18.JUL.2017 8 MIN READ | 8 MIN READ

Your morning cup does more than boost your energy. Do you know what’s in your daily caffeine fix?

Coffee and tea are well-loved drinks that contain caffeine, a chemical component that may confer both beneficial and adverse effects on our health. Dr Ooi Yau Wei, cardiologist at Mount Elizabeth Novena Hospital, explains the advantages and disadvantages of caffeine.

The effects of caffeine are manifold, affecting various parts of the body, including the brain, heart, stomach and hormones.

Our bodies contain adenosine, a hormone that is responsible for slowing the nervous system and relaxing the body. When we drink caffeine, it blocks the effects of adenosine, resulting in greater alertness, mental energy and concentration.

Caffeine and your brain

Caffeine has been shown to influence cognition and mood. Its effects, however, vary depending on the amount of caffeine and time of consumption.

In rested individuals, caffeine in low and moderate doses improves vigilance and reaction time. In sleep-deprived individuals, caffeine has positive effects on learning and decision-making. Individuals who are habitual consumers of coffee and tea have been shown to perform better on various tests of cognitive performance such as reaction time and visual-spatial skills.

Caffeine can alleviate headache symptoms significantly. It is frequently used alone or in combination with other headache treatment medications. However, regular caffeine consumption can also lead to chronic migraine and analgesic rebound headaches (headaches caused by overusing headache/pain-relief medication).

Caffeine and your heart

Low to moderate coffee consumption (up to 3 cups per day) has been shown to protect against heart attacks. However, taking more than 3 cups of caffeine a day may trigger coronary (heart artery) problems and heart rhythm irregularities in people with underlying heart disease. Thus, patients at risk of heart problems should avoid drinking large quantities of caffeine.

For people who seldom take caffeine, an episode of caffeine intake can raise their blood pressure significantly. However, there is little or no acute effect on habitual coffee drinkers.

Downsides of caffeine

For all the good that caffeine does, caffeine intake has its downsides too.

Since caffeine can boost mental and physical energy, it is little wonder that many individuals turn to caffeine regularly to maintain their active, busy lifestyles. However, consuming high levels of caffeine may lead to symptoms such as headache, rapid heart rate, anxiety, tremors, and insomnia.

In the long term, caffeine dependence may lead to generalised anxiety disorder, nervousness, insomnia, irritability, and even panic attacks.

Caffeine has also been linked to a higher risk of osteoporosis. Research suggests that high coffee intake may be associated with lower bone density and increased fracture risk in women, particularly those with low calcium intake. One way to counter this is to increase intake of calcium-rich food, or calcium-fortified drinks.

Signs of caffeine withdrawal

Like all stimulants, caffeine can be addictive and give you withdrawal symptoms when you stop taking it. Here's how to tell if you're undergoing caffeine withdrawal:

If you experience

  • Headache
  • Tiredness/fatigue
  • Decreased energy
  • Decreased alertness
  • Drowsiness/sleepiness
  • Depressed mood
  • Difficulty concentrating
  • Irritability
  • Fuzzy/foggy mind

How much caffeine should I take?

For most adults, consumption of up to 400mg of caffeine a day appears to be safe. Here’s the amount of caffeine in our common drinks.

  • Coffee (235ml): 102 – 200mg
  • Espresso (30ml): 30 – 90mg
  • Tea (235ml): 40 – 120mg
  • Coke (355ml): 35 – 47mg
  • Mountain Dew (355ml): 118mg

The average US adult's coffee consumption is about 2 cups per day, which is the equivalent of approximately 280mg of caffeine, although coffee varies greatly in caffeine content. Individuals who consume 4 or more cups of coffee daily are considered to be heavy coffee drinkers.

Given all the benefits and risks caffeine might bring, the research suggests that the pros still outweigh the cons, provided you do not have any existing medical problems which can potentially be made worse with caffeine. When taken in moderate amounts, caffeine can improve mood and performance. Perhaps your daily cup has more benefits than you thought.

Ooi Yau Wei
Mount Elizabeth Hospital

Dr Ooi Yau Wei is a cardiologist practising at Mount Elizabeth Novena Hospital, Singapore.