Hello and welcome to the Nutrition Facts podcast, I’m your host Dr. Michael Greger.
Now, I know I’ve made a name for myself in explaining how not to do certain things – just look at my books – How NOT to Die – and my upcoming book, How NOT to Diet. But what I want to share with you is actually quite positive: what’s the best way to live a healthy life? Here are some answers.
The facts behind today’s story are quite astounding. Did you know that one in every 10 couples is unable to become pregnant? And that’s after a year of trying. In our first story we look at a possible link between poultry consumption and female infertility.
Pregnant women, in particular, may want to stay away from all meat. We learned that meat is so packed with sex steroid hormones that when pregnant women eat meat, it may affect the development of their sons’ genital organs while still in the womb such that when they grow up, they have decreased fertility. When moms eat meat during pregnancy, it “may alter a man’s testicular development in utero, and adversely affect his reproductive capacity.”
But in this study, they just looked at beef. And we know that all meat has these hormones, and they only looked at the fertility of the next generation. So, in effect, this study showed eating meat may lead to fewer grandchildren.
But what about your own fertility? Is there a direct effect of meat consumption on fertility in women? Fact, or fiction?
Fact. And not just any study, but the famous Harvard Nurses study, which followed 18,000 women trying to get pregnant for eight years, and measured what they ate. They found that meat intake was indeed associated with infertility. Adding just a single serving of meat per day was associated with a 30% greater risk of anovulatory infertility meaning the meat consumption appeared to interfere with ovulation. And this increased risk was due mostly to the intake of poultry.
To break it down: eat a single serving of any meat, and you increase your infertility risk 30%. Red meat increases infertility risk 40%. But just a single serving of chicken, half a chicken breast a day and women increase their infertility risk more than 50%, worse than bacon and hot dogs!
Now, while animal protein was associated with increased risk of infertility, consuming protein from vegetable sources appeared to have the opposite effect protecting, improving fertility. The researchers aren’t sure why, but they think it might have something to do with the fact that animal protein intake increases the levels of a growth hormone called IGF-1, which has been linked not only to infertility but to cancer, whereas eating veggie protein doesn’t seem to have that adverse effect.
In summary, they concluded that replacing animal sources of protein, particularly chicken with vegetable sources of protein like beans may reduce the risk of infertility because of anovulation, or failure to ovulate.
In our next story we look at the ongoing global drop in male fertility. There’s research that points to links between saturated fat intake and lack of sufficient fruits and vegetables.
In 1992 a controversial paper was published, suggesting sperm counts have been dropping around the world over the last 50 years. However, this remains a matter of debate. It’s notoriously difficult to determine sperm counts in the general population for an obvious reason. If you go ask men for samples, less than 1 in 3 tend to agree to participate.
Finally though, a study of tens of thousands of men studied over a 17 year period. And, they did indeed find a significant decline in sperm concentration, about a 30% drop, as well as a drop in the percentage of normal looking sperm. Most looked normal in the 90’s but more recently that has dropped to less than half. This may constitute a serious public health warning. Semen quality may actually be related to life expectancy. In a study of more than 40,000 men visiting a sperm lab during a 40-year period, they found a decrease in mortality was associated with an increase in semen quality, suggesting that semen quality may therefore be a fundamental biomarker of overall male health. So declining sperm counts could be like the canary in the coal mine, for us, and future generations. Even when defective sperm are capable of fertilizing an egg, creating a child with abnormal sperm may have serious implications for that child’s future health.
What role may diet play? I profiled first-of-its-kind Harvard study suggesting that a small increase in saturated fat intake was associated with a substantially lower sperm count, but not all fat was bad, higher intakes of omega-3’s was associated with a more favorable sperm shape. This may help explain why researchers at UCLA were able to improve sperm vitality, movement, and shape by giving men about 18 walnuts a day for 12 weeks. Though walnuts, as a whole food, have more than just omega 3’s but also other important micronutrients. In a study of men aged 22 through 80, older men who ate diets containing lots of antioxidants and micronutrients, for example vitamin C had the genetic integrity of sperm from much younger men.
The antioxidants we eat not only end up in our semen, but are concentrated there. The amount of vitamin C ends up nearly 10 times more concentrated in our testicles than the rest of our bodies. Why? Because sperm are highly susceptible to damage induced by free radicals, and accumulating evidence suggests that this oxidative stress plays an important role in male infertility, so we should eat lots of antioxidants, which is to say eat lots of fruits and vegetables. Why not just take antioxidant pills? Because in pill form antioxidants may have unexpected adverse effects. So more fruits and vegetables and perhaps less meat and dairy, which is where most saturated fat is found, but the Harvard data were considered preliminary. They studied fewer than 100 men, but it was the best we had until now. The higher the saturated fat intake the lower the sperm count, up to a 65% reduction in total sperm count. These findings are of potentially great public interest, because changes in diet over the past decades may be part of the explanation for the recently reported high frequency of subnormal human sperm counts. In any case, the current findings suggest that adapting dietary intake toward eating less saturated fat may be beneficial for both general and reproductive health.
In our final story, we discover how five cents’ worth of seaweed a day may dramatically improve a major cause of disability and compromised quality of life among women.
“Endometriosis is a chronic disease which is under-diagnosed, under-reported, and under-researched.” For patients, it “can be a nightmare of misinformation, myths, taboos, lack of diagnosis, and problematic hit-and-miss treatments overlaid by a painful, chronic, stubborn disease.” Pain is what best characterizes the disease: pain, painful intercourse, heavy irregular periods, and infertility. About one in a dozen young women suffer, and it accounts for about half the cases of pelvic pain and infertility. It’s caused by what’s called “retrograde menstruation.” Instead of the blood going down, it goes up into the abdominal cavity, where bleeding tissue of the uterine lining can implant onto other organs.
You can have the lesions surgically removed, but the recurrence rate within five years is as high as 50%. Now, “endometriosis is an estrogen-dependent disease.” So, might the anti-estrogenic effects of the phytoestrogens in flax seeds and soy foods help as they appear to in breast cancer? I couldn’t find studies on flax, but soy food consumption “may indeed reduce the risk of endometriosis.” But, I couldn’t find any studies on treating the disease with soy. There’s another food, though, associated with decreased breast cancer risk, seaweed.
Seaweeds have special types of fiber and phytonutrients not found among land plants. So, it’s not like choosing to get your beta-carotene from carrots versus a sweet potato. If you want these unique seaweed components, some of which may have anticancer properties, we need to find a way to incorporate sea vegetables into our diet.
Anticancer properties, such as anti-estrogen effects; Japanese women have among “the lowest rates of breast, endometrial, and ovarian cancers.” They have longer menstrual cycles, and lower estrogen levels circulating in their blood. And, that may help account for their low risk of estrogen-dependent cancers. We assumed this was their soy intake, but the seaweed might be helping as well.
You can drip seaweed broth on human ovary cells that make estrogen, and see estrogen levels drop, because it’s either inhibiting production, or facilitating breakdown of estrogen—and may even block estrogen receptors, lowering the activity of the estrogen you do produce. This is in a petri dish, though, but it happens in women, as well.
They estimate that an effective estrogen-lowering dose of seaweed for an average American woman might be around five grams a day. But, no one has apparently tried testing it on cancer patients yet. But, it has been tried on endometriosis. Three women with abnormal cycles, two of which with endometriosis volunteered to add a tiny amount of “dried, powdered bladderwrack,” a common seaweed, to their daily diet. It effectively lengthened their cycles, and reduced the duration of their periods and, not just by a little.
Subject #1: A 30-year history of irregular periods averaging every 16 days, but, having just a teaspoon, a quarter-teaspoon, of this seaweed powder a day added ten days onto her cycle, up to 26 days. And, a half-teaspoon a day brought her up to like 31, nearly doubling the length of her cycle. And, they all experienced marked reductions in blood flow, and a decreased duration of menstruation. Poor subject #1 was having periods every 16 days that lasted nine days long. Can you imagine? After 30 years of this kind of craziness, just a half-teaspoon of seaweed a day, and she was having periods just once a month, and only lasting about four days. And, most importantly, in the two women suffering from endometriosis, they reported substantial alleviation of their pain. How is that possible? A drop in estrogen levels. A 75% drop after just a quarter-teaspoon of seaweed powder a day; 85% after a half-teaspoon.
Now, obviously, with just a couple women, no control group, we have to do bigger, better studies. But, look when this study was published, more than a decade ago, and not a single such study has been published since. Does the research world just not care about women? Millions of women are suffering with these conditions. Who’s going to fund it, though? That much seaweed costs less than five pennies; so, a larger study may never be done. But, with no downsides, I would suggest endometriosis sufferers give it a try.
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