The Plastic Diet: What Tiny Particles Could Mean for Your Health

How much plastic are we eating and is it affecting our health?

Despite growing unease about plastics, their omnipresence in our environment and the problem of plastic pollution, since 2004 (to 2018*1), the world has created as much plastic as it did in the previous fifty years, and it is estimated that the total mass of virgin plastics ever made amounts to 8.3 billion tonnes, mainly derived from natural gas and crude oil, used as chemical feedstocks and fuel sources. Between 1950 and 2015, a total of 6.3 billion tonnes of primary and secondary (recycled) plastic waste was generated, of which around 9% has been recycled, and 12% burnt, with the remaining 79% either being stored in landfill or having been released directly into the natural environment.*1

The presence of plastics absolutely everywhere, in soil, in the oceans, rivers, and in plants, mammals and fish that we eat means that tiny particles of plastic are now in our bodies too.

Is that a concern?

Plastic pollution in oceans

How much plastic do we eat?

Scientists estimate that the average person ingests the equivalent of about 5g microplastics per week- that's about the weight of a credit card and they can accumulate in our bodies over time.

These tiny particles of plastic can travel throughout the body and into different organs via the blood stream. It has been estimated that the human brain may contain about 7g plastic.*2

Where does it come from?

It has long been identified that all along the food chain there are plastics being ingested by animals (such as in the sea by fish and seafood), in feedstock, in soil (entering plants and then animals who eat those plants) and even in the air. Therefore it is no surprise that we too eat a fair amount of plastic.

These plastic micro or nano (even smaller) particles come from an incredible number of sources- clothes, cosmetics, electronics, tyres, kitchen containers and utensils and so much more.

What does this mean for health?

Until recently, because plastics are a relatively new invention, no long term data was available to study the health effects of plastics on health. Plastics really exploded onto the market in a big way in the 1950's and so here we are 70 or so years down the track and now we can begin to see some trends.

A 2024 review of meta-analyses identified 759 meat-analyses focussed on the effect of exposure to plastics and plastic-associated chemicals on human health. Not all were high quality studies, however, with this big a sample patterns can be observed.*3

Firstly, effects can be seen. Plastics are impacting on health. Different classes of plastics can have different effects. Bisphenol A (BPA) is associated with type 2 diabetes in adults, insulin resistance in children and adults, polycystic ovary syndrome, obesity and hypertension (high blood pressure) in children and adults and cardiovascular disease.

A plasticiser group called phthalates are associated with miscarriage, insulin resistance in children and adults, with additional associations between certain phthalates and decreased birth weight, Type 2 diabetes in adults, precocious puberty in girls, reduced sperm quality, endometriosis, adverse cognitive development and intelligence quotient loss, adverse fine motor and psychomotor development and elevated blood pressure in children and asthma in children and adults.

The list goes on. It is too detailed and complex for most of us to absorb properly and for each class of plastics there are varying degrees of evidence for harm and different health impacts.

Do plastics affect our gut microbiome?

The gut microbiota is made up of trillions of bacteria, viruses and archae and is influential on immune health, mental health, digestive health and much more. There is concern that when microplastics come into contact with these microbes they are affecting how well they produce short chain fatty acids, which are anti inflammatory and protective against cancer.

Studies on humans have been difficult but mouse models do show that the ingestion of plastics of the polystyrene variety increase the chances of developing inflammatory bowel disease.*4 We cannot presume that the same happens in humans but it seems likely that this and other changes occur when the microbiome is disrupted. Certainly the incidence of IBD has rising in recent decades and plastics may be one of the causes.

Interestingly, some bacteria have been found in some human microbiomes that can break down certain plastics. This small study on 6 people found bacteria in the gut were degrading low-density polyethylene and polypropylene.*5. Will we evolve to deal with more plastics in our bodies? And will that have knock on effects on other roles that the microbiota play? Certainly there is much more work to do to understand what is happening.

So what can we do right now?

Due to the ubiquity of plastics in our environments it is easy to throw up your hands in the air and think that you have no control over this phenomenon. However, we can all contribute in small ways to reducing plastic usage and many small acts do add up to large impacts over time.

Additionally, it is a market economy and so if we all avoid plastics as much as possible, lower demand will lead to less plastic being produced.

• Buy as few foods as possible in plastic packaging. Let your local supermarket know as often as possible that you want less packaging. Take your own produce bags and shopping bags. Buy loose fruit and vegetables. Choose cardboard boxes over bags (eg for cereals). Shop at the local farmers market.

• Reduce to a minimum or even ban the use of cling wrap in your home. In particular do not cover warm food with it, or reheat food with cling wrap still over it. Be inventive! (What did your grandmother use?!) Cover dishes with a plate, a saucepan lid, a wax wrap or dry foods with a teatowel.

• If you have space, grow your own foods, and use organic compost or make your own. It's not foolproof but it will cut down the exposure to plastics.

• Never, ever buy water in plastic bottles or refill cheap plastic water bottles. The more sturdy BPA-free ones are a better option, otherwise choose stainless steel or glass.

• Take a reusable coffee cup everywhere.

• Swap to wooden chopping boards at home.

• Reuse time and time again the plastic bags you still have at home instead of binning them.

• Choose clothing made of natural fibres. (they feel better too!)

• Don't buy cleaning products in single use plastic containers, or make your own natural ones. Here are some ideas!

• Avoid plastic toys.

• Buy in bulk to reduce packaging.

• Buy less stuff!

When we all do these things, all of us, all of the time, then the impact grows exponentially. It won't reverse the effects of plastics in the system or in our bodies right away, but we can start to create change.

Every July a campaign called Plastic Free July has a month of promoting ideas and resources to reduce plastic pollution. Check it out and see what you can do!

In our lifetimes we will probably all have our health affected in some way or another by plastics in our environments and in our bodies; evolving research will reveal more and more what those are. But even with our partial knowledge we can see the dangers emerging and do something about it.

Sources:

1. Plastic Pollution and Potential Solutions. Christopher J Rhodes, Sci prog 2018 https://pubmed.ncbi.nlm.nih.gov/30025551/

2. https://www.sciencenews.org/article/microplastics-human-bodies-health-risks

3. An Umbrella Review of Meta-Analyses Evaluating Associations between Human Health and Exposure to Major Classes of Plastic-Associated Chemicals. Christos Symeonedis et al. Ann Glob Health 2024 https://pubmed.ncbi.nlm.nih.gov/39183960/

4. Polydisperse polystyrene microplastics exacerbate colitis through gut microbiota-butyrate-PPARγ axis disruption in mice

   Zhian Zhai. Journal of Hazardous Materials, April 2026 https://www.sciencedirect.com/science/article/pii/S0304389426007004?via%3Dihub

5. Identification of plastic-degrading bacteria in the human gut. Jang et al. Sci Total Environ. 2024 https://pubmed.ncbi.nlm.nih.gov/38670383/