Food Contaminants Worsen Metabolic Problems in Obese Mice

Obese Rat

Story at-a-glance -

  • Mice fed low doses of food contaminants like dioxin, PCB, bisphenol A (BPA) and phthalates over the course of a lifetime experienced significant negative metabolic changes
  • The study suggests low doses of contaminants, even at levels normally considered to be without health impacts in humans, do in fact affect humans over the long term
  • When it comes to staying healthy, avoiding processed foods and replacing them with fresh, whole foods is important, as is sourcing your fresh foods from sustainable, responsible growers

By Dr. Mercola

What happens when you eat low doses of food contaminants like dioxin, PCB, bisphenol A (BPA) and phthalates over the course of a lifetime, starting in utero via your mother's consumption?

This is what French researchers recently set out to determine, albeit via a study on mice instead of humans.

"Mice were challenged from preconception throughout life with a high-fat diet containing pollutants commonly present in food… added at low doses in the tolerable daily intake range," the study, published in the FASEB Journal reported.1

Both male and female mice were affected by the contaminants, in quite different but equally disturbing ways. And considering that low doses of these same contaminants are pervasive in the food supply, it's not a stretch to think of yourself as just another lab rat...

Common Food Contaminants Lead to Potentially Dangerous Metabolic Changes

For the study, mice were fed a high-fat diet to which low doses of dioxin, PCB, BPA and phthalates were added (the mice were also born to mothers fed this diet). Compared to a control group of mice fed a contaminant-free high-fat diet, the contaminant group experienced significant metabolic changes. Specifically:

  • In females, glucose intolerance worsened and their estrogen pathway was altered
  • In males, both cholesterol and lipid metabolism were altered

The researchers noted:

"In males, pollutants increased the expression of hepatic [liver-related] genes (from 36 to 88%) encoding proteins related to cholesterol biosynthesis and decreased (40%) hepatic total cholesterol levels.

In females, there was a marked deterioration of glucose tolerance, which may be related to the 2-fold induction of estrogen sulfotransferase and reduced expression of estrogen receptor α (25%) and estrogen target genes (>34%).

Because of the very low doses of pollutants used in the mixture, these findings may have strong implications in terms of understanding the potential role of environmental contaminants in food in the development of metabolic diseases."

Endocrine-Disrupting Chemicals Likely to Cause Harm Even at Low 'Safe' Doses

The chemical contaminants used in the study were chosen not only because they're pervasive in the food supply, but also because they're known endocrine disruptors. The glands of your endocrine system and the hormones they release influence almost every cell, organ, and function of your body. It is instrumental in regulating mood, growth and development, tissue function, metabolism, as well as sexual function and reproductive processes.

Endocrine disrupters are substances or mixtures that alter the functions of your endocrine system and consequently cause adverse health effects, either in your body or in your offspring. These types of chemicals can exert their effects by:

  • Mimicking the biological activity of your hormones by binding to a cellular receptor. This can initiate your cell's normal response to the naturally-occurring hormone at the wrong time or to an excessive extent (agonistic effect).
  • Binding to the receptor but not activating it. Instead the presence of the chemical on the receptor prevents binding of the natural hormone (antagonistic effect).
  • Binding to transport proteins in your blood, thus altering the amounts of natural hormones that are present in your blood circulation.
  • Interfering with the metabolic processes in your body, affecting the synthesis or breakdown rates of your natural hormones.

The strongest evidence showing that exposure to these types of environmental chemicals can lead to disruption of endocrine function comes from the bizarre changes seen in a number of wildlife species, such as male fish transforming into females, frogs developing a variety of defects like multiple testes or ovaries, and hermaphrodite bears, just to name a few.  

Yet, it's commonly stated that these chemicals are not dangerous to humans because they exist at such low levels, even as research suggests otherwise. For instance, of 115 published animal studies, 81 percent found significant effects from even low-level exposure to BPA.

And the latest study only adds to this undeniable knowledge:

"With this study, we have succeeded in providing proof-of-concept that low doses of contaminants, even at levels normally considered to be without health impacts in humans, do in fact affect humans when subjected to chronic exposure, and when the contaminants are combined with a high-calorie diet," the researchers said.2

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What Are the Long-Term Health Risks from Exposure to Common Food Contaminants?

A typical American comes in regular contact with some 6,000 chemicals and an untold number of potentially toxic substances on a less frequent basis. There are about 75,000 chemicals regularly manufactured and imported by US industries, so you could be exposed to any number of them. Disturbingly, many of them have never been fully tested for safety, and virtually none have been studied in combination with one another, which is how real-world exposure occurs and where their toxicities can be amplified exponentially.

Upwards of 20 environmental chemicals, most of them endocrine-disrupting chemicals, have been shown to cause weight gain when exposure occurs during fetal and infant development, although some are also linked to adult exposures. Others, including BPA, PCBs, phthalates and agricultural pesticides can lead to health problems including:

Non-descended testes in young males Breast cancer in women Prostate cancer in men
Developmental effects on the nervous system in children Attention deficit hyperactivity in children Thyroid cancer


According to a World Health Organization (WHO) and United Nations Environment Program (UNEP) report:3

"The diverse systems affected by endocrine-disrupting chemicals likely include all hormonal systems and range from those controlling development and function of reproductive organs to the tissues and organs regulating metabolism and satiety. Effects on these systems can lead to obesity, infertility or reduced fertility, learning and memory difficulties, adult-onset diabetes or cardiovascular disease, as well as a variety of other diseases."

Specifically, health problems linked to some of the most common food contaminants include:

  • BPA: Plasticizing chemicals like BPA, found in plastics and canned food linings, disrupt embryonic development and are linked to heart disease and cancer. Beware that many manufacturers of 'BPA-free' products have simply replaced BPA with bisphenol-S (BPS), an equally toxic chemical. More recently, research has found that other bisphenols used in the production of consumer products, namely, bisphenols M, AP and P, are actually more toxic to DNA than BPA.4
  • Phthalates: Phthalates dysregulate gene expression and cause genital anomalies, especially in baby boys, that may pass down several generations. Phthalates are found in vinyl flooring, detergents, automotive plastics, soap, shampoo, deodorants, fragrances, hair spray, nail polish, plastic bags, food packaging, garden hoses, inflatable toys, blood-storage bags, and intravenous medical tubing.
  • Dioxins: Dioxins are a byproduct of industrial processes, such as chlorine bleaching of paper products and the manufacturing of some pesticides. Because they are persistent environmental pollutants, they accumulate in the food chain and more than 90 percent of human exposure is through foods like meat, dairy products and fish. According to WHO, "Dioxins are highly toxic and can cause reproductive and developmental problems, damage the immune system, interfere with hormones and also cause cancer."5
  • PCBs: Like dioxins, PCBs are persistent organic pollutants (POPs) that persist in the environment and resist breaking down, accumulating in the food chain and posing serious risks to human health and the environment. For instance, even though PCBs have been banned in the US for decades, they are still present in your environment. PCBs and other POPs have caused birth defects and other abnormalities among wildlife, along with damage to virtually every human bodily system.

Tips for Finding the Purest Foods Possible

When it comes to staying healthy, avoiding processed foods and replacing them with fresh, whole foods is the "secret" you've been looking for. The more steps your food goes through before it reaches your plate, the greater your chances of contamination becomes. If you are able to get your food locally, you eliminate numerous routes that could expose your food to contamination with not only disease-causing pathogens but also with the chemical contaminants noted above, which often exist in food packaging.

It's also important to choose your fresh foods wisely, as you'll want to focus on those grown in non-polluted areas using organic farming methods. Whatever food you're looking to eat, whether organic or locally grown, from either your local supermarket or a farmer's market, the following are signs of a high-quality, healthy food. Most often, the best place to find these foods is from a sustainable agricultural group in your area. You can also review my free nutrition plan to get started on a healthy eating program today:

It's grown without pesticides and chemical fertilizers (organic foods fit this description, but so do some non-organic foods) It's not genetically engineered It contains no added growth hormones, antibiotics, or other drugs
It does not contain artificial anything, nor any preservatives It is fresh (if you have to choose between wilted organic produce or fresh conventional produce, the latter may still be the better option as freshness is important for optimal nutrient content) It was not grown in a concentrated animal feeding operation (CAFO)
It is grown with the laws of nature in mind (meaning animals are fed their native diets, not a mix of grains and animal byproducts, and have free-range access to the outdoors) It is grown in a sustainable way (using minimal amounts of water, protecting the soil from burnout, and turning animal wastes into natural fertilizers instead of environmental pollutants)