Are Nanoparticles in Food a No-No?

By Prabarna Ganguly

Our world is teeming with “nano”-everything, ranging from nano cars and iPod nano (I’m still having trouble letting go), to nano drones and nano Wi-Fi routers. The irony: these are not “nano” in size at all! They are large-scale devices and implementations that are visible to the naked eye, therefore residing in the millimeter to meter range. But there is one field where the word “nano” is rarely used -in the world of food, and curiously, nanoscale is a major part of it.

So why the hush-hush, and what should we understand about the unseeable agents in the food we consume?

It’s a nanoworld after all

The prefix “nano” is derived from the Greek word νᾶνος (Latin nanus), meaning “dwarf”.

As a measurement scale, it means one billionth of a meter (1 nm = 10^-9 m). To get a sense of how small this nanoscale is, imagine a sheet of paper, which is approximately 100,000 nm in thickness, or a red blood cell, which is 2000 to 5000 nm in size. Nanoscale deals with matter that are almost 100,000 times smaller than the thickness of one sheet of paper, and half the size of a red blood cell. Health Canada defines particles between 1 and 100 nm to be “nano” in size. We are therefore talking about incredibly small materials.

One of the biggest challenges in communicating about food and nanotechnology has been to reduce the public misconception that every nanomaterial in food is engineered into it and is toxic. This is an entirely false notion. There are many natural foods which contain nanoscale particles, and have been eaten safely for thousands of years.

Let’s take the case of milk and dairy products. Homogenized milk consists of nanometer-sized fat globule droplets that help maintain its structural integrity, and contains proteins in the nanoscale range that make digestion of milk easy, especially for infants.

Nanoparticles in homogenized milk. Source: Foodhighs

The dairy industry has made use of these naturally-occurring micro and nanosized structures such as casein micelles, fat globules, and whey proteins, to build major types of products including :

  1. Emulsions (ex: butter)

  2. Foams (ex: ice cream, whipped cream)       

  3. Complex liquids (ex: milk)

  4. Plastic solids (ex: cheese)

  5. Gel networks (ex: yoghurt)

So, we understand that there are natural, harmless, nanoparticles in our food that we consume daily. However, the main question is: What problems does introducing nanotechnology in food solve?

Nutrient availability

This might come as a surprise to some, but humans absorb many nutrients poorly. Although the gastrointestinal (GI) tract facilitates the digestion and absorption of food, fluids, and other other biological compounds, absorption for many molecules can be as low as 10%. This reduced availability of certain nutrients has led humans to commonly intake dietary supplements, such as vitamin C and zinc. Such overcompensation can sometimes lead to ingesting higher than suggested doses of these supplements. The most common side effects of ingesting high doses (2g/day) of vitamin C include nausea, abdominal pain, and diarrhoea. Osmotic diarrhoea is caused by unabsorbed vitamin C metabolized by bacteria in the colon. Scientists are therefore finding ways to improve availability of nutrients such as vitamins, iron, calcium, and curcumin (debatable effects) in the body, without the side effects posed by oral administration, using nanodelivery systems.

Water purification

Clean water is essential to sustain all living organisms. However, increased industrialization and a rapidly expanding global population has placed a high demand for freshwater. This increased burden has also increased the amount of wastewater being generated with aquatic pollutants such as dyes and heavy metals. Since many of these pollutants can have detrimental effects on human health and pose environmental threats, a variety of carbon or metal-based “nanoadsorbents” are being deployed to remove aquatic pollutants and improve water quality.

Changing sensory and physical properties of food

Humans are picky regarding how they experience food, be it with respect to the smell, color, taste, or even the touch. Nanomaterials have been used for decades to encapsulate that perfect sensory blend. Titanium dioxide functions as a lightening agent in confectionery, providing a white, bright appearance. Silicon dioxide is used to thicken pastes, and carry fragrances or flavor in food.     

Other major links between nanotechnology and the food industry include extending storage life, enhancing food security, and detection of pathogens, toxins and pesticides.

Is small always better?

In 2006, 20 billion US dollars were devoted to nanotechnology-based research in agriculture and food processing. Despite the preponderance of nanomaterials used by food industries, our knowledge regarding their safety remains inadequate. The question is: how toxic are nanomaterials at concentrations at which they are used? It is necessary to address this issue because nanomaterials, due to their miniscule size, affect the body differently than bulkier materials. Nanoparticles have a high surface area, which means that they can chemically interact with many biological reactions in the body. Health Canada and other food agencies currently have guidelines for reporting possible adverse effects of food-related nanoparticles on human health. Biological models such as zebrafish and rodents are being used to determine potential toxicological effects of such nanomaterials.

Also, once consumed, these nanoparticles can enter sewage systems. Sewage water treatment plants need to find ways to degrade organic and inorganic nanomaterial water contaminants. Designing organic nanomaterials that are biodegradable, filterable, and minimally invasive to the environment, could help decrease their disadvantages.

Finally, it will be of critical importance to engage in an open and public conversation on the benefits and drawbacks of a nanotechnology-driven food system. Because whether we like it or not, we are its consumers!

Development of nanotechnology in the food science sector.  Source:  He, X. & Hwan, H.M. 2016

Development of nanotechnology in the food science sector. Source: He, X. & Hwan, H.M. 2016