Sept. 5, 2024 – Microplastics: the itty-bitty particles scattered throughout our food, beauty products, and even the air we breathe.
Research has shown that microplastics may have a range of health implications, from heart disease and stroke to digestive problems, and they may even cause cancer.
But did you know these microscopic bits can also trigger weight gain? Microplastics can influence our levels of cortisol, or stress hormones, said Christopher Thompson, MD, a Harvard Medical School researcher who specializes in weight loss.
“Microplastics are hormone disruptors and can mimic cortisol, estrogen, and other hormones,” he said.
Cortisol is a hormone found in our bodies that helps regulate our blood sugars, lessen inflammation, and keep our blood pressure in check. High levels of cortisol are known to adversely affect our weight. Too much of this stress hormone can cause Cushing’s syndrome, which can make you gain weight in your midsection, around your neck, and in your face, and can also trigger high blood pressure.
“Cortisol is linked to obesity in many ways, and people recognize it as that,” Thompson said. “If you have a microplastic that's mimicking cortisol and the effect of cortisol, you can see how that would be tied to weight gain.”
Here’s what makes this tricky. Microplastics are largely found in ultra-processed foods – like hot dogs, chips, and cookies – which make up more than half of the diet for U.S. adults, according to the CDC.
“We know that ultra-processed food can be quite detrimental to metabolism,” said Angel Nadal, PhD, a physiology professor at Miguel Hernandez University of Elche in Spain. “I wouldn't neglect microplastics, and their endocrine-disrupting effect, as an important factor in this.”
Microplastics can be more difficult to survey and measure than other environmental challenges of the past – like heavy metals – so new tracking methods are needed to find more data on their risks and effects, said Andrew West, PhD, a neurology professor at Duke University School of Medicine in Durham, NC.
“These are new types of molecules that we haven't seen before in our daily exposures,” he said. “Concentrations continue to rise as we put more and more into the environment, and it's returning as smaller and smaller particles (which makes it harder for us to find them). If they wind up integrating in important pathways that determine health outcomes, I think it is going to have important effects that we have to better understand.”
There are ways you can limit your exposure to microplastics.
“You never want to microwave your food in a plastic container because you're going to be transferring those plastics at a higher rate into your food,” Thompson said. “That's exactly what they're doing when they're processing food: They're heating up elements of the food in plastic, combining it together, and putting it in a plastic wrapper.”
It’s important to note that in today’s world, it is impossible to completely avoid microplastics. That’s why your goal should be to lessen your exposure instead, Thompson said. You can do this by eating whole foods that aren't packaged in plastic, like meat, fruits, and vegetables. You should also try to avoid using plastic water bottles and eating utensils, as well as plastic cutting boards, he said.
“You have to build a plan to minimize microplastic consumption,” Thompson said. “There's nothing that's been proven to remove microplastics from the human body. Yet, there's some early research suggesting maybe certain probiotics can help trap them in your feces.”
Bisphenol A (BPA) is an industrial chemical used in certain plastic products – like water bottles and food containers – that the FDA says is generally safe for humans if ingested in small doses. “In animals, such chemicals have been shown to produce metabolic disruption, insulin resistance, and increase weight,” according to Nadal. “In humans, epidemiological studies have associated exposure to these chemicals with diabetes and obesity.”
You may have seen some packaging with a “BPA free” label. However, “BPA free” does not mean it's safe, said Thompson. Manufacturers will often substitute BPA for its “chemical cousins,” bisphenol F and bisphenol S. These chemicals are also hormone disruptors, he warned.
“We're allowed these chemical substitutions, and it gives us a false sense of security where it must be safe for my kid or myself,” Thompson said. “Well, it's not. It's all plastics: It's not trying to find the one that doesn't have the bad chemicals in it.”
