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Once in a great moon, something comes around that changes the way you think about things. Explorer Christopher Columbus’ idea of a round earth, the idea of electricity and the desktop computer are but a few of these. Upon reading two meta-analyses of antioxidant supplements for male infertility, a similar change in perspective has occurred.
What is a Meta-analysis?
A meta-analysis is a 100-year old statistical term used to describe a certain way of evaluating evidence that, when viewed separately, is relatively unconvincing. Meta-analyses seek to find effects or outcomes that might not discernable 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 resides at the moment on any particular subject. Notably, biological studies and randomized controlled trials still rank higher on the totem pole of good evidence than meta-analyses in medicine.
Antioxidants and Male Infertility
Antioxidants have been the rage 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 fared that well. 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, it is thought 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 zinc, 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 latest Cochrane review https://www.cochrane.org/CD007411/MENSTR_antioxidant-vitamins-and-minerals-for-male-subfertility analyzed 48 randomized, controlled trials (4179 couples) in which male partners of infertile couples were given antioxidant supplements (or placebo) while their partners underwent IVF (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 here’s what the meta-analysis found:
- A 3.4-fold higher rate of pregnancies in the antioxidant group (522 men)
- A 4.2-fold higher rate of live births among antioxidant users (277 men)
- Significant improvements in both sperm concentration with antioxidants, although this was much weaker than the pregnancy data.
The Alpha Sperm World View
Our 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 follows 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