How to Avoid BPA

The purported link between obesity and hormone-disrupting plastics chemicals like bisphenol A (BPA) was initially based in part on observations that the rise in chemical exposure seemed to coincide with the rise of the obesity epidemic, but that may only be a coincidence. Many other changes over the last half century, like an increase in fast-food consumption and watching TV, would seem to be simpler explanations. But why are our pets getting fatter, too? Fido isn’t drinking more fries or drinking more soda. Of course, the more we watch Seinfeld reruns, the less we may walk the dog, but what about our cats? They’re also getting fatter. Are we giving both them and our kids a few too many treats? That would seem to be an easier explanation than some pervasive obesity-causing chemical in the environment building up in the pet and person food chains.

How then do we explain the results of a study of more than 20,000 animals from 24 populations, showing they are all getting fatter? The odds that this could happen just by chance is about 1 in 10 million. The study’s “findings reveal that large and sustained population increases in body weight” are occurring across the board, even in those without access to vending machines or getting less physical education in schools. Perhaps some environmental pollutant is involved. I discuss this in my video How to Avoid the Obesity-Related Plastic Chemical BPA.

We’re exposed to a whole cocktail of new chemicals besides BPA, but the reason researchers have zeroed in on it is because of experiments showing that BPA can accelerate the production of new fat cells, at least in a petri dish. This was at more than a thousand times the concentration found in most people’s bloodstream, though. We didn’t know if the same thing happened at typical levels…until now. Most people have between 1 and 20 nanomoles of BPA in their blood, but even 1 nanomole may significantly boost human fat cell production. So, even low levels may be a problem, but that’s in a petri dish. What about in people?

Why not just measure the body weights of a population exposed to the chemical compared to a population not exposed to the chemical? There is virtually no unexposed population: BPA is everywhere. In that case, how about those with higher levels compared to those with lower levels? This is what researchers at New York University did, and the amount of BPA flowing through the bodies of children and adolescents “was significantly associated with obesity.” However, since it was a cross-sectional study, a snapshot in time, we don’t know which came first. Maybe instead of the high BPA levels leading to obesity, the obesity led to high BPA levels, since the chemical is stored in fat. Or, perhaps BPA is a marker for the same kinds of processed foods that can make you fat. What we need are prospective studies that measure exposure and then follow people over time. We never had anything like that…until now! And indeed, researchers found that higher levels of BPA and some other plastics chemicals were significantly associated with faster weight gain over the subsequent decade. So, how can we stay away from the stuff?

Though we inhale some from dust and get some through our skin touching BPA-laden receipts, 90 percent of exposure is from our diet. How can we tell? When we have people fast and drink water only out of glass bottles for a few days, their BPA levels drop as much as tenfold.

Fasting isn’t very sustainable, though.

What happens with a three-day fresh foods intervention, where families switch away from canned and packaged foods for a few days? A significant drop in BPA exposure. If we do the experiment the other way, adding a serving of canned soup to people’s daily diet, we see a thousand percent rise in BPA levels in their urine compared to a serving of soup prepared with fresh ingredients. That study used a ready-to-serve canned soup, which, in the largest survey of North American canned foods, was found to have about 85 percent less BPA than condensed soups, but the worst was canned tuna.


I previously touched upon bisphenol A in BPA Plastic and Male Sexual Dysfunction. Some companies make canned foods without BPA, for example, Eden Foods. (See Do Eden Beans Have Too Much Iodine? for more information.) You can also buy aseptic packaged beans or boil your own. Personally, I like pressure-cooking them.

For more on BPA, see:

Phthalates are another concerning class of plastics chemicals. I covered those in Avoiding Adult Exposure to Phthalates and What Diet Best Lowers Phthalate Exposure?.

In health,
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:

Where to Buy Tea Low in Lead

China burns about half of the world’s coal, spewing heavy metals such as mercury and lead into the atmosphere that affect the development of neighboring children. What if you don’t live in China or eat anything produced there? You could still be exposed to the mercury that settles in the oceans if you eat fish and other seafood. What if you drink something from China? Tea. China is one of the world’s biggest tea exporters, but their rapid industrialization has raised concerns about contamination with lead, a toxin that can affect almost every organ in the body. The more lead there is in the soil, the more lead there is that ends up in the tea leaves. And, the closer to the highway the tea is grown, the higher the lead levels. This suggests that leaded gas, which wasn’t banned in China until the year 2000, may be playing a role in the contamination of tea grown there.

Just like larger and longer-living fish accumulate more mercury, longer-living tea leaves accumulate more lead. Young tea leaves appear to have two to six times less lead than mature leaves, so the young leaves that are used to make green and white tea have significantly less lead than the older leaves used to make black and oolong tea. As well, the lead in black and oolong tea appears to be released much more readily into the tea water when brewed. This means the health risk from lead may be 100 times lower for green tea compared to oolong and black.

Because certain fungicides may have heavy metal impurities, one might assume organic teas would be less contaminated. However, a study of 30 common teas taken from North American store shelves showed no less toxic element contamination in organic teas than regular teas, though, organic teas would presumably have much less pesticide contamination. In terms of lead, the source of the tea—that is, the country of origin—appears to be the most important factor.

So, how much tea is safe to drink? Based on the most stringent safety limits in the world, such as California’s Prop 65 parameters, and the largest studies of tea lead contamination from around the world, I was able to come up with guidelines I outline in my video Lead Contamination of Tea.

If you’re not pregnant and drinking only green tea, it doesn’t matter where you get your tea. You can drink as much as you want, as long as you’re drinking the green tea and throwing away the leaves or bags. Given the average levels of lead in Chinese black tea samples, however, more than three cups a day would exceed the daily safety limit for lead. What if you’re eating tea leaves—for example, drinking matcha tea, which is powdered green tea—or throwing tea leaves into your smoothie like I do? In that case, two or three heaping teaspoons is the limit. The exception is Japanese green tea, which is so low in lead that you can safely eat 15 spoonfuls per day, but I caution consuming more than 8 teaspoons given the risk of exceeding the daily recommended limit for caffeine intake for adults.

What about children? For a 70-pound 10-year-old, lead isn’t a problem if they’re drinking green tea. But the safe caffeine intake for children is probably around three milligrams per kilogram, which would limit a child to about four cups of green tea per day. For caffeine reasons, I recommend adding no more than two spoonfuls of Japanese green tea to a child’s smoothie. And for lead reasons, children should have no more than one teaspoon of Chinese green tea leaves. When it comes to black tea, children shouldn’t drink more than one cup per day and should not eat the tea leaves at all.

Pregnant women should be able to drink one cup of green tea per day throughout pregnancy, regardless of source. The limit for Japanese green tea is really just the caffeine limit of about four cups per day. I do not recommend drinking black tea during pregnancy or eating any kind of tea leaves, unless you know you’re getting tea from a low lead source.


I’ve long been an advocate of teas, but the information I’ve shared with you here has led me to change my daily diet. If you look at my smoothie recipe in A Better Breakfast, for example, you’ll see I’ve recommended throwing in tea leaves, and Is Matcha Good for You? doesn’t hide the fact that I’ve been a big fan of matcha. I still enjoy both, but am now more careful about where my tea is sourced. As soon as I learned of this, I made announcements on Facebook, Twitter, and Google+ to inform everyone. So, if you closely follow my recommendations (which I elaborate on extensively in my book, How Not to Die), please make sure to keep an eye on our social media where I can post updates within minutes of learning about the latest news.

I’ve got a whole slew of tea videos, including:

Where else might you find heavy metal risk (besides my music collection :)?

In health,
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:

The post Where to Buy Tea Low in Lead appeared first on NutritionFacts.org.

Foods to Avoid to Help Prevent Diabetes

We’ve known that being overweight and obese are important risk factors for type 2 diabetes, but, until recently, not much attention has been paid to the role of specific foods. I discuss this issue in my video, Why Is Meat a Risk Factor for Diabetes?

A 2013 meta-analysis of all the cohorts looking at the connection between meat and diabetes found a significantly higher risk associated with total meat consumption––especially consumption of processed meat, particularly poultry. But why? There’s a whole list of potential culprits in meat: saturated fat, animal fat, trans fats naturally found in meat, cholesterol, or animal protein. It could be the heme iron found in meat, which can lead to free radicals and iron-induced oxidative stress that may lead to chronic inflammation and type 2 diabetes, or advanced glycation end (AGE) products, which promote oxidative stress and inflammation. Food analyses show that the highest levels of these so-called glycotoxins are found in meat—particularly roasted, fried, or broiled meat, though any foods from animal sources (and even high fat and protein plant foods such as nuts) exposed to high dry temperatures can be potent sources of these pro-oxidant chemicals.

In another study, researchers fed diabetics glycotoxin-packed foods, like chicken, fish, and eggs, and their inflammatory markers––tumor necrosis factor, C-reactive protein, and vascular adhesion molecules––shot up. “Thus, in diabetes, environmental (dietary) AGEs promote inflammatory mediators, leading to tissue injury.” The good news is that restriction of these kinds of foods may suppress these inflammatory effects. Appropriate measures to limit AGE intake, such as eliminating meat or using only steaming and boiling as methods for cooking it, “may greatly reduce the already heavy burden of these toxins in the diabetic patient.” These glycotoxins may be the missing link between the increased consumption of animal fat and meats and the development of type 2 diabetes.

Since the 2013 meta-analysis was published, another study came out in which approximately 17,000 people were followed for about a dozen years. Researchers found an 8% increased risk for every 50 grams of daily meat consumption. Just one quarter of a chicken breast’s worth of meat for the entire day may significantly increase the risk of diabetes. Yes, we know there are many possible culprits: the glycotoxins or trans fat in meat, saturated fat, or the heme iron (which could actually promote the formation of carcinogens called nitrosamines, though they could also just be produced in the cooking process itself). However, we did learn something new: There also appears to be a greater incidence of diabetes among those who handle meat for a living. Maybe there are some diabetes-causing zoonotic infectious agents––such as viruses––present in fresh cuts of meat, including poultry.

A “crucial factor underlying the diabetes epidemic” may be the overstimulation of the aging enzyme TOR pathway by excess food consumption––but not by the consumption of just any food: Animal proteins not only stimulate the cancer-promoting hormone insulin growth factor-1 but also provide high amounts of leucine, which stimulates TOR activation and appears to contribute to the burning out of the insulin-producing beta cells in the pancreas, contributing to type 2 diabetes. So, it’s not just the high fat and added sugars that are implicated; critical attention must be paid to the daily intake of animal proteins as well.

According to a study, “[i]n general, lower leucine levels are only reached by restriction of animal proteins.” To reach the leucine intake provided by dairy or meat, we’d have to eat 9 pounds of cabbage or 100 apples to take an extreme example. That just exemplifies the extreme differences in leucine amounts provided by a more standard diet in comparison with a more plant-based diet.

I reviewed the role endocrine-disrupting industrial pollutants in the food supply may play in a three-part video series: Fish and Diabetes, Diabetes and Dioxins, and Pollutants in Salmon and Our Own Fat. Clearly, the standard America diet and lifestyle contribute to the epidemic of diabetes and obesity, but the contribution of these industrial pollutants can no longer be ignored. We now have experimental evidence that exposure to industrial toxins alone induces weight gain and insulin resistance, and, therefore, may be an underappreciated cause of obesity and diabetes. Consider what’s happening to our infants: Obesity in a six-month-old is obviously not related to diet or lack of exercise. They’re now exposed to hundreds of chemicals from their moms, straight through the umbilical cord, some of which may be obesogenic (that is, obesity-generating).

The millions of pounds of chemicals and heavy metals released every year into our environment should make us all stop and think about how we live and the choices we make every day in the foods we eat. A 2014 review of the evidence on pollutants and diabetes noted that we can be exposed through toxic spills, but “most of the human exposure nowadays is from the ingestion of contaminated food as a result of bioaccumulation up the food chain. The main source (around 95%) of [persistent pollutant] intake is through dietary intake of animal fats.”


For more on the information mentioned here, see the following videos that take a closer look at these major topics:  

AGEs: Glycotoxins, Avoiding a Sugary Grave, and Reducing Glycotoxin Intake to Prevent Alzheimer’s.

TOR: Why Do We Age?, Caloric Restriction vs. Animal Protein Restriction, Prevent Cancer From Going on TOR, and Saving Lives By Treating Acne With Diet

Viruses: Infectobesity: Adenovirus 36 and Childhood Obesity

Poultry workers: Poultry Exposure and Neurological Disease, Poultry Exposure Tied to Liver and Pancreatic Cancer, and Eating Outside Our Kingdom

Industrial pollutants: Obesity-Causing Pollutants in Food, Fish and Diabetes, Diabetes and Dioxins, and Pollutants in Salmon and Our Own Fat

The link between meat and diabetes may also be due to a lack of sufficient protective components of plants in the diet, which is discussed in my videos How May Plants Protect Against Diabetes?, Plant-Based Diets for DiabetesPlant-Based Diets and Diabetes, and How Not to Die from Diabetes.

In health,

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: