🕷️ Crawler Inspector

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Raw Queries and Responses

1. Shard Calculation

Query:

Response:

Calculated Shard: 11 (from laksa146)

2. Crawled Status Check

Query:

curl -X POST \
  'http://laksa011.int.ahrefs:8124/' \
  -H 'Content-Type: text/plain' \
  -H 'X-ClickHouse-Database: crawler3' \
  -H 'Authorization: Basic YXBpOg==' \
  -d 'SELECT getAhrefsURLFromUnparsed(src_unparsed) AS found_url, ifNull(toUnixTimestamp(download_stamp), 0) AS crawl_time, ifNull(toUnixTimestamp(props_url_first_seen), 0) AS first_indexed_time, download_http_code AS http_code, src_unparsed AS src_unparsed, src_root_hash AS src_root_hash, history_drop_reason AS history_drop_reason, meta_title AS meta_title, meta_descriptions AS meta_descriptions, attrs_boilerpipe_text AS attrs_boilerpipe_text, attrs_markdown AS attrs_markdown, attrs_readable_markdown AS attrs_readable_markdown, meta_canonical AS meta_canonical FROM crawler3.page_info_local FINAL PREWHERE (src_root_hash, src_unparsed) IN ((getAhrefsRootHashFromUnparsed(getAhrefsUnparsedNoserviceFromURL(\'https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe\')), getAhrefsUnparsedNoserviceFromURL(\'https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe\'))) FORMAT JSONEachRow'

Response:

{"found_url":"https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe","crawl_time":1775636727,"first_indexed_time":1659996821,"http_code":200,"src_unparsed":"org,heart!www,\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe s443","src_root_hash":"6217059405564628611","history_drop_reason":null,"meta_title":"Is caffeine a friend or foe? | American Heart Association","meta_descriptions":["Caffeine can provide some health benefits, but too much can do harm, according to the research."],"attrs_boilerpipe_text":"Published: August 8, 2022\nBy Laura Williamson, American Heart Association News\nPlease note: This article was published more than two years ago, so some information may be outdated. If you have questions about your health, always contact a health care professional.\n(Svetlana Monyakova\/iStock via Getty Images)\nLea en español\nCaffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer.\nBut how much is too much?\nCaffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day.\nOne of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco.\n\"The literature on the whole shows that coffee consumption is generally not a detriment to health,\" he said. \"But I am very reluctant to recommend anyone begin drinking coffee if they aren't otherwise doing so, or to increase consumption for any health benefit.\"\nStudies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson's disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses.\nAccording to the\nFood and Drug Administration\n, as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg.\nIn moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood.\nDetermining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That's because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently.\n\"The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another,\" Marcus said.\nHe and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association's Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks.\nThe\nfindings\n, which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers.\nMarcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. \"The effects of caffeine are attenuated when you drink it regularly,\" he said. \"The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism.\"\nPeople who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said.\nIn his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. \"I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference.\" But he does not give a blanket recommendation to avoid caffeine.\nMarcus doesn't distinguish between the caffeine that people get from coffee versus hot or iced tea. \"There may be health differences between the two, but they haven't been studied yet,\" he said.\nHe is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits.\nResearch\nhas found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours.\n\"In general, I would caution against the use of energy drinks,\" Marcus said.\nThere are other ways to stay alert.\n\"The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits,\" such as getting a good night's sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder.\nIf you have questions or comments about this American Heart Association News story, please email\neditor@heart.org\n.","attrs_markdown":"[Skip to main content](https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe#main-content)\n\n- [Heart Attack and Stroke Symptoms](https:\/\/www.heart.org\/en\/about-us\/heart-attack-and-stroke-symptoms)\n- [Volunteer](https:\/\/www.heart.org\/en\/volunteer)\n- [Learn CPR](https:\/\/cpr.heart.org\/en\/)\n- [ShopHeart](https:\/\/www.shopheart.org\/?utm_source=heart.org&utm_medium=Referral&utm_campaign=AHA-Parent-Site-Top-Nav-Desktop)\n\nMenu\n\nClose Menu\n\n- Healthy Living\n  - [Healthy Living](https:\/\/www.heart.org\/en\/healthy-living)\n  - [Healthy Eating](https:\/\/www.heart.org\/en\/healthy-living\/healthy-eating)\n    - [Add Color](https:\/\/www.heart.org\/en\/healthy-living\/healthy-eating\/add-color)\n    - 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[Home](https:\/\/www.heart.org\/en\/)\n2. [News](https:\/\/www.heart.org\/en\/news)\n3. [Is caffeine a friend or foe?](https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe)\n\nPublished: August 8, 2022\n***\n# Is caffeine a friend or foe?\nBy Laura Williamson, American Heart Association News\n\n**Please note: This article was published more than two years ago, so some information may be outdated. If you have questions about your health, always contact a health care professional.**\n***\n\n[![X formerly known as Twitter](https:\/\/www.heart.org\/en\/-\/media\/Feature\/Navigation\/Social\/x_color.svg?h=54&iar=0&mw=1910&w=54&sc_lang=en)](https:\/\/x.com\/intent\/post?url=https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe) [![Facebook](https:\/\/www.heart.org\/en\/-\/media\/Feature\/Navigation\/Social\/facebook.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](https:\/\/www.facebook.com\/sharer\/sharer.php?u=https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe) [![LinkedIn](https:\/\/www.heart.org\/en\/-\/media\/Feature\/Navigation\/Social\/linkedin.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](https:\/\/www.linkedin.com\/shareArticle?url=https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe) [![Email](https:\/\/www.heart.org\/en\/-\/media\/Feature\/Social\/mail.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](mailto:?subject=Is%20caffeine%20a%20friend%20or%20foe%3F&body=https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe)\n\n![Copy site URL to your clipboard](https:\/\/www.heart.org\/en\/-\/media\/Feature\/Social\/copylink.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)\n\n[![Print](https:\/\/www.heart.org\/en\/-\/media\/Feature\/Social\/print.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/is-caffeine-a-friend-or-foe)\n\n![Svetlana Monyakova\/iStock via Getty Images](https:\/\/www.heart.org\/-\/media\/Images\/News\/2022\/August-2022\/0808EIOLICaffeine_SC.jpg?sc_lang=en)\n\n*(Svetlana Monyakova\/iStock via Getty Images)*\n\n*[Lea en español](https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/la-cafeina-es-amiga-o-enemiga \"Se abre en la ventana actual.\")*\n\nCaffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer.\n\nBut how much is too much?\n\nCaffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day.\n\nOne of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco.\n\n\"The literature on the whole shows that coffee consumption is generally not a detriment to health,\" he said. \"But I am very reluctant to recommend anyone begin drinking coffee if they aren't otherwise doing so, or to increase consumption for any health benefit.\"\n\nStudies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson's disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses.\n\nAccording to the [Food and Drug Administration](https:\/\/www.fda.gov\/consumers\/consumer-updates\/spilling-beans-how-much-caffeine-too-much \"Open in current window.\"), as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg.\n\nIn moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood.\n\nDetermining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That's because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently.\n\n\"The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another,\" Marcus said.\n\nHe and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association's Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks.\n\nThe [findings](https:\/\/www.abstractsonline.com\/pp8\/#!\/9349\/presentation\/18156 \"Open in current window.\"), which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers.\n\nMarcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. \"The effects of caffeine are attenuated when you drink it regularly,\" he said. \"The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism.\"\n\nPeople who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said.\n\nIn his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. \"I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference.\" But he does not give a blanket recommendation to avoid caffeine.\n\nMarcus doesn't distinguish between the caffeine that people get from coffee versus hot or iced tea. \"There may be health differences between the two, but they haven't been studied yet,\" he said.\n\nHe is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits. [Research](https:\/\/www.heart.org\/en\/news\/2019\/05\/29\/energy-drinks-may-provide-jolt-to-heart-function-blood-pressure \"Open in current window.\") has found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours.\n\n\"In general, I would caution against the use of energy drinks,\" Marcus said.\n\nThere are other ways to stay alert.\n\n\"The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits,\" such as getting a good night's sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder.\n\n*If you have questions or comments about this American Heart Association News story, please email [editor@heart.org](mailto:editor@heart.org).*\n***\n\n## *American Heart Association News Stories*\n*American Heart Association News covers heart disease, stroke and related health issues. Not all views expressed in American Heart Association News stories reflect the official position of the American Heart Association. Statements, conclusions, accuracy and reliability of studies published in American Heart Association scientific journals or presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect the American Heart Association’s official guidance, policies or positions.*\n\n*Copyright is owned or held by the American Heart Association, Inc., and all rights are reserved. [Permission](https:\/\/www.heart.org\/en\/about-us\/editorial-guidelines\/news-staff\/using-news-content \"Open in current window.\") is granted, at no cost and without need for further request, for individuals, media outlets, and non-commercial education and awareness efforts to link to, quote, excerpt from or reprint these stories in any medium as long as no text is altered and proper attribution is made to American Heart Association News.*\n\n*Other uses, including educational products or services sold for profit, must comply with the American Heart Association’s Copyright Permission Guidelines. [See full terms of use](https:\/\/www.heart.org\/en\/about-us\/statements-and-policies\/copyright-permission-guidelines \"Open in current window.\"). These stories may not be used to promote or endorse a commercial product or service.*\n\n*HEALTH CARE DISCLAIMER: This site and its services do not constitute the practice of medical advice, diagnosis or treatment. Always talk to your health care provider for diagnosis and treatment, including your specific medical needs. If you have or suspect that you have a medical problem or condition, please contact a qualified health care professional immediately. If you are in the United States and experiencing a medical emergency, call 911 or call for emergency medical help immediately.*\n\nRelated Articles\n\n[![Yagi Studio\/DigitalVision, Getty Images](https:\/\/www.heart.org\/-\/media\/Images\/News\/2020\/December-2020\/1214EIOLITea_SC.jpg?h=600&w=800&sc_lang=en&hash=F258BEA7CE9C499EA54B63B991B115CB) Teatime can be good for your health](https:\/\/www.heart.org\/en\/news\/2020\/12\/14\/teatime-can-be-good-for-your-health)\n\n[![Eternity in an Instant\/DigitalVision, Getty Images](https:\/\/www.heart.org\/-\/media\/Images\/News\/2021\/August-2021\/0813CoffeeDrinks_SC.jpg?h=600&w=800&sc_lang=en&hash=183D393B6DDCE85E44D133ACD521A8AC) Customized drinks have gone viral – and may be a recipe for disaster](https:\/\/www.heart.org\/en\/news\/2021\/08\/13\/customized-drinks-have-gone-viral-and-may-be-a-recipe-for-disaster)\n\n[![Kubra Cavus\/iStock, Getty Images](https:\/\/www.heart.org\/-\/media\/Images\/News\/2021\/November-2021\/1115SSRRCoffeeHeartbeat_SC.jpg?h=600&w=800&sc_lang=en&hash=57344FB64FF7EC6B0D42B6EE6D1D2F1D) Coffee boosts physical activity, cuts sleep, affects heartbeat, study suggests](https:\/\/www.heart.org\/en\/news\/2021\/11\/15\/coffee-boosts-physical-activity-cuts-sleep-affects-heartbeat-study-suggests)\n\nDonate today to help end heart disease and stroke for everyone.\n\n[Donate Now](https:\/\/mygiving.heart.org\/-\/XNPQFTPG \"Donate Now\")\n\n\\*All health\/medical information on this website has been reviewed and approved by the American Heart Association, based on scientific research and American Heart Association guidelines. 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All rights reserved. Unauthorized use prohibited.  \n The American Heart Association is a qualified 501(c)(3) tax-exempt organization.   \n \\*Red Dress ™ DHHS, Go Red ™ AHA ; National Wear Red Day® is a registered trademark.\n\n## Speed Bump\n×\n\n![American Heart Association logo](https:\/\/www.heart.org\/-\/media\/Images\/Logos\/Global-Do-No-Edit\/Two-Click\/ahalogo.png?h=165&w=280&sc_lang=en&hash=E4F07F7A44585F05A690B33CEC7B6E8D)\n\nThis link is provided for convenience only and is not an endorsement of either the linked-to entity or any product or service.\n\n[Proceed]()","attrs_readable_markdown":"Published: August 8, 2022\n***\nBy Laura Williamson, American Heart Association News\n\n**Please note: This article was published more than two years ago, so some information may be outdated. If you have questions about your health, always contact a health care professional.**\n***\n\n![Svetlana Monyakova\/iStock via Getty Images](https:\/\/www.heart.org\/-\/media\/Images\/News\/2022\/August-2022\/0808EIOLICaffeine_SC.jpg?sc_lang=en)\n\n*(Svetlana Monyakova\/iStock via Getty Images)*\n\n*[Lea en español](https:\/\/www.heart.org\/en\/news\/2022\/08\/08\/la-cafeina-es-amiga-o-enemiga \"Se abre en la ventana actual.\")*\n\nCaffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer.\n\nBut how much is too much?\n\nCaffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day.\n\nOne of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco.\n\n\"The literature on the whole shows that coffee consumption is generally not a detriment to health,\" he said. \"But I am very reluctant to recommend anyone begin drinking coffee if they aren't otherwise doing so, or to increase consumption for any health benefit.\"\n\nStudies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson's disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses.\n\nAccording to the [Food and Drug Administration](https:\/\/www.fda.gov\/consumers\/consumer-updates\/spilling-beans-how-much-caffeine-too-much \"Open in current window.\"), as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg.\n\nIn moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood.\n\nDetermining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That's because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently.\n\n\"The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another,\" Marcus said.\n\nHe and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association's Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks.\n\nThe [findings](https:\/\/www.abstractsonline.com\/pp8\/#!\/9349\/presentation\/18156 \"Open in current window.\"), which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers.\n\nMarcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. \"The effects of caffeine are attenuated when you drink it regularly,\" he said. \"The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism.\"\n\nPeople who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said.\n\nIn his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. \"I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference.\" But he does not give a blanket recommendation to avoid caffeine.\n\nMarcus doesn't distinguish between the caffeine that people get from coffee versus hot or iced tea. \"There may be health differences between the two, but they haven't been studied yet,\" he said.\n\nHe is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits. [Research](https:\/\/www.heart.org\/en\/news\/2019\/05\/29\/energy-drinks-may-provide-jolt-to-heart-function-blood-pressure \"Open in current window.\") has found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours.\n\n\"In general, I would caution against the use of energy drinks,\" Marcus said.\n\nThere are other ways to stay alert.\n\n\"The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits,\" such as getting a good night's sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder.\n\n*If you have questions or comments about this American Heart Association News story, please email [editor@heart.org](mailto:editor@heart.org).*","meta_canonical":null}

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URL	https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe
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Meta Title	Is caffeine a friend or foe? \| American Heart Association
Meta Description	Caffeine can provide some health benefits, but too much can do harm, according to the research.
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Boilerpipe Text	Published: August 8, 2022 By Laura Williamson, American Heart Association News Please note: This article was published more than two years ago, so some information may be outdated. If you have questions about your health, always contact a health care professional. (Svetlana Monyakova/iStock via Getty Images) Lea en español Caffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer. But how much is too much? Caffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day. One of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco. "The literature on the whole shows that coffee consumption is generally not a detriment to health," he said. "But I am very reluctant to recommend anyone begin drinking coffee if they aren't otherwise doing so, or to increase consumption for any health benefit." Studies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson's disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses. According to the Food and Drug Administration , as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg. In moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood. Determining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That's because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently. "The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another," Marcus said. He and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association's Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks. The findings , which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers. Marcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. "The effects of caffeine are attenuated when you drink it regularly," he said. "The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism." People who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said. In his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. "I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference." But he does not give a blanket recommendation to avoid caffeine. Marcus doesn't distinguish between the caffeine that people get from coffee versus hot or iced tea. "There may be health differences between the two, but they haven't been studied yet," he said. He is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits. Research has found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours. "In general, I would caution against the use of energy drinks," Marcus said. There are other ways to stay alert. "The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits," such as getting a good night's sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder. If you have questions or comments about this American Heart Association News story, please email editor@heart.org .
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[Home](https://www.heart.org/en/) 2. [News](https://www.heart.org/en/news) 3. [Is caffeine a friend or foe?](https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe) Published: August 8, 2022 * # Is caffeine a friend or foe? By Laura Williamson, American Heart Association News Please note: This article was published more than two years ago, so some information may be outdated. If you have questions about your health, always contact a health care professional. * [![X formerly known as Twitter](https://www.heart.org/en/-/media/Feature/Navigation/Social/x_color.svg?h=54&iar=0&mw=1910&w=54&sc_lang=en)](https://x.com/intent/post?url=https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe) [![Facebook](https://www.heart.org/en/-/media/Feature/Navigation/Social/facebook.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](https://www.facebook.com/sharer/sharer.php?u=https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe) [![LinkedIn](https://www.heart.org/en/-/media/Feature/Navigation/Social/linkedin.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](https://www.linkedin.com/shareArticle?url=https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe) [![Email](https://www.heart.org/en/-/media/Feature/Social/mail.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](mailto:?subject=Is%20caffeine%20a%20friend%20or%20foe%3F&body=https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe) ![Copy site URL to your clipboard](https://www.heart.org/en/-/media/Feature/Social/copylink.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en) [![Print](https://www.heart.org/en/-/media/Feature/Social/print.svg?h=52&iar=0&mw=1910&w=52&sc_lang=en)](https://www.heart.org/en/news/2022/08/08/is-caffeine-a-friend-or-foe) ![Svetlana Monyakova/iStock via Getty Images](https://www.heart.org/-/media/Images/News/2022/August-2022/0808EIOLICaffeine_SC.jpg?sc_lang=en) (Svetlana Monyakova/iStock via Getty Images) [Lea en español](https://www.heart.org/en/news/2022/08/08/la-cafeina-es-amiga-o-enemiga "Se abre en la ventana actual.") Caffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer. But how much is too much? Caffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day. One of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco. "The literature on the whole shows that coffee consumption is generally not a detriment to health," he said. "But I am very reluctant to recommend anyone begin drinking coffee if they aren't otherwise doing so, or to increase consumption for any health benefit." Studies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson's disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses. According to the [Food and Drug Administration](https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much "Open in current window."), as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg. In moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood. Determining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That's because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently. "The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another," Marcus said. He and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association's Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks. The [findings](https://www.abstractsonline.com/pp8/#!/9349/presentation/18156 "Open in current window."), which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers. Marcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. "The effects of caffeine are attenuated when you drink it regularly," he said. "The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism." People who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said. In his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. "I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference." But he does not give a blanket recommendation to avoid caffeine. Marcus doesn't distinguish between the caffeine that people get from coffee versus hot or iced tea. "There may be health differences between the two, but they haven't been studied yet," he said. He is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits. [Research](https://www.heart.org/en/news/2019/05/29/energy-drinks-may-provide-jolt-to-heart-function-blood-pressure "Open in current window.") has found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours. "In general, I would caution against the use of energy drinks," Marcus said. There are other ways to stay alert. "The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits," such as getting a good night's sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder. If you have questions or comments about this American Heart Association News story, please email [editor@heart.org](mailto:editor@heart.org). *** ## American Heart Association News Stories American Heart Association News covers heart disease, stroke and related health issues. Not all views expressed in American Heart Association News stories reflect the official position of the American Heart Association. Statements, conclusions, accuracy and reliability of studies published in American Heart Association scientific journals or presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect the American Heart Association’s official guidance, policies or positions. Copyright is owned or held by the American Heart Association, Inc., and all rights are reserved. 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Readable Markdown	Published: August 8, 2022 * By Laura Williamson, American Heart Association News Please note: This article was published more than two years ago, so some information may be outdated. If you have questions about your health, always contact a health care professional. * ![Svetlana Monyakova/iStock via Getty Images](https://www.heart.org/-/media/Images/News/2022/August-2022/0808EIOLICaffeine_SC.jpg?sc_lang=en) (Svetlana Monyakova/iStock via Getty Images) [Lea en español](https://www.heart.org/en/news/2022/08/08/la-cafeina-es-amiga-o-enemiga "Se abre en la ventana actual.") Caffeine jump-starts your day and puts a bounce in your step. It can help you focus, improve your mood and maybe even help you live longer. But how much is too much? Caffeine, a natural stimulant, can be found in a variety of foods, such as coffee beans, tea leaves, cacao beans, guarana berries and yerba maté leaves. It also can be synthetically created and added to beverages such as soda and energy drinks. Research shows that about 90% of U.S. adults consume some form of caffeine every day. One of the most popular ways people consume it is through coffee. Because of that, most caffeine research centers around this drink, said Dr. Greg Marcus, associate chief of cardiology for research and a professor of medicine at the University of California, San Francisco. "The literature on the whole shows that coffee consumption is generally not a detriment to health," he said. "But I am very reluctant to recommend anyone begin drinking coffee if they aren't otherwise doing so, or to increase consumption for any health benefit." Studies have found caffeine can do both good and harm. People who regularly drink coffee may be less likely to develop chronic illnesses, such as cardiovascular disease, diabetes, Parkinson's disease and some cancers. A few studies suggest they are less likely to die from heart disease and other illnesses. According to the [Food and Drug Administration](https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much "Open in current window."), as much as 400 milligrams of caffeine a day – equal to four or five cups of coffee – is considered safe for healthy adults. An 8-ounce cup of green or black tea has 30-50 mg of caffeine. Energy drinks may contain 40-250 mg for every 8 ounces, and a 12-ounce can of caffeinated soda contains 30-40 mg. In moderate doses – up to two 8-ounce cups of coffee – caffeine can make people less tired and more alert. Some studies suggest it can reduce appetite and lower the risk for depression. But high doses – 12 cups or more – can make people feel anxious, raise blood pressure and lead to heart palpitations and trouble sleeping. For people who consume caffeine regularly, stopping consumption abruptly can lead to symptoms of withdrawal, such as headaches, fatigue and depressed mood. Determining how much is too much can be tough. A moderate amount of caffeine for one person may feel like a high dose for someone else. That's because some people metabolize caffeine faster than others, Marcus said. Factors such as how much someone weighs and what medications they take also can play a role. The bottom line is, caffeine affects everyone differently. "The compound is complex, and we need to recognize that not only might there be benefits and harms, but this may vary from one person to another," Marcus said. He and his colleagues recently completed one of the few randomized studies on caffeine consumption, which he presented at the American Heart Association's Scientific Sessions last year. The researchers asked participants to drink – or refrain from drinking – coffee for no more than two consecutive days each for two weeks. The [findings](https://www.abstractsonline.com/pp8/#!/9349/presentation/18156 "Open in current window."), which are considered preliminary until the full results are published in a peer-reviewed journal, showed that people were more physically active and slept less on days they drank coffee than on days they went without. They also had more irregular heartbeats from the lower chambers of the heart but fewer episodes of abnormally rapid heartbeats from the upper chambers. Marcus said one limitation of the study was that people were starting and stopping caffeine consumption, which could be causing an exaggerated reaction in people who were used to drinking it every day. "The effects of caffeine are attenuated when you drink it regularly," he said. "The body adapts to that caffeine level. And more regular consumption of caffeine can speed up the metabolism." People who metabolized caffeine faster had fewer problems sleeping than those whose bodies broke it down more slowly, he said. In his cardiology practice, Marcus tells patients who are having trouble sleeping or experiencing abnormal heart rhythms to see what role caffeine might be playing. "I generally advise that it is reasonable for patients bothered by trouble sleeping or with palpitations to experiment with their caffeine consumption. Take some time off of caffeine to see if it makes a difference." But he does not give a blanket recommendation to avoid caffeine. Marcus doesn't distinguish between the caffeine that people get from coffee versus hot or iced tea. "There may be health differences between the two, but they haven't been studied yet," he said. He is less flexible about the consumption of energy drinks, which typically have a higher concentration of caffeine, as well as added sweeteners or carbohydrates and no evidence they provide any health benefits. [Research](https://www.heart.org/en/news/2019/05/29/energy-drinks-may-provide-jolt-to-heart-function-blood-pressure "Open in current window.") has found energy drinks can cause abnormal electrical activity in the heart and higher blood pressure that persists for several hours. "In general, I would caution against the use of energy drinks," Marcus said. There are other ways to stay alert. "The best strategies and overall most healthy strategies to boost alertness are long-term healthy habits," such as getting a good night's sleep and exercising regularly, Marcus said. He recommends people who have trouble staying awake consult a physician to see if they have sleep apnea or another sleep disorder. If you have questions or comments about this American Heart Association News story, please email [editor@heart.org](mailto:editor@heart.org).
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