June 16th, 2010 § § permalink
The testes must be kept cool for the proper production of sperm. One way the human body achieves this is to house them outside the body. Another is to have a network of veins surrounding the artery pumping blood into the testis: the veins take the heat away in a “counter-current” heat exchange similar to a radiator. (The human body is an amazing piece of engineering.)
Arteries don’t need to worry about moving blood; there’s a huge amount of pressure coming from the heart to help with that. But once the blood goes through the capillaries and into the veins, getting back to the heart isn’t easy. Veins have little valves to help hold the blood while it pulses its way back. If those little valves start to separate, the vein expands, causing the condition known as a “varicose vein.” Varicose veins can happen in many places in the body, often visibly in the skin of the legs, but, believe it or not, also in the scrotum. And if varicose veins develop in the scrotum, they can disturb the counter-current heat exchange. The testes then get hot, posing a problem for developing sperm cells.
Varicose veins in the scrotum are called a “varicocele,” and there are three kinds. A grade I varicocele can’t be felt or seen without equipment like ultrasound. Almost all experts now consider grade I varicoceles to be unimportant. Varicoceles that can be felt (grade II) or visible by the naked eye (grade III) are the ones that may cause problems with sperm production. Some men have such high sperm production that their varicoceles don’t significantly alter their chance of making women pregnant. But many men’s testes are affected by grade II or III varicoceles.
Inside of a man, the left vein draining the testis back towards the heart is longer than the right. As a result, varicoceles are most often found in the left scrotum. Sometimes, they’re on both sides, and infrequently, they’re on the right side alone. A right sided varicocele that suddenly appears in adult life is worrisome, as it may be a sign of kidney cancer.
What can be done about a varicocele that may be throwing a wrench into the sperm factory? A urologist can tie or clip the veins in a procedure called “varicocelectomy,” or an interventional radiologist can inject material into the veins to block the flow of blood.
June 9th, 2010 § § permalink
A first test of male fertility is the semen analysis. You do your thing, and a technician counts the sperm, sees how they’re moving, what they look like and whether they’re alive. For decades, the World Health Organization has published criteria for these numbers to alert a man that he might have a problem when it comes to impregnating a woman. Until recently, the numbers were a consensus of expert opinion, but in the latest edition, the WHO criteria changed substantially.
What the WHO is currently doing is to dispense with expert opinion, and just lay the numbers out for all to see. Table II from the paper shows the numbers for men from couples who conceived within a year. Take sperm concentration, for example. For centile 5, the sperm concentration is 15 million per ml. That means that only 5% of couples where the man had 15 million/ml sperm or less conceived within a year. For centile 50, the concentration was 73 million/ml, meaning that 50% of couples conceived within a year when the sperm concentration was up to that number. You get the idea.
The problem is that people like cutoffs, and in the latest edition, the WHO chose centile 5 as the line in the sand. It’s a good number for thinking that below it, couple infertility likely involves the male. But keep in mind that at centile 10, only 10% of couples conceived within a year. In other words, having sperm numbers above the centile 5 cutoff doesn’t guarantee that the sperm are trouble free.
Frankly, I think the WHO numbers are most useful to get a ballpark idea of how fertility may be related to what’s inside the semen. I prefer the approach David Guzick and colleagues took, where they applied a statistical method called Classification and Regression Tree (CART) analysis to sperm, which gives two cutoffs in a “green light, yellow light, red light” fashion. For example, CART analysis came up with 13.5 million/ml and 48 million/ml for sperm concentration. At 13.5 million/ml sperm or less, the “red light,” couple infertility likely involves the male. At 48 million/ml or more, your sperm probably are “green light” good to go. Between 13.5 million/ml and 48 million/ml, the “yellow light,” sperm may or may not be the problem. You can find the Guzick CART cutoffs here.
A lot of people, including doctors and fertility specialists, are confused about the new WHO cutoffs. Expect a little consternation about them for a bit.
WHO Table II Distribution of values, lower reference limits and their 95% CI for semen parameters from fertile men whose partners had a time-to-pregnancy of 12 months or less
|Semen volume (ml)
|Sperm concentration (106/ml)
|Total number (106/Ejaculate)
|Total motility (PR + NP, %)*
|Progressive motility (PR, %)*
|Normal forms (%)
*PR, progressive motility (WHO, 1999 grades a + b); NP, non-progressive motility (WHO, 1999 grade c).
June 6th, 2010 § § permalink
Can diet help sperm production? We are what we eat, and the sperm factory is such an active one that it would be strange if diet didn’t affect sperm one way or another.
Antioxidants protect the body from free radicals, which are released from unstable compounds as they break down and damage molecules in cells. (I’ve always loved the phrase “free radical,” which conjures images of 1960s miscreants running amok inside the body.) Antioxidants soak up these bad actors and prevent their misdeeds. But knowing which antioxidants work and in what dose is still being learned. I discussed Coenzyme Q10, which may function as an antioxidant, in a previous post.
Jaime Mendiola and colleagues reported in the March issue of Fertility and Sterility that men with a lower intake of carbohydrates, fiber, folate, vitamin C and lycopene and a higher intake of protein and total fat had worse sperm than men with the opposite diet. I’d of course like to see studies which involve giving specific antioxidants first and then measuring sperm improvement relative to a placebo, but this is a promising start.
Bottom line: if you’re worried about your sperm, a diet higher in fiber, folate, vitamin C and lycopene, and lower in fat can’t hurt.
June 3rd, 2010 § § permalink
I’ve been doing some updates to the blog, and now have a new look if you’re reading this on an iPhone, iPod touch, Android, Blackberry or other web enabled mobile device. Check it out:
June 1st, 2010 § § permalink
Adam recently asked about a product which claimed to improve semen. There are many of those out there, and many are vitamins and combinations of vitamins. These “nutraceuticals” can be found in drug stores, in groceries, on the internet and elsewhere.
A big problem with claims about how a nutraceutical may improve sperm and semen is that most aren’t based on studies that have a placebo, a pill that looks just like the vitamin but doesn’t have the ingredients being studied. Why is that a problem? Because nature virtually guarantees that if you start out with a bunch of men that happen to have lower than average sperm or whatever, and you measure their sperm (or whatever) before and after treatment, they will always improve. It’s an effect called “regression to the mean.” It’s like if you took twenty people with colds and gave them all a pill and waited two weeks, most would get better. Was it due to the pill or to just nature doing its thing? You don’t know. The way to figure it out would be to give half of them the pill, and half of them a pill that looked like that one but had no active ingredients, and compare how the two groups did over that two weeks. That’s called a “controlled study,” and it’s critical in figuring out if a drug or vitamin works.
Last year, two controlled studies were published looking at a vitamin involved in the energy machine inside cells called “Coenzyme Q10” and sperm. In one, men with poorly wiggling sperm who took 200 mg daily improved while taking the vitamin compared to men taking placebo. In another, men taking 300 mg daily improved in both sperm number and motility compared to men taking placebo.
They’re small studies, and bigger studies are always better. But Coenzyme Q10 might help sperm numbers and especially motility. (I have absolutely no relationship, financial or otherwise, to companies that make it.)