for Your Sperm and You
As noted, your testicles are designed to maintain sperm at a temperature just slightly below your core body temperature. As such, the underwear and other clothes you wear can negatively impact your sperm quality and count. Even the clothes you wear to bed can make a difference. Not only will sleeping naked positively impact your sperm, but you will receive many other health benefits.
Most of the benefits result from the fact sleeping naked helps prevent overheating, which can have a significant impact on your sleep quality. As you fall asleep, your body temperature drops, and this drop in your core temperature actually helps you sleep better.
As you wake, your body temperature rises, which is why it's much more difficult to fall asleep and stay asleep when you're hot. Because most people keep their homes too warm and also wear pajamas to bed, it's no wonder complaints of frequent waking and restless sleep are common. By the way, studies note the optimal room temperature for sleep is between 60 to 68 degrees Fahrenheit.
Other Health Benefits of Sleeping Naked
Besides allowing your testicles to breathe, sleeping naked has also been shown to boost your:31,32,33,34
• Blood circulation — Your blood flow is less restricted without clothing, which benefits your entire body, especially your heart and muscles.
• Hormone balance — By allowing your body to stay cooler at night, sleeping naked helps decrease your cortisol, increase growth hormone levels and balance melatonin, all of which help promote healthy sleep patterns. Sleeping naked is also known to reduce anxiety, food cravings and stress.
• Metabolism — Lowering your body temperature helps activate brown fat — a type of body fat known to regulate your body temperature by generating heat. Research suggests higher levels of brown fat boost your metabolism and promote better blood sugar control and higher insulin sensitivity.
One small study found sleeping in mild cold (66 degrees F) increased brown fat amounts and activity, while sleeping in mild warmth (81 degrees F) suppressed it.35
• Skin and genitals — Bacteria thrive in warm, moist areas, so shunning pajamas and underwear can be particularly beneficial for women prone to yeast infections. Your armpits and skin in general also benefit from being able to breathe at night.
• Sex life — Skin-to-skin contact releases the "bonding hormone" oxytocin, which promotes feelings of attachment and emotional closeness. Since sexual contact typically occurs while naked, sleeping in the nude increases the possibility of sex, which can increase feelings of intimacy and closeness.
Infertility is a complex issue. Beyond the type of underwear you choose are a myriad of factors affecting your ability to join with your partner in the joys of starting a family. While it may not be the only course of action you may take, if having a baby is a top priority for you and infertility has been a concern, you may want to switch to boxers, avoid tight clothing and sleep naked. Given the simple nature of these changes, what have you got to lose?