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.

This is the next article in our ‘Light and health’ series, where we look at how light affects our physical and mental health in sometimes surprising ways. Read other articles in the series.

It’s spring and you’ve probably noticed a change in when the Sun rises and sets. But have you also noticed a change in your mood?

We’ve known for a while that light plays a role in our wellbeing. Many of us tend to feel more positive when spring returns.

But for others, big changes in light, such as at the start of spring, can be tough. And for many, bright light at night can be a problem. Here’s what’s going on.

An ancient rhythm of light and mood

In an earlier article in our series, we learned that light shining on the back of the eye sends “timing signals” to the brain and the master clock of the circadian system. This clock coordinates our daily (circadian) rhythms.

“Clock genes” also regulate circadian rhythms. These genes control the timing of when many other genes turn on and off during the 24-hour, light-dark cycle.

But how is this all linked with our mood and mental health?

Circadian rhythms can be disrupted. This can happen if there are problems with how the body clock develops or functions, or if someone is routinely exposed to bright light at night.

When circadian disruption happens, it increases the risk of certain mental disorders. These include bipolar disorder and atypical depression (a type of depression when someone is extra sleepy and has problems with their energy and metabolism).

Light on the brain

Light may also affect circuits in the brain that control mood, as animal studies show.

There’s evidence this happens in humans. A brain-imaging study showed exposure to bright light in the daytime while inside the scanner changed the activity of a brain region involved in mood and alertness.

Another brain-imaging study found a link between daily exposure to sunlight and how the neurotransmitter (or chemical messenger) serotonin binds to receptors in the brain. We see alterations in serotonin binding in several mental disorders, including depression.

What happens when the seasons change?

Light can also affect mood and mental health as the seasons change. During autumn and winter, symptoms such as low mood and fatigue can develop. But often, once spring and summer come round, these symptoms go away. This is called “seasonality” or, when severe, “seasonal affective disorder”.

What is less well known is that for other people, the change to spring and summer (when there is more light) can also come with a change in mood and mental health. Some people experience increases in energy and the drive to be active. This is positive for some but can be seriously destabilising for others. This too is an example of seasonality.

Most people aren’t very seasonal. But for those who are, seasonality has a genetic component. Relatives of people with seasonal affective disorder are more likely to also experience seasonality.

Seasonality is also more common in conditions such as bipolar disorder. For many people with such conditions, the shift into shorter day-lengths during winter can trigger a depressive episode.

Counterintuitively, the longer day-lengths in spring and summer can also destabilise people with bipolar disorder into an “activated” state where energy and activity are in overdrive, and symptoms are harder to manage. So, seasonality can be serious.

Alexis Hutcheon, who experiences seasonality and helped write this article, told us:

[…] the season change is like preparing for battle – I never know what’s coming, and I rarely come out unscathed. I’ve experienced both hypomanic and depressive episodes triggered by the season change, but regardless of whether I’m on the ‘up’ or the ‘down’, the one constant is that I can’t sleep. To manage, I try to stick to a strict routine, tweak medication, maximise my exposure to light, and always stay tuned in to those subtle shifts in mood. It’s a time of heightened awareness and trying to stay one step ahead.

So what’s going on in the brain?

One explanation for what’s going on in the brain when mental health fluctuates with the change in seasons relates to the neurotransmitters serotonin and dopamine.

Serotonin helps regulate mood and is the target of many antidepressants. There is some evidence of seasonal changes in serotonin levels, potentially being lower in winter.

Dopamine is a neurotransmitter involved in reward, motivation and movement, and is also a target of some antidepressants. Levels of dopamine may also change with the seasons.

But the neuroscience of seasonality is a developing area and more research is needed to know what’s going on in the brain.

How about bright light at night?

We know exposure to bright light at night (for instance, if someone is up all night) can disturb someone’s circadian rhythms.

This type of circadian rhythm disturbance is associated with higher rates of symptoms including self-harm, depressive and anxiety symptoms, and lower wellbeing. It is also associated with higher rates of mental disorders, such as major depression, bipolar disorder, psychotic disorders and post-traumatic stress disorder (or PTSD).

Why is this? Bright light at night confuses and destabilises the body clock. It disrupts the rhythmic regulation of mood, cognition, appetite, metabolism and many other mental processes.

But people differ hugely in their sensitivity to light. While still a hypothesis, people who are most sensitive to light may be the most vulnerable to body clock disturbances caused by bright light at night, which then leads to a higher risk of mental health problems.

Where to from here?

Learning about light will help people better manage their mental health conditions.

By encouraging people to better align their lives to the light-dark cycle (to stabilise their body clock) we may also help prevent conditions such as depression and bipolar disorder emerging in the first place.

Healthy light behaviours – avoiding light at night and seeking light during the day – are good for everyone. But they might be especially helpful for people at risk of mental health problems. These include people with a family history of mental health problems or people who are night owls (late sleepers and late risers), who are more at risk of body clock disturbances.

Alexis Hutcheon has lived experience of a mental health condition and helped write this article.

If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.

Jacob Crouse, Research Fellow in Youth Mental Health, Brain and Mind Centre, University of Sydney; Emiliana Tonini, Postdoctoral Research Fellow, Brain and Mind Centre, University of Sydney, and Ian Hickie, Co-Director, Health and Policy, Brain and Mind Centre, University of Sydney

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