Many of us rely on coffee to get us up and out the door in the morning – let's be frank, it’s more like to get us through the day at work. Whether you’re a one cup, two cup, or full blown self-diagnosed caffeine addict, there are side effects – good and bad – to consuming coffee that you should know.

Throughout the years, research has shown that the ol’ cup of jo may have more than meets the eye – we now know that there are certain health benefits associated with drinking coffee other than keeping us alert, like helping to reduce the risk of developing type II diabetes, protect against neurodegenerative diseases, and lower the risk of liver cirrhosis. Quite a big job for a little mug.

But it’s not all rosy – many people suffer from unpleasant side effects when drinking coffee, and there may be some health risks for certain individuals.

How drinking coffee affects your body

How drinking coffee affects your body: caffeine metabolism

When we think of coffee, we often think of caffeine – the psychoactive compound that naturally occurs in lots of different plant species. When you drink a cup of coffee, caffeine is absorbed quickly into the bloodstream, within about 45 minutes, and its effects last between 4-6 hours.

Caffeine itself is metabolised by the liver, and broken down into other metabolites: paraxanthine, theophylline, and theobromine – the latter is also found in chocolate. These compounds are partly responsible for some of the physiological effects that we associate with coffee – for example its diuretic effect, as theobromine relaxes blood vessels and increases urine volume, meaning you pee more.

Caffeine exerts most of its familiar effects by blocking adenosine receptors. Adenosine is a neurotransmitter which promotes sleep, so when receptors are blocked you feel awake and alert. However, this causes adenosine to build up in the brain, and you later get a sudden flood of this neurotransmitter which leads to that familiar ‘caffeine crash’. 

As caffeine affects adenosine receptors, it also affects the activity of another important neurotransmitter in the brain, dopamine, which is involved in lots of different pathways in the body including ‘motivation-reward’ pathways in the brain and motor control.

Why is coffee good for you

Why is coffee good for you? Vitamins and minerals in coffee

Other than caffeine, coffee contains compounds such as chlorogenic acid, caffeic acid, and cafestol. These compounds are important because they are probably implicated in mediating some of the health benefits of coffee – which aren’t found with other caffeine-based drinks or tablets. It is thought that some of these compounds also have antioxidant activity and may explain some of the health benefits of moderate intake (1). In fact, coffee is actually one of the top dietary sources of polyphenol antioxidants in the Western World, and is thought to have more antioxidant activity than cocoa and green tea (2) (3).

The type of beans, the roasting process, and brewing methods do make a difference here, but there is little agreement about what type of drink tends to have the greatest antioxidant potential. However, lighter roasting, green coffee beans, and boiled coffee like Turkish coffee, are thought to have the most antioxidant activity.

Coffee also contains magnesium and fibre – an espresso contains approximately 5% of your recommended daily intake of magnesium, and between 1.2g and 3g of soluble fibre depending on cup size. Though you should aim for about 6-8g of soluble fibre a day, this obviously doesn’t mean that you should rely on coffee for fibre, or drink it instead of eating a variety of nutrient-dense foods which are also packed with other beneficial compounds! (4)

Potential health benefits of drinking coffee

Potential health benefits of drinking coffee

Over the years, coffee has been linked to various health benefits. Most recently and importantly, it has been associated with a lower risk of developing:

1. Type II Diabetes

In the short term, caffeine has been found to decrease insulin sensitivity and impair glucose tolerance, both of which might contribute to the risk of developing type 2 diabetes. It is also a nervous system stimulant, which can cause the release of adrenaline which raises heart rate and increases blood sugar. 

However, longer-term data from cohort and epidemiological studies has suggested that regular moderate coffee consumption – under 4 cups a day – lowers the risk of developing this disease and helps to maintain normal glucose tolerance (5). It is thought the mechanisms behind this could be related to chlorogenic acid or other compounds in coffee beans.

2. Parkinson’s Disease

Several case-control studies have suggested that coffee may help to reduce the risk of some neurodegenerative diseases, including Parkinson’s Disease. It is thought that coffee affects Parkinson’s risk via its effect on brain pathways – particularly linked to how caffeine binds to adenosine receptors and modulates dopamine activity. This action is also linked to preventing HIAPP amyloid protein formation – amyloid plaques are one of the primary marker of Alzheimer’s disease. Recent meta-analysis suggested that this protection is seen to be strongest with 3 cups a day (6). However, the association is stronger in men, and further research is needed on how female hormone therapy might interact with caffeine and affect risk factors for women. 

3. Liver Disease

Some studies have found that moderate coffee consumption can help to protect against alcoholic cirrhosis and could potentially protect against liver damage (7).

4. Multiple Sclerosis

There is some very interesting, albeit preliminary, animal-based research on whether coffee consumption could potentially decrease the risk of developing MS in humans by suppressing inflammation. However, more research is needed to evaluate these claims (8).

Potential negative effects of drinking coffee

Potential negative effects of drinking coffee

Drinking too much coffee affects each person differently depending on their tolerances and sensitivities. When looking to wean off of coffee, bear in mind that no matter how many cups you are used to having per day, withdrawal symptoms and side effects like headaches, fatigue, drowsiness, low mood, difficulty concentrating, and irritability can affect anyone, are common, and can come up quickly. The best way to avoid a ‘caffeine crash’ is to gradually cut back on your regular intake over time.

1. On insomnia and anxiety

If you know you are sensitive to caffeine, be careful to limit your consumption as research shows that too much can lead to heightened anxiety, heart palpitations, and exacerbated panic attacks (9). Also, many people find that consuming caffeine late in the afternoon can affect their sleep patterns and keep them awake. If you have trouble sleeping or struggle with insomnia, try not to drink caffeine after 2pm.

2. On pregnancy

If you are expecting, always consult your Doctor regarding your diet. Drinking too much coffee while pregnant is thought to increase the risk of complications, so it is advised that pregnant women should limit their caffeine intake to 200mg a day or less, which is equivalent to 2 cups of coffee.

3. On blood pressure

According to research, regular coffee intake does temporarily increase blood pressure, but the effect is thought to be small (10). However, other caffeinated products like energy drinks may have different, and potentially negative, effects on blood pressure. If you have any concerns regarding your health, speak to your Doctor as soon as possible.

Whether you think of coffee as an addictive drug or black gold, now you know the best ways to avoid caffeine crash, or wean off of your caffeine addiction, while being aware of the potential positive and negative side effects of consuming coffee.

READ NEXT: Tried and tested remedies and products to help you wean off of caffeine.



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