What's lurking in your candy could be more frightening than just sugar and calories. A new breed of additives found in a range of foods is largely untested, and the potential effects are unclear.

Some of the major research on the subject came about thanks to an eight-year-old and his candy.

Arizona State University engineering professor Paul Westerhoff noticed that after eating a multi-coloured Gobstopper candy, his son had a white coating on his tongue.

Curious about what caused it, Westerhoff studied the contents on the candy and found that it contained titanium dioxide, an ingredient that is added to all sorts of consumer products, including sunscreens, cosmetics and food.

Titanium dioxide found in foods from candy to yogurt

The additive itself, which is used to make food appear whiter, is not necessarily harmful to humans. It's been approved by the U.S. Food and Drug Administration as "generally recognized as safe" for consumption for many years. 

But many foods don't just contain regular titanium dioxide — they contain a nano-sized version of the additive.

That means the additive comes in the form of particles that are billionths of a metre in size, instead of the micro-sized chunks approved for use in the 1960s, which were millionths of a metre in size.

Westerhoff and his colleagues tested dozens of foods and personal care products.

They found nano-sized titanium dioxide in about one-third of the items, including Mentos Fresh Mint Gum, Kool-Aid Blue Raspberry, Betty Crocker Whipped Frosting and M&Ms, as well as some types of Greek yogurt, cheese and cereals. 

Research still unclear on effects of nano-additives

The research, though, is unclear on how significant the difference between micro-sized and nano-sized additives is. The micro-sized additives have been around for decades and have been significantly tested.

The nano-sized version is the same molecule, but in smaller packets — so it is unclear if it would have any difference in effect.

Jared Schoepf is a PhD student who studies nano-scale additives such as titanium dioxide, working with Westerhoff at Arizona State University. He said there are potential concerns with the nano-sized additives.

"Once it gets small enough — so less than about 100 nanometres — the particles are able to enter into your cells," he said. "And that's where some problems can arise. Once they get inside, they can create inflammation and other concerns that potentially can lead to, maybe, cancer or something further down the road."

There have been studies looking at the safety of the nano-additive. But at this point, the studies have been relatively small in scale and have used huge doses of the products, well beyond normal consumption.

One study in particular reported that cultured intestinal cells exposed to large doses showed adverse effects such as DNA damage or damage to proteins and to the fats of the cell.

Nano-additives found in clothing as well as food

The studies suggest this is something to monitor with more realistic doses, but that there isn't any need to panic just yet.

Generally, things on the nano scale function very differently than on the microscale. For example, when used as an additive at the nano scale, silver has antimicrobial properties and has been shown to be a persistent pollutant of our waterways. Nano-silver is often used in athletic gear to reduce smell in clothing.

Titanium dioxide and other nano-additives are currently being investigated for what they do in the human gut. It has yet to be determined whether they are, in fact, absorbed into the cells, and if they are, what the consequences are for the cell.