Male Fertility and Dietary Pollutants
Infertility affects 10–15 percent of couples attempting to conceive, and in about half the cases the problem is in the man. A recent Harvard study found that increasing saturated fat intake just 5 percent was associated with a 38 percent lower sperm count, but why? It may be because of endocrine-disrupting industrial pollutants that build up in animal fat, particularly fish, as I describe in my video Xenoestrogens & Sperm Counts, but male fertility is not just about the number of sperm, but also how well they work.
A recent study, featured in my 5-min video Male Fertility and Diet, found that successful pregnancy and fertilized egg implantation outcomes are decreased in patients reporting a more frequent intake of meat. The researchers blame industrial pollutants and steroids present in animal products. They conclude that couples having trouble conceiving must be advised about the dramatic effects diet may play on treatment success for both men and women, 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 this new study, which may be because of the antioxidant and nutrient content.
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. However, as an accompanying editorial to a study exploring this phenomenon pointed out, the steroids could also be interacting with other xenobiotics—industrial chemicals present in meat—such as pesticides and dioxin-like pollutants, and even chemicals that may be present in the plastic wrap (see Dioxins in the Food Supply). For more on the hormones used in meat production, see my video Anabolic Steroids in Meat.
Heavy metals may also play a role. Lead and cadmium exposure, as measured by levels in the bloodstream, were associated with a significantly longer time to conceive. Where might exposure be coming from? Common types of seafood from 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. 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.
For more on heavy metal exposure (dietary as opposed to auditory), see:
- Cannibalistic Feed Biomagnification
- Dietary Theory of Alzheimer’s
- Drug Residues in Meat
- Filled Full of Lead
- Get the Lead Out
- Heavy Metals in Protein Powder Supplements
- Nerves of Mercury
- Some Ayurvedic Medicine Worse Than Lead Paint Exposure
The only beverage associated with infertility in women was soft drinks, though this may be from an indirect route, since soda is linked to obesity and obesity is then linked to reduced fertilization rates. However, Harvard researchers conducted 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. What about Coke versus Pepsi? Tax-payer money hard at work for this head-to-head test. Neither of them really worked—Coke nor Pepsi—though they explain their methods for preparing the “sperm-cola mixtures” differed from the Harvard group. Bottom line: soda probably isn’t good for you going into any orifice.
For more on both male and female infertility, see my videos Soy Hormones & Male Infertility and Meat Hormones & Female Infertility.
-Michael Greger, M.D.
PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.
Image credit: Jug Jones/ Flickr
Trans Fat in Animal Fat
Trans fats are bad. They may increase one’s risks of heart disease, sudden death, diabetes—and perhaps even aggression. Trans fat intake has been associated with overt aggressive behavior, impatience, and irritability.
Trans fats are basically found in only one place in nature: animal fat. The food industry, however, found a way to synthetically create these toxic fats by hardening vegetable oil in a process called hydrogenation, which rearranges their atoms to make them behave more like animal fats.
Although most of America’s trans fat intake has traditionally come from processed foods containing partially-hydrogenated oils, a fifth of the trans fats in the American diet used to come from animal products—1.2 grams out of the 5.8 total consumed daily. Now that trans fat labeling has been mandated, however, and places like New York City have banned the use of partially hydrogenated oils, the intake of industrial-produced trans fat is down to about 1.3, so about 50 percent of America’s trans fats come now from animal products.
Which foods naturally have significant amounts of trans fat? According to the official USDA nutrient database, cheese, milk, yogurt, burgers, chicken fat, turkey meat, bologna, and hot dogs contain about 1 to 5 percent trans fats (see the USDA chart in Trans Fat In Meat And Dairy). There are also tiny amounts of trans fats in non-hydrogenated vegetable oils due to steam deodorization or stripping during the refining process.
Is getting a few percent trans fats a problem, though? The most prestigious scientific body in the United States, the National Academies of Science (NAS), concluded that the only safe intake of trans fats is zero. In their report condemning trans fats, they couldn’t even assign a Tolerable Upper Daily Limit of intake because “any incremental increase in trans fatty acid intake increases coronary heart disease risk.” There may also be no safe intake of dietary cholesterol, which underscores the importance of reducing animal product consumption. See my video Trans Fat, Saturated Fat, and Cholesterol: Tolerable Upper Intake of Zero.
There’s been controversy, though, as to whether the trans fats naturally found in animal products are as bad as the synthetic fats in partially hydrogenated junk food. The latest study supports the notion that trans fat intake, irrespective of source—animal or industrial—increases cardiovascular disease risk, especially, it appears, in women.
“Because trans fats are unavoidable on ordinary, non-vegan diets, getting down to zero percent trans fats would require significant changes in patterns of dietary intake,” reads the NAS report. One of the authors, the Director of Harvard’s Cardiovascular Epidemiology Program, famously explained why—despite this—they didn’t recommend a vegan diet: “We can’t tell people to stop eating all meat and all dairy products,” he said. “Well, we could tell people to become vegetarians,” he added. “If we were truly basing this only on science, we would, but it is a bit extreme.”
Wouldn’t want scientists basing anything on science now would we?
“Nevertheless,” the report concludes, “it is recommended that trans fatty acid consumption be as low as possible while consuming a nutritionally adequate diet.”
Even if you eat vegan, though, there’s a loophole in labeling regulations that allows foods with a trans fats content of less than 0.5 grams per serving to be listed as having—you guessed it—zero grams of trans fat. This labeling is misguiding the public by allowing foods to be labeled as ”trans fat free” when they are, in fact, not. So to avoid all trans fats, avoid meat and dairy, refined oils, and anything that says partially hydrogenated in the ingredients list, regardless of what it says on the Nutrition Facts label.
More on trans fat can be found in my videos Blocking the First Step of Heart Disease and Breast Cancer Survival and Trans Fat.
While unrefined oils such as extra virgin olive should not contain trans fats, to boost the absorption of carotenoids in your salad why not add olives themselves or whole food sources of fat such as nuts or seeds? Other videos on oils include:
-Michael Greger, M.D.
PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death and More Than an Apple a Day.
Image credit: PKMousie / Flickr
