Olive oil is synonymous with the Mediterranean diet, and the health benefits of both are well documented.

Olive oil reduces the risk of heart disease, cancer, diabetes and premature death. Olives also contain numerous healthy nutrients.

Now evidence is mounting about the health benefits of olive leaves, including from studies in a recent review.

Here’s what’s in olive leaves and who might benefit from taking olive leaf extract.

What’s in olive leaves?

Olive leaves have traditionally been brewed as a tea in the Mediterranean and drunk to treat fever and malaria.

The leaves contain high levels of a type of antioxidant called oleuropein. Olives and olive oil contain this too, but at lower levels.

Generally, the greener the leaf (the less yellowish) the more oleuropein it contains. Leaves picked in spring also have higher levels compared to ones picked in autumn, indicating levels of oleuropein reduce as the leaves get older.

Olive leaves also contain other antioxidants such as hydroxytyrosol, luteolin, apigenin and verbascoside.

Antioxidants work by reducing the oxidative stress in the body. Oxidative stress causes damage to our DNA, cell membranes and tissues, which can lead to chronic diseases such as cancer and heart disease.

Are olive leaves healthy?

One review and analysis combined data from 12 experimental studies with 819 participants in total. Overall, olive leaf extract improved risk factors for heart disease. This included healthier blood lipids (fats) and lowering blood pressure.

The effect was greater for people who already had high blood pressure.

Most studies in this review gave olive leaf extract as a capsule, with daily doses of 500 milligrams to 5 grams for six to 48 weeks.

Another review and analysis published late last year looked at data from 12 experimental studies, with a total of 703 people. Some of these studies involved people with high blood lipids, people with high blood pressure, people who were overweight or obese, and some involved healthy people.

Daily doses were 250-1,000mg taken as tablets or baked into bread.

Individual studies in the review showed significant benefits in improving blood glucose (sugar) control, blood lipid levels and reducing blood pressure. But when all the data was combined, there were no significant health effects. We’ll explain why this may be the case shortly.

Another review looked at people who took oleuropein and hydroxytyrosol (the antioxidants in olive leaves). This found significant improvement in body weight, blood lipid profiles, glucose metabolism and improvements in bones, joints and cognitive function.

The individual studies included tested either the two antioxidants or olive leaf incorporated into foods such as bread and cooking oils (but not olive oil). The doses were 6-500mg per day of olive leaf extract.

So what can we make of these studies overall? They show olive leaf extract may help reduce blood pressure, improve blood lipids and help our bodies handle glucose.

But these studies show inconsistent results. This is likely due to differences in the way people took olive leaf extract, how much they took and how long for. This type of inconsistency normally tells us we need some more research to clarify the health effects of olive leaves.

Can you eat olive leaves?

Olive leaves can be brewed into a tea, or the leaves added to salads. Others report grinding olive leaves into smoothies.

However the leaves are bitter, because of the antioxidants, which can make them hard to eat, or the tea unpalatable.

Olive leaf extract has also been added to bread and other baked goods. Researchers find this improves the level of antioxidants in these products and people say the foods tasted better.

Is olive leaf extract toxic?

No, there seem to be no reported toxic effects of eating or drinking olive leaf extract.

It appears safe up to 1g a day, according to studies that have used olive leaf extract. However, there are no official guidelines about how much is safe to consume.

There have been reports of potential toxicity if taken over 85mg/kg of body weight per day. For an 80kg adult, this would mean 6.8g a day, well above the dose used in the studies mentioned in this article.

Pregnant and breastfeeding women are recommended not to consume it as we don’t know if it’s safe for them.

What should I do?

If you have high blood pressure, diabetes or raised blood lipids you may see some benefit from taking olive leaf extract. But it is important you discuss this with your doctor first and not change any medications or start taking olive leaf extract until you have spoken to them.

But there are plenty of antioxidants in all plant foods, and you should try to eat a wide variety of different coloured plant foods. This will allow you to get a range of nutrients and antioxidants.

Olive leaf and its extract is not going to be a panacea for your health if you’re not eating a healthy diet and following other health advice.

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.

The war in Ukraine has had impacts around the world. Supply chains have been disrupted, the cost of living has soared and we’ve seen the fastest-growing refugee crisis since World War II. All of these are in addition to the devastating humanitarian and economic impacts within Ukraine.

Our international team was conducting a global study on wellbeing in the lead up to and after the Russian invasion. This provided a unique opportunity to examine the psychological impact of the outbreak of war.

As we explain in a new study published in Nature Communications, we learned the toll on people’s wellbeing was evident across nations, not just in Ukraine. These effects appear to have been temporary – at least for the average person.

But people with certain psychological vulnerabilities struggled to recover from the shock of the war.

Tracking wellbeing during the outbreak of war

People who took part in our study completed a rigorous “experience-sampling” protocol. Specifically, we asked them to report their momentary wellbeing four times per day for a whole month.

Data collection began in October 2021 and continued throughout 2022. So we had been tracking wellbeing around the world during the weeks surrounding the outbreak of war in February 2022.

We also collected measures of personality, along with various sociodemographic variables (including age, gender, political views). This enabled us to assess whether different people responded differently to the crisis. We could also compare these effects across countries.

Our analyses focused primarily on 1,341 participants living in 17 European countries, excluding Ukraine itself (44,894 experience-sampling reports in total). We also expanded these analyses to capture the experiences of 1,735 people living in 43 countries around the world (54,851 experience-sampling reports) – including in Australia.

A global dip in wellbeing

On February 24 2022, the day Russia invaded Ukraine, there was a sharp decline in wellbeing around the world. There was no decline in the month leading up to the outbreak of war, suggesting the change in wellbeing was not already occurring for some other reason.

However, there was a gradual increase in wellbeing during the month after the Russian invasion, suggestive of a “return to baseline” effect. Such effects are commonly reported in psychological research: situations and events that impact our wellbeing often (though not always) do so temporarily.

Unsurprisingly, people in Europe experienced a sharper dip in wellbeing compared to people living elsewhere around the world. Presumably the war was much more salient for those closest to the conflict, compared to those living on an entirely different continent.

Interestingly, day-to-day fluctuations in wellbeing mirrored the salience of the war on social media as events unfolded. Specifically, wellbeing was lower on days when there were more tweets mentioning Ukraine on Twitter/X.

Our results indicate that, on average, it took around two months for people to return to their baseline levels of wellbeing after the invasion.

Different people, different recoveries

There are strong links between our wellbeing and our individual personalities.

However, the dip in wellbeing following the Russian invasion was fairly uniform across individuals. None of the individual factors assessed in our study, including personality and sociodemographic factors, predicted people’s response to the outbreak of war.

On the other hand, personality did play a role in how quickly people recovered. Individual differences in people’s recovery were linked to a personality trait called “stability”. Stability is a broad dimension of personality that combines low neuroticism with high agreeableness and conscientiousness (three traits from the Big Five personality framework).

Stability is so named because it reflects the stability of one’s overall psychological functioning. This can be illustrated by breaking stability down into its three components:

1. low neuroticism describes emotional stability. People low in this trait experience less intense negative emotions such as anxiety, fear or anger, in response to negative events
2. high agreeableness describes social stability. People high in this trait are generally more cooperative, kind, and motivated to maintain social harmony
3. high conscientiousness describes motivational stability. People high in this trait show more effective patterns of goal-directed self-regulation.

So, our data show that people with less stable personalities fared worse in terms of recovering from the impact the war in Ukraine had on wellbeing.

In a supplementary analysis, we found the effect of stability was driven specifically by neuroticism and agreeableness. The fact that people higher in neuroticism recovered more slowly accords with a wealth of research linking this trait with coping difficulties and poor mental health.

These effects of personality on recovery were stronger than those of sociodemographic factors, such as age, gender or political views, which were not statistically significant.

Overall, our findings suggest that people with certain psychological vulnerabilities will often struggle to recover from the shock of global events such as the outbreak of war in Ukraine.

Luke Smillie, Professor in Personality Psychology, The University of Melbourne

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

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.