Could tea, chocolate and apples help lower your blood pressure?
By Christian Heiss, University of Surrey
We're constantly told to "eat healthy", but what does that actually mean? Even doctors sometimes struggle to offer clear, practical advice on which specific foods support health, why they work and what real benefits people can expect.
A growing body of research is starting to offer some answers. Along with colleagues, I have researched whether a group of plant compounds called flavan-3-ols could help lower blood pressure and improve blood vessel function. The results suggest these everyday compounds may have real potential for protecting heart health.
From RTÉ Radio 1's Today with Claire Byrne, Dr Paddy Barrett from Blackrock Clinic on how to reduce your blood pressure
Flavan-3-ols – sometimes called flavanols or catechins – are natural plant compounds that belong to the flavonoid family. They're part of what gives plants their colour and helps protect them from sunlight and pests.
For us, they show up in some of our most familiar foods: cocoa, green and black tea, grapes, apples and even some berries. That slightly tart or bitter note you taste in dark chocolate or strong tea? That's flavan-3-ols at work.
Scientists have long been interested in their health effects. In 2022, the Cosmos trial (Cocoa Supplement and Multivitamin Outcomes Study), which followed over 21,000 people, found that cocoa flavanols, but not multivitamin supplements, reduced deaths from cardiovascular disease by 27%. Our study set out to dig even deeper, focusing specifically on their effects on blood pressure and endothelial function (how well blood vessels dilate and respond to blood flow).
From Irish Heart Foundation, what is blood pressure?
We analysed data from 145 randomised controlled trials involving more than 5,200 participants. These studies tested a range of flavan-3-ol-rich foods and supplements, including cocoa, tea, grapes, apples and isolated compounds like epicatechin, and measured their effects on two key cardiovascular markers: blood pressure and flow-mediated dilation (FMD): a measure of how well the inner lining of blood vessels functions.
The studies ranged from short-term (a single dose) to longer-term interventions lasting weeks or months. On average, participants consumed about 586 mg of flavan-3-ols daily; roughly the amount found in two to three cups of tea, one to two servings of dark chocolate, two tablespoons of cocoa powder, or a couple of apples. Regular consumption of flavan-3-ols led to an average drop in office blood pressure of 2.8 mmHg systolic (the top number) and 2.0 mmHg diastolic (the bottom number).
But for people who started with elevated blood pressure or diagnosed hypertension, the benefits were even greater with reductions of up to 6–7 mmHg systolic and 4 mmHg diastolic. That's comparable to the effects of some prescription blood pressure medications and could significantly lower the risk of heart attacks and strokes.
From HSE Talking Health and Wellbeing podcast, a discussion on hearthHealth with Janis Morrissey from the Irish Heart Foundation
We also found that flavan-3-ols improved endothelial function, with an average 1.7% increase in FMD after sustained intake. This benefit appeared even in participants whose blood pressure was already normal, suggesting these compounds may help protect blood vessels through multiple pathways.
Side effects were uncommon and typically mild, usually limited to minor digestive issues, suggesting that adding flavan-3-ol-rich foods to your diet is generally safe.
Supporting cardiovascular health
While the benefits were most pronounced in those with high blood pressure, even people with normal readings saw improvements in vascular function. This suggests flavan-3-ols may help prevent cardiovascular problems before they begin.
From RTÉ Radio 1's Ray D'Arcy Show, Prof Robert Byrne from the Mater Private Network on how to improve heart health
High blood pressure is one of the major drivers of heart disease worldwide, even at levels that don't qualify as full-blown hypertension (140/90 mmHg or higher). Recent guidelines from the European Society of Cardiology now recognise that even "elevated" blood pressure (120–139 systolic and 70–89 diastolic) carries increased risk.
Lifestyle changes, particularly diet and exercise, are recommended by doctors as first-line strategies. But patients and even healthcare providers often lack clear, specific guidance on which foods truly make a difference. Our findings help fill this gap by showing that boosting flavan-3-ol intake through everyday foods may offer a simple, evidence-based way to support cardiovascular health.
What about supplements?
Some studies tested supplements or isolated flavan-3-ol compounds, but these generally showed smaller effects than whole foods like tea or cocoa. This may be because other beneficial compounds in whole foods work together, enhancing absorption and effectiveness.
At present, it appears both safer and more effective to focus on getting flavan-3-ols from foods rather than high-dose supplements, especially for people taking medications, since interactions are not fully understood.
The studies we reviewed suggest that 500–600 mg of flavan-3-ols daily may be enough to see benefits. You could reach this by combining two to three cups of green or black tea, one to two servings (about 56g) of dark chocolate or two to three tablespoons of cocoa powder, two to three apples, plus other flavan-3-ol-rich fruits like grapes, pears and berries.
Small daily swaps, then, like trading a sugary snack for an apple and a piece of dark chocolate or adding an extra cup of tea, could gradually improve your heart health over time. Because flavan-3-ol content can vary between foods, monitoring your blood pressure at home may help you see if it's making a difference for you.
Combined with other healthy habits, flavan-3-ols may offer a meaningful – and delicious – boost to cardiovascular health
More research is needed, particularly in people with diabetes, where the results were less consistent. We also need to better understand how flavan-3-ols interact with medications and whether even greater benefits can be achieved when combined with other healthy habits.
But the evidence is now strong enough to recommend flavan-3-ol-rich foods as part of a heart-healthy diet. As clinicians seek practical, affordable lifestyle strategies for patients, these findings bring us closer to the idea of using food as medicine.
Of course, flavan-3-ols aren't a magic fix and they won't replace medication for everyone. But combined with other healthy habits, they may offer a meaningful – and delicious – boost to cardiovascular health. And unlike many health fads, this isn't about exotic superfoods or expensive powders. It's about foods many of us already enjoy, used a little more intentionally.
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RTÉ News
a day ago
- RTÉ News
Could tea, chocolate and apples help lower your blood pressure?
Analysis: New research suggests that plant compounds found in everyday food may have real potential for protecting heart health By Christian Heiss, University of Surrey We're constantly told to "eat healthy", but what does that actually mean? Even doctors sometimes struggle to offer clear, practical advice on which specific foods support health, why they work and what real benefits people can expect. A growing body of research is starting to offer some answers. Along with colleagues, I have researched whether a group of plant compounds called flavan-3-ols could help lower blood pressure and improve blood vessel function. The results suggest these everyday compounds may have real potential for protecting heart health. From RTÉ Radio 1's Today with Claire Byrne, Dr Paddy Barrett from Blackrock Clinic on how to reduce your blood pressure Flavan-3-ols – sometimes called flavanols or catechins – are natural plant compounds that belong to the flavonoid family. They're part of what gives plants their colour and helps protect them from sunlight and pests. For us, they show up in some of our most familiar foods: cocoa, green and black tea, grapes, apples and even some berries. That slightly tart or bitter note you taste in dark chocolate or strong tea? That's flavan-3-ols at work. Scientists have long been interested in their health effects. In 2022, the Cosmos trial (Cocoa Supplement and Multivitamin Outcomes Study), which followed over 21,000 people, found that cocoa flavanols, but not multivitamin supplements, reduced deaths from cardiovascular disease by 27%. Our study set out to dig even deeper, focusing specifically on their effects on blood pressure and endothelial function (how well blood vessels dilate and respond to blood flow). From Irish Heart Foundation, what is blood pressure? We analysed data from 145 randomised controlled trials involving more than 5,200 participants. These studies tested a range of flavan-3-ol-rich foods and supplements, including cocoa, tea, grapes, apples and isolated compounds like epicatechin, and measured their effects on two key cardiovascular markers: blood pressure and flow-mediated dilation (FMD): a measure of how well the inner lining of blood vessels functions. The studies ranged from short-term (a single dose) to longer-term interventions lasting weeks or months. On average, participants consumed about 586 mg of flavan-3-ols daily; roughly the amount found in two to three cups of tea, one to two servings of dark chocolate, two tablespoons of cocoa powder, or a couple of apples. Regular consumption of flavan-3-ols led to an average drop in office blood pressure of 2.8 mmHg systolic (the top number) and 2.0 mmHg diastolic (the bottom number). But for people who started with elevated blood pressure or diagnosed hypertension, the benefits were even greater with reductions of up to 6–7 mmHg systolic and 4 mmHg diastolic. That's comparable to the effects of some prescription blood pressure medications and could significantly lower the risk of heart attacks and strokes. From HSE Talking Health and Wellbeing podcast, a discussion on hearthHealth with Janis Morrissey from the Irish Heart Foundation We also found that flavan-3-ols improved endothelial function, with an average 1.7% increase in FMD after sustained intake. This benefit appeared even in participants whose blood pressure was already normal, suggesting these compounds may help protect blood vessels through multiple pathways. Side effects were uncommon and typically mild, usually limited to minor digestive issues, suggesting that adding flavan-3-ol-rich foods to your diet is generally safe. Supporting cardiovascular health While the benefits were most pronounced in those with high blood pressure, even people with normal readings saw improvements in vascular function. This suggests flavan-3-ols may help prevent cardiovascular problems before they begin. From RTÉ Radio 1's Ray D'Arcy Show, Prof Robert Byrne from the Mater Private Network on how to improve heart health High blood pressure is one of the major drivers of heart disease worldwide, even at levels that don't qualify as full-blown hypertension (140/90 mmHg or higher). Recent guidelines from the European Society of Cardiology now recognise that even "elevated" blood pressure (120–139 systolic and 70–89 diastolic) carries increased risk. Lifestyle changes, particularly diet and exercise, are recommended by doctors as first-line strategies. But patients and even healthcare providers often lack clear, specific guidance on which foods truly make a difference. Our findings help fill this gap by showing that boosting flavan-3-ol intake through everyday foods may offer a simple, evidence-based way to support cardiovascular health. What about supplements? Some studies tested supplements or isolated flavan-3-ol compounds, but these generally showed smaller effects than whole foods like tea or cocoa. This may be because other beneficial compounds in whole foods work together, enhancing absorption and effectiveness. At present, it appears both safer and more effective to focus on getting flavan-3-ols from foods rather than high-dose supplements, especially for people taking medications, since interactions are not fully understood. The studies we reviewed suggest that 500–600 mg of flavan-3-ols daily may be enough to see benefits. You could reach this by combining two to three cups of green or black tea, one to two servings (about 56g) of dark chocolate or two to three tablespoons of cocoa powder, two to three apples, plus other flavan-3-ol-rich fruits like grapes, pears and berries. Small daily swaps, then, like trading a sugary snack for an apple and a piece of dark chocolate or adding an extra cup of tea, could gradually improve your heart health over time. Because flavan-3-ol content can vary between foods, monitoring your blood pressure at home may help you see if it's making a difference for you. Combined with other healthy habits, flavan-3-ols may offer a meaningful – and delicious – boost to cardiovascular health More research is needed, particularly in people with diabetes, where the results were less consistent. We also need to better understand how flavan-3-ols interact with medications and whether even greater benefits can be achieved when combined with other healthy habits. But the evidence is now strong enough to recommend flavan-3-ol-rich foods as part of a heart-healthy diet. As clinicians seek practical, affordable lifestyle strategies for patients, these findings bring us closer to the idea of using food as medicine. Of course, flavan-3-ols aren't a magic fix and they won't replace medication for everyone. But combined with other healthy habits, they may offer a meaningful – and delicious – boost to cardiovascular health. And unlike many health fads, this isn't about exotic superfoods or expensive powders. It's about foods many of us already enjoy, used a little more intentionally.
Irish Times
06-07-2025
- Irish Times
‘My Cosmos plants are struggling. How can I help them thrive?'
Some Cosmos bedding plants I recently planted in our new garden have struggled to get going. Their leaves have yellowed and they look stunted. Any suggestions as to what the problem is? In my old garden I grew these very easily. Rachel O'L, Kilkenny A fast-growing, floriferous, half-hardy annual, Cosmos bipinnatus is easily raised from seed sown under cover in spring. This very decorative member of the daisy family is great for quickly adding height and colour to a container display or summer border. It also makes an excellent cut flower. A wide range of varieties are available, with flowers in shades of pink as well as white, lemon-yellow and apricot. Annual cosmos is typically very vigorous, so much so that the standard advice is to avoid planting it into too rich a soil in order to encourage flower production over an excess of leafy growth. That said, plants can become sometimes infected by diseases such as aster yellows or fusarium, which cause stunted growth and yellowing of the foliage. Like most members of the daisy family, this species loves full sun and a free-draining soil, so overwatering, or growing plants in wet, poorly drained soil or in deep shade can also cause similar symptoms. There's also a chance that your plants may be suffering from what's known as lime-induced chlorosis. This happens when the soil has a high pH (a pH above 7), meaning it's alkaline or high in lime. READ MORE Plants vary in their ability to grow well in these kinds of soils. Ericaceous plants such as azalea, pieris, camellia and rhododendron, for example, can only be grown in soils where the pH is quite acidic (ideally a pH of 5-6). But most plant species including cosmos are happiest when the pH is just slightly acidic to neutral, with a pH of 6.5-7. In alkaline soils, however, an excess of lime can interfere with a plant's ability to absorb phosphorus, iron and manganese as well as other nutrients, causing the symptoms you describe. So I'd suggest you test your soil's pH, always a good idea with a new garden and something that can be done easily at home using a test widely available in most good garden centres. For accurate results, use a soil sample from an area that hasn't been recently manured or fertilised. Correcting an overly high soil pH is complicated and typically involves using products that acidify the soil, such as sulphur, aluminium sulphate and sulphur of iron, also known as ferrous sulphate. Mulching with pine needles or bark mulch are other solutions. But it's very important that this is done carefully and cautiously as the amount required will depend upon the degree of alkalinity. Bear in mind, too, that making the soil too acidic can also have a negative impact on plant growth. Detailed advice on .
RTÉ News
04-07-2025
- RTÉ News
More people presenting with hay fever due to high pollen levels
A Clare-based GP has said "there's been a big change" in people attending the medical practice for hay fever. Her remarks come after the Copernicus Atmosphere Monitoring Service reported that pollen levels were so extreme in parts of Europe during Spring, that even people not known to suffer allergies felt the effects of hay fever. Dr Yvonne Williams said patients, who have never had hay fever before, are attending the practice, saying "the normal medicines, the antihistamines, they get over the counter just aren't working for them this year". Speaking on RTÉ's Today with Claire Byrne, she added that others are wondering "why their head cold hasn't gotten better" or why it is "going on much longer than a cold and wondering what's wrong with them, they've never had hay fever before". She said those affected by allergies can try avoidance measures such as washing pollen from hair at night and keeping doors and windows closed. She said hay fever sufferers can also try "simple things" like placing Vaseline around the nose or wearing wrap around sunglasses to keep pollen out the eyes. Medicines are also available, Dr Williams said, including antihistamines, eye drops and nose sprays. But she warned some antihistamines can "make people sleepy and you have to be careful if you're driving with those". "Your pharmacy will be a great point of contact and then your GP, if you can't control it with over-the-counter medication because it can affect your sleep, it can make you tired - that has implications," she said. "For the asthmatics, that drip of hay fever and the constant sniffle - can trigger off quite bad flares of asthma and really make your asthma go out of control," she added. Scientists say that climate change is altering the production and distribution of pollen and spores, as more and more people have reported developing allergy symptoms. As winter frost thaws earlier and spring weather gets warmer, plants and trees flower earlier, extending the pollen season and misery for allergy sufferers. Around a quarter of adults in Europe suffer from airborne allergies, including severe asthma, while the proportion among children is 30 to 40%. That figure is expected to rise to half of Europeans by 2050, according to the World Health Organization. Assistant Professor at Dublin City University in the School of Chemical Sciences said "basically anyone" can have the symptoms of hay fever. "If the pollen levels get high enough, people who never have suffer from them will actually start exhibiting symptoms," Dr David O'Connor said. Dr O'Connor said pollen season starts in January and runs until September, but he said "we've noticed in our work, it's like getting longer - the start date has been pushed into December and the end date is actually heading towards October". "Also, we see increasing concentrations of the pollen as well and actually the amount of allergen in the pollen is also increasing," he added. Speaking on the same programme, he noted a pollen forecast is available for people to access on the Met Éireann website, allowing people to take mitigating measures ahead of high pollen levels. "Just kind of like your weather forecast, if you know it's gonna be raining tomorrow, you might bring a coat or an umbrella with you, if you know it's gonna be a high pollen concentration day tomorrow, you can take your antihistamine and wear your mask," he said. Dr O'Connor warned hay fever can be dangerous for those with asthma, explaining for such individuals "if they breathe in high concentrations of pollen it can actually give them an asthma attack. "That's where it goes from a well-being problem to actually a life or death problem," he added.
