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Tag: polycyclic aromatic hydrocarbons

  • Treating Hashimoto’s Disease (Hypothyroidism) Naturally with Diet  | NutritionFacts.org

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    What were the results of a randomized, double-blind, placebo-controlled trial of a daily half teaspoon of powdered black cumin in Hashimoto’s patients?

    “Autoimmune thyroiditis, also known as Hashimoto’s thyroiditis, is an organ-specific autoimmune disorder,” where our body attacks our own thyroid gland, often leading to hypothyroidism due to destruction and scarring of the gland itself. We know there’s a genetic component, since identical twins are more likely to share the disease than fraternal twins. “However, even with identical twins, the concordance rate was only about 50%, emphasizing that important factors such as the environment play a role in disease pathogenesis.” Indeed, even if your identical twin, who has basically your exact same DNA, has the disease, there’s only like a flip of a coin’s chance you’ll get it. Genes load the gun, but the environment may pull the trigger.

    More than 90 synthetic chemicals were noted to show disruption of hormonal balance or thyroid dysfunction.” However, only a few such ‘pollutants show evidence that they contribute to autoimmune thyroid disease.” These include polyaromatic hydrocarbons. Smokers get a lot of them from cigarettes, but in nonsmokers, exposure comes almost entirely from food, as you can see below and at 1:18 in my video Diet for Hypothyroidism: A Natural Treatment for Hashimoto’s Disease. 

    Polycyclic aromatic hydrocarbons are primarily formed when muscle meats, such as beef, pork, fish, or chicken, are cooked using high-temperature methods, such as grilling. PBBs, polybrominated biphenols, are a type of flame-retardant chemical no longer manufactured in the United States, but are still found in the aquatic food chain. PCBs, polychlorinated biphenols, are used in a number of industrial processes and end up in people’s bodies, again, largely through the consumption of fish, but also eggs and other meats, as seen here and at 1:41 in my video.

    So, one might suspect those eating plant-based diets would have lower rates of hypothyroidism, and, indeed, despite their lower iodine intake, vegan diets tended to be protective. But they’ve never been put to the test in an interventional trial. A modification of the Paleolithic diet has been tried in Hashimoto’s patients, but it didn’t appear to improve thyroid function. What did, though, is Nigella Sativa. That name should sound familiar to anyone who’s read my book How Not to Diet or watched my live Evidence-Based Weight Loss presentation. Nigella Sativa is the scientific name for black cumin, which is just a simple spice that’s also used for a variety of medicinal purposes.

    In one study, Hashimoto’s patients received a half teaspoon of powdered black cumin every day for eight weeks in a randomized, double-blind, placebo-controlled trial. Not only was there a significant reduction in body weight, which is why I profiled it in my book, but the black cumin also significantly reduced the thyroid-stimulating hormone, a sign that thyroid function was improving. It even lowered the level of autoimmune anti-thyroid antibodies, as well as increased blood levels of thyroid hormone T3 in these Hashimoto’s patients. In addition, there was a significant drop in Interleukin 23, a proinflammatory cell signal thought to help promote the autoimmune inflammation of the thyroid, which “further confirms the anti-inflammatory nature of the plant.” And what were the side effects? There was a 17 percent drop in “bad” LDL cholesterol, as shown below and at 3:19 in my video.

    Given the fact that patients with Hashimoto’s may be at particularly high risk of developing heart disease, this is exactly the kind of side effects we’d want. “Considering these health-promoting effects of N. Sativa [black cumin], it can be considered as a therapeutic approach in the management of Hashimoto-related metabolic abnormalities.”

    A similar trial failed to find a benefit, though. Same dose, same time frame, but no significant changes in thyroid function. In contrast with the previous study, though, the study participants were not all Hashimoto’s patients, but rather hypothyroid for any reason, and that may have diluted the results. And it’s possible that telling patients to take the black cumin doses with their thyroid hormone replacement therapy may have interfered with its absorption, which is an issue similar to other foods and drugs, and why patients are normally told to take it on an empty stomach. Since there are no downsides—it’s just a simple spice—I figure, why not give it a try? The worst that can happen is you’ll have tastier food.

    Doctor’s Note:

    I get a lot of questions about thyroid function, and I am glad to have been able to do this series. If you missed any of the other videos, see the related posts below.

    For more on black cumin, see my book How Not to Diet and my presentation Evidence-Based Weight Loss. 

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    Michael Greger M.D. FACLM

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  • Chemical Safety, Cultivated Meat, and Our Health  | NutritionFacts.org

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    More than 95 percent of human exposure to industrial pollutants like dioxins and PCBs comes from fish, other meat, and dairy.

    By cultivating muscle meat directly, without associated organs like intestines, the incidence of foodborne diseases “could be significantly reduced,” as could exposure to antibiotics, “pesticides, arsenic, dioxins, and hormones associated with conventional meat.” Currently, the U.S. Food and Drug Administration has approved seven hormone drugs to bulk up the production of milk and meat. “In the European Union, there exists a total ban on such use,” however. Even without injected hormones, though, animal products naturally have hormones because they come from animals. “Eggs, example given, contribute more to the dietary intake of estradiol [estrogens] than beef, whether the animal is legally treated with hormones or not.” After all, eggs come straight from a hen’s ovaries, so, of course, they’re swimming with hormones. But if you’re directly growing just muscle meat or egg white protein, you don’t need to include reproductive organs, adrenal glands, or any of the associated hormones.

    “Chemical safety is another concern for meat produced under current production systems.” There are chemical toxicants and industrial pollutants that build up in the food chain, such as pesticides, PCBs, heavy metals, and flame retardants, but there is no food chain with cultivated meat. We could produce all the tuna we wanted, with zero mercury.

    When the World Health Organization determined that processed meat was a known human carcinogen and unprocessed meat a probable human carcinogen, it wasn’t even talking about the carcinogenic environmental pollutants. When researchers tested retail meat for the presence of “33 chemicals with calculated carcinogenic potential,” like polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides like DDT, and dioxin-like PCBs, they concluded that, in order to reduce the risk of cancer, we should limit beef, pork, or chicken consumption to a maximum of five servings a month.

    Why cultivate meat at all when you can just buy organic? Surprisingly, “consumption of organic meat does not diminish the carcinogenic potential associated with the intake of persistent organic pollutants (POPs).” A number of studies have recently compared the presence of environmental contaminants in organic meat versus conventional meat, and the researchers found, surprisingly, that organic meat was sometimes more contaminated. Not only organic beef either. Higher levels were also found in pork and poultry.

    If you look at the micropollutants and chemical residues in both organic and conventional meat, several environmental contaminants, including dioxins, PCBs, lead, and arsenic, were measured at significantly higher levels in the organic samples. As you can see below and at 2:56 in my video, The Human Health Effects of Cultivated Meat: Chemical Safety, the green is organic meat, and the blue is conventional. 

    Cooking helps to draw off some of the fat where the PCBs are concentrated, as shown here and at 3:01.

    Seafood seems to be an exception. Steaming, for example, generally increases contaminant levels, increasing contaminant exposure and concentrating mercury levels as much as 47 percent, as you can see here and at 3:15 in my video. Better not to have toxic buildup in the first place.

    More than 95 percent of human exposure to industrial pollutants like dioxins and PCBs comes from foods like meat, including fatty fish, and dairy, but the pollutants don’t appear magically. The only way the chicken, fish, and other meat lead to human exposure is because the animals themselves built up a lifetime of exposure in our polluted world, from incinerators, power plants, sewer sludge, and on and on, as you can see here and at 3:40 in my video.

    Unlike conventional meat production, a slaughter-free harvest would not only mean no more infected animals, but no more contaminated animals either. In terms of pollutants, it would be like taking a time machine back before the Industrial Revolution.

    Doctor’s Note:

    Cultivated meat means less contamination with fecal residues, toxic pollutants, antibiotics, and hormones; up to 99 percent less environmental impact; and zero pandemic risk. Cultivated meat allows people to have their meat and eat it, too, without affecting the rest of us.

    This is the final video in this cultivated meat series. If you missed the first two, check out the videos on Food Safety and Antibiotic Resistance.

    I previously did a video series on plant-based meats; see the related posts below.

    All videos in the plant-based meat series are also available in a digital download from a webinar I did. SeeThe Human Health Implications of Plant-Based and Cultivated Meat for Pandemic Prevention and Climate Mitigation.

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    Michael Greger M.D. FACLM

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  • Is Stainless Steel or Cast Iron Cookware Best? Is Teflon Safe? | NutritionFacts.org

    Is Stainless Steel or Cast Iron Cookware Best? Is Teflon Safe? | NutritionFacts.org

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    What is the best type of pots and pans to use?

    In my last video, I expressed concerns about the use of aluminum cookware. So, what’s the best type of pots and pans to use? As I discuss in my video Stainless Steel or Cast Iron: Which Cookware Is Best? Is Teflon Safe?, stainless steel is an excellent option. It’s the metal chosen for use “in applications where safety and hygiene are considered to be of the utmost importance, such as kitchenware.” But what about studies showing that the nickel and chromium in stainless steel, which keeps the iron in stainless unstained by rust, can leach into foods during cooking? The leaching only seems to occur when the cookware is brand new. “Metal leaching decreases with sequential cooking cycles and stabilizes after the sixth cooking cycle,” after the sixth time you cook with it. Under more common day-to-day conditions, the use of stainless steel pots is considered to be safe even for most people who are acutely sensitive to those metals. 

    A little leaching metal can even be a good thing in the case of straight iron, like a cast iron skillet, which can have the “beneficial effect” of helping to improve iron status and potentially reduce the incidence of iron deficiency anemia among children and women of reproductive age. The only caveat is that you don’t want to fry in cast iron. Frying isn’t healthy regardless of cookware type, but, at hot temperatures, vegetable oil can react with the iron to create trans fats. 

    What about using nonstick pans? Teflon, also known as polytetrafluoroethylene (PTFE), “is used as an inner coating material in nonstick cookware.” Teflon’s dark history was the subject of a 2019 movie called Dark Waters, starring Mark Ruffalo and Anne Hathaway. Employees in DuPont’s Teflon division started giving birth to babies with deformities before “DuPont removed all female staff” from the unit. Of course, the corporation buried it all, hiding it from regulators and the public. “Despite this significant history of industry knowledge” about how toxic some of the chemicals used to make Teflon were, it was able to keep it hidden until, eventually, it was forced to settle for more than half a billion dollars after one of the chemicals was linked to “kidney and testicular cancers, pregnancy-induced hypertension, ulcerative colitis, and high cholesterol.”

    “At normal cooking temperatures, PTFE-coated cookware releases various gases and chemicals that present mild to severe toxicity.” As you can see below and at 2:38 in my video, different gases are released at different temperatures, and their toxic effects have been documented. 

    You’ve heard of “canaries in the coal mine”? This is more like “canaries in the kitchen, as cooking with Teflon cookware is well known to kill pet birds,” and Teflon-coated heat lamp bulbs can wipe out half a flock of chickens. 

    “Apart from the gases released during heating the cooking pans, the coating itself starts damaging after a certain period. It is normally advised to use slow heating when cooking in Teflon-coated pans,” but you can imagine how consumers might ignore that. And, if you aren’t careful, some of the Teflon can start chipping off and make its way into the food, though the effects of ingestion are unknown.

    I could find only one study that looks at the potential human health effects of cooking with nonstick pots and pans. Researchers found that the use of nonstick cookware was associated with about a 50 percent increased risk of colorectal cancer, but that may be because of what they were cooking. “Non-stick cookware is used in hazardous cooking methods (i.e. broiling, frying, grilling or barbecuing) at high temperatures mainly for meat, poultry or fish,” in which carcinogenic heterocyclic amines (HCA) are formed from the animal protein. Then, the animal fat can produce another class of carcinogens called polycyclic aromatic hydrocarbons (PAH). Though it’s possible it was the Teflon itself, which contains suspected carcinogens like that C8 compound from the movie Dark Waters, also known as PFOA, perfluorooctanoic acid.

    “Due to toxicity concerns, PFOA has been replaced with other chemicals such as GenX, but these new alternatives are also suspected to have similar toxicity.” We’ve already so contaminated the Earth with it, though, that we can get it prepackaged in food before it’s even cooked, particularly in dairy products, fish, and other meat; now, “meat is the main source of human exposure” to these toxic pollutants. Of those, seafood is the worst. In a study of diets from around the world, fish and other seafood were “major contributors” of the perfluoroalkyl substances, as expected, given that everything eventually flows into the sea. Though the aquatic food chain is the “primary transfer mechanism” for these toxins into the human diet, “food stored or prepared in greaseproof packaging materials,” like microwave popcorn, may also be a source. 

    In 2019, Oral-B Glide dental floss was tested. Six out of 18 dental floss products researchers tested showed evidence of Teflon-type compounds. Did those who used those kinds of floss end up with higher levels in their bloodstream? Yes, apparently so. Higher levels of perfluorohexanesulfonic acid were found in Oral-B Glide flossers, as you can see below and at 5:28 in my video.

    There are a lot of environmental exposures in the modern world we can’t avoid, but we shouldn’t make things worse by adding them to consumer products. At least we have some power to “lower [our] personal exposure to these harmful chemicals.”

    This is the second in a three-video series on cookware. The first was Are Aluminum Pots, Bottles, and Foil Safe?, and the next is Are Melamine Dishes and Polyamide Plastic Utensils Safe?.

    What about pressure cooking? I covered that in Does Pressure Cooking Preserve Nutrients?.

    So, what is the safest way to prepare meat? See Carcinogens in Meat. 

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    Michael Greger M.D. FACLM

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  • Say No to Fish for Five Years Before Pregnancy  | NutritionFacts.org

    Say No to Fish for Five Years Before Pregnancy  | NutritionFacts.org

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    Advisories telling pregnant women to cut down on fish consumption may be too late for certain persistent pollutants. 

    If you intentionally expose people to mercury by feeding them fish (like tuna) for 14 weeks, the level of mercury in their bloodstream goes up, as you can see in the graph below and at 0:14 in my video Avoiding Fish for Five Years Before Pregnancy. As soon as they stop eating fish, it drops back down such that they can detox by half in about 100 days. (So, the half-life of total mercury in our blood is approximately 100 days.) Even if you eat a lot of fish, within a few months of stopping, you can clear much of the mercury out of your blood. But what about your brain? 

    The results from modeling studies are all over the place, providing “some extreme estimates (69 days vs. 22 years).” When put to the test, though, autopsy findings suggest the half-life may be even longer still at 27.4 years. Once mercury gets in our brains, it can be decades before our body can get rid of even half of it. So, better than detoxing is not “toxing” in the first place. 

    That’s the problem with advisories that tell pregnant women to cut down on fish intake. For pollutants with long half-lives, such as PCBs and dioxins, “temporary fish advisory-related decreases in daily contaminant intake will not necessarily translate to appreciable decreases in maternal POP [persistent organic pollutant] body burdens,” which help determine the dose the baby gets. 

    Consider this: As you can see in the graph below and at 1:32 in my video, an infant may be exposed to a tumor-promoting pollutant called PCB 153 if their mom ate fish. But if mom ate only half the fish or no fish at all for one year, levels wouldn’t budge much. A substantial drop in infant exposure levels may only be seen if the mom had cut out all fish for five years before getting pregnant. That is the “fish consumption caveat.” “[T]he only scenarios that produced a significant impact on children’s exposures required mothers to eliminate fish from their diets for 5 years before their children were conceived. The model predicted that substituting produce for fish would reduce prenatal and breastfeeding exposures by 37% each and subsequent childhood exposures by 23%.” So, “a complete ban on fish consumption may be preferable to targeted, life stage–based fish consumption advisories…” 

    If you are going to eat fish, though, which is less polluted—wild-caught or farmed fish? In a recent study, researchers measured the levels of pesticides, such as DDT, PCBs, polycyclic aromatic hydrocarbons, and toxic elements, such as mercury and lead, in a large sample of farmed and wild-caught seafood. In general, they found that farmed fish were worse. Think of the suspect as farmed and dangerous. The measured levels of most organic and many inorganic pollutants were higher in the farmed seafood products and, consequently, so were the intake levels for the consumer if such products were consumed. For example, as you can see in the graphs below and at 3:09 in my video, there was significantly more contamination by polycyclic hydrocarbons, persistent pesticides, and PCBs in all of the farmed fish samples, including the salmon and seabass (though it didn’t seem to matter for crayfish), and the wild-caught mussels were actually worse. If you split adult and child consumers into those only eating farmed seafood or only eating wild-caught seafood, the level of pollutant exposure was significantly worse with the farmed seafood.  

    Overall, the researchers, who were Spanish, investigated a total of 59 pollutants and toxic elements. They concluded: “Taking all these data as a whole, and based on the rates of consumption of fish and seafood of the Spanish population, our results indicate that a theoretical consumer who chose to consume only aquaculture [farmed] products would be exposed to levels of pollutants investigated about twice higher than if this theoretical consumer had chosen only products from extractive fisheries [wild-caught fish].” So, when it comes to pollutants, you could eat twice the amount of fish if you stuck to wild-caught. That’s easier said than done, though. Mislabeling rates for fish and other seafood in the United States are between 30 and 38 percent, so the average fraud rate is around one in three.  

    In my previous video on this topic, How Long to Detox from Fish Before Pregnancy, I mentioned a study that suggests detoxing from fish for one year to lower mercury levels, but other pollutants take longer to leave our system. 

    For optimum brain development, consider a pollutant-free source of omega-3 fatty acids. Check out Should Vegan Women Supplement with DHA during Pregnancy?. 

    Aside from pollutants, there are other reasons we may want to avoid excessive amounts of animal protein. See Flashback Friday: The Effect of Animal Protein on Stress Hormones, Testosterone, and Pregnancy.

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    Michael Greger M.D. FACLM

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  • Wildfire Masking Is Just Different

    Wildfire Masking Is Just Different

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    Late last night, New Yorkers were served a public-health recommendation with a huge helping of déjà vu: “If you are an older adult or have heart or breathing problems and need to be outside,” city officials said in a statement, “wear a high-quality mask (e.g. N95 or KN95).”

    It was, in one sense, very familiar advice—and also very much not. This time, the threat isn’t viral, or infectious at all. Instead, masks are being urged as a precaution against the thick, choking plumes of smoke from Canada, where wildfires have been igniting for weeks. The latest swaths of the United States to come into the crosshairs are the Midwest, Ohio Valley, Northeast, and Mid-Atlantic.

    The situation is, in a word, bad. Yesterday, New Haven, Connecticut, logged its worst air-quality reading on record; in parts of New York and Pennsylvania, some towns have been shrouded in pollutants at levels the Environmental Protection Agency deems “hazardous”—the more severe designation on its list. It is, to put it lightly, an absolutely terrible time to go outside. And for those who “have to go outdoors,” says Linsey Marr, an environmental engineer at Virginia Tech, “I’d strongly recommend wearing a mask.”

    The masking advice might understandably spark some whiplash. For the majority of Americans, face coverings are still most saliently a COVID thing—a protective covering meant to be worn when engaging in risky gatherings indoors. Now, though, we’re having to flip the masking script: Right now, it’s outdoor air that we most want to guard our airways against. In more ways than one, the best masking practices in this moment will require snubbing some of our basest COVID-fighting instincts.

    The COVID masking mindset can, to be fair, still be helpful to game out the risks at play. Viral outbreaks and wildfires both introduce dangerous particles into the eyes and the airway; both can be blocked with the right barriers. The difference is the source: Pathogens travel primarily aboard people, making crowds and crummy indoor airflow some of the biggest risks; fires and their smoky, ashy by-products, meanwhile, can get stoked and moved about by the very outdoor winds we welcome during viral outbreaks. Conflagrations clog the air with all sorts of pollutants—among them, carbon monoxide, which can poison people by starving them of oxygen, and a class of chemicals called polycyclic aromatic hydrocarbons that’s been linked to increased cancer risk. But the primary perils are the fine-particulate-matter components of soot, ash, and dust, fine enough to be borne over great distances until they reach an unsuspecting face.

    Once breathed in, these particles, which the EPA tracks by a metric known as PM2.5, can deposit deep in the airway and possibly even infiltrate the blood. The flecks irritate the moist membranes that line the nose, mouth, lungs, and eyes; they spark bouts of inflammation, triggering itching and irritation. Chronic exposure to them has been linked to heart and lung issues, and the risks are especially high for individuals with chronic medical conditions—burdens that concentrate among people of color and the poor—as well as for older adults and children.

    But N95s and many other high-quality masks have their roots in environmental health; they were designed specifically to filter out microscopic particulate matter that travels through the air. And they’re astoundingly good at their job. Jose-Luis Jimenez, an aerosol scientist at the University of Colorado at Boulder, recently put their performance to the test with an N95 strapped to his own face. Using an industry-standard test, he measured the particulate matter outside the mask, then checked how much made it through the device and into the space around his nose and mouth. Percentage-wise, he told me, “it removes 99.99 … I didn’t measure how many nines; it was working so well.” On broader scales, too, the protective math plays out: Well-fitting masks can curb smoke-related hospitalizations; studies back up their importance as a firefighting mainstay.

    The key, Jimenez told me, is choosing the right mask and getting it flush against your face. Experts in the field even get professionally fit-tested to avoid contamination infiltrating through any gaps. Surgical masks, cloth masks, or any other loose accessories that aren’t specifically designed to filter out tiny particles just won’t do the trick, though they’re still better than not covering up at all. (If that sounds familiar, it should; viral or smoky, “masks don’t care what the particle is,” Marr told me. “They care about the size.”)

    N95 masks aren’t perfect protectives either. They don’t shield the eyes, and they aren’t great at staving off carbon monoxide and the other gaseous pollutants that wildfires emit. (That’s for a reason: Allowing gas through masks is how we continue to breathe while wearing them.) But gases are volatile and quickly dissipate; for Americans hundreds or even thousands of miles from the source of the smoke, “it’s going to be the particulate matter that is most concerning to us,” Marr told me. Even in the parts of New York and Pennsylvania where PM2.5 has rocketed up to dangerous levels, the carbon-monoxide stats have remained low.

    Considering how dicey the discourse over masking has gotten, masking advice won’t necessarily be embraced by all. Less than a month after the official end of the United States’ COVID public-health emergency, people are fatigued by face coverings and other mitigations. And we’re fast entering the stretch of the year when having synthetic polymer fabrics strapped across your face can get downright miserable, especially in the humidity of northeastern heat. But when it comes to avoiding the harms of wildfire smoke, experts generally consider masks a second-line defense. The first priority is trying to minimize any exposure at all—which, for now, means staying indoors with the doors and windows tightly shut, especially for people at highest risk. Paula Olsiewski, an environmental-health researcher at the Johns Hopkins Center for Health Security, also recommends running whatever air filters might be available; air conditioners, portable air cleaners, and DIY air filters all help.

    It’s also a good time, experts told me, to be mindful of the differences between filtration and ventilation, or increasing flow to turn over stale air. Both are crucial, sustainable interventions against respiratory viruses. But in the context of wildfires, excellent ventilation could actually increase harm, Jimenez told me, by allowing in excess smoke. For right now, stale indoor air—a classic COVID foe—is a smoke-avoider’s ally. The masks come in for anyone who must go outside in a part of the country where the air quality is bad—say, above an index of 150 or so.

    The move might feel especially counterintuitive for people who have long since stopped masking against COVID—or even ones who still do, simply because the rules don’t mesh. Through the flip-flopping guidance of mask everywhere to mask until you’re vaccinated to actually, mask after you’re vaccinated too to mask only indoors, Americans never hit much of a stable rhythm with the practice. The inertia may be especially powerful on the East Coast, which has largely been spared from the scourge of wildfires that’s constantly plaguing the West. (That puts the U.S. well behind other countries, especially in East Asia, where masking against viruses and pollutants indoors and out has long been commonplace; even in California, N95 and HEPA shortages aren’t anything new.)

    That said, our COVID-centric view on masking was always going to get a wake-up call. Wildfires—and viral outbreaks, for that matter—are expected to become more common going forward, even in regions that haven’t historically experienced them. And for all their weariness with COVID, Americans now have far more awareness of and, in many cases, access to masks than they did just a few years ago. The wildfires aren’t good news, but maybe a mask-friendly response to them can be. Smoke does, from a public-health perspective, have one thing going for it, Olsiewski told me: It is visible and ominous in ways that a microscopic virus is not. “People can see that their air is not clean,” she told me. It’ll take more than ash and haze to break through the divisiveness around masks. But a threat this obvious might at least forge a tiny crack.

    This story is part of the Atlantic Planet series supported by the HHMI Department of Science Education.

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    Katherine J. Wu

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