Are the BPA-Free Plastics Like Tritan Safe?

Do BPA-free plastics such as Tritan, have human hormone-disrupting effects? And what about BPS and BPF?

Recent human studies indicate that exposure to the plastics chemical BPA may be associated with infertility, miscarriage, premature delivery, reduced male sexual function, polycystic ovaries, altered thyroid and immune function, diabetes, heart disease, and more. Yet, “[a]s recently as March 2012, FDA stated that low levels of BPA in food are considered safe.” However, just months later, to its credit, the agency banned the use of BPA plastics in baby bottles and sippy cups. Regulators standing up to industry? Maybe I shouldn’t be so cynical! But, wait. The ban was at the behest of the plastics industry. It had already stopped using BPA in baby bottles so it was their idea to ban it.

The industry had switched from BPA to similar compounds like BPF and BPS. So, our diets now contain everything from BPA to BPZ, and the majority of us have these new chemicals in our bodies as well. Are they any safer?

As I discuss in my video Are the BPA-Free Alternatives Safe?, based on the similarities of their chemical structures, they are all predicted to affect testosterone production and estrogen receptor activity, as you can see at 1:40 in my video. However, they were only recently put to the test.

As you can see at 1:50 in my video, we’ve known BPA significantly suppresses testosterone production, and, from “the first report describing BPS and BPF adverse effects on physiologic function in humans,” we know those compounds do, too. Well, kind of. The experiments were performed on the testicles of aborted human fetuses. But, the bottom line is that BPS and BPF seem to have “antiandrogenic anti-male hormone effects that are similar to those of BPA.” So when you’re assured you shouldn’t worry because your sales slip is BPA-free, the thermal paper may just contain BPS instead. What’s more, BPS receipts may contain up to 40 percent more BPS than they would have contained BPA. So BPA-free could be even worse. In fact, all BPA-replacement products tested to date released “chemicals having reliably detectable EA,” estrogenic activity.

This includes Tritan, which is specifically marketed as being estrogen-activity-free. As you can see at 3:06 in my video, however, researchers dripped an extract of Tritan on human breast cancer cells in a petri dish, and it accelerated their growth. This estrogenic effect was successfully abolished by an estrogen blocker, reinforcing it was an estrogen effect. Now, the accelerated growth of the cancer cells from the Tritan extract occurred after the plastic was exposed to the stressed state of simulated sunlight. Only one out of three Tritan products showed estrogen activity in an unstressed state, for instance when they weren’t exposed to microwaving, heat, or UV rays. “Because there would be no value in trading one health hazard for another, we should urgently focus on the human health risk assessment of BPA substitutes.”

In the meanwhile, there are steps we can take to limit our exposure. We can reduce our use of polycarbonate plastics, which are usually labeled with recycle codes three or seven, and we can opt for fresh and frozen foods over canned goods, especially when it comes to tuna and condensed soups. Canned fruit consumption doesn’t seem to matter, but weekly canned vegetable consumption has been associated with increased BPA exposure. If you do use plastics, don’t microwave them, put them in the dishwasher, leave them in the sun or a hot car, or use once they’re scratched. But using glass, ceramic, or stainless steel containers is probably best.


For more on BPA, check out my videos:

Unfortunately, BPA isn’t the only plastics chemical that may have adverse health effects. See:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Eating Seaweed Salad May Boost Immune Function

Eating seaweed salad may boost the efficacy of vaccinations and help treat cold sores, herpes, Epstein-Barr virus, and shingles.

Billions of pounds of seaweed are harvested each year, the consumption of which “has been linked to a lower incidence of chronic diseases,” both physical and mental. For example, women who eat more seaweed during pregnancy appear to be less depressed and experience fewer seasonal allergy symptoms. There’s a problem with these cross-sectional, correlational studies, however, in that they can’t prove cause and effect. Maybe seaweed consumption is just an indicator that people generally are following “traditional Japanese dietary customs,” which have lots of different aspects that could protect against disease. To know for certain whether seaweed can modulate immune function, you have to put it to the test.

As I discuss in my video How to Boost Your Immune System with Wakame Seaweed, typically, researchers start out with in vitro studies, meaning in a test tube or a petri dish, which make for quicker, cheaper, and easier experiments. One study, for example, took eight different types of seaweed and essentially made seaweed teas to drip onto human immune system cells in a petri dish. Studies like these showed that the seaweed wakame, which is the kind you find in seaweed salad, can quadruple the replication potential of T cells, which are an important part of our immune defense against viruses like herpes simplex virus.

No one actually gave seaweed to people with herpes until a study published in 2002. Researchers gave people suffering from various herpes infections about two grams a day of pure powdered wakame, which is equivalent to about a quarter cup of seaweed salad. “All fifteen patients with active Herpetic viral infections”—including herpes virus 1, the cause of oral herpes, which causes cold sores; herpes virus 2, which causes genital herpes; herpes virus 3, which causes shingles and chicken pox; and herpes virus 4, also known as Epstein-Barr virus, which causes mono—“experienced significant lessening or disappearance of symptoms,” as you can see at 2:06 in my video. There was no control group in the study, but with no downsides to eating seaweed, why not give it a try?

Researchers also found that wakame boosted antibody production, so could it be useful to boost the efficacy of vaccines? The elderly are particularly vulnerable to suffering and dying from influenza. While the flu vaccine can help, ironically, the elderly are less likely to benefit from it because immune function tends to decline as we get older. So, researchers took 70 volunteers over the age 60. As you can see at 2:50 in my video, their baseline level of antibodies against a flu virus was about 10 GMT. What you’re looking for in a vaccination is to get a two-and-a-half-fold response, so we’d like to see that antibody level get up to at least 25 GMT to consider it an effective response. The vaccine only boosted levels to 15 to 20 GMT, though. What happened after the subjects were given some wakame extract every day for a month before the vaccination? Their levels jumped up to 30 to 35 GMT. The researchers used an extract in a pill rather than the real thing, though, so they could perform this randomized placebo-controlled study. After all, it’s kind of hard to make a convincing placebo seaweed salad.

“It is hoped that the popular seaweeds eaten daily in Japan, though almost unknown around the world outside of Japanese restaurants, will be consumed…for possible immunopotentiation”—that is, immune-boosting potential—“and for attenuating the burden of infectious diseases in the elderly.”

What else can seaweed salad do (other than taste delicious)? See my video Wakame Seaweed Salad May Lower Blood Pressure.

In general, sea vegetables are good sources of iodine, as I discuss in Iodine Supplements Before, During, and After Pregnancy, and may also be one reason Japanese women have historically had such low rates of breast cancer, which I cover in Which Seaweed Is Most Protective Against Breast Cancer?.


What else can we do to boost our immunity? Check out my videos:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

What Happens When Pregnant Women Eat More Animal Protein

Are high-protein diets during pregnancy healthful or harmful? That question was answered about 40 years ago in the infamous Harlem Trial of 1976: a “randomized controlled trial of nutritional supplementation pregnancy, in a poor black urban population in the United States.” The study, which I discuss in my video The Effect of Animal Protein on Stress Hormones, Testosterone, and Pregnancy, “was begun when protein was commonly assumed to be deficient in the diet of the poor.” Had researchers actually analyzed their diets before they started, they would have realized that this wasn’t true, but why let facts get in the way of assumptions? So, the researchers split poor black pregnant women into three groups, each receiving one of the following treatments: (1) an extra 40 grams of animal protein a day, which is essentially a couple cans of Ensure, (2) an extra 6 grams of animal protein, or (3) no extra protein. Then they sat back and watched what happened. The high-protein group suffered “an excess of very early premature births and associated neonatal [infant] deaths, and there was significant growth retardation” in the babies who survived. More protein meant more prematurity, more deaths, and more growth retardation, which you can see reflected in the chart at 1:00 in my video.

What’s more, 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 systolic 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 discussed in my video Animal Protein, Pregnancy, and Childhood Obesity, or the animal protein-induced rise in the growth hormone IGF-1. Or, it could be due to a steroid stress hormone called cortisol.

As you can see in the chart at 2:01 in my video, a single meal high in animal protein can nearly double the level of the stress hormone in the blood within a half hour of consumption, much more than a meal closer to the recommended level of protein. When subjects are given a meal of crab, tuna fish, and cottage cheese, the stress hormone level shoots up. If they’re instead given some barley soup and a vegetable stir-fry on rice, the stress hormone level goes down after the meal, as you can see at 2:27 in my video. Imagine eating meat-fish-dairy meals day after day. Doing so “may chronically stimulate” our stress response axis “and increase the release of vasoactive hormones” that could increase our blood pressure. And, all that extra cortisol release has been linked to increased risk for elevated blood levels of insulin, triglycerides, and cholesterol.

When men on a high-protein diet, “such as meat, fish, poultry, egg white,” were switched to a high-carb diet of bread, vegetables, fruit, and sugary junk, their cortisol levels dropped about a quarter within 10 days. At the same time, their testosterone levels shot up by about the same amount, as you can see at 3:09 in my video. High-protein diets suppress testosterone. That is why, if men eating plant-based diets begin to eat meat every day, their testosterone levels go down and some estrogens actually go up, and 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, there is a 75 percent drop in testosterone levels in the months leading up to a competition. Testosterone levels were cut by more than half, which is enough to drop a guy into an abnormally low range, as you can see at 3:47 in my video. It’s ironic that they’re eating protein to look manly on the outside, but it can make 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 and body fat. What does cortisol have to do with weight?

There’s actually a disease caused by having too much cortisol, called Cushing’s syndrome, which can increase abdominal obesity. Even in normal women, though, chronic stress and chronic high cortisol levels can contribute to obesity. What’s more, if they’re pregnant, high-meat and low-carb diets may increase cortisol levels in the moms, which can lead to inappropriate fetal exposure to cortisol, which, in turn, can affect the developing fetus, resetting her or his whole stress response thermostat and leading to higher cortisol levels in later adult life. This can have serious, life-long health consequences. Every maternal daily portion of meat and fish was associated with 5 percent higher cortisol levels in their children as much as 30 years later, though green vegetable consumption was found to be protective. Higher meat consumption, such as 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, as you can see at 5:12 in my video.

As well, the adult children of mothers who ate a lot of meat during pregnancy don’t only have higher stress hormone levels, they also appear to react more negatively to whatever life throws at them. Researchers put them through the Trier Test, which involves public speaking in front of a panel of judges, following by a live math exercise. You can see in my video at 5:36 a chart comparing the stress hormone responses in those whose moms ate less than two servings of meat per day, about two servings a day, or about two to three servings a day. Note that before the test started, the cortisol levels of the two groups eating less meat started out about the same, but their exaggerated cortisol response was laid bare when exposed to a stressful situation. The real-world effects of this are that after that sort of test, when people are given their own private snack buffet with fruits and veggies versus fatty, sugary, comfort foods like chocolate cake, guess who may eat less of the fruits and veggies? Those who have high chronic stress levels. “Cortisol has been implicated as a factor in motivating food intake” even when we aren’t really hungry.

It’s no surprise then that a woman’s animal protein intake during pregnancy may lead to larger weight gain for her children later in life—and maybe even for her grandchildren. “Remarkably, recent evidence suggests that the long-term consequences of adverse conditions during early development may not be limited to one generation, but may lead to poor health in the generations to follow, even if these individuals develop in normal conditions themselves.” Indeed, 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.


Whoa, there was a lot to unpack! Rather than break it up, since so much of it was tied together, as you could see, I compiled everything into this one, heftier piece. You may want to read this a second time and watch the video to absorb it all.

For more on how a woman’s diet during pregnancy can affect her children, see Maternal Diet May Affect Stress Responses in Children and Animal Protein, Pregnancy, and Childhood Obesity.

Protein is such a misunderstood nutrient. For more information, check out:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: