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.

It’s a well-known fact that to lose weight, you either need to eat less or move more. But how many calories do you really need to cut out of your diet each day to lose weight? It may be less than you think.

To determine how much energy (calories) your body requires, you need to calculate your total daily energy expenditure (TDEE). This is comprised of your basal metabolic rate (BMR) – the energy needed to sustain your body’s metabolic processes at rest – and your physical activity level. Many online calculators can help determine your daily calorie needs.

If you reduce your energy intake (or increase the amount you burn through exercise) by 500-1,000 calories per day, you’ll see a weekly weight loss of around one pound (0.45kg).

But studies show that even small calorie deficits (of 100-200 calories daily) can lead to long-term, sustainable weight-loss success. And although you might not lose as much weight in the short-term by only decreasing calories slightly each day, these gradual reductions are more effective than drastic cuts as they tend to be easier to stick with.

Hormonal changes

When you decrease your calorie intake, the body’s BMR often decreases. This phenomenon is known as adaptive thermogenesis. This adaptation slows down weight loss so the body can conserve energy in response to what it perceives as starvation. This can lead to a weight-loss plateau – even when calorie intake remains reduced.

Caloric restriction can also lead to hormonal changes that influence metabolism and appetite. For instance, thyroid hormones, which regulate metabolism, can decrease – leading to a slower metabolic rate. Additionally, leptin levels drop, reducing satiety, increasing hunger and decreasing metabolic rate.

Ghrelin, known as the “hunger hormone”, also increases when caloric intake is reduced, signalling the brain to stimulate appetite and increase food intake. Higher ghrelin levels make it challenging to maintain a reduced calorie diet, as the body constantly feels hungrier.

Insulin, which helps regulate blood sugar levels and fat storage, can improve in sensitivity when we reduce calorie intake. But sometimes, insulin levels decrease instead, affecting metabolism and leading to a reduction in daily energy expenditure. Cortisol, the stress hormone, can also spike – especially when we’re in a significant caloric deficit. This may break down muscles and lead to fat retention, particularly in the stomach.

Lastly, hormones such as peptide YY and cholecystokinin, which make us feel full when we’ve eaten, can decrease when we lower calorie intake. This may make us feel hungrier.

Fortunately, there are many things we can do to address these metabolic adaptations so we can continue losing weight.

Weight loss strategies

Maintaining muscle mass (either through resistance training or eating plenty of protein) is essential to counteract the physiological adaptations that slow weight loss down. This is because muscle burns more calories at rest compared to fat tissue – which may help mitigate decreased metabolic rate.

Gradual caloric restriction (reducing daily calories by only around 200-300 a day), focusing on nutrient-dense foods (particularly those high in protein and fibre), and eating regular meals can all also help to mitigate these hormonal challenges.

But if you aren’t someone who wants to track calories each day, here are some easy strategies that can help you decrease daily calorie intake without thinking too much about it:

1. Portion control: reducing portion sizes is a straightforward way of reducing calorie intake. Use smaller plates or measure serving sizes to help reduce daily calorie intake.

2. Healthy swaps: substituting high-calorie foods with lower-calorie alternatives can help reduce overall caloric intake without feeling deprived. For example, replacing sugary snacks with fruits or swapping soda with water can make a substantial difference to your calorie intake. Fibre-rich foods can also reduce the calorie density of your meal.

3. Mindful eating: practising mindful eating involves paying attention to hunger and fullness cues, eating slowly, and avoiding distractions during meals. This approach helps prevent overeating and promotes better control over food intake.

4. Have some water: having a drink with your meal can increase satiety and reduce total food intake at a given meal. In addition, replacing sugary beverages with water has been shown to reduce calorie intake from sugars.

4. Intermittent fasting: restricting eating to specific windows can reduce your caloric intake and have positive effects on your metabolism. There are different types of intermittent fasting you can do, but one of the easiest types is restricting your mealtimes to a specific window of time (such as only eating between 12 noon and 8pm). This reduces night-time snacking, so is particularly helpful if you tend to get the snacks out late in the evening.

Long-term behavioural changes are crucial for maintaining weight loss. Successful strategies include regular physical activity, continued mindful eating, and periodically being diligent about your weight and food intake. Having a support system to help you stay on track can also play a big role in helping you maintain weight loss.

Modest weight loss of 5-10% body weight in people who are overweight or obese offers significant health benefits, including improved metabolic health and reduced risk of chronic diseases. But it can be hard to lose weight – especially given all the adaptations our body has to prevent it from happening.

Thankfully, small, sustainable changes that lead to gradual weight loss appear to be more effective in the long run, compared with more drastic lifestyle changes.

Alexandra Cremona, Lecturer, Human Nutrition and Dietetics, University of Limerick

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