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Caffeine: Does it Power You Up or Slow You Down?

Chev. Prof. Renald Blundell from the Department of Physiology and Biochemistry, published an article in the Malta Independent on Sunday 13 August 2023, titled Caffeine - Wakes or breaks? .

Discovered in the coffee forests of Ethiopia in the 15th century, coffee arrived in Europe by the 17th century and rapidly spread across the globe. Today, coffee is a key source of caffeine, a psychoactive stimulant that affects the central nervous system. Caffeine content in coffee beans varies, ranging from 0.4% to 2.4% by dry weight, and its effect on individuals can vary based on hereditary factors. Beyond coffee, caffeine is found in cola, tea, cocoa, and chocolate, and it ranks among the top three mood-altering substances globally, alongside alcohol and nicotine.

Caffeine Content in Common Beverages and Foods

  • Coffee (237ml): 80-100mg
  • Espresso (30ml): 64mg
  • Cold Brew (237ml): 250mg
  • Latte (240ml): 64-126mg
  • Mocha (240ml): 70-140mg
  • Decaf Coffee (237ml): 2-15mg
  • Hot Chocolate (237ml): 19mg
  • Green Tea (237ml): 20mg
  • Chocolate (43g bar): 31mg
  • Soft Drinks (350ml): 34mg
  • Caffeine Tablet: 200mg
  • Black Tea (230ml): 47mg
  • Red Bull (237ml): 80mg
  • Cola (237ml): 40mg

Excessive intake of coffee can pose health risks, such as:

  1. General Toxicity:

    • A lethal dose is estimated at 10g for a 65kg adult, but fatalities from as low as 6.5g have been reported. Common signs of caffeine toxicity include nervousness, irritability, insomnia, and heart palpitations.

  2. Cardiovascular Effects:

    • Consumption exceeding 150mg may reduce heart rate, raise cholesterol, and increase blood pressure. Drinking more than four cups per day may elevate the risk of heart disease, though moderate intake (under 400mg/day) shows no significant impact on cardiovascular health.

  3. Bone Health and Calcium Loss:

    • Caffeine increases calcium excretion through urine. Consuming over 760mg of caffeine (more than 1000ml of coffee) per day can lead to calcium loss, potentially increasing the risk of bone fractures.

  4. Behavioural Changes:

    • Moderate caffeine consumption has been linked to improved memory, reaction time, and mental alertness. Higher doses may reduce tiredness but also lead to anxiety or irritability.

  5. Cancer Risk:

    • While coffee contains acrylamide, a potentially cancer-causing substance, no strong evidence links moderate coffee consumption to increased cancer risk in humans. On the contrary, some studies suggest that coffee may reduce the risk of certain cancers like liver and endometrial cancer.

  6. Fertility and Pregnancy:

    • Women: Caffeine intake over 300mg/day may affect conception, possibly due to hormonal changes or conditions like endometriosis.
    • Men: Caffeine levels above 400mg/day may reduce sperm motility in heavy smokers but generally does not affect male fertility.

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