It has been a long winter, filled with many viruses and cost-of-living pressures, on top of the usual mix of work, study, life admin and caring responsibilities.

Stress is an inevitable part of life. In short bursts, our stress response has evolved as a survival mechanism to help us be more alert in fight or flight situations.

But when stress is chronic, it weakens the immune system and makes us more vulnerable to illnesses such as the common cold, flu and COVID.

Stress makes it harder to fight off viruses

When the immune system starts to break down, a virus that would normally have been under control starts to flourish.

Once you begin to feel sick, the stress response rises, making it harder for the immune system to fight off the disease. You may be sick more often and for longer periods of time, without enough immune cells primed and ready to fight.

In the 1990s, American psychology professor Sheldon Cohen and his colleagues conducted a number of studies where healthy people were exposed to an upper respiratory infection, through drops of virus placed directly into their nose.

These participants were then quarantined in a hotel and monitored closely to determine who became ill.

One of the most important factors predicting who got sick was prolonged psychological stress.

Cortisol suppresses immunity

“Short-term stress” is stress that lasts for a period of minutes to hours, while “chronic stress” persists for several hours per day for weeks or months.

When faced with a perceived threat, psychological or physical, the hypothalamus region of the brain sets off an alarm system. This signals the release of a surge of hormones, including adrenaline and cortisol.

In a typical stress response, cortisol levels quickly increase when stress occurs, and then rapidly drop back to normal once the stress has subsided. In the short term, cortisol suppresses inflammation, to ensure the body has enough energy available to respond to an immediate threat.

But in the longer term, chronic stress can be harmful. A Harvard University study from 2022 showed that people suffering from psychological distress in the lead up to their COVID infection had a greater chance of experiencing long COVID. They classified this distress as depression, probable anxiety, perceived stress, worry about COVID and loneliness.

Those suffering distress had close to a 50% greater risk of long COVID compared to other participants. Cortisol has been shown to be high in the most severe cases of COVID.

Stress causes inflammation

Inflammation is a short-term reaction to an injury or infection. It is responsible for trafficking immune cells in your body so the right cells are present in the right locations at the right times and at the right levels.

The immune cells also store a memory of that threat to respond faster and more effectively the next time.

Initially, circulating immune cells detect and flock to the site of infection. Messenger proteins, known as pro-inflammatory cytokines, are released by immune cells, to signal the danger and recruit help, and our immune system responds to neutralise the threat.

During this response to the infection, if the immune system produces too much of these inflammatory chemicals, it can trigger symptoms such as nasal congestion and runny nose.

What about chronic stress?

Chronic stress causes persistently high cortisol secretion, which remains high even in the absence of an immediate stressor.

The immune system becomes desensitised and unresponsive to this cortisol suppression, increasing low-grade “silent” inflammation and the production of pro-inflammatory cytokines (the messenger proteins).

Immune cells become exhausted and start to malfunction. The body loses the ability to turn down the inflammatory response.

Over time, the immune system changes the way it responds by reprogramming to a “low surveillance mode”. The immune system misses early opportunities to destroy threats, and the process of recovery can take longer.

So how can you manage your stress?

We can actively strengthen our immunity and natural defences by managing our stress levels. Rather than letting stress build up, try to address it early and frequently by:

1) Getting enough sleep

Getting enough sleep reduces cortisol levels and inflammation. During sleep, the immune system releases cytokines, which help fight infections and inflammation.

2) Taking regular exercise

Exercising helps the lymphatic system (which balances bodily fluids as part of the immune system) circulate and allows immune cells to monitor for threats, while sweating flushes toxins. Physical activity also lowers stress hormone levels through the release of positive brain signals.

3) Eating a healthy diet

Ensuring your diet contains enough nutrients – such as the B vitamins, and the full breadth of minerals like magnesium, iron and zinc – during times of stress has a positive impact on overall stress levels. Staying hydrated helps the body to flush out toxins.

4) Socialising and practising meditation or mindfulness

These activities increase endorphins and serotonin, which improve mood and have anti-inflammatory effects. Breathing exercises and meditation stimulate the parasympathetic nervous system, which calms down our stress responses so we can “reset” and reduce cortisol levels.

Sathana Dushyanthen, Academic Specialist & Lecturer in Cancer Sciences & Digital Health| Superstar of STEM| Science Communicator, The University of Melbourne

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

In recent years, there’s been increasing hype about the potential health risks associated with so-called “ultra-processed” foods.

But new evidence published this week found not all “ultra-processed” foods are linked to poor health. That includes the mass-produced wholegrain bread you buy from the supermarket.

While this newly published research and associated editorial are unlikely to end the wrangling about how best to define unhealthy foods and diets, it’s critical those debates don’t delay the implementation of policies that are likely to actually improve our diets.

What are ultra-processed foods?

Ultra-processed foods are industrially produced using a variety of processing techniques. They typically include ingredients that can’t be found in a home kitchen, such as preservatives, emulsifiers, sweeteners and/or artificial colours.

Common examples of ultra-processed foods include packaged chips, flavoured yoghurts, soft drinks, sausages and mass-produced packaged wholegrain bread.

In many other countries, ultra-processed foods make up a large proportion of what people eat. A recent study estimated they make up an average of 42% of total energy intake in Australia.

How do ultra-processed foods affect our health?

Previous studies have linked increased consumption of ultra-processed food with poorer health. High consumption of ultra-processed food, for example, has been associated with a higher risk of type 2 diabetes, and death from heart disease and stroke.

Ultra-processed foods are typically high in energy, added sugars, salt and/or unhealthy fats. These have long been recognised as risk factors for a range of diseases.

It has also been suggested that structural changes that happen to ultra-processed foods as part of the manufacturing process may lead you to eat more than you should. Potential explanations are that, due to the way they’re made, the foods are quicker to eat and more palatable.

It’s also possible certain food additives may impair normal body functions, such as the way our cells reproduce.

Is it harmful? It depends on the food’s nutrients

The new paper just published used 30 years of data from two large US cohort studies to evaluate the relationship between ultra-processed food consumption and long-term health. The study tried to disentangle the effects of the manufacturing process itself from the nutrient profile of foods.

The study found a small increase in the risk of early death with higher ultra-processed food consumption.

But importantly, the authors also looked at diet quality. They found that for people who had high quality diets (high in fruit, vegetables, wholegrains, as well as healthy fats, and low in sugary drinks, salt, and red and processed meat), there was no clear association between the amount of ultra-processed food they ate and risk of premature death.

This suggests overall diet quality has a stronger influence on long-term health than ultra-processed food consumption.

When the researchers analysed ultra-processed foods by sub-category, mass-produced wholegrain products, such as supermarket wholegrain breads and wholegrain breakfast cereals, were not associated with poorer health.

This finding matches another recent study that suggests ultra-processed wholegrain foods are not a driver of poor health.

The authors concluded, while there was some support for limiting consumption of certain types of ultra-processed food for long-term health, not all ultra-processed food products should be universally restricted.

Should dietary guidelines advise against ultra-processed foods?

Existing national dietary guidelines have been developed and refined based on decades of nutrition evidence.

Much of the recent evidence related to ultra-processed foods tells us what we already knew: that products like soft drinks, alcohol and processed meats are bad for health.

Dietary guidelines generally already advise to eat mostly whole foods and to limit consumption of highly processed foods that are high in refined grains, saturated fat, sugar and salt.

But some nutrition researchers have called for dietary guidelines to be amended to recommend avoiding ultra-processed foods.

Based on the available evidence, it would be difficult to justify adding a sweeping statement about avoiding all ultra-processed foods.

Advice to avoid all ultra-processed foods would likely unfairly impact people on low-incomes, as many ultra-processed foods, such as supermarket breads, are relatively affordable and convenient.

Wholegrain breads also provide important nutrients, such as fibre. In many countries, bread is the biggest contributor to fibre intake. So it would be problematic to recommend avoiding supermarket wholegrain bread just because it’s ultra-processed.

So how can we improve our diets?

There is strong consensus on the need to implement evidence-based policies to improve population diets. This includes legislation to restrict children’s exposure to the marketing of unhealthy foods and brands, mandatory Health Star Rating nutrition labelling and taxes on sugary drinks.

These policies are underpinned by well-established systems for classifying the healthiness of foods. If new evidence unfolds about mechanisms by which ultra-processed foods drive health harms, these classification systems can be updated to reflect such evidence. If specific additives are found to be harmful to health, for example, this evidence can be incorporated into existing nutrient profiling systems, such as the Health Star Rating food labelling scheme.

Accordingly, policymakers can confidently progress food policy implementation using the tools for classifying the healthiness of foods that we already have.

Unhealthy diets and obesity are among the largest contributors to poor health. We can’t let the hype and academic debate around “ultra-processed” foods delay implementation of globally recommended policies for improving population diets.

Gary Sacks, Professor of Public Health Policy, Deakin University; Kathryn Backholer, Co-Director, Global Centre for Preventive Health and Nutrition, Deakin University; Kathryn Bradbury, Senior Research Fellow in the School of Population Health, University of Auckland, Waipapa Taumata Rau, and Sally Mackay, Senior Lecturer Epidemiology and Biostatistics, University of Auckland, Waipapa Taumata Rau

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