TL;DR while experts have varying opinions on whether you can drink coffee before a blood test or not, the rule of thumb is to know what kind of fast you'll need to do. Some allow coffee (and even eating), while others will be better off without both. The best way to know is to ask the medical professional prior to the test to eliminate any doubts!
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You’re a coffee lover. Coffee’s part of your morning routine.
But what if you have to take a blood test first thing in the morning? Can you still have your caffeine fix?
This seems to be the million dollar question for many. So today, we’re embarking on a mission to find out what the real deal is.
WebMD answers the question about why one needs to fast: [1]
Nutrients in food and drinks go into your bloodstream and can change things measured by the tests, skewing your results. For instance, if you eat or drink before a fasting blood glucose test, your blood sugar probably will be higher than if you hadn’t had anything. When you’re fasting, doctors get a baseline result so tests can be compared to give a true picture of your sugar levels over time.
Registered nurse Kathy Reutter writing at One Medical, says many people mistakenly think they need to avoid water during fasts. [2] Not so, she says. In fact, drinking enough water may help you feel better during a fast and also plump the veins for an easier blood draw by the phlebotomist. She states that blood is about 50 percent water.
But what about coffee? Is drinking it acceptable when fasting?
Doctors keep telling patients that it’s all right to have black coffee before fasting blood work.
However, if you go through various online reports, you’ll note one thing - THEY SAY DIFFERENT THINGS! It seems that jury’s still out on this one.
So here’s the game plan. We’ve taken the liberty to put together what various reports say and we’ll try to come up with a conclusion. Wait 'til you get to the end of this article for the verdict.
“While you may consider black coffee little more than water, drinking it causes you to absorb caffeine and other organic compounds into your bloodstream. You need only plain water, without added vitamins, flavoring or carbonation, to achieve the correct fluid and electrolyte balance in your blood chemistry.”
According to Livestrong, "a fasting glucose test measures the level of glucose in the blood during a fasted state," so you need to avoid food and beverage intake for at least 8 hours. [8]
“Fasting is defined as eating and drinking nothing but water. These narrow parameters allow lab technicians and physicians the greatest diagnostic margin by introducing no dietary variables into the procedure. While you may consider black coffee little more than water, drinking it causes you to absorb caffeine and other organic compounds into your bloodstream. You need only plain water, without added vitamins, flavoring or carbonation, to achieve the correct fluid and electrolyte balance in your blood chemistry. In some instances, your doctor will ask you to avoid only certain foods, beverages or medications before a test.”
It depends to some extent on what test is being performed, but for many that require fasting, intake of non-carbohydrate containing liquids a few hours before blood work will not impact results.
Luckily, there are various guidelines available to know whether it’s safe to go with black coffee before heading to the clinic, or just steer clear altogether.
The British National Health Service has the following fasting guidelines on some common tests: [10]
Medical News Today also has additional guidelines, as follows: [9]
Drinking coffee and eating are OK before some blood tests but not others, and some doctors say any black coffee at all before is OK even before a cholesterol test as long as you don’t add cream or sugar.
But if you still find yourself in doubt, it’s best to ask a medical professional. In fact, upon recommendation of a blood test, you should double-check with your doctor. They may be ordering tests that they haven't told you about — tests that do require fasting.
[1] https://www.webmd.com/cholesterol-management/fasting-blood-tests#1
[2] http://www.onemedical.com/blog/live-well/blood-draw-faq/
[3] https://www.health.harvard.edu/staying-healthy/ask-the-doctor-what-blood-tests-require-fasting
[4] https://www.everydayhealth.com/cholesterol-specialist/coffee-before-cholesterol-testing.aspx
[5] https://www.ncbi.nlm.nih.gov/pubmed/15928258
[6] http://www.cbsnews.com/news/fasting-may-not-be-necessary-before-cholesterol-test/
[7] http://www.livestrong.com/article/492574-can-i-have-coffee-if-im-fasting-before-blood-work/
[8] https://www.livestrong.com/article/464282-can-you-drink-coffee-the-morning-you-have-a-fasting-blood-sugar-test/
Careful about falling asleep at work or you could become an Internet meme like this poor fellow.
Unless you work outdoors or indoors in a job where you are physically active all day, it can be difficult for some people who have desk jobs to stay awake at work without caffeine.
Maybe the most important thing you can do to make sure you don’t nod off at work is to get a good night of sleep, at least 7 to 8 hours, at a regular time every night. Boredom can also cause you to nod off. Other than getting a good night’s sleep and having a fascinating job, there are things you can do to stay awake.
How do investment bankers stay awake on their 18-hour shifts?
Investment bankers work such long hours that many resort to chemical stimuli. There have been rumors of methamphetamine and cocaine use among investment bankers to burn the midnight oil. Other investment bankers take Ritalin or Adderall, which are given to children with ADHD but which are stimulants for adults. But the mainstay is probably coffee, energy drinks, and other concoctions containing caffeine.
Some law students spend 60 hours a week studying. Those who’ve been through law school advise prospective students to leave the Xbox at home so they’re not tempted with potentially ruinous distraction. How do law students get energy to study so much?
One thing many law school students do not do is party and socialize a lot. This has a doubly salutary effect because the time spent not partying is time they can spend studying. And then they are not out of sorts, hung over or over-tired the next day from partying.