Once in a great moon, something comes around that changes the way you think about things. Galileo’s dismissal of the earth-centered universe, the invention of electricity and the desktop computer are but a few of these. Upon reading a recent meta-analysis of antioxidant supplements for male infertility, did my world-view change? Not really. But I did take notice.
What is a Meta-analysis?
A meta-analysis is a 100 year old statistical term used to describe a certain way of combining evidence that, when viewed separately, is relatively unconvincing. Meta-analyses seek to more powerfully estimate an effect or outcome than might be possible from a bunch of smaller studies, especially if there are differences in their design and execution. A big problem with meta-analyses is that their quality depends on the data that they analyze, and garbage in means garbage out. Not to bore you further, but this type of analysis has become very trendy in medicine lately as a way to figure out where truth rests at the moment on a particular subject.
Antioxidants and Male Infertility
Antioxidants have been the rage in the literature for years as cancer preventing and anti aging agents. In more recent studies in which placebo (sugar pill) controls were used, however, they haven’t looked so sharp. Like with cancer or aging, oxidants are thought to be a fundamental cause of male infertility as they clearly damage DNA, reduce sperm motility and otherwise render sperm dysfunctional. And these effects cannot be good for male fertility. In fact, many think that as much as half of male infertility is due to oxidative stress. But the role of antioxidants such as the water-soluble vitamins A, C and E, metals such as selenium and zine, and the natural antioxidants found in blueberries (anthocyanins), tomatoes (lycopene), other fruits, vegetables, nuts and tea (theaflavins) have not been found to reliably improve sperm quality or male fertility in small studies. Hence, in comes the meta-analysis to the rescue.
The Antioxidant Meta-analysis
This Cochrane review analyzed 34 randomized, controlled trials (2876 couples) in which male partners of infertile couples were given antioxidant supplements (or placebo) while their partners underwent assisted reproduction (no all natural conceptions here). Any type or dose of antioxidant was included and pregnancy and sperm outcomes tracked. In general, the studies that were reviewed weren’t stellar stuff, but the meta-analysis showed a 4 fold higher rate of live births among antioxidant users (based on 3 studies and 20 births). There was also a 4 fold higher rate of conceptions in the antioxidant group (15 studies, 96 pregnancies total). Finally, the meta-analysis suggested that there were significant improvements in both sperm concentration (from 7 studies) and motility (from 10 studies) with antioxidants, although this was much weaker than the pregnancy data.
The Turek Clinic World View of Antioxidants and Male Infertility
My belief in antioxidant supplements for male fertility comes from simple reasoning:
- Oxidants hurt cells.
- Sperm are cells.
- Antioxidants can protect cells from the oxidant-induced damage.
- Antioxidants can therefore help decrease oxidative damage to sperm.
Along with the following observations, there comes a conclusion:
- Probably the best antioxidants are found in the diet
- Most men have terrible, antioxidant-poor diets
- If men ate more fruits and vegetables, maybe fertility would improve
- Barring this change in diet, men should view antioxidant supplements similar to the way women view “prenatal” vitamins, and take them.