Hello and welcome to Nutrition Facts. I’m your host, Dr. Michael Greger. Today, we’re going to explore smart nutrition choices based, naturally, on facts. Whenever there’s a new drug or surgical procedure, you can be assured that you and your doctor will probably hear about it because there’s a corporate budget driving its promotion; but, what about advances in the field of nutrition? That’s what this podcast is all about.
Today we’re going to discuss the latest research on women’s health. We’re going to dive into three different topics that affect the quality of life for women throughout the lifespan. First up – is a study that takes a close look at the effects of diet during pregnancy.
A group of women were randomized to eat more meat and dairy when they were pregnant. Here’s what the researchers found out.
“High-protein diets during pregnancy: healthful or harmful?” A question answered about forty years ago, in the infamous Harlem Trial of 1976: a “randomized controlled trial of nutritional supplementation in pregnancy, in a poor black urban population.” The “study…was begun at a time when protein was [just] assumed to be deficient in the diet[s] of the poor…” Had they actually analyzed their diets before they started, they would have realized that wasn’t true. But, why let facts get in the way of assumptions?
So, they split poor black pregnant women into three groups, and gave them an extra 40 grams of animal protein a day—basically a couple cans of Ensure, versus about six extra grams of animal protein, or no extra protein, and sat back, and watched what happened. The high-protein group suffered “an excess of very early premature births and associated [infant] deaths,” as well as “significant growth retardation” in the babies that survived. More protein meant more prematurity, more deaths, and more growth retardation.
And, when kids grow up, animal protein intake during pregnancy has been associated with children becoming overweight later in life, and getting high blood pressure. The “offspring of mothers who reported eating more meat and fish” had higher blood pressure in adulthood. This was part of another failed dietary intervention trial, in which mothers were advised to eat a pound of meat a day. The increased weight gain and high blood pressure may be due to the obesity-causing chemical pollutants in the meat supply, as I’ve talked about before, or the animal protein-induced rise in the growth hormone IGF-1, or it could be due to a steroid stress hormone, called cortisol.
A single meal high in animal protein can nearly double the level of stress hormone in the blood within a half hour of consumption—much more than a meal closer to the recommended level of protein. Give someone a meal of crabmeat, tuna fish, cottage cheese, and the stress hormone levels shoot up. But, instead, give someone some barley soup, and a vegetable stir-fry on rice, and the stress hormone level goes down after the meal.
And, imagine if you did the meat, fish, dairy meal-after-meal, day-after-day. You could chronically stimulate your stress response axis, and increase the release of vasoactive hormones that can increase your blood pressure. And, all that extra cortisol release has been linked to increased risk for elevated blood levels of insulin, triglycerides, and cholesterol.
If you take men on a high-protein diet—”meat, fish, poultry, egg white[s]”—and switch them to a high-carb diet of “bread, vegetables, fruit, and [sugary junk,]” their cortisol levels drop about a quarter within ten days. At the same time, their testosterone levels shoot up by about the same amount. High-protein diets suppress testosterone. That’s why if you take men eating plant-based diets, and have them start eating meat every day, their testosterone levels go down, and actually some estrogens go up.
That’s why bodybuilders can get such low testosterone levels. It’s not the steroids they’re taking. If you look at natural bodybuilders, who don’t use steroids, 75% drop in testosterone levels in the months leading up to a competition. Testosterone levels cut by more than half; enough to drop a guy into an abnormally low range. It’s ironic that they’re eating protein to look manly on the outside, but it makes them less and less manly on the inside. And, from an obesity standpoint, in general, a drop in testosterone levels may increase the risk of gaining weight—you gain body fat.
What does cortisol have to do with weight? Well, there’s actually a disease caused by having too much cortisol, called Cushing’s syndrome. And, this is kind of a before-and-after in terms of abdominal obesity, which is most of that white. Even in normal women, though, chronic stress—chronic high cortisol levels—can contribute to obesity. And, if they’re pregnant, high-meat, low-carb diets may increase cortisol levels in the mom—which can lead to inappropriate fetal exposure to cortisol, which, in turn, can affect the developing fetus, resetting their whole stress-response thermostat, leading to higher cortisol levels their whole life, which can have serious health consequences that can stick with them their whole lives.
And indeed, that’s what they found. Every maternal daily portion of meat and fish was associated with 5% higher cortisol levels in their children as much as thirty years later—though green vegetable consumption was found to be protective. Higher meat and fish consumption—like three servings a day, compared to one or two—was associated with significantly higher cortisol levels. But, eating greens every day appeared to blunt some of that excess stress response.
And, the adult children of mothers who ate a lot of meat during pregnancy don’t just walk around with higher stress hormone levels, but also appear to react more negatively to whatever life throws at them.
Now, the real-world effects of this is that after that sort of test, if you give people their own private snack buffet, with fruits and veggies versus fatty, sugary, comfort foods like chocolate cake, guess who eats less fruits and veggies? Those who have these high chronic stress levels. Cortisol has been implicated as a factor in motivating food intake, even when you’re not really hungry.
So, no surprise that animal protein intake during pregnancy may lead to larger weight gain for her children later in life, and maybe even her grandchildren. That’s how much the stress axis can get mucked around. Recent evidence suggests that the long-term adverse consequences “may not be limited to one generation;…the diet of a pregnant mother may affect the development and disease risk of her children and even her grandchildren… Ultimately, these findings [may] shed light on [our rapidly expanding epidemics] of diabetes, obesity, and [heart disease].”
Here’s a question. Let’s say you have polycystic ovary syndrome – a condition by which your body produces cysts on your ovaries. Which foods and cooking methods should you choose? Here are some answers.
“Over the [last] 2 decades there has been increasing evidence supporting an important contribution from food-derived advanced glycation end products (AGEs),” also known as glycotoxins, to “increased oxidative stress and inflammation, processes that play a major role in the causation of chronic diseases”—including, potentially, polycystic ovary syndrome. Women with PCOS tend to have nearly twice the circulating AGE levels in their bloodstream.
Polycystic ovary syndrome may be “the most common [hormonal] abnormality” among young women in the United States, a common cause of infertility, menstrual dysfunction, and excess facial and body hair. Now, “the prevalence of obesity” is also higher in women with PCOS. So, since the highest AGE levels are found in broiled, grilled, fried, and roasted foods of mostly “animal origin,” is it possible that this causal chain starts with a bad diet—like lots of fried chicken—which leads to obesity, which then, in turn, leads to PCOS? So, what we eat maybe is only indirectly related to PCOS, through weight gain? No, because the same link between high AGE levels and PCOS was found in lean women, as well.
“As chronic inflammation and increased [oxidative] stress have been incriminated in the [disease process] of PCOS, the role of AGEs as [pro-]inflammatory and [pro-]oxidant mediators may [indeed] be linked with the metabolic and reproductive abnormalities of the syndrome.” And, further, the buildup of AGE inside polycystic ovaries themselves suggests “a potential role of AGEs” contributing to the disease process itself, beyond just some of the consequences.”
“RAGE [is] highly expressed” in ovarian tissues. In other words, the receptor—that’s the R in RAGE—the receptor in the body for these advanced glycation end products—is concentrated, for some reason, in the ovaries. So, ovaries may be particularly sensitive to their effects. So, AGEs might indeed be contributing “to the cause of polycystic ovary syndrome…and infertility.” So, should we just cut down on meat, cheese, and eggs? Or, we can always come up with AGE absorption-blocking drugs.
We know “AGEs have been implicated in the development of many” chronic diseases. Specifically, “food-derived AGEs…play an important role;” diet is a major source of these pro-inflammatory AGEs. Indeed, cutting down on these dietary glycotoxins “reduces the inflammatory response.” But, stewed chicken just doesn’t taste as good as fried chicken. So, therefore, you can have your KFC and eat it, too. Just take this drug with it every time you eat, to cut down on the absorption of these toxins. And, it works—it actually lowers AGE blood levels. This oral absorbent drug, AST-120, is just a preparation of activated charcoal. That’s like what you give for drug overdoses, and when people are poisoned. I’m sure if you took some ipecac with your KFC, your levels would go down, too.
You know, there’s another way you can reduce your absorption—by reducing your intake in the first place. Simple, safe, feasible. The first thing you do is stop smoking. The glycotoxins in cigarette smoke “may contribute to” the increase in heart disease and cancer among smokers. Then, you can decrease your intake of high-AGE foods, while increasing your intake of foods that may help pull AGEs out of your system, like brown rice and mushrooms. And, we can eat foods high in antioxidants, like berries, herbs, and spices.
“Dietary AGE intake can be…decreased [even just by] changing the method of cooking” from the high-temperature dry cooking methods to low heat, higher humidity. In other words, moving away from “broiling, searing, [frying” to more “stewing, steaming, and boiling.” But, what we eat may be more important than how we cook it. For example, boiled chicken has less than half the glycotoxins of roasted chicken. But, even deep-fried potatoes [have] less than boiled meat.
We could also eat foods raw, which doesn’t work as well for blood pudding, but we can choose raw nuts and nut butters, which may have 30 times less glycotoxins than roasted. And, we can stay away from high-AGE processed foods, such as puffed, shredded, and flaked breakfast cereal.
Why does it matter? Because study after study has shown that switching someone to a low-AGE diet can lower the inflammation within their bodies. Even just a single high-AGE meal can profoundly impair our artery function within just two hours of consumption. Fried or broiled chicken breast and veggies, compared to steamed or boiled chicken breast and veggies. The same ingredients; just different cooking methods. Now, you’ll notice that even the steamed or boiled chicken meal still impaired arterial function. So, you could certainly choose to eat even healthier, but significantly better than the fried or broiled.
Ironically, “the amount of AGEs administered during this [high-AGE] intervention,” this profoundly-impair-your-artery-function amount of AGEs, “was similar to the average estimated daily intake by the general population,” the Standard American Diet. That’s why you can decrease inflammation in people, putting them on a low-AGE diet. But, an increase in inflammation was less apparent when people switched from their regular diet to a high-AGE diet, because they’re already eating a high-AGE diet, so many of these glycotoxins in their regular diet.
Do we have evidence reducing AGE intake actually helps with polycystic ovaries? Yes. Within just two months, baseline diet; switch to a high-AGE diet, to a low-AGE diet, and you see parallel changes in insulin sensitivity, oxidative stress, hormonal status, with the take home being that those with PCOS may want to try a low-AGE diet, which in the study meant restricting meat to once a week that’s only boiled, poached, stewed or steamed, and cutting out fast food-type foods and soda. What about instead of steamed chicken, we ate no meat at all?
Rather than measuring blood levels, which vary with each meal, like if you just ate some roasted nuts or something, we can measure the level of glycotoxins stuck in your body tissues over time instead, with a fancy gizmo that measures the amount of light your skin gives off, because AGEs are fluorescent. And so, no surprise, this turns out to be a strong predictor of overall mortality. So, the lower the better, and “the one factor…consistently associated with” reduced skin fluorescence, this reduced AGEs coming out of your body, was a vegetarian diet, which suggests that eating more plant-based “may reduce exposure to [these] preformed dietary AGEs,” potentially reducing tissue AGEs, as well as chronic disease risk.
Bacterial vaginosis is the most common vaginal infection in women ages 14 through 55. So what’s the best remedy? Here’s a study that looks at the effectiveness of vitamin C.
A study published in 1999 raised the exciting possibility that “cheap, simple, innocuous, and ubiquitous vitamin C supplements could prevent [a condition known as] pre-eclampsia.” But, a decade of research later, we realized that was merely a false hope, and that vitamin C supplements appear to play little role in women’s health.
But, they’re talking about oral vitamin C, not vaginal vitamin C, which has been found to be an effective treatment for bacterial vaginosis—an all-too-common gynecological disorder characterized by a fishy-smelling, watery-gray discharge.
Bacterial vaginosis “can best be described as an ‘ecological disaster’ of the vaginal microflora.” The normal lactobacillus-type good bacteria get displaced by an army of bad bacteria. Probiotics may help, repopulating with good bacteria, but the reason the bad bacteria took over in the first place was that the pH was off.
I’ve talked about the role diet may play in the development of this condition. For example, “saturated fat [intake] may increase vaginal pH,” allowing for the growth of undesirables. So, why not try to re-acidify the vagina with ascorbic acid, otherwise known as vitamin C? Now, this isn’t just plain vitamin C tablets, but specially formulated “silicon-coated” supplements that release vitamin C slowly, so as not to be irritating. How well do they work? 100 women suffering from the condition split into two groups, and the vaginal vitamin C beat out placebo.
But how does vitamin C compare to the conventional therapy, an antibiotic gel? This is an important question. “Although perceived as a mild medical problem,” bacterial vaginosis may increase the risk of several gynecological complications, including problems during pregnancy, where you want to avoid taking drugs whenever possible.
The vitamin C appeared to work as effectively as the antibiotic. And so, especially like in the first trimester when you really don’t want to be putting drugs up there, vitamin C can really help. And, for women with recurrent episodes, using the vitamin C for six days after each cycle appears to cut “the risk of recurrence” in half.
To see any graphs, charts, graphics, images, or studies mentioned here, please go to the Nutrition Facts podcast landing page. There, you’ll find all the detailed information you need plus links to all the sources we cite for each of these topics.
NutritionFacts.org is a nonprofit, science-based public service, where you can sign up for free daily updates on the latest in nutrition research via bite-sized videos and articles.
Everything on the website is free. There’s no ads, no corporate sponsorship. It’s strictly non-commercial. I’m not selling anything. I just put it up as a public service, as a labor of love, as a tribute to my grandmother, whose own life was saved with evidence-based nutrition.
Thanks for listening to Nutrition Facts. I’m Dr. Michael Greger.
This is just an approximation of the audio content, contributed by Allyson Burnett.
Previous Podcast
Next Podcast
