can caffeine improve your exercise performance?

13/09/2019
by Ahmad Salah

Coffee is one of the most popular drinks in the world. Nearly half the adult population in Australia drink it.

Aside from enjoying the taste, the main reason we drink coffee is to get caffeine into our bloodstream. Caffeine can help keep you awake, increase alertness, improve your concentration, enhance cognitive performance, and sharpen short-term memory and problem-solving skills.

It can also enhance physical performance.

We’ve reviewed the evidence

In a recent umbrella review, we summarised the findings from all meta-analyses that explored the effects of caffeine on exercise performance. A meta-analysis is a method that allows us to combine results from multiple studies to estimate the true effect.

Our review included more than 300 primary studies with more than 4,800 participants.

We found improvements in sports performance following caffeine intake that range from 2% to 16%.

Those who respond most strongly to caffeine might see improvements of around 16%, but this is unusual. For the average person, improvements will likely be between about 2% and 6%.

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This may not seem like much in the context of everyday life. But particularly in competitive sports, relatively small improvements in performance can make a big difference.

We found caffeine can enhance our ability to run and cycle for longer periods, or to complete a given distance in a shorter time frame. It could also allow us to perform more repetitions with a given weight in the gym, or to increase the total weight lifted.

How does caffeine have these effects?

When we get tired, a chemical called adenosine binds to its receptors in the brain. The chemical structure of caffeine is similar to that of adenosine, and when ingested, it competes with adenosine for these receptors – which tell our brains how fatigued we are.

During waking hours, adenosine slows down brain activity and results in feelings of fatigue. When we have caffeine, the caffeine binds to the adenosine receptors and has the opposite effect of adenosine. It reduces fatigue and our perception of effort (for example, how hard it feels to perform an exercise).

Researchers once thought the effects of caffeine would be reduced in people who regularly drink a lot of coffee, but studies have shown that caffeine has performance-enhancing effects regardless of habits.

Does coffee = caffeine?

In one study, drinking coffee or taking caffeine in a capsule resulted in similar improvements in cycling performance. When the caffeine dose is matched, caffeine and coffee seem to be equally beneficial for improving performance.

But the dose of caffeine in a coffee may vary based on the type of coffee bean, preparation method, and size of the cup. It may also vary between different coffee brands, and even within the same brand at different times.

On average though, one cup of brewed coffee usually contains between 95 and 165mg of caffeine.

Experts believe caffeine doses between 3 and 6 mg/kg are needed to improve performance. That’s 210 to 420mg for a 70kg person, or about two cups of coffee.

For safety reasons, those who don’t normally drink coffee should begin with a lower dose. The optimal dose, of course, varies between individuals, so there’s room to experiment a little.

Aside from caffeine capsules or coffee, researchers are exploring other sources of caffeine for their effects on exercise performance. These include chewing gums, bars, mouth rinses, and energy drinks. But this area of research is relatively new and needs further investigation.

How long before my workout should I drink coffee?

Experts recommend ingesting caffeine roughly 45-90 minutes before exercising. Some forms of caffeine such as caffeine gum are absorbed faster and can elicit a performance-enhancing effect even when consumed ten minutes before exercise.

Does this mean we should all start loading up on caffeine? Well, perhaps not just yet. Although people who ingest caffeine usually improve their performance, for some, the effects may be negligible.

And overdosing on caffeine can have some really unpleasant side effects, including insomnia, nervousness, restlessness, stomach irritation, nausea, vomiting, and headaches.

A certain amount of individual experimentation is needed to find out if caffeine will improve your exercise performance, or just give you a headache.

But for those looking for simple ways to gain a slight performance edge, getting more caffeine into your bloodstream might just be the ticket.

why do I get a headache when I haven’t had my coffee?

13/09/2019
by Ahmad Salah

Caffeine is our favourite drug. But if we miss out on our fix, it can be a real headache, in more ways than one.

Caffeine is a stimulant. It quickly enters our brain and blocks the (adenosine) receptors that are responsible for dulling brain activity. By blocking the dulling of our brain, we feel a sense of invigoration, focus and subtle euphoria. These feelings can also enhance our performance of certain focused tasks, like driving or staying awake through the whole lecture.

This is the upside of caffeine. The downside is how we feel when we are not getting our usual dose. Because of the anticipated highs of brain activity after our cup, the lows without it seem longer and deeper.

The other problem is that caffeine is addictive. When we aren’t getting what we’re used to, we can feel tired, inattentive, irritable and moody. This is known as withdrawal. Many people regularly drink caffeinated beverages just to avoid feeling this way.

By far the most common symptom of caffeine withdrawal is headaches. These are typically mild and short-lived, usually only lasting for a day or two, although they can sometimes last for up to week. They usually feel a bit like a tense band wrapped across your head and are sometimes called tension-type headaches as a result. However, caffeine withdrawal can also trigger a full-on migraine in some sufferers.

Why we get headaches with withdrawal (as well as many other causes) is mostly because our face and head is the most active as well as the most sensitive part of our body. For our brain to accurately know what’s happening, the signals it receives from the senses have to be spot on.

Any distortion of the signal and the message can become lost in translation, or even result in the wrong message being received. One theory for headaches is our fuzzy brain misinterprets some of the innocuous signals it gets from our head, and calls them a headache.

Some level of caffeine withdrawal would be experienced by maybe half of all regular tea or coffee drinkers, if their regular drug supply would be completely cut off. The more we drink and the more regularly we drink caffeine, the more likely we’d experience withdrawal symptoms if we were to go without.

However, withdrawal can happen even in people who usually drink just a single cup every day who then forego caffeine. Equally, only three days of continuous coffee drinking is enough to make you feel bad when the coffee runs out.

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Caffeine withdrawal only occurs with abstinence. Small amounts of caffeine (just a quarter of a cup) will keep the headaches at bay. Even if the espresso machine is broken and you have to have a (half-less caffeinated) latte, you won’t go into withdrawal.

But if you’re going cold turkey, withdrawal headaches typically peak a day or two after removing all caffeine from the menu. Withdrawal does not happen within a few hours of the last cup, despite the protestation of the habitual coffee drinker.

Of course, if withdrawal is really the problem, the remedy is simple. Any headache caused by lack of caffeine is rapidly and often completely relieved within 30 minutes to an hour of drinking a cup of tea or coffee.

Some of this is the fix and the anticipation of it. In fact, Australian researchers have found giving someone experiencing caffeine withdrawal a de-caf, but telling them it’s caffeinated, is enough to make them feel better. Of course this trick won’t work if you buy the coffee yourself.

Surprisingly though, caffeine also has some painkiller properties. Simple pain-killers such as non-steroidal anti-inflammatories, aspirin or paracetamol can be more effective when formulated with some caffeine (in each dose about two to three times that in a regular cup of coffee).

For hypnic “alarm clock” headaches that wake sufferers at night, hangover-headaches and some migraine-sufferers, a cup of tea or coffee can be an effective pain-killer on its own.

This analgesia is not just because we feel less stressed or less distracted by pain after a cup of tea or coffee. It turns out the same adenosine receptors blocked by caffeine are also implicated in the origin of headache as well as other kinds of pain.

More than 90% of all adults drink coffee or tea, rousing us from our slumber and providing the revitalising energy to do the things that need to be done. It’s not hard to imagine the headaches without it.

does drinking coffee help you live longer?

13/09/2019
by Ahmad Salah

There’s only one thing better than a hot cup of coffee in the morning: a new research paper telling you your daily habit is good for your health. Headlines this week presented the good news from the journal JAMA Internal Medicine:

Like many previous studies, the JAMA paper found people who drank coffee had a lower risk of dying of any cause – and specifically, of dying from heart disease and cancer – over the course of the study.

But this study only shows a correlation between drinking coffee and a lower risk of early death. It doesn’t show coffee was the cause of the lower risk.

The research is important, however, because it overturns the theory that people who drink six or more cups of coffee a day are at greater risk of early death. This issue had not been effectively addressed in previous studies.

How was the research conducted?

This was a prospective trial, which tracked almost half a million British residents over ten years as part of the UK Biobank study.

In a prospective trial, subjects are recruited, then their health and illness are followed over time. We have a good idea of how healthy they were to start off with. We also have a good idea of other factors that could impact their health from the start, rather than trying to reconstruct them after they have developed a disease.

In a baseline questionnaire, subjects gave detailed responses to coffee consumption (how much, how often, what types of coffee and whether it was caffeinated or decaffeinated), as well as other factors such as alcohol, tea, race, education, physical activity, body mass index (BMI) and smoking (including intensity, type of tobacco and time since quitting).

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The volunteers were all genotyped to determine their genetic variations of major caffeine metabolising enzymes.

The participants’ health status was monitored during the study and, if they died, their cause of death was determined by the National Health Service using internationally recognised criteria.

What did they find?

After taking into account factors such as smoking and alcohol intake, the researchers found fewer coffee drinkers died than those who didn’t drink coffee over the ten-year study period.

Depending on the amount consumed, coffee drinkers were around 5-10% less likely to die from heart disease, cancer and other causes during the study period than non-coffee drinkers.

Compared to non-coffee drinkers, those who consumed one cup of coffee a day had an 8% lower risk of premature death; this increased to a 16% lower risk for those who drank six cups a day. People who drank up to eight cups of coffee a day were 14% less likely to die prematurely than non-coffee drinkers.

This pattern was seen for all types of coffee, including instant and decaffeinated coffee.

The researchers found drinking six or more cups of coffee a day was not associated with an increased risk of death. While some previous studies had hinted at this (see here and here) the relationship was still uncertain. The current study is the most extensive exploration of high coffee intake to date.

They also found people who had a history of cancer, diabetes, heart attack or stroke were not at a higher risk of death from drinking a moderate amount of coffee.

Finally, and most importantly, the researchers found people who were less able to break down caffeine were not at higher risk of death.

Previously, researchers had thought people who broke down caffeine more slowly would have higher risks of heart disease because they had higher levels of caffeine in the blood than the average person. This turns out not to be so.

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What does it all mean?

As with the previous studies, this is a correlation study. So, while there was an association between coffee consumption and a lower risk of death, we still can’t say coffee was the cause of the lower risk of death.

There may be some other environmental variable that was not accounted for. Coffee consumption may entail more walking, for instance, which was not captured in the lifestyle questionnaires.

But it is still plausible coffee causes the lowered death risk. While coffee is most notable for its caffeine content, it also contains a host of antioxidants such a caffeic acid and cholorogenic acid, which might have health benefits.

This may be why the risk of death in the JAMA study was also lower for those who drank decaffeinated coffee. Decaf has been similarly effective in reducing the risk of heart disease in other studies.

Despite a recent US court ruling coffee companies in California must carry cancer warning labels, this study supports previous research that coffee consumption is protective against cancer, particularly of the colon and liver.

Coffee consumption is also thought to be protective against type two diabetes, Parkinson’s and Alzheimer’s disease. However, the effect of coffee consumption is modest, and should not replace other factors such as diet and exercise.

On the other hand, women who drink coffee may have an increased fracture risk, and may wish to reduce coffee consumption during pregnancy.

This week’s JAMA study might not be reason enough to start drinking coffee, but if you love the drink, you needn’t worry about having another cup. – Ian Musgrave


Blind peer review

This is a fair and accurate assessment. Although an observational study, it is still good news for coffee drinkers. We’re unlikely to ever have a large, randomised controlled trial that can truly answer this question of causation.

One limitation of the study, which is described in the paper, is that the researchers just asked participants to tick which type of coffee they predominately drink. So there may be some mis-classification of people who regularly drank more than one type of coffee. – Clare Collins


is caffeine actually bad for kids?

13/09/2019
by Ahmad Salah

A recent article in The Guardian said coffee stunting kids’ growth is just a myth promoted by 19th-century manufacturers of a coffee substitute.

So does this mean the long-thought wisdom that coffee is bad for kids is a lie?

Caffeine and diet

In one study, kids who drank caffeine were more likely to have poor diets. Chris Barnes/Flickr, CC BY

Kids normally need a lot of extra nutrition during their adolescent growth spurt, and you might expect the appetite-suppressing effect of caffeine to result in poorer dietary intake and reduced growth.

However, data from the Penn State Young Women’s Health Study indicated growth in teenage girls did not appear to be affected by their caffeine intake – there was no correlation at all.

The girls with the lowest caffeine intakes did have better diets, though, eating less sugar and more fruit and dairy foods. And this may show what the main problem is with kids and caffeine: its association with factors that affect health in other ways.

Caffeine and tooth decay

American data from nationwide health audits indicate that nearly three-quarters of US children consume caffeine, with the most common source being soft drinks (including energy drinks).

Apart from the caffeine content, these sugary drinks – in fact any carbonated drinks – are high in tooth-damaging acid. Compared to adults, kids are more vulnerable to tooth decay as their saliva is less effective at rinsing the teeth and their tooth enamel is softer.

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Calories

Another problem is that caffeine-containing soft drinks, iced tea products and Starbucks-style cream-laden coffee drinks are a concentrated source of extra calories in the diet, and their liquid form means our bodies aren’t good at judging when we have had enough.

This makes them a poor choice of drink if there is concern about risk of obesity, and the addictive caffeine in them can make it a harder habit to break.

Sleeping patterns

But what about a weak milky cup of coffee, tea or cocoa, without sugar? While these don’t pose the same nutritional problems, the caffeine might still have an impact on kids’ health by affecting their sleep patterns.

Kids need a lot of sleep. The Australian Sleep Health Foundation recommends up to 11 hours per night for children, or eight to ten hours for teenagers.

It’s hard for teens to get the amount of sleep they need, because they are naturally “night people”. If normal school and work hours require them to be up by seven or eight in the morning it is then important for them to be asleep by ten – something they will often find difficult. It is even harder if they consume caffeine.

Kids will be more affected by caffeine which might affect their sleep. Jessica Lucia/Flickr, CC BY

Even an early afternoon coffee could have an effect because it can last in the body for up to eight hours, and kids are affected by much smaller caffeine doses because of their smaller body size.

And just as for adults, caffeine can cause anxiety, nausea and headache, as well as affecting heart rhythm in susceptible people.

In one study in children, even one milligram of caffeine per kilogram of body weight caused significant changes in blood pressure and heart rate, as well as nausea in many of the participants.

An average Australian eight-year-old girl weighs about 25 kilograms, and that dose would be equivalent to a cup of tea or five squares of chocolate, or half a weak cappuccino.

Small amounts

But, as previously pointed out, there are also some well-documented health benefits associated with a low-to-moderate intake of coffee – potentially a reduced risk of dementia, depression, diabetes and cancer.

And caffeine-boosted alertness, concentration and mood can be beneficial for children as well as adults, as long as the dose is low enough to avoid unwanted side-effects and addiction. Just note – for kids, that dose is a lot lower than you might have thought.


Jamaica Blue Mountain Coffee

10/09/2019
by Ahmad Salah

jamaica evokes a lot of positive associations in us, good weather, peaceful music and beautiful women on the beach. Not to mention one of the most valuable coffees in the world, the world famous Blue Mountain, which gives a lot of pleasure to the coffee lovers. The stock market value of this coffee is twenty times of the normal coffee. Its unique flavor is characterized by a mellow aroma and a slightly nutty, soft flavor. James Bond, the famous character of the brilliant spy stories also appraises, not to mention the Japanese emperor.

Jamaica’s climate is humid and it’s high altitude areas makes it the perfect place for growing high-quality coffee. True to its name, Jamaican Blue Mountain is grown in the foggy, bluish Blue Mountain (which by the way also inspired the name of a record label founded by Chris Blackwell). The annually harvested beans are grown over 900 meters and are selected one by one, manually. The coffee cherries are immediately deprived of flesh after harvest, this ensures the typically mild flavor.

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The British naturalized coffee production in Jamaica, in the first half of the 18th century. This was also the beginning of the Blue Mountain coffee’s career. However, it only became famous when Japanese investors began to deal with the growing area in the late 60’s. The Japanese market was always open to specialties, so they began to pay a high price for the extra quality coffee. In fact, 90% of the total yield is bought up by the land of the rising sun.

Coffee lovers should become familiar with this special variety, but it is important to buy from a reliable source because there are many fakes on the market. It is interesting also that this coffee is transported in barrels, unlike other varieties that are expedited in coffee bags.v

a special role of coffee to take care of your skin

10/09/2019
by Ahmad Salah

If your cup overfloweth with cold brew coffee grounds, these homemade hacks will lighten the load (and work wonders!).

When it comes to delicious homemade cold brew, we stand by our Trade Cold Brew Bags not only for their incredible ease of use, but also for the quick cleanup. While you can simply toss or commercially compost these bags, there’s another multi-purpose: skincare.

True, making cold brew at home not only does wonders for your taste buds, budget, and time — your face and body can reap the benefits too! Clarifying and revitalizing, coffee has many purported benefits that make it an ideal ingredient for DIY skincare treatments.

Brown Sugar Body Scrub

If you’ve ever DIYed a body scrub, it was probably sugar-based like this coffee and brown sugar version. Sweet smelling and gently exfoliating, sugar scrubs are a great way to remove dead cells, leaving your skin fresh and inviting.

And because brown sugar is a humectant, meaning it helps your skin absorb water from the environment, brown sugar pairs well with coarser coffee grounds to refine the exfoliation and leave skin satiny smooth and perfectly hydrated.

Coconut Coffee Lip Scrub

Coconut oil is the MVP of homemade bath products. Here with the help of cold brew grounds, this coconut coffee lip scrub will leave your lips silky-smooth and ready for your favorite mug.

Virgin coconut oil has been shown to have antimicrobial properties and has also been linked with increased skin hydration and reduced inflammation. In short, coconut has a lot going on for it and so does this scrub!

Vanilla Coffee Scrub Soap

Sweet smelling and gentle, a vanilla coffee soap bar is great for full-body exfoliation. And since each batch makes four bars, you won’t have to worry about running out any time soon.

While coffee holds up the exfoliation end of the bargain, vanilla pulls its weight with surprising antibacterial properties.

Coffee Bath Bombs

While we don’t recommend the 12 to 18 hour soak we do for our Trade Cold Brew bags, you may want to hang out in this tub about that long.

Coffee bath bombs will leave your skin feeling revitalized and your bathroom smelling like your favorite café. Bathe it in with coffee’s topical health benefits while you calm your skin — and your mind!

source :

https://blog.drinktrade.com/2019/05/24/diy-skincare-coffee-ground-scrubs/

Interesting Facts About Kenyan Coffee

09/09/2019
by Ahmad Salah

according to experts, Kenya is one of coffee’s most reliable sources, due to stringent quality control system in Africa – and to the environmentally conscious cultivation of the shrubs with a low amount of chemicals. Here are some interesting facts about Kenyan coffee:

The 1800s, when it all started

Although Kenya is a neighbor of Ethiopia, the cultivation of coffee started only in the late 1800s, due to a Scottish missionary, John Paterson. However, until 1923 coffee was only produced in areas inhabited by European settlers, then it spread to other regions of the country.

A prefect tropical climate

The country’s tropical climate is more than ideal for the coffee production. It is difficult to distinguish between months with balanced temperature, seasons are virtually nonexistent. Two rainy period (April-June and October-November) will diversify the microclimate and the remaining dry months comes the harvest.

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Constantly improving coffee production

Today, Kenya is among the 20 largest coffee producing countries in the world, but quality is more important than the quantity. Many people agree that Africa’s top coffee quality control operates in Kenya, which is mostly due to the strict regulation of the sector by the one-party system after the colonial period. The political system turned into a multi-party republic in the last decade, the market became free, but the regulation remained.

Selling through the auction house

The auction system was introduced in the 30’s, most of the materials are still sold through this. The majority of the coffee is grown on smaller plantations and the Coffee Board of Kenya buys it up. The organization selects the beans, do the tastings and auctions them at the auction. This forces the farmers to produce the highest quality coffee. This process ensures consistency of high-quality coffees and recognized character.

A wide range of producers, a distinctive taste

The country’s total production is given by 700 thousand primary producers. In most cases, the characteristic taste is due to the wet processing procedure and the highly popular SL28’s and SL34’s variants.

Not every bean is the same

The coffee beans are basically classified according to size, the system is easy to review: AA is the top category, followed by the A and B. The peaberry part is separated, with PB mark. Although size is not necessarily indicative of the quality, but bad beans are filtered during the selection, which in turn is a major advantage.

source :

http://cafeflavour.com/interesting-facts-about-kenyan-coffee/

A Brief History Of American Coffee Culture

04/09/2019
by Ahmad Salah

Coffee is as much a part of American culture as are blue jeans and rock-n-roll. Although getting a late start on the coffee wagon, the US has since revolutionized the coffee scene, from the introduction of Starbucks to the modern resurgence in coffee rituals and expertise.

Coffee’s genesis, like most foods, is a story tangled within centuries-old folklore. A popular legend tells of a goat herder named Kaldi who is said to have discovered coffee beans on the Ethiopian plateau hundreds of years ago. His goats, which snacked on the ancient fruit-bearing shrubs, galloped around filled with energy. Testing the fruit himself, Kaldi had a similar reaction, disclosing his discovery with a local monastery. The abbot – who made a beverage from the red berry – shared the drink with other monks, and knowledge of the natural stimulant quickly spread across the continent.

Before a modern version of coffee appeared, its cherry-like fruit was used in a variety of preparations, some of which included wine-like substances. By the 15th century, coffee was being cultivated and traded in Arabia, and its beans – stripped from its pulp exterior – were roasted and brewed. Public coffee houses, called qahveh khaneh, sprang up across the east as places where people could exchange information over a cup of the much-loved potion. Traveling to Europe, coffee quickly became the morning beverage of choice over beer and wine, and by the mid-1600s, there were over 300 coffee houses in London – often frequented by famous artists, writers, and intellects.

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Coffee was finally brought to the New World by the British in the mid-17th century. Coffee houses were popular, but it wasn’t until the Boston Party in 1773 that America’s coffee culture was changed forever: the revolt against King George III generated a mass switch from tea to coffee amongst the colonists. The demand for coffee flourished, and after the Dutch had secured coffee seedlings towards the end of the 1600s, coffee cultivation expanded outside of Arabia for the first time. Travelers and traders carried seeds to new lands, and coffee trees were planted across the globe.

By the 18th century, coffee had become one of the world’s most profitable commodities. Consumption and popularity in the US increased, especially during the Civil War, and savvy businessmen were looking for a way to profit from it. In 1864, Pittsburgh-born brothers John and Charles Arbuckle began selling pre-roasted coffee by the pound, getting rich by selling it to cowboys in the West. James Folger, who sold coffee to gold miners in California, also saw great success. Several other big name coffee brands, including Maxwell House and Hills Brothers, quickly followed suit. Post-war, instant coffee was introduced to the market and remained popular until Starbucks opened in Seattle in 1971. Starbucks made coffee geographically available to people across America, tailoring the beverage to the unique palate of every customer.

Today, the coffee revolution continues to grow. A grass-roots movement that started in small, independently owned coffee shops is refining what Starbucks gave us: it’s now an artistic craft – much like that of wine or beer – that uses sustainable, locally roasted, fair trade beans. Where the beans are grown, how they are roasted, and the brewing process are all looked at closely. This coffee expertise is growing amongst young people, many using it as training for the culinary world. As much as a string of fresh rosemary or a juicy, ripe tomato bear a myriad of complex flavors, coffee does, too.


source :

https://theculturetrip.com/north-america/usa/articles/a-brief-history-of-american-coffee-culture/

Majority of Wild Coffee Species at Risk of Extinction

04/09/2019
by Ahmad Salah

more than half of the world’s 124 wild coffee plant species meet the criteria for inclusion on the International Union for Conservation of Nature’s Red List of Threatened Species, according to reports published today (January 16) in Science Advances and Global Change Biology. The authors say extinctions among the species would limit plant breeders’ options in developing new types of coffee in the future.

The study, carried out at Britain’s Royal Botanic Gardens, Kew, found that 60 percent of wild coffee species are at risk, a figure that “is extremely high, especially when you compare this to a global estimate of 22% for plants,” says coauthor Eimear Nic Lughadha in a statement. “Some of the coffee species assessed have not been seen in the wild for more than 100 years, and it is possible that some may already be extinct.”

Popular Mechanics reports that most wild coffee species are found in subsaharan Africa, although some live as far afield as Pacific islands. Many of the threatened species live in Madagascar and Tanzania. The threats vary among taxa, but include drought and deforestation. Among those at risk is Arabica, the wild cousin of the commercially grown plant that makes up 60 percent of coffee sales worldwide.

Coauthor Aaron Davis tells Reuters that the threatened species could be a resource for breeders looking to tweak commercial coffee strains by, for example, helping them withstand changing climate conditions or resist disease. “There are many countries which depend on coffee for the . . . bulk of their export earnings,” he tells the wire service. “It’s estimated there are 100 million people producing coffee in farms around the world.”

source :

https://www.the-scientist.com/news-opinion/majority-of-wild-coffee-species-at-risk-of-extinction--study-finds-65329

How Coffee Affects the Body Clock?

04/09/2019
by Ahmad Salah

Coffee, tea, and other caffeinated drinks can make a person feel more awake and alert, but new research suggests that, when consumed in the evening, caffeine might also delay the body’s internal clock. A paper published in Science Translational Medicine today (September 16) shows that people given a dose of caffeine a few hours before their normal bedtimes exhibited a delay in their circadian rhythms of more than half an hour.

“We already knew that caffeine is a stimulant and can keep you awake and make it difficult to fall asleep at night if taken too close to bedtime,” said behavioral neurologist Charmane Eastman of Rush University in Chicago, who was not involved in the work. “This study shows that caffeine can also make your internal circadian body clock later, which could make it difficult to fall asleep the next night even if you don’t take caffeine again.”

A person’s circadian rhythms are established by a variety of temporal cues such as sunrise and sunset, feeding times, body temperature fluctuations, and levels of certain hormones. And resisting these cues is hard. Many people’s sleep and daily routines are disturbed by the one-hour shift to daylight saving, for example, let alone by a long-haul flight across multiple time zones. Yet these latest results from Kenneth Wright and his colleagues at the University of Colorado, Boulder, and John O’Neill at the MRC Laboratory of Molecular Biology in Cambridge, U.K., suggest that shifting one’s sleep-wake clock might be as simple as drinking a well-timed cup of coffee.

Caffeine is thought to induce wakefulness by binding adenosine receptors on brain cells, causing the release of excitatory neurotransmitters. But recent evidence suggests this might not be caffeine’s only effect. “There had been research done in other species like algae and fruit flies suggesting caffeine could impact the circadian clock,” said Wright, “but nothing had been done in humans.”

For the present work, Wright and colleagues gave study participants caffeine pills—equivalent to a double espresso—three hours before the subjects’ habitual bedtimes and took saliva samples every half hour or so to measure the levels of melatonin—a hormone that accumulates in the body in the hours or darkness and signals the onset of sleep. The caffeine pills caused the subjects’ normal nightly melatonin peaks to be delayed by approximately 40 minutes.

In separate positive control experiments, the team exposed the same participants to three hours of bright light at bedtime—known to delay the circadian clock. This light exposure, equivalent to that of the midday sun, delayed the subjects’ melatonin peaks by approximately 85 minutes. Combining the bright light exposure with the caffeine consumption did not significantly increase the melatonin delay, possibly because the light intensity had already maximized the shift, the authors speculated.

O’Neill then examined human cells to figure out the molecular mechanisms involved in the circadian delay. Caffeine treatment of human osteosarcoma cells has previously been shown to delay the oscillations of circadian clock gene reporters, and O’Neill discovered that this effect was dependent on the adenosine A1 receptor. Caffeine’s stimulatory effects, on the other hand, have been shown to largely depend on the adenosine A2A receptor, providing a molecular explanation for caffeine’s different but related effects.

“One interesting property of the circadian clock is that whereas a light pulse late in the evening delays our rhythm, a light pulse in the morning advances it,” said molecular neurobiologist Malcolm von Schantz of the University of Surry, U.K., who was not involved in the work. “This paper only reports the results of a single time point, and one could hypothesize that in a similar fashion, a dose of caffeine in the morning may help advance our rhythms.” If so, he added, “then a strong coffee in the morning will both help our wakefulness and the synchronization of our body clocks.”

Wright and his colleagues plan to examine the clock-shifting effects of caffeine in the morning and at other times of day. “Now we have to think about properly timed use of caffeine,” he said, because although caffeine consumption in the evening is generally ill-advised, it could help people overcome jet lag when traveling westward.

The question, he added, is: “If we time it appropriately, can we help you beat the jetlag without disturbing your sleep?”

source :

https://www.the-scientist.com/news-opinion/how-caffeine-affects-the-body-clock-34819

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