Mitochondria are critical for male sexual performance
Summary
Blood flow throughout the body, including the penis, is controlled by smooth muscle tissues that surround the blood vessels. When these muscles tense, vasoconstriction shuts off blood flow. When they relax, vasodilation increases blood flow.
Vasodilation is actuated by production of nitric oxide (NO) in a thin layer of endothelial cells that line blood vessels.
When mitochondria in the endothelial cells are damaged, they become incapable of producing sufficient nitric oxide for vasodilation. A myriad of vascular disorders, including erectile dysfunction (ED), can result. That's why erectile dysfunction (ED) is considered a clinical marker of metabolic disorder and a harbinger of more serious, life-threatening vascular disease.
Viagra (sildenafil) induces an erection by temporarily overcoming insulin resistance, boosting nitric oxide production and increasing blood flow to the penis. However, it does nothing to resolve the underlying metabolic origins of erectile dysfunction.
Deliberate cold exposure is notorious for "shrinking" male genitalia in the short-term, but in the long run an ice bath may be the best thing men can do to improve insulin sensitivity and sexual performance.
Is an ice bath like Viagra?
Ben Greenfield isn't bashful
One of the few male authors who isn’t bashful about biohacking for sexual performance is Ben Greenfield. He’s written several articles about using red light, electricity, sound waves, and supplements for improving the frequency and quality of his erections. In his Boundless (Greenfield 2020) book, he describes penis exercises to strengthen the pelvic floor muscles that control the angle of an erection. He’s even injected stem cells into his penis and appeared on the Joe Rogan Experience podcast to talk about it (Greenfield 2018).
And as far as I know, Greenfield is the first person to point out that “cold thermogenesis leads to increased nitfric oxide (NO) production — aka Viagra for your body” (Greenfield 2020).
Cold thermogenesis leads to increased nitric oxide production — aka Viagra for your body. - Ben Greenfield 2020.
Regardless of what you think of Greenfield's penile adventures, the science of deliberate cold exposure bears him out. Despite the fact that cold exposure can temporarily shrink male genitalia, both Viagra and the ice bath ultimately boost mitochondria for production of nitric oxide (NO) in the endothelial cells that line the blood vessels. With that extra nitric oxide, the smooth muscles tissues that control blood flow will relax enough to dilate blood vessels and increase blood pressure in the penis.
The result of both Viagra and the ice bath can be improved male sexual function, so in that way Greenfield is correct that an ice bath is like Viagra for the body. But Greenfield never pointed out the important differences between the two when it comes to male sexual performance and vascular health in general.
That's what this article is for.
Erectile dysfunction is a mitochondrial disorder
Erections are energy-intensive
The mechanics by which a man achieves and maintains an erection are metabolically intensive -- particularly in the thin layer of tissue that lines the blood vessels called endothelial cells. Their job is to produce nitric oxide to cause vasodilation by relaxing the smooth muscle tissues that control blood flow. When the arteries upstream of the penis are dilated, the increased blood pressure engorges two balloon-like chambers running the length of the penis called the corpus cavernosum, causing the penis to enlarge and stiffen. Without nitric oxide, there's no blood flow into the penis and no erection.
The problem is that nitric oxide production requires energy. For decades, researchers thought that endothelial cells got that energy via an alternative metabolic pathway called glycolysis, rather than from mitochondria. However, new research reveals that this view was a misconception. Previous studies examined endothelial metabolism during proliferation (e.g., cell division) rather than nitric oxide production. It was not until 2022 that the mistake was corrected by a series of experiments conducted at the University of Strathclyde (Glasgow UK) that demonstrated that mitochondria -- not glycolysis -- provide the energy source for nitric oxide synthesis:
Our work highlights the idea that arterial endothelial cells (EC) require mitochondrial respiration for the control of vascular tone and suggests that aberrant mitochondrial energy production may underlie endothelial dysfunction. - Wilson et al. (2022)
The problem of erectile dysfunction originates in the mitochondria of the endothelial cells. When those mitochondria become damaged, they can no longer produce sufficient energy for nitric oxide synthesis.
The most common mechanism by which mitochondria become damaged is by too many carbohydrates in the diet. When sugar & starch intake exceeds immediate energy demands, mitochondria can become overwhelmed and produce an excess of what are called reactive oxygen species (ROS). In small quantities, these ROS signal metabolic changes (including production of new mitochondria) that help the body adapt to demanding energetic conditions. However, in larger quantities, these ROS will damage mitochondrial DNA, slowing their rate of energy production.
The result of mitochondrial damage is insulin resistance. By slowing the rate of glucose transport from the blood stream into the cell, mitochondria are spared from overwork. The unfortunate result is increased blood sugar.
By the time insulin resistance is observable, mitochondria have already been damaged (Tang et al. 2014) -- not just in endothelial cells, but throughout the body. Because symptoms often show up in erectile dysfunction before they appear anywhere else (Sallam et al. 2021), erectile dysfunction is now considered an early clinical marker of insulin resistance (Yao et al. 2013).
If left unchecked, other cardiovascular maladies will appear as mitochondrial damage gets worse and endothelial function declines further. In fact, every leading cause of death from chronic illness, including obesity, heart disease, cancer, Alzheimer’s, atherosclerosis, Type 2 diabetes, and hypertension (high blood pressure) is related to some underlying vascular dysfunction associated with insulin resistance (Sanchez et al. 2017).
Metabolic remedies for better sex
More mitochondria means more better hard-ons
Therapies that correct for insulin resistance will improve endothelial production of nitric oxide, enhance sexual performance, and ameliorate the risk of chronic illness from vascular dysfunction. For example, the myriad cardiovascular benefits of sauna can be explained by the fact that sauna promotes vasodilation and nitric oxide production (e.g., Ikeda et al. 2005).
Therapeutic intervention to promote endothelial cell mitochondrial energy production may be an effective strategy to combat vascular dysfunction in a range of diseases. - Wilson et al. (2022)
Low carbohydrate, ketogenic, and intermittent fasting diets have been shown to be effective for resolving insulin resistance and boosting male sexual performance. For example, a new study of enrolled Brazilian men suffering from low testosterone and insulin resistance in a 3-week clinical trial to test the effects of a low carbohydrate diet on sexual function. Their diet allowed about 30g/day to be from carbohydrates -- about 30% of total caloric intake. While that low carb compared to the Standard American Diet (SAD), depending on activity level, it's borderline for people who want to remain in ketosis and it is not difficult to maintain. Diets in the study control group were calibrated to provide the same caloric intake.
The results were remarkable. After just 3 weeks, the low carbohydrate group lost weight, reduced their waist circumference measurements, increased their testosterone levels from an average of 229 ng/dL to 310.7 ng/dL, and increased their scores on the International Index of Erectile Function (da Silva Schmitt 2023).
As I wrote in Ice Baths for Mitochondrial Therapy, one of the best things you can do to improve mitochondrial function is deliberate cold exposure.
Cold exposure recruits brown fat for cold thermogenesis, and because mitochondria are more dense in brown fat than any other cell type in the body, nothing stimulates production of new mitochondria quite like an ice bath. - Seager (2023)
When thermoreceptors in the skin sense cold temperatures, they signal the autonomic nervous system to activate cold thermogenesis — i.e., production of heat to keep the body warm in the cold. There are two mechanisms for it: 1) muscle shivering, and 2) brown fat (or brown adipose tissue, BAT) activation.
Because fewer than 10% of the US population over 40 years old has any detectable brown fat, most of us are familiar with muscle shivering as the only method of cold thermogenesis. The muscle motion burns up glucose reserves, converts blood glucose into carbon dioxide and water, and releases heat to warm the body. However, after a week of a regular cold exposure practice, the body becomes acclimated to cold exposure by recruiting new brown fat. That's when shivering will become less pronounced.
Cold acclimation happens via a process called mitobiogenesis — the production of new mitochondria — in fat cells. The process can turn white fat cells into beige, and then into brown, as they add mitochondria. Brown fat cells are packed with thousands of mitochondria for heat production.
Because more mitochondria means more glucose conversion power, cold acclimation drives insulin sensitivity way up, which is another way of saying that insulin resistance goes way down. For example, one study exposed eight German men with Type 2 diabetes to 10 days of mild (60F) cold air for several hours a day, dressed only in a T-shirt and shorts. Researchers measured an average 43% improvement in glucose sensitivity, even though the men were instructed not to exercise or alter their diets (Hanssen et al. 2015).
When insulin sensitivity improves, it is not just in new brown fat cells, but throughout the body. That is, cold exposure improves systemic insulin sensitivity in all the cells of the body — including endothelial cells.
Cold acclimation for 10 days has very marked positive effects on whole-body and skeletal muscle insulin sensitivity and thereby provide a new avenue to improve the metabolic health of patients with Type 2 diabetes. - Hanssen et al. (2015).
Improved insulin sensitivity means improved nitric oxide synthesis in endothelial cells, which means better vasodilation, which means better blood circulation to the penis. Thus, an ice bath is one of the best things a man can do for his long-term sexual function.
Viagra (sildenafil) vs ice baths
Same effects, different mechanisms
Rather than a long-term improvement in insulin sensitivity, Viagra works by temporarily overcoming insulin resistance to promote nitric oxide production for vasodilation. Not surprisingly, Viagra can have a myriad of other vascular benefits related to improved circulation. For example, it was originally formulated to treat hypertension. Only after men in Pfizer's clinical trials reported more frequent erections did Pfizer decide to seek FDA approval for impotence.
One of the most remarkable uses of Viagra is to help babies recovery from hypoxic brain injury (Xiong & Wintermark 2022). Compared with endothelial cells, brain cells contain far more mitochondria and use far more energy in total. For example, in adults up to 30% of total metabolic energy is consumed in brain cells. However, because infants are not just using their brains, but rapidly growing their brains, energy use in the infant brain can exceed 60% in the first several months after birth. Thus, the benefits of Viagra on accelerating recovery from brain injury in infants may be due to its capacity to boost mitochondrial function in the tissues that most need it. Not surprisingly, evidence suggests that a regular ice bath practice will also provide benefits for both hypertension and brain health.
However, it is perplexing to also discover that Viagra can adversely effect eyesight (Ausó et al. 2021). The retina is the single-most energy intensive tissue in the body, so we might expect that any drug that enhances mitochondrial function might also benefit retinal function. For example, I've noticed an temporary improvement in my vision after my ice bath, and some customers have reported to me that they have, too. I've often wondered if that improvement is due to stimulation of mitochondria throughout my body, and improved retinal function as a result. However, in the case of Viagra, the opposite is true, as impaired vision (among other adverse effects) has been reported after Viagra use.
This fact highlights the fact that ice baths and Viagra can achieve the same sexual performance outcomes via different pathways. Whereas ice baths are a long-term improvement in mitochondrial function that resolves insulin resistance, Viagra is a short-term solution for sexual performance that overcomes insulin resistance without resolving it. Thus, Viagra has a potential for toxic adverse effects that ice baths do not.
Viagra works by making withdrawals from the metaphorical mitochondrial bank account. The ice bath works by making deposits.
Ice baths stoke sexual desire
Viagra doesn't make anyone horny
There's another important difference between Viagra and ice baths for better sex. Whereas Viagra will improve sexual responsiveness in men, it does not necessarily improve sexual desire (libido). An erection requires nitric oxide, but sex drive runs on testosterone -- and as I wrote in How to Use Cold Plunge Therapy to Boost Testosterone, following up an ice bath practice with some light exercise will provide a testosterone boost.
That may explain why women do not experience an increase in sexual desire from taking Viagra. In men, Viagra can help overcome anxieties related to sexual performance that may create greater interest is sex, but the effect is less pronounced in women -- even though women also have erectile tissues (e.g., the clitoris) and their vascular circulation is controlled by endothelial cells in the exact same way as men. One study of more than 200 menopausal women showed that Viagra is well tolerated and improves both sexual arousal and sexual satisfaction in women, but does not boost desire (Berman et al. 2003).
Only an ice bath practice will provide the sexual double boost of arousal and performance. Moreover, when practicing together, an ice bath can be like Couples Cold Therapy by stimulating expression of several neurotransmitters associated with feelings of love.
A few months ago, Andrew Huberman, PhD forwarded to me a recent study that backs up the assertion that cold water immersion improves sex health. Conducted on behalf of the Czech Army, this was the first scientific study to explicitly adopt my protocol of exercise after whole-body cold water immersion, as described in What Happened to My Testosterone… and The Prostate Protocol.
Researchers exposed 17 male and 8 female soldiers to two minutes of swimming in cold, 3°C water, followed by several minutes of rewarming exercises (Néma et al. 2023). After 8 weeks of "periodic" deliberate cold exposure the soldiers experienced several health benefits, including:
less anxiety.
smaller waist (less visceral fat).
improved sexual satisfaction.
In Cold Boosts Sexual Satisfaction, I wrote that their sexual improvement might be due to increased libido resulting from the testosterone boost the soldiers get from cold stimulation. But now I think it may also be that increased insulin sensitivity gave their endothelial cells a boost that improved sexual arousal and performance, too.
Can a man get an ice bath erection?
Cold water is no barrier to healthy male sex function
My own experience has been that the ice bath is no barrier to an erection. While it’s not ordinarily an arousing experience for me, when in the right company I’ve experienced hard-ons in the ice bath that rival any I’ve had when warm and dry. I’ve also heard from men who tell me that they’ve observed an increase in their nighttime and morning erections since they’ve adopted a practice of regular ice baths.
My personal research hasn't reached anywhere near the breadth of Greenfield's, but a recent debate on Dr. Sean OMara's Twitter feed is consistent with my experience. Dr. OMara is 60 years old, and maintains that he's able to sustain better erections at his current age than he could when he was 25. He attributes the improvement to adopting a carnivore diet in his mid-50's that reduced his visceral (belly) fat.
Because visceral fat is characteristic of insulin resistance, anything that trims visceral fat is likely to both improve endothelial function and boost testosterone. For example, OMara advocates for sprint training as well as a carnivore diet, and judging by the pictures he's posted, the combination has trimmed his body composition to a level much leaner than mine. So, depending on how degraded OMara's metabolism was at an age when he was probably in medical school, it's possible that his recent improvements have put a bigger bounce in his blood flow compared to when he was in his mid-twenties.
In Calories & Cold Exposure, I explained that ice baths are typically ineffective for long-term, overall weight loss. But they have been shown to remodel body fat. In How To Increase Brown Fat, I showed how cold exposure will reduce visceral fat in favor of subcutaneous.
The effects of the ice bath for changing body composition are another indication that cold exposure is a plus for male sexual function. Dr. OMara would likely approve.
What's clear from reading about Greenfield and OMara's stories is that men don't talk anywhere near enough with other men about sex. My sense is that women talk a lot more about male sexual function than men do, and as a result the ladies are in some ways better informed. Nonetheless, in an article called New Year, New Dick (Greenfield 2018), Greenfield's wife describes how she "found time" for her part in Greenfield's experiments in erection. She said, "We had sex several times a week instead of our usual one or two."
That surprised me.
I was thinking that after all the biohacking boosts Greenfield was bringing to his body, he and Mrs. Greenfield would probably be going at it several times a day -- never mind the once or twice a week she referenced has the "before" condition.
I can't say that my own sexual performance is better now than it was when I was in my mid-20's. For the most part, I'm pleased to say that it's only declined a little bit from then to now.
My girlfriend has asked me to promise I won't do anything more to further boost my testosterone or increase my sexual function. Although she's 13 years younger than me, sometimes she gets tired.
References
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About the Author
Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience.