Coffee: how much is too much?

Hmm coffee. There’s nothing I like more than my Kathmandu plunger of coffee in the morning. I’m probably like a lot of kiwis, and 54% of those in the US it turns out. Sixty five percent of whom claim they ‘need’ their coffee in the morning. Me? If I go happen to go without it, I feel mildly aggrieved that I wasn’t able to experience the pleasure of the first sip, which is preferable to the thumping headache others report experiencing if they miss it. It enhances my morning rather than controls it. Regardless of what camp you fall into, as New Zealander’s we are a proud coffee drinking nation, therefore it’s not surprising that one of the most commonly asked questions I get ‘am I drinking too much coffee*?’ And I have to say that’s like asking ‘how long is a piece of string?’ Like most things, we can’t look at caffeine consumption in isolation of other behavioural and physiological factors. We have to view it in context of the overall lifestyle for that person.

coffee

If this is you, take comfort in the fact that you are among friends. (Image stolen from Pinterest)

In fact, if you look at some of the media headlines which report consumption of coffee at a population level, it is all looking pretty good. It used to be frowned upon for its diuretic effect in the body, yet we now know that for habitual drinkers, around four cups per day does not cause dehydration.  Moderate consumption (of around 3-5 cups per day) places people at a lower risk for cardiovascular diseasereduced risk of type 2 diabeteslower risk of cirrhosis, non alcoholic fatty liver disease and hepatitis C. I know what you’re thinking: order me a Frappuccino and make it a Grande.

Not so fast.

When we look at studies of coffee consumption in the academic literature, we have to view it with the same light that we do the studies which conclude that saturated fat is associated with heart disease, or that red meat increases risk of cancer: these studies are observational and take a snapshot look at the population  – therefore the same inherent limitations exist: there is no cause and effect, it is just an association – when you ask a population once about their coffee intake you seldom get a clear picture of what they are drinking. Perhaps it IS a triple shot short black straight up from the café downstairs, or it’s a ½ teaspoon Moccona made with trim milk and hot water. In addition, we don’t always know the other lifestyle factors that occur in conjunction with the coffee consumption. Perhaps those with the lowest health risk who drink coffee are also people who are also regularly active, their body weight is within a healthy range for them, they may lead less stressful lives. Whilst these can be statistically adjusted in the studies, I tend to agree with those who argue that it’s always difficult to adjust away the accumulated affects of a healthy lifestyle.

Importantly, what studies like these are reporting are population averages. For example, if we track two groups of people over time (either those that consume coffee and those that don’t), we might find that in the group that drinks coffee, the actual intakes vary from two cups of coffee to eight cups of coffee a day. We might find that those who drink coffee have better sleep patterns than those that don’t. We would average out the intake and conclude that perhaps four drinks of coffee per day enhances sleep. However, it is highly likely there will be differences in those that drink two cups of coffee per day compared to those that drink eight cups. We also don’t know whether those that drink coffee have habitually done so, or have recently taken it up. Nor are we sure that those who don’t drink it have decided not to due to issues related to obtaining enough sleep. Further, among the group that actually do drink coffee, what is it about the lifestyles of the people in the study that drive them to drink eight cups of coffee in a day? These questions aren’t able to be addressed in population-based research in a way that is meaningful for the individual. In real life, we don’t work with the ‘average’ person, and at the individual level the coffee intake is not the problem – it’s the symptom of underlying issues that need addressing.

So what are the downsides of too much coffee? Coffee, or caffeine rather, is a stimulant. It elevates cortisol production (a stress hormone) which increases the load on the hypothalamic pituitary adrenal (HPA) axis, the regulatory system that is responsible (among other things) for regulating our thyroid metabolism, digestion, immune system and stress and sex hormone production. If you consume two espressos per day and feel more or less on top of everything from day to day, then this elevation in cortisol from the caffeine is more likely to be transient and if anything, the stress may well be good (after all, we need a certain amount of stress to thrive in everyday life). However, if you consume those two espressos on top of disrupted sleep, a rather heavy workload, a high training load (for an athlete) and might also be going through some relationship difficulty, then the accumulation of stressors will lead to a chronic elevation of adrenaline and cortisol. Over time this can cause disruption of the HPA axis, resulting in fatigue, increased susceptibility to illness, weight gain, and reduced ability to cope with further stress. None of these are desirable and, in fact, are becoming more common as our lifestyles are becoming busier. This collection of symptoms is referred to as adrenal fatigue, and while not always acknowledged as such in the medical arena, there are many people suffering the effects of burn out due to a chronic stress overload.

To add to this, caffeine is an adenosine antagonist, which means that it takes the place of adenosine on receptors in the brain and blocks its activity. Adenosine is responsible for producing a more relaxed state and preparing us to get ready to wind down. Caffeine blocks this and therefore the neurotransmitters responsible for invoking an alert state are allowed to continue on, making you feel less sleepy after taking it. Useful if looking for a second wind later on in the day. However, given that caffeine has a half life of around 6 hours (meaning it takes that long to metabolise), when consumed in large amounts later in the day it is going to impact on sleep, regardless of how convinced you are that this isn’t the case for you. While you might not have any trouble getting to sleep, certainly the quality of sleep is compromised. This lack of restorative sleep not only impacts physiologically (increasing insulin resistance), but increases cortisol levels and the likelihood of reaching for foods and stimulants to level out energy levels the following day.

So…are YOU drinking too much?  If it leaves you feeling relaxed and calm then it probably only makes you more awesome. If it leaves you feeling a bit jittery and wired, or you use it to get through the day, perhaps you need to evaluate whether that long black is contributing to your health or stealthily removing it. Only you can determine that.

*the only thing I can say with almost certainty is that coffee made from Jungle Beans (or its derivative Zee) is best avoided regardless of context.

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