A recent study has suggested Shingrix, a relatively new vaccine given to protect older adults against shingles, may delay the onset of dementia.

This might seem like a bizarre link, but actually, research has previously shown an older version of the shingles vaccine, Zostavax, reduced the risk of dementia.

In this new study, published last week in the journal Nature Medicine, researchers from the United Kingdom found Shingrix delayed dementia onset by 17% compared with Zostavax.

So how did the researchers work this out, and how could a shingles vaccine affect dementia risk?

From Zostavax to Shingrix

Shingles is a viral infection caused by the varicella-zoster virus. It causes painful rashes, and affects older people in particular.

Previously, Zostavax was used to vaccinate against shingles. It was administered as a single shot and provided good protection for about five years.

Shingrix has been developed based on a newer vaccine technology, and is thought to offer stronger and longer-lasting protection. Given in two doses, it’s now the preferred option for shingles vaccination in Australia and elsewhere.

In November 2023, Shingrix replaced Zostavax on the National Immunisation Program, making it available for free to those at highest risk of complications from shingles. This includes all adults aged 65 and over, First Nations people aged 50 and older, and younger adults with certain medical conditions that affect their immune systems.

What the study found

Shingrix was approved by the US Food and Drugs Administration in October 2017. The researchers in the new study used the transition from Zostavax to Shingrix in the United States as an opportunity for research.

They selected 103,837 people who received Zostavax (between October 2014 and September 2017) and compared them with 103,837 people who received Shingrix (between November 2017 and October 2020).

By analysing data from electronic health records, they found people who received Shingrix had a 17% increase in “diagnosis-free time” during the follow-up period (up to six years after vaccination) compared with those who received Zostavax. This was equivalent to an average of 164 extra days without a dementia diagnosis.

The researchers also compared the shingles vaccines to other vaccines: influenza, and a combined vaccine for tetanus, diphtheria and pertussis. Shingrix and Zostavax performed around 14–27% better in lowering the risk of a dementia diagnosis, with Shingrix associated with a greater improvement.

The benefits of Shingrix in terms of dementia risk were significant for both sexes, but more pronounced for women. This is not entirely surprising, because we know women have a higher risk of developing dementia due to interplay of biological factors. These include being more sensitive to certain genetic mutations associated with dementia and hormonal differences.

Why the link?

The idea that vaccination against viral infection can lower the risk of dementia has been around for more than two decades. Associations have been observed between vaccines, such as those for diphtheria, tetanus, polio and influenza, and subsequent dementia risk.

Research has shown Zostavax vaccination can reduce the risk of developing dementia by 20% compared with people who are unvaccinated.

But it may not be that the vaccines themselves protect against dementia. Rather, it may be the resulting lack of viral infection creating this effect. Research indicates bacterial infections in the gut, as well as viral infections, are associated with a higher risk of dementia.

Notably, untreated infections with herpes simplex (herpes) virus – closely related to the varicella-zoster virus that causes shingles – can significantly increase the risk of developing dementia. Research has also shown shingles increases the risk of a later dementia diagnosis.

The mechanism is not entirely clear. But there are two potential pathways which may help us understand why infections could increase the risk of dementia.

First, certain molecules are produced when a baby is developing in the womb to help with the body’s development. These molecules have the potential to cause inflammation and accelerate ageing, so the production of these molecules is silenced around birth. However, viral infections such as shingles can reactivate the production of these molecules in adult life which could hypothetically lead to dementia.

Second, in Alzheimer’s disease, a specific protein called Amyloid-β go rogue and kill brain cells. Certain proteins produced by viruses such as COVID and bad gut bacteria have the potential to support Amyloid-β in its toxic form. In laboratory conditions, these proteins have been shown to accelerate the onset of dementia.

What does this all mean?

With an ageing population, the burden of dementia is only likely to become greater in the years to come. There’s a lot more we have to learn about the causes of the disease and what we can potentially do to prevent and treat it.

This new study has some limitations. For example, time without a diagnosis doesn’t necessarily mean time without disease. Some people may have underlying disease with delayed diagnosis.

This research indicates Shingrix could have a silent benefit, but it’s too early to suggest we can use antiviral vaccines to prevent dementia.

Overall, we need more research exploring in greater detail how infections are linked with dementia. This will help us understand the root causes of dementia and design potential therapies.

Ibrahim Javed, Enterprise and NHMRC Emerging Leadership Fellow, UniSA Clinical & Health Sciences, University of South Australia

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

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.

Sweating is our body’s way of cooling down, a bit like an internal air conditioner.

When our core temperature rises (because it’s hot outside, or you’re exercising), sweat glands all over our skin release a watery fluid. As that fluid evaporates, it takes heat with it, keeping us from overheating.

But sweating can vary from person to person. Some people might just get a little dewy under the arms, others feel like they could fill a swimming pool (maybe not that dramatic, but you get the idea).

So what’s a normal amount of sweat? And what’s too much?

Why do some people sweat more than others?

How much you sweat depends on a number of factors including:

• your age (young kids generally sweat less than adults)
• your sex (men tend to sweat more than women)
• how active you are.

The average person sweats at the rate of 300 millilitres per hour (at 30°C and about 40% humidity). But as you can’t go around measuring the volume of your own sweat (or weighing it), doctors use another measure to gauge the impact of sweating.

They ask whether sweating interferes with your daily life. Maybe you stop wearing certain clothes because of the sweat stains, or feel embarrassed so don’t go to social events or work.

If so, this is a medical condition called hyperhidrosis, which affects millions of people worldwide.

People with this condition most commonly report problematic armpit sweating, as you’d expect. But sweaty hands, feet, scalp and groin can also be an issue.

Hyperhidrosis can be a symptom of another medical condition, such as an overactive thyroid, fever or menopause.

But hyperhidrosis can have no obvious cause, and the reasons behind this so-called primary hyperhidrosis are a bit of a mystery. People have normal numbers of sweat glands but researchers think they simply over-produce sweat after triggers such as stress, heat, exercise, tobacco, alcohol and hot spices. There may also be a genetic link.

OK, I sweat a lot. What can I do?

1. Antiperspirants

Antiperspirants, particularly ones with aluminium, are your first line of defence and are formulated to reduce sweating. Deodorants only stop body odour.

Aluminum chloride hexahydrate, aluminium chloride or the weaker aluminum zirconium tetrachlorohydrex glycinate react with proteins in the sweat glands, forming a plug. This plug temporarily blocks the sweat ducts, reducing the amount of sweat reaching the skin’s surface.

These products can contain up to 25% aluminium. The higher the percentage the better these products work, but the more they irritate the skin.

2. Beat the heat

This might seem obvious, but staying cool can make a big difference. That’s because you have less heat to lose, so the body makes less sweat.

Avoid super-hot, long showers (you will have more heat to loose), wear loose-fitting clothes made from breathable fabrics such as cotton (this allows any sweat you do produce to evaporate more readily), and carry a little hand fan to help your sweat evaporate.

When exercising try ice bandanas (ice wrapped in a scarf or cloth, then applied to the body) or wet towels. You can wear these around the neck, head, or wrists to reduce your body temperature.

Try also to modify the time or place you exercise; try to find cool shade or air-conditioned areas when possible.

If you have tried these first two steps and your sweating is still affecting your life, talk to your doctor. They can help you figure out the best way to manage it.

3. Medication

Some medications can help regulate your sweating. Unfortunately some can also give you side effects such as a dry mouth, blurred vision, stomach pain or constipation. So talk to your doctor about what’s best for you.

Your GP may also refer you to a dermatologist – a doctor like myself who specialises in skin conditions – who might recommend different treatments, including some of the following.

4. Botulinum toxin injections

Botulinum toxin injections are not just used for cosmetic reasons. They have many applications in medicine, including blocking the nerves that control the sweat glands. They do this for many months.

A dermatologist usually gives the injections. But they’re only subsidised by Medicare in Australia for the armpits and if you have primary hyperhidrosis that hasn’t been controlled by the strongest antiperspirants. These injections are given up to three times a year. It is not subsidised for other conditions, such as an overactive thyroid or for other areas such as the face or hands.

If you don’t qualify, you can have these injections privately, but it will cost you hundreds of dollars per treatment, which can last up to six months.

5. Iontophoresis

This involves using a device that passes a weak electrical current through water to the skin to reducing sweating in the hands, feet or armpits. Scientists aren’t sure exactly how it works.

But this is the only way to control sweating of the hands and feet that does not require drugs, surgery or botulinum toxin injections.

This treatment is not subsidised by Medicare and not all dermatologists provide it. However, you can buy and use your own device, which tends to be cheaper than accessing it privately. You can ask your dermatologist if this is the right option for you.

6. Surgery

There is a procedure to cut certain nerves to the hands that stop them sweating. This is highly effective but can cause sweating to occur elsewhere.

There are also other surgical options, which you can discuss with your doctor.

7. Microwave therapy

This is a newer treatment that zaps your sweat glands to destroy them so they can’t work any more. It’s not super common yet, and it is quite painful. It’s available privately in a few centres.

Michael Freeman, Associate Professor of Dermatology, Bond University

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