Think twice before putting bright-white candy or toothpaste in your mouth.

If you consume or use any of these routinely, you may begin to lose the ability to think once, much less twice.

The cause for concern is a metal compound called titanium dioxide, which is commonly used to whiten processed foods and personal care products.

Titanium dioxide is generally considered pretty safe … but there's much less certainty about the safety of tiny particles of this metal compound.

That's disturbing, because more and more foods and cosmetics contain so-called "nanoparticles” of titanium dioxide.

What are nanoparticles?
Nanoparticles are incredibly small particles, not much bigger than large molecules.

They measure between one and 100 billionth of one meter (a meter is about three feet) across.

Nanoparticles are small enough to get into human cells … yet scientists know little about how they affect our bodies.

And they don't know how much nano-size titanium dioxide is added to various food products … which makes it very hard to study the potential health risks.

Nevertheless, the U.S. Food and Drug Administration (FDA) approves the use of these invisibly small metal particles in foods and cosmetics.

Titanium nanoparticles pose proven health risks
Worldwide research has shown that titanium nanoparticles pose real health risks.

For the most part, those risks are related to increased oxidation or "rusting” of our cells and tissues.

Oxidation caused by titanium nanoparticles damages our cells and DNA, and promotes inflammation and self-destructive immune responses.

In part, their impact on human DNA explains why U.S. and international agencies classify titanium nanoparticles as possible cancer-causing agents.

Before we delve into disturbing new findings, it's important to know which foods and cosmetics are most likely to contain titanium nanoparticles.

Which foods and cosmetics carry these minuscule bits of metal?
Three years ago, scientists at Arizona State University tested 89 food and personal care products, looking for titanium dioxide.

They tested white-colored sweets and dairy products, as well as personal care products such as toothpaste and sunscreen.

And they were surprised to find that titanium dioxide levels in personal care products ranged from 1% to almost 10% titanium by weight. 

Worse, they found that more than one third (36%) of the titanium dioxide used in the foods they tested were nano-sized particles.

White candies and other white-colored sweets, such as doughnuts, had the highest titanium levels, with up to 340 milligrams (1/10 of 1 ounce) per serving.

The Arizona team found the highest levels in these categories of foods:
  • Candies with hard outer shells, such as M&Ms and white-coated chewing gums (like Chiclets).
  • Low-fat milk, soy drinks, rice-based drinks, mayonnaise, and processed white cheese singles.
And they found the highest levels in these categories of personal care products:
  • Toothpaste and sunscreens
  • White-colored shampoos, deodorants, and shaving creams
Based on government diet surveys, the Arizona researchers calculated that children consume two to four times as much titanium dioxide – much of it in nanoparticle form – as adults do.

How can you avoid eating or applying titanium nanoparticles?

Your best bet is to choose organic foods, and select "natural" or organic cosmetics that either don't list it as an ingredient, or list no undisclosed coloring agents.

The Arizona team noted that food sources account for the vast majority of titanium nanoparticles released into wastewater treatment plants.

Many of these tiny titanium particles passes right through the filters at wastewater plants, straight into rivers, lakes, and the ocean. 

Study sees brain damage risk from titanium nanoparticles
Recently, researchers from the University of Nebraska-Lincoln (UNL) reported a disturbing discovery.

They found that even modest consumption of titanium nanoparticles could harm the brain's most numerous cells (Wilson CL et al. 2015). 

The researchers examined how three types of titanium dioxide nanoparticles affected so-called "astrocyte” brain cells.

Among other critical functions, astrocytes help regulate the brain's neurotransmitters (such as serotonin and dopamine), and supply energy to the cells that process their signals.

The Nebraska team exposed astrocyte cells from rats to levels of titanium nanoparticles well below the levels previously shown to kill brain cells.

At the highest level of exposure (100 parts per million or PPM), two types of titanium nanoparticles killed nearly two-thirds of the astrocyte-type brain cells within a day

That kill rate fell to between half and one-third of cells at 50 PPM, settling to about one-quarter at 25 PPM.

This matters because titanium nanoparticles are found in the brains of animals whose blood-brain barriers are similar to people's.

"There's evidence building up now that some of these particles can actually cross the (blood-brain) barrier,” said Oleh Khalimonchuk, the UNL biochemist who co-authored the study.

Surviving brain cells were damaged
The Nebraska researchers made another, even more troubling discovery.

They found that brain cells that survived exposure to titanium nanoparticles were harmed by the tiny bits of metal.

This damage related to a neurotransmitter called glutamate … which accounts for the irresistible taste of MSG, soy sauce, aged hard cheeses (such as Parmesan), tomatoes, and certain other foods.

(Glutamate is responsible for the savory "5th taste” – in addition to sweetness, sourness, bitterness, and saltiness – which the Japanese call umami.)

Astrocyte brain cells normally absorb and use glutamate, which plays wide-ranging roles in thinking, memory and learning … along with the formation, movement, and maintenance of other brain cells.

However, when brain cells are unable to absorb glutamate – causing it to accumulate outside them – it becomes a toxin that kills brain cells and may increase the risk of Alzheimer's and Parkinson's disease.

The Nebraska team reported that one type of titanium nanoparticle reduced the astrocytes' absorption of glutamate by 31 percent, even at very low levels (25 PPM), while another type decreased absorption of glutamate by 45 percent.

The scientists also discovered that titanium nanoparticles harmed the astrocytes' mitochondria … tiny cellular "factories” that regulate energy production as well as signaling between brain cells.

"These events are oftentimes predecessors of cell death,” said Dr. Khalimonchuk. "Those little damages add up over time. Ultimately, they're going to cause a major problem.”

Raising the alarm
The Nebraska team hopes the study will prompt further research on the dangers of nanoparticles in consumer and industrial products.

"We're hoping that this study will get some discussion going, because these nanoparticles have not been regulated,” said co-author Srivatsan Kidambi. "If you think about anything white – milk, chewing gum, toothpaste, powdered sugar – all these have nanoparticles in them.

As Dr. Kidambi said, "We've found that some nanoparticles are safe and some are not, so we are not saying that all of them are bad. Our reasoning is that … we need to have a classification of ‘safe' versus ‘not safe,' along with concentration thresholds (for each type). It's about figuring out how the different forms affect the biology of cells.”

The team's research was funded in part by the U.S. National Institutes of Health.

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