Coffee: How much is a good thing?

There is conventional wisdom: too many cups of coffee can be bad for you. There are also a surprising number of of extremely rigorous reports confirming a certain number of cups of coffee per day may be a good thing. What is most often missing is the definition of ‘a cup’, given that long ago I learnt that the amount of caffeine in a ‘cup of coffee’ can vary by a factor of 10x.

Background.

Years ago I was looking to move from a capsules style coffee machine to an expresso machine which would make changing between regular and decaffeinated coffee more difficult. This triggered a research project: is decaffeinated coffee worth bothering with anyway? Apart from the pros and cons of decaf, the big thing I learnt is that the caffeine in a ‘cup of coffee’ can range from 40mg to over 400mg, which is from the same amount as a cup of tea, to the same amount as 10 cups of tea. Note that a ‘grande’ is 470ml (16 fl oz) and a shot of expresso is around 30 ml, so technically per ml there is more caffeine in the expresso, at least until frothed milk of a latte or cappuccino, or additional hot water of a long coffee is added. Surprisingly, ‘per cup’, expresso has the lowest level of caffeine of the common ways of having coffee.

On this page I will collect information on what is in a ‘cup of coffee’, as well as the research into positive and negative claims in the the impact on health. Plus, I encountered some questions as to how long coffee drinking will remain affordable. Early days, but information will grow.

The case for ‘drink coffee and live longer’.

The Data.

This large prospective cohort study of a half million people found inverse associations for coffee drinking with mortality [that is coffee drinkers had less deaths], including among participants drinking 1 up to 8 or more cups per day. No differences were observed in analyses that were stratified by genetic polymorphisms affecting caffeine metabolism.

JAMA- Journal of the American Medical Association report.

They followed a group of 1,567 people, aged 20 years and older, over an 18-year period.

The initial data came from the Valencia Nutritional Study, which was conducted in 1994. It assessed a range of food groups, including drinks, such as coffee.

Their findings suggest that drinking between one and six-and-a-half cups of coffee per day can lower your risk of cancer and what scientists call “all-cause” mortality (meaning, any kind of death).

DW (Deustche Welle) – Spanish study shows coffee still good for your health

There is a body of evidence that some of the side effects of coffee may actually be good for you, and they appear to have nothing to do with caffeine. But Dr Karl Kruszelnicki’s grind is the observational studies that make up the ‘statistics’ behind the health benefits.

Dr Karl Kruszelnicki: July 2016 (other comments quoted here)

Is this scientific?

The Spanish study reported in the above quote, is one I specifically was looking for a reference on, as it is have been widely peer reviewed, has a large sample size, and studied over an 18 year period. However, even that study does not match best scientific principles, because there is a limit to the ability to experiment on humans. To follow ‘best practice’, it is necessary to take the sample group at random, without regard to their existing coffee habits, and randomly divide into two subgroups. One subgroup would consume a placebo that is indistinguishable from coffee for the period of the trial, and the other group would consume coffee, and no one would know which group they are in. There are many reasons this type of trial would be neither practical, nor ethical.

Without the ‘double blind’ type rigour, there are limits to what can be inferred from the data. Since the participants are people who choose to drink coffee, they may already be different in other ways than non-coffee drinkers. Are they at the same wealth level? Are they more social? Still, all things considered, the weight of data is very compelling, and especially compelling with to reduction in diabetes levels. However, the adage still applies: correlations is not causation.

More Links.

Just what is in ‘a cup’ of coffee?

A Cup of Coffee.

Well, not literally. There is a recipe for what we call a ‘cup of coffee’.

Start with beans from a coffee plant. The beans go through steps of being pulped, fermented, dried, and milled, before finally being roasted. It is a lot of steps. Some time after roasting, grind the coffee. As soon as possible after grinding, run hot water through the ground coffee to extract the ‘essence’ of the coffee, which includes caffeine, and at least 20 other chemicals, many of which may be as significant as caffeine in terms of flavour, health and even staying awake.

So a ‘coffee drink’ is mostly water, infused by extracts from coffee. Then there is most often added cream or milk, plus possibly sweetener.

Why Expresso is different.

Coffee made as expresso has a different mix of what is extracted from the beans. Almost all other methods of making coffee ‘pour’ boiling, or even slightly above boiling temperature, water over the ground coffee. Generally, the water must be as hot as possible to ensure sufficient extraction. With the goal of changing the balance of extracts from t coffee, the expresso process uses lower temperature water, and compensates by first compressing the coffee and forcing the less than boiling water through the packed ground coffee grinds under pressure. Using lower temperature water means that just adding cold milk or water would result in a tepid drink, so milk is heated by ‘frothing’ before being added to expresso. However by using heated frothed milk, far milk can be added without resulting a tepid drink. The result is that expresso coffees such as a latte or cappuccino may have a greater percentage of milk that is common with other coffee drinks.

How Much Caffeine per cup?

I will add some comparison data between filter, French press etc, but the main focus will be on determining caffeine per cup of expresso, as there are many variables.

Expresso is lower in caffeine and the oils that contain the caffeine, due to the reduced extraction temperature and the use of pressure, which changed the mix of what is extracted from the beans. Expresso can be extracted at a range of temperatures, usually 90C to 95C, and collect and add data a I find it. But I will start with what I recall from previous research.

The following all affect the amount of caffeine:

  • Beans.
  • Roast.
  • Grind.
  • Tamping pressure.
  • Extraction Temperature.

Arabica beans are lower in caffeine than Robusta beans, although these days almost all beans are Arabica.

I will dig around and add links and sources of information. I will start with what I recall from my original research, and add references as I find them. One of my first sources was study that found that at a Starbucks coffee outlet, a ‘Grande’ of regular filter coffee had 400mg of caffeine, while an expresso from the same location had only 41mg of caffeine. (this section still to be completed)

Decaf Anyone?

To be added. Is there any benefit to opting for decaf?

Objections? Any health case against coffee?

I am still to research this fully.

Sidebar: Experiences with coffee at home.

This section also to be added, but only of interest to anyone considering making expresso at home, and finding yet another persons experience interesting.

Is there enough? Coffee drinking is spreading, will it remain affordable?

The US is around 25th in a table of coffee drinking nations, and on average people in the US drink between 1/2 to 1/3 as much coffee per year as those in Scandinavia. The Finns, who drink 3x as much coffee as Americans, do also have a longer life expectancy, but not as long as Japanese, who have almost caught the US coffee consumption per capita, but are not there yet. The longer life cannot not be attributed just to coffee, but the coffee is certainly not killing the Finns either. So what if the world all consumed coffee at the same rate, not as the Finns, but as the more moderate Americans, who themselves, might live a little longer if they drank more?

The US consumption is listed on that table as 9.26 lbs (4.200kgs) per capita per year, and I have this data on total worldwide coffee production as 172.46 million 60 kg bags in 2019. Using the 9.26lbs per capita:

4.200 * 328 million / 60 = 23 million 60 kg bags.

Yet direct data from statistica shows actual US consumption at 26.5 bags. Close, but suggesting either not all coffee bags purchased are consumed, with 13% of the coffee not being consumed. In reality this, may also be discrepancy between sources of data.

Now consider if the entire globe of people in 2019 had equal access to those 172.46 million 60kg coffee bags produced globally, then multiplying the number of bags by the ratio of people in the US(0.323 billion) compared to the rest of the world (7.5 billion): would allocate only 7.7 million 60 kg bags to the US.

177.46 * (328,231,337 / 7,543,334,085) = 7.72

As 7.72 million bags is less than 1/3 of the coffee the US currently consumes, the poorer nations gaining wealth to the point where the level of coffee consumed in the US, which is 1/3 of that in Finland and possibly below the ideal consumption, became the global ‘typical’ level, then coffee production must increase threefold, or people in richer countries reduce their coffee consumption. The average US coffee drinker would drop from 2.9 cups per day, to less than 1 cup per day, or more realistically, the price of coffee rises until only 1/3 of current coffee drinkers can still aford coffee.

Factor in the expected population growth in the next few decades and their seems a very real risk that coffee will become a more scarce commodity as some countries more people will be able to afford and want to drink coffee in line with current trends, but finding land to grow three or even four times as much coffee is not really practical, given all the competing demands for more land..

This figures is less than means, even to reach Just to be conservative, using the using the lower figure of 23.18 show This matches closely with the statistic direct data

Conclusion.

Those advocating population is not a problem will typically promote how there is no danger of the world starving, as we can easily produce sufficient wheat to feed an even bigger population. But what is our ability to provide ‘optional’ products for the world such as chocolate, or coffee? The reality is, we can provide more than enough wheat, which means those who are is less developed countries, and all addition people added through population growth, remain on a very basic diet and do not consume commodities such as coffee or chocolate, standards of living in the west can remain at current levels. However, people in China, India and elsewhere in Asia and Africa and developing nations continue, well developing, commodities and such as coffee and chocolate are going to move in the direction of housing, and become only accessible by the rich. The more people the world adds, the greater the challenge.

So if you are over 40, then consider multiple cups of coffee per day may even lengthen your life. But if younger, then maybe best not to start a habit that may become too expensive.

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