Plastic is in our clothes, cars, mobile phones, water bottles and food containers. But recent research adds to growing concerns about the impact of tiny plastic fragments on our health.

A study from the United States has, for the first time, found microplastics in human brains. The study, which has yet to be independently verified by other scientists, has been described in the media as scary, shocking and alarming.

But what exactly are microplastics? What do they mean for our health? Should we be concerned?

What are microplastics? Can you see them?

We often consider plastic items to be indestructible. But plastic breaks down into smaller particles. Definitions vary but generally microplastics are smaller than five millimetres.

This makes some too small to be seen with the naked eye. So, many of the images the media uses to illustrate articles about microplastics are misleading, as some show much larger, clearly visible pieces.

Microplastics have been reported in many sources of drinking water and everyday food items. This means we are constantly exposed to them in our diet.

Such widespread, chronic (long-term) exposure makes this a serious concern for human health. While research investigating the potential risk microplastics pose to our health is limited, it is growing.

How about this latest study?

The study looked at concentrations of microplastics in 51 samples from men and women set aside from routine autopsies in Albuquerque, New Mexico. Samples were from the liver, kidney and brain.

These tiny particles are difficult to study due to their size, even with a high-powered microscope. So rather than trying to see them, researchers are beginning to use complex instruments that identify the chemical composition of microplastics in a sample. This is the technique used in this study.

The researchers were surprised to find up to 30 times more microplastics in brain samples than in the liver and kidney.

They hypothesised this could be due to high blood flow to the brain (carrying plastic particles with it). Alternatively, the liver and kidneys might be better suited to dealing with external toxins and particles. We also know the brain does not undergo the same amount of cellular renewal as other organs in the body, which could make the plastics linger here.

The researchers also found the amount of plastics in brain samples increased by about 50% between 2016 and 2024. This may reflect the rise in environmental plastic pollution and increased human exposure.

The microplastics found in this study were mostly composed of polyethylene. This is the most commonly produced plastic in the world and is used for many everyday products, such as bottle caps and plastic bags.

This is the first time microplastics have been found in human brains, which is important. However, this study is a “pre-print”, so other independent microplastics researchers haven’t yet reviewed or validated the study.

How do microplastics end up in the brain?

Microplastics typically enter the body through contaminated food and water. This can disrupt the gut microbiome (the community of microbes in your gut) and cause inflammation. This leads to effects in the whole body via the immune system and the complex, two-way communication system between the gut and the brain. This so-called gut-brain axis is implicated in many aspects of health and disease.

We can also breathe in airborne microplastics. Once these particles are in the gut or lungs, they can move into the bloodstream and then travel around the body into various organs.

Studies have found microplastics in human faeces, joints, livers, reproductive organs, blood, vessels and hearts.

Microplastics also migrate to the brains of wild fish. In mouse studies, ingested microplastics are absorbed from the gut into the blood and can enter the brain, becoming lodged in other organs along the way.

To get into brain tissue, microplastics must cross the blood-brain-barrier, an intricate layer of cells that is supposed to keep things in the blood from entering the brain.

Although concerning, this is not surprising, as microplastics must cross similar cell barriers to enter the urine, testes and placenta, where they have already been found in humans.

Is this a health concern?

We don’t yet know the effects of microplastics in the human brain. Some laboratory experiments suggest microplastics increase brain inflammation and cell damage, alter gene expression and change brain structure.

Aside from the effects of the microplastic particles themselves, microplastics might also pose risks if they carry environmental toxins or bacteria into and around the body.

Various plastic chemicals could also leach out of the microplastics into the body. These include the famous hormone-disrupting chemicals known as BPAs.

But microplastics and their effects are difficult to study. In addition to their small size, there are so many different types of plastics in the environment. More than 13,000 different chemicals have been identified in plastic products, with more being developed every year.

Microplastics are also weathered by the environment and digestive processes, and this is hard to reproduce in the lab.

A goal of our research is to understand how these factors change the way microplastics behave in the body. We plan to investigate if improving the integrity of the gut barrier through diet or probiotics can prevent the uptake of microplastics from the gut into the bloodstream. This may effectively stop the particles from circulating around the body and lodging into organs.

How do I minimise my exposure?

Microplastics are widespread in the environment, and it’s difficult to avoid exposure. We are just beginning to understand how microplastics can affect our health.

Until we have more scientific evidence, the best thing we can do is reduce our exposure to plastics where we can and produce less plastic waste, so less ends up in the environment.

An easy place to start is to avoid foods and drinks packaged in single-use plastic or reheated in plastic containers. We can also minimise exposure to synthetic fibres in our home and clothing.

Sarah Hellewell, Senior Research Fellow, The Perron Institute for Neurological and Translational Science, and Research Fellow, Faculty of Health Sciences, Curtin University; Anastazja Gorecki, Teaching & Research Scholar, School of Health Sciences, University of Notre Dame Australia, and Charlotte Sofield, PhD Candidate, studying microplastics and gut/brain health, University of Notre Dame Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

According to social media, carbs come in various guises: naked carbs, net carbs, complex carbs and more.

You might be wondering what these terms mean or if all carbs are really the same. If you are into “carb counting” or “cutting carbs”, it’s important to make informed decisions about what you eat.

What are carbs?

Carbohydrates, or “carbs” for short, are one of the main sources of energy we need for brain function, muscle movement, digestion and pretty much everything our bodies do.

There are two classifications of carbs, simple and complex. Simple carbs have one or two sugar molecules, while complex carbs are three or more sugar molecules joined together. For example, table sugar is a simple carb, but starch in potatoes is a complex carb.

All carbs need to be broken down into individual molecules by our digestive enzymes to be absorbed. Digestion of complex carbs is a much slower process than simple carbs, leading to a more gradual blood sugar increase.

Fibre is also considered a complex carb, but it has a structure our body is not capable of digesting. This means we don’t absorb it, but it helps with the movement of our stool and prevents constipation. Our good gut bacteria also love fibre as they can digest it and use it for energy – important for a healthy gut.

What about ‘naked carbs’?

“Naked carbs” is a popular term usually used to refer to foods that are mostly simple carbs, without fibre or accompanying protein or fat. White bread, sugary drinks, jams, sweets, white rice, white flour, crackers and fruit juice are examples of these foods. Ultra-processed foods, where the grains are stripped of their outer layers (including fibre and most nutrients) leaving “refined carbs”, also fall into this category.

One of the problems with naked carbs or refined carbs is they digest and absorb quickly, causing an immediate rise in blood sugar. This is followed by a rapid spike in insulin (a hormone that signals cells to remove sugar from blood) and then a drop in blood sugar. This can lead to hunger and cravings – a vicious cycle that only gets worse with eating more of the same foods.

What about ‘net carbs’?

This is another popular term tossed around in dieting discussions. Net carbs refer to the part of the carb food that we actually absorb.

Again, fibre is not easily digestible. And some carb-rich foods contain sugar alcohols, such as sweeteners (like xylitol and sorbitol) that have limited absorption and little to no effect on blood sugar. Deducting the value of fibre and sugar alcohols from the total carbohydrate content of a food gives what’s considered its net carb value.

For example, canned pear in juice has around 12.3g of “total carbohydrates” per 100g, including 1.7g carb + 1.7g fibre + 1.9g sugar alcohol. So its net carb is 12.3g – 1.7g – 1.9g = 8.7g. This means 8.7g of the 12.3g total carbs impacts blood sugar.

The nutrition labels on packaged foods in Australia and New Zealand usually list fibre separately to carbohydrates, so the net carbs have already been calculated. This is not the case in other countries, where “total carbohydrates” are listed.

Does it matter though?

Whether or not you should care about net or naked carbs depends on your dietary preferences, health goals, food accessibility and overall nutritional needs. Generally speaking, we should try to limit our consumption of simple and refined carbs.

The latest World Health Organization guidelines recommend our carbohydrate intake should ideally come primarily from whole grains, vegetables, fruits and pulses, which are rich in complex carbs and fibre. This can have significant health benefits (to regulate hunger, improve cholesterol or help with weight management) and reduce the risk of conditions such as heart disease, obesity and colon cancer.

In moderation, naked carbs aren’t necessarily bad. But pairing them with fats, protein or fibre can slow down the digestion and absorption of sugar. This can help to stabilise blood sugar levels, prevent spikes and crashes and support personal weight management goals. If you’re managing diabetes or insulin resistance, paying attention to the composition of your meals, and the quality of your carbohydrate sources is essential.

A ketogenic (high fat, low carb) diet typically restricts carb intake to between 20 and 50g each day. But this carb amount refers to net carbs – so it is possible to eat more carbs from high-fibre sources.

Some tips to try

Some simple strategies can help you get the most out of your carb intake:

• reduce your intake of naked carbs and foods high in sugar and white flour, such as white bread, table sugar, honey, lollies, maple syrup, jam, and fruit juice

• opt for protein- and fibre-rich carbs. These include oats, sweet potatoes, nuts, avocados, beans, whole grains and broccoli

• if you are eating naked carbs, dress them up with some protein, fat and fibre. For example, top white bread with a nut butter rather than jam

• if you are trying to reduce the carb content in your diet, be wary of any symptoms of low blood glucose, including headaches, nausea, and dizziness

• working with a health-care professional such as an accredited practising dietitian or your GP can help develop an individualised diet plan that meets your specific needs and goals.

Correction: this article has been updated to indicate how carbohydrates are listed on food nutrition labels in Australia and New Zealand.

Saman Khalesi, Senior Lecturer and Discipline Lead in Nutrition, School of Health, Medical and Applied Sciences, CQUniversity Australia; Anna Balzer, Lecturer, Medical Science School of Health, Medical and Applied Sciences, CQUniversity Australia; Charlotte Gupta, Postdoctoral research fellow, CQUniversity Australia; Chris Irwin, Senior Lecturer in Nutrition and Dietetics, School of Health Sciences & Social Work, Griffith University, and Grace Vincent, Senior Lecturer, Appleton Institute, CQUniversity Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.