5 min|Rhiannon Lockhart

Caffeine: Friend or Foe? Weighing the Evidence for Your Health


There’s a lot of talk around caffeine

Is it good for me? Bad for me? Can I use it for fasting? How late in the day can I drink it? How many cups of coffee is too many cups of coffee? These questions are for good reason – tea and coffee actually round out the top 3 most consumed beverages in the world (after water). We’re going to dive to the bottom of the caffeine debate, giving you the pros and cons of your favourite morning cup to help you decide whether it’s right for you!

How does caffeine work in your body?

Caffeinated beverages and foods are absorbed into your bloodstream within 45 minutes of ingestion. (1) While everyone metabolizes caffeine differently, it typically takes about 2.5-4.5 hours for the average person. Pregnancy and medications like oral contraceptives, antidepressants, cardiovascular medications and antibiotics can all impact how caffeine is metabolized in your body. (1)

If you have ever had a cup of coffee or caffeinated tea, you likely know some of the positive effects it can have like better mental clarity or feelings of wakefulness. Alternatively, you may have also experienced the jitters or inability to sleep - all of this can depend on how your body responds to and tolerates certain amounts of caffeine.


Much of the researched benefits around caffeine consumption are based on moderate intake of coffee, meaning 2-5 cups per day. (2) Even better is that many of the benefits of drinking coffee can be found in a decaffeinated brew! (3)

A few of the benefits of consuming caffeine on a regular basis include:

  • Full-strength coffee consumption has been associated with a reduced risk of Parkinson's disease and liver cirrhosis (1)

  • Coffee and tea have been shown to have a protective effect against some neurodegenerative conditions (4)

  • Tea and coffee’s antioxidant components have been shown to be protective against certain types of cancer (4)

  • There is an inverse relationship between caffeine consumption and type 2 diabetes (4)

  • Regular brewed coffee and decaffeinated options have been shown to reduce overall mortality rate (3)

  • May aid in the prevention of gallstones (3) (5)

  • Coffee is often found to enhance fitness and cognitive performance

  • Caffeinated tea, due to a compound called l-theanine, often supports mental clarity without the residual jitters or crash that some experience with full-brew coffee

While there are many benefits, there are some negative side effects to caffeine intake:

  • Caffeine intake is associated Increases in blood pressure (6)

  • It can increase feelings of anxiety, especially at high doses about 1200mg (this looks like two to three 20 oz coffees from Starbucks).

  • Caffeine intake has been shown to reduce sleep quality for some people, depending on the time of consumption (4)

  • Caffeine, particularly from coffee, can flare up heartburn symptoms

How to make your coffee better:

It is important to remember that the benefits above are based around caffeine intake, not caffeine with added sweeteners, flavourings and fillers. And for some, adding certain ingredients can help to reduce some of the negative side effects.

  1. Skip the sugars and sweeteners: This also includes the flavoured lattes and iced drinks from many chain coffee shops. Not only are these added calories, but they can have a pretty negative effect on our blood sugar. For some people, coffee alone can send our sugar levels out of balance, so adding refined sweeteners without any fat or protein, can leave us feeling more tired and increase sugar cravings later in the day.

  2. Add a fat: cream, coconut milk, unsweetened almond milk. These are all great additions to your morning cup.

  3. Don’t have it on an empty stomach (especially if you have a lot of stress!): While I know that it’s quite trendy to consume black coffee on an empty stomach to prolong a fast, it can do more harm to our hormones and increase risk of burnout. Before you sip on your coffee or tea, have a bite to eat – ideally something with 20-30g of protein.

  4. Choose decaf for the second half of your day: If you are someone that needs an afternoon cup, swap to decaf in the afternoon. You will still get some caffeine, however it will reduce the potential effects come bedtime.

Who should reduce their caffeine intake?

  1. If you’re pregnant: pregnant people should keep caffeine intake under 200mg per day. For reference, that’s about four cups of regular brewed black tea or two 6-oz cups of coffee.

  2. If you deal with anxiety at any level: for many people living with anxiety, reducing or eliminating caffeine has had a positive effect on their mental health. Try swapping to decaffeinate coffee, tea with lower caffeine levels or try an herbal alternative.

  3. If you have difficulty controlling your blood pressure: studies show that caffeine can have a negative effect on blood pressure. (6) This means reducing our intake is important, especially for those who find it difficult to control with other measures.


  1. https://jamanetwork.com/journals/jama/fullarticle/2789026

  2. https://www.hsph.harvard.edu/news/hsph-in-the-news/is-coffee-good-or-bad-for-your-health/

  3. https://www.hsph.harvard.edu/nutritionsource/food-features/coffee/

  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6003581/

  5. https://jamanetwork.com/journals/jama/article-abstract/190309

  6. https://www.ahajournals.org/doi/10.1161/01.hyp.33.2.647

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