Wait, so coffee can actually be good for our health? A Charles Sturt academic said coffee has more benefits, other than making us happy and making Mondays tolerable. In the lead up to International Coffee Day we break down the health benefits, risks, ‘normal’ intake and why this cup of Joe has us running to the bathroom.

By Lecturer in Nutrition and Dietetics with the Charles Sturt School of Allied Health, Exercise and Sports Sciences in Wagga Wagga Dr Marissa Samuelson.

What is in coffee?

The coffee bean itself contains more than 1,000 bioactive compounds, including caffeine. It also contains some nutrients, including oils, carbohydrates and protein. Of course, the overall content of your daily cuppa then also depends on what you add in relation to things like milk, cream or sweeteners.

What are the health benefits of coffee consumption, if any?

It is important to be clear when we are talking about the benefits of drinking coffee, we are talking about the benefits of the actions of all of these combined bioactives, not just caffeine. The impact of caffeine on its own is different to the impact of coffee as a complete food.

A recent review of the literature found that drinking coffee can have multiple benefits, depending on the individual and how often we drink coffee. At the levels of about three to four cups per day (where one cup is 200mL), there is a positive impact on heart, bone (more so for men than women), kidney and liver health. This level of intake is associated with a reduced risk of gout, type 2 diabetes, Parkinson’s disease, depression and some cancers. Drinking coffee at this level does not increase blood pressure as commonly thought. Also, there is thought to be only a small effect of drinking coffee on the urge to pass urine (wee) and therefore the risk of dehydration, and this is made up for by the fact we are also drinking fluid in our cuppa.

What are the risks of coffee consumption, if any?

There are some circumstances where caffeine consumption can cause problems, including:

• Pregnancy: due to the relationship between caffeine intake and pregnancy loss, low birth weight and preterm birth, it is recommended that pregnant women have no more than 200mg of caffeine per day, choose decaf or avoid caffeine completely if they are concerned or have a higher risk pregnancy.
• People with pre-existing disease (including digestive diseases, bone fractures in women, high blood lipids, acute lymphocytic leukemia and bladder and lung cancers): these individuals should consult their health practitioner about whether coffee is likely to be problematic. For example, those with pre-existing anxiety disorders could experience the jitters, insomnia and anxiety.
• Coffee can also affect the absorption of non-haem iron from meals, however, this generally doesn’t appear to translate into iron deficiency in the longer term.

What don’t we know?

There is mixed evidence for coffee and

• The increased risk of Alzheimer’s disease
• Weight management
• Inflammation
• Mental health
• The impact on the gut
• Migraines

Until we have more knowledge, it is best to talk to your health practitioner about the role coffee and caffeine may play in the management of these conditions.

How much coffee should I drink?

It is important for people to get individual advice about how much coffee is safe for them to consume. A recent review concluded that three to four cups per day (where one cup is 200ml) is safe, unless contraindicated, to maximise health benefits and minimise health risks.

With respect to caffeine, most Australian guidelines suggest limiting caffeine in healthy individuals in total to <400mg/day. For example, the NHFA recommends the following for heart health:

Guidance for daily tea/coffee intake in adults:

• up to four espresso shots (or four coffee pods) or
• up to five cups of instant coffee or
• up to seven cups of tea a day

Pregnant and lactating women should limit intakes to no more than half the recommendations for healthy adults.

Once we exceed that amount, there may be negative health impacts such as more fluid loss and raised blood pressure.

The amount of caffeine varies depending on the type of coffee – for example, a shot of espresso is 100mg where a cup of instant is about 80mg.

The other thing to think about is what other sources of caffeine you have in your diet, such as tea. A cup of tea has about 50mg of caffeine.

What type of coffee should I be drinking?

Does the type of coffee make a difference to health impacts? The answer, like many aspects of nutrition, is ‘it’s complicated’. There seems to generally be no differences between caffeinated versus decaffeinated coffee. Roasting level also doesn’t affect caffeine content. On the flip side, there may be a higher amount of a bioactive that increases the risk of cardiovascular disease (CVD) in unfiltered coffee, thus filtered coffee may be a better choice for those at higher risk of CVD. There is also not enough data to make any recommendations about whether adding milk has any impact on health outcomes of drinking coffee.

What neurological receptors are in-play when coffee stimulates the system? What is the impact on mood and sleep?

The key stimulant in coffee is caffeine. Caffeine works on our nervous and gastrointestinal system and is thought to increase chemicals in the body like serotonin and dopamine, which helps us pay better attention and can improve our cognitive function.

Caffeine binds to receptors in the brain called adenosine receptors, which stimulates wakefulness.

The degree to which these receptors ‘hold on’ to caffeine varies across people, therefore there can be differences in how people respond to caffeine. For those whose receptors take longer to ‘let go’ of caffeine, it might be better to not drink coffee or caffeine containing drinks in the later part of the day.

There is also likely to be a difference in how fast we metabolise caffeine. This can have implications for how much people should be drinking. These days, it is possible to work this out whether you are a slow or fast metaboliser through genetic testing.

Is coffee addictive? How serious can an addiction to coffee be on your health?

While some people might experience dependence on coffee or withdrawal symptoms if they stop drinking coffee, there is no evidence of long-term adverse effects of habitual coffee intake. The symptoms experienced during withdrawal, such as headaches and nausea, are related to those receptors mentioned before that caffeine binds to in our brain. When we drink a certain amount of coffee over a long period, the body makes more receptors to cope with the additional caffeine. Without caffeine, these receptors bind to a different chemical called adenosine, which causes drowsiness and the other symptoms of withdrawal.

How young is too young to drink coffee?

Again, the concern with young people drinking coffee relates to the consumption of caffeine. There is evidence of the following negative impacts of caffeine consumption in children and adolescents, even in small amounts (the equivalent of approximately two cans of cola):

• Increased sleep disorders and anxiety
• Interference with brain development

At excessive levels, caffeine intake in children can be associated with

• High heart rate
• Excess urination
• Nausea and vomiting

There may also be a potential role of caffeine in ADHD.

As a result, food and drinks containing caffeine are not suitable for children or adolescents under the age of 18.

How does caffeine affect your body when you exercise, for example, when runners sometimes take caffeine supplements during a marathon or post exercise?

There is evidence that caffeine may improve athletic performance (by enhancing perception of effort or avoiding fatigue), however, this does not extend to coffee. Like all supplements, caffeine supplements may have side effects and use needs to be discussed with the person’s health practitioner.

Why does it stimulate the urge for number twos (make you need to poop)?

Coffee stimulates our bowel muscles to move faster leading to the urge to poo – this can be as quickly as a few minutes after consuming coffee for some people. Researchers are still working on another mystery chemical that might add to this faster movement of poo. This can be worse for those with pre-existing gut issues, such as IBS.