Transcript: Male Fertility and Diet
Infertility affects 10–15% of couples attempting to conceive and in about half the cases a problem is found in the man. A recent Harvard study found that increasing saturated fat intake just 5% was associated with a 38% lower sperm count, but why? I've talked about the role of xenoestrogens, endocrine disrupting industrial pollutants that build up in animal fat, particularly fish, but male fertility is not just about sperm count—the number of sperm, but about how well the sperm work.
A recent study found that "successful pregnancy and fertilized egg implantation outcomes are decreased in patients reporting a more frequent intake of meat. This finding is consistent with poor semen quality associated with a higher intake of products that may incorporate these chemicals and steroids. The use of these compounds in the food industry results in an increased total level of xenoestrogens and sex steroids in processed foods, such as meat or milk, whose intake contributes significantly to daily exposures. Xenoestrogens are highly lipophilic substances that can accumulate in fat-rich foods, such as meat, and may be suspected as partially responsible for the decline in semen quality. Conclusion: Couples having trouble conceiving must be advised about the drastic effect of both the male and female lifestyle on treatment success.”
This is consistent with previous findings that “frequent intake of fat-laden foods like meat products or milk may negatively affect semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.” Vegetable consumption was also found protective in the new study, which may be because of the antioxidant and nutrient content.
The adverse effects of meat could be from other pollutants as well. Exposure even as an infant to low levels of dioxin can permanently reduce sperm quality. The general consensus is that human sperm quality has declined over time in different areas. We're still not sure why, but dioxins may be playing a causal role.
The reason why maternal beef consumption may alter a man’s testicular development and adversely affect his future reproductive capacity is thought to be due to the anabolic steroids implanted into the animals, but as the accompanying editorial pointed out, "the steroids could also be interacting with other xenobiotic, meaning industrial chemicals present in meat, such as pesticides and dioxin-like pollutants, and even chemicals that may be present in the plastic wrap.
Heavy metals may also play a role. Lead and cadmium exposure as measured by levels in the bloodstream was associated with a significantly longer time to conceive. Where might exposure be coming from? Common types of seafood right out of fish markets and supermarkets were sampled. The highest cadmium levels were found in tuna; highest lead levels in scallops and shrimp. The greatest risk from different metals resided in different fish; some of which got really high. Thus, the risk information given to the public (mainly about mercury) does not present a complete picture. There are other toxic metals in fish as well.
The largest and oldest fish had some of highest levels, and we see that with other animals as well. For example, contamination of beef by cadmium and lead is clearly dependent on the age of the animal.
The only beverage associated with infertility in women was soft drinks, though this may be from an indirect route, with soda linked to obesity and obesity then linked to reduced fertilization rates, though there has been a study on one really direct route, the effectiveness of Coca Cola as a spermicidal agent in vaginal douching. Diet coke apparently had the strongest effect, Harvard researchers published in the New England Journal of Medicine.
What about Coke versus Pepsi? Tax-payer money hard at work for this head to head test. And neither of them really worked—Coke nor Pepsi, though they explain their methods for preparing the sperm-cola mixtures differed from the Harvard group. Bottomline: soda probably isn't good for you going into any orifice.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Ariel Levitsky.
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