Matcha has experienced a surge in popularity in recent months, leading to reports of global shortages and price increases.

If you haven’t been caught up in the craze, matcha is a powdered version of green tea. On a cafe menu you might see a hot or iced matcha latte, or even a matcha-flavoured cake or pastry. A quick google brings up countless recipes incorporating matcha, both sweet and savoury.

Retailers and cafe owners have suggested the main reasons for matcha’s popularity include its “instagrammable” looks and its purported health benefits.

But what are the health benefits of matcha? Here’s what the evidence says.

First, what is matcha?

Matcha is a finely ground powder of green tea leaves, which come from the plant Camellia sinensis. This is the same plant used to make green and black tea. However, the production process differentiates matcha from green and black tea.

For matcha, the tea plant is grown in shade. Once the leaves are harvested, they’re steamed and dried and the stems are removed. Then the leaves are carefully ground at controlled temperatures to form the powder.

The production process for green tea is simpler. The leaves are picked from the unshaded plants, heated and then dried. We then steep the dried leaves in hot water to get tea (whereas with matcha the whole leaf is consumed).

With black tea, after the leaves are picked they’re exposed to air, which leads to oxidation. This makes the leaves black and gives the tea a different flavour.

A source of phytonutrients

Phytonutrients are chemical compounds found in plants which have a range of benefits for human health. Matcha contains several.

Chlorophyll gives plants such as Camellia sinensis their green colour. There’s some evidence chlorophyll may have health benefits – including anti-inflammatory, anti-cancer and anti-obesity effects – due to its antioxidant properties. Antioxidants neutralise free radicals, which are unstable molecules that harm our cells.

Theanine has been shown to improve sleep and reduce stress and anxiety. The only other known dietary source of theanine is mushrooms.

Caffeine is a phytonutrient we know well. Aside from increasing alertness, caffeine has also demonstrated antioxidant effects and some protection against a range of chronic and neurodegenerative diseases. However, too much caffeine can have negative side effects.

Interestingly, shading the plants while growing appears to change the nutritional composition of the leaf and may lead to higher levels of these phytonutrients in matcha compared to green tea.

Another compound worth mentioning is called catechins, of which there are several different types. Matcha powder similarly has more catechins than green tea. They are strong antioxidants, which have been shown to have protective effects against bacteria, viruses, allergies, inflammation and cancer. Catechins are also found in apples, blueberries and strawberries.

What are the actual health benefits?

So we know matcha contains a variety of phytonutrients, but does this translate to noticeable health benefits?

A review published in 2023 identified only five experimental studies that have given matcha to people. These studies gave participants about 2–4g of matcha per day (equivalent to 1–2 teaspoons of matcha powder), compared to a placebo, as either a capsule, in tea or in foods. Matcha decreased stress and anxiety, and improved memory and cognitive function. There was no effect on mood.

A more recent study showed 2g of matcha in older people aged 60 to 85 improved sleep quality. However, in younger people aged 27 to 64 in another study, matcha had little effect on sleep.

A study in people with obesity found no difference in the weight loss observed between the matcha group and the control group. This study did not randomise participants, and people knew which group they had been placed in.

It could be hypothesised that given you consume all of the leaf, and given levels of some phytonutrients may be higher due to the growing conditions, matcha may have more nutritional benefits than green tea. But to my knowledge there has been no direct comparison of health outcomes from green tea compared to matcha.

There’s lots of evidence for green tea

While to date a limited number of studies have looked at matcha, and none compared matcha and green tea, there’s quite a bit of research on the health benefits of drinking green tea.

A systematic review of 21 studies on green tea has shown similar benefits to matcha for improvements in memory, plus evidence for mood improvement.

There’s also evidence green tea provides other health benefits. Systematic reviews have shown green tea leads to weight loss in people with obesity, lower levels of certain types of cholesterol, and reduced blood pressure. Green tea may also lower the risk of certain types of cancer.

So, if you can’t get your hands on matcha at the moment, drinking green tea may be a good way to get your caffeine hit.

Although the evidence on green tea provides us with some hints about the health benefits of matcha, we can’t be certain they would be the same. Nonetheless, if your local coffee shop has a good supply of matcha, there’s nothing to suggest you shouldn’t keep enjoying matcha drinks.

However, it may be best to leave the matcha croissant or cronut for special occasions. When matcha is added to foods with high levels of added sugar, salt and saturated fat, any health benefits that could be attributed to the matcha may be negated.

Evangeline Mantzioris, Program Director of Nutrition and Food Sciences, Accredited Practising Dietitian, University of South Australia

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

When spring arrives, so do warnings about thunderstorm asthma. But a decade ago, most of us hadn’t heard of it.

So where did thunderstorm asthma come from? Is it a new phenomenon?

In 2016, the world’s most catastrophic thunderstorm asthma event took Melbourne by surprise. An increase in warnings and monitoring is partly a response to this.

But there are also signs climate change may be exacerbating the likelihood of thunderstorm asthma, with more extreme weather, extended pollen seasons and a rise in Australians reporting hay fever.

A landmark catastrophe

The first time many Australians heard of thunderstorm asthma was in November 2016, when a major event rocked Melbourne.

During a late night storm, an estimated 10,000 people were rushed to hospitals with severe asthma attacks. With thousands of calls on emergency lines, ambulances and emergency departments were unprepared to handle the rapid increase in people needing urgent medical care. Tragically, ten of those people died.

This was the most catastrophic thunderstorm asthma event in recorded history and the first time deaths have ever occurred anywhere in the world.

In response, the Victorian Department of Health implemented initiatives, including public awareness campaigns and improvements to health and emergency services, to be ready for future thunderstorm asthma events.

A network of pollen monitoring stations was also set up across the state to gather data that helps to predict future events.

A problem for decades

While this event was unexpected, it wasn’t the first time we’d had thunderstorm asthma in Australia – we’ve actually known about it for decades.

Melbourne reported its first instance of thunderstorm asthma back in 1984, only a year after this phenomenon was first discovered in Birmingham in the United Kingdom.

Thunderstorm asthma has since been reported in other parts of Australia, including Canberra and New South Wales. But it is still most common in Melbourne. Compared to any other city (or country) the gap is significant: over a quarter of all known events worldwide have occurred in Melbourne.

Why Melbourne?

Melbourne’s location makes it a hotspot for these kinds of events. Winds coming from the north of Melbourne tend to be dry and hot as they come from deserts in the centre of Australia, while winds from the south are cooler as they come from the ocean.

When hot and cool air mix above Melbourne, it creates the perfect conditions for thunderstorms to form.

Northern winds also blow a lot of pollen from farmlands into the city, in particular grass pollen. This is not only the most common cause of seasonal hay fever in Melbourne but also a major trigger of thunderstorm asthma.

Why grass pollen?

There’s a particular reason grass pollen is the main culprit behind thunderstorm asthma in Australia. During storms there is a lot of moisture in the air. Grass pollen will absorb this moisture, making it swell up like a water balloon.

If pollen absorbs too much water whilst airborne, it can burst or “rupture,” releasing hundreds of microscopic particles into the air that can be swept by powerful winds.

Normally, when you breathe in pollen it gets stuck in your upper airway – for example, your nose and throat. This is what causes typical hay fever symptoms such as sneezing or runny nose.

But the microscopic particles released from ruptured grass pollen are much smaller and don’t get stuck as easily in the upper airway. Instead, they can travel deep into your airways until they reach your lungs. This may trigger more severe symptoms, such as wheezing or difficulty breathing, even in people with no prior history of asthma.

So who is at risk?

You might think asthma is the biggest risk factor for thunderstorm asthma. In fact, the biggest risk factor is hay fever.

Up to 99% of patients who went to the emergency department during the Melbourne 2016 event had hay fever, while a majority (60%) had no prior diagnosis of asthma.

Every single person hospitalised was allergic to at least one type of grass pollen. All had a sensitivity to ryegrass.

Is thunderstorm asthma becoming more common?

Thunderstorm asthma events are rare, with just 26 events officially recorded worldwide.

However there is evidence these events could become more frequent and severe in coming years, due to climate change. Higher temperatures and pollution could be making plants produce more pollen and pollen seasons last much longer.

Extreme weather events, including thunderstorms, are also expected to become more common and severe.

In addition, there are signs rates that hay fever may be increasing. The number of Australians reporting allergy symptoms have risen from 15% in 2008 to 24% in 2022. Similar trends in other countries has been linked to climate change.

How can I prepare?

Here are three ways you can reduce your risk of thunderstorm asthma:

• stock up on allergy medication and set up an asthma action plan with your GP
• check daily pollen forecasts for the estimated pollen level and risk of a thunderstorm asthma event in your local area
• on days with high pollen or a high risk of thunderstorm asthma, spend less time outside or wear a surgical face mask to reduce your symptoms.

Kira Morgan Hughes, PhD Candidate in Allergy and Asthma, School of Life and Environmental Sciences, Deakin University

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