The bright side of your brew: caffeine's health benefits

Caffeine is one of the most popular and widely consumed stimulants in the world. It's found naturally in plants such as the coffee bean, the tea leaf (Camellia Sinensis), guarana berries, cacao beans, cola nuts and yerba mate. (1) 

Many people, including me, limit their caffeine intake because of its negative effect on their body. But, caffeine can affect our body in positive ways too – beyond the well-known mental energy-boost. In this month’s blog, I explore the positive effects of caffeine.

Firstly, what is caffeine?

Caffeine is an alkaloid. An alkaloid is an organic compound, made naturally by plants, that contains nitrogen, and typically has a physiological effect on the human body. Morphine, quinine and nicotine are other examples of alkaloids. (2) 

What happens after that first sip? 

After you swallow caffeine, it’s absorbed through your stomach and the rest of your gastrointestinal (GI) tract. After 30 – 45 minutes it’s released into your bloodstream and makes its way around your body (peaking in concentration at around 1 hour). Caffeine is metabolised (broken down into usable parts: ‘metabolites’) by the liver. It crosses the brain, placental and breast barriers, which means it enters your brain, and if you are a pregnant female or a new mother, your amniotic fluid and breast milk.  It's excreted via the kidneys then bladder as well as through sweat and saliva.(1) 

There’s a big variance in the speed that we each metabolise caffeine, with its half-life (the number of hours it takes for the level of caffeine in our body to reduce by half) ranging from around 2 to 12 hours, with the average being 4–5 hours. So, in theory, some people could still have some caffeine present in their body almost 24 hours after drinking it.  (1) 

The feel-good side to caffeine

While too much caffeine can have a toxic effect on our body, moderate amounts can be good for us. Here are some of the most common upsides of caffeine:

Your brain on caffeine

·      The most well-known benefit of caffeine is its powerful brain boost: caffeine stimulates our nervous system to release adrenaline which lifts our state of alertness and focus and creates wakefulness in the brain and body.   (3) (4) 

·        Improves mood and reduces depression: caffeine increases the sensitivity of our dopamine (the ‘feel-good’ neurotransmitter) receptors, enhancing dopamine function - which improves motivation, drive and reduces depression. (3) 

·       Brain disease protection:  studies show that caffeine in coffee can help reduce the risk of developing the brain disease Alzheimer’s, by reducing the build-up of damaging plaques in the brain. It also reduces the risk of developing Parkinson’s disease. (5) 

Caffeine and your body

·        Supports cell health: caffeine is an antioxidant, so it helps to protect our cells from damage caused by free radicals. Some research also shows caffeine can trigger damaged cell death through a process called autophagy.  (1) 

·        Supports weight loss: Caffeine breaks down fats in the body by increasing energy expenditure. (1) 

·        Promotes wound healing: Caffeine activates fibroblasts – cells that build collagen, which helps to close wounds and strengthen tissues. Its ability to narrow blood vessels improves blood flow to the wound, helping deliver the oxygen and nutrients needed for recovery. (1) 

·        Healthy bowels: caffeine stimulates muscle contraction in the colon and GI tract, which can improve bowel improvements.  (1) 

·        Improves athletic performance: scientists believe caffeine may enhance physical performance by helping muscles release more calcium (important for movement), by saving energy in muscles, and by blocking brain receptors that normally makes us feel tired. (6) 

When caffeine isn't so kind

The flipside to caffeine is that it can cause a myriad of unpleasant and sometimes dangerous side effects such as restlessness, anxiety, tremors, tinnitus, headache, and insomnia and heart palpitations.

General advice suggests we should limit caffeine intake to 200 mg in one sitting or 400 mg per day (approx. 3/4 coffees or approx. 10 teas across the day). (5) 

However, our genetics also influence our unique response to caffeine, so pay attention to your own body’s reaction.

Whether positive or negative, caffeine is a powerful bioactive molecule that not only has a big impact on our body, it also adds to the complex flavour profile of both coffee and tea. 

If you’d like to learn more about how caffeine in tea and which type of tea has the most caffeine, read my blog: Which has more caffeine: green tea, black tea or coffee?

~ Anna

Notes and citations

Thanks to Clay Banks on Unsplash for the gorgeous header image.

1) Vundrala Sumedha Reddy, S. Shiva, Srinidhi Manikantan, Seeram Ramakrishna. Pharmacology of caffeine and its effects on the human body, European Journal of Medicinal Chemistry Reports, Volume 10, 2024, 100138, ISSN 2772-4174, https://www.sciencedirect.com/science/article/pii/S2772417424000104. Accessed 27 June 2025

2) The Editors of Encyclopaedia Britannica. "alkaloid". Encyclopedia Britannica, 2 Jun. 2025, https://www.britannica.com/science/alkaloid. Accessed 27 June 2025.

3) The Knowledge Project Podcast, ‘Neuroscientist: How Caffeine Works and What It Does to Your Body with Andrew Huberman' https://www.youtube.com/watch?v=OT0IsU6V-q8">https://www.youtube.com/watch?v=OT0IsU6V-q8 Accessed 27 June 2025.

4) Tom M. McLellan, John A. Caldwell, Harris R. Lieberman,A review of caffeine’s effects on cognitive, physical and occupational performance, Neuroscience & Biobehavioral Reviews, Volume 71, 2016, Pages 294-312, ISSN 1497634,  https://www.sciencedirect.com/science/article/pii/S0149763416300690). Accessed 27 June 2025

5) Rodak K, Kokot I, Kratz EM. Caffeine as a Factor Influencing the Functioning of the Human Body-Friend or Foe? Nutrients. 2021 Sep 2;13(9):3088. doi: 10.3390/nu13093088. PMID: 34578966; PMCID: PMC8467199. https://pmc.ncbi.nlm.nih.gov/articles/PMC8467199/ Accessed 27 June 2025.

6) Martins GL, Guilherme JPLF, Ferreira LHB, de Souza-Junior TP, Lancha AH Jr. Caffeine and Exercise Performance: Possible Directions for Definitive Findings. Front Sports Act Living. 2020 Dec 11;2:574854. doi: 10.3389/fspor.2020.574854. PMID: 33345139; PMCID: PMC7739593. https://pmc.ncbi.nlm.nih.gov/articles/PMC7739593/  Accessed 27 June 2025.

 

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