http://cen.acs.org/articles/91/i5/Caffeine-Jitters.html

Some interesting tidbits:

"On the basis of the survey, the team concluded that 400 mg of caffeine per day (or about three 8-oz cups of brewed coffee) is a safe dose for healthy adults to consume . At and below this level, the average person does not experience negative mood changes or heart problems, the report stated."

(400 mg is 5 2oz espresso shots)

"Some people tolerate caffeine and can ingest large quantities of the compound without ill effects, and others can't"

"Fifty percent of the caffeine a person takes in gets cleared from the body, on average, in five hours. But studies have shown this rate can vary because of other drug use: Women taking oral contraceptives break down caffeine slower than those not on a contraceptive pill, and people who smoke process the stimulant faster than those who don't."

"The agency relented, but it put a limit of 0.02% on the amount of compound allowed to be added to cola-type beverages. That's a concentration of about 6 mg per oz, a threshold that drinks like Pepsi Max (5.8 mg per oz) bump up against but don't surpass.
But "beverage" limitations don't apply to drinks like Monster Energy or 5-Hour Energy. These caffeine-rich products are sold as something different: dietary supplements."

"Reports of adverse events connected with 5-Hour Energy shots are also being scrutinized by FDA. Since 2009, the agency has received about 90 filings related to the product, including records of 13 deaths."

One thing I have personally noticed is that I feel the espresso caffeine a lot stronger than I do in a soda, even though they have the same amount. I suppose that is because I drink an espresso a lot more quickly.

Interesting topic.

Regarding caffeine in espresso, the usual stated amount of caffeine in espresso is 30-50 mg per espresso (or per 30 ml shot). However this is likely based on a traditional "normale" which uses 7-9 grams to pull a 25-30 ml shot. The brew ratio is lower than what a lot of people pull these days.

Some people still pull singles using that low a dose, but most will use a double basket with somewhere between 14-21g of coffee. The volume of extraction is often higher, with 40-45 ml being common. I think sometimes shots are pulled at 50ml or more without realizing it, especially if blonding takes a while to happen.

The traditional espresso also tends to use slightly darker roasts like Illy or Segafredo, for example. These coffees will definitely have less caffeine per gram than third wave or Nordic types of roasts which don't go into second crack.

Taking a very rough average of a 1.5 oz shot and say a 16g dose, the caffeine range is probably closer to 90-140 mg per espresso beverage. With lighter coffees this could be a bit higher still. So probably 3-4 of these types of espressos would fall under the "safe" limit as discussed in the article.

Coca cola has about 35 mg of caffeine per can, so it's no surprise that you feel the espresso kick a lot more!

Interesting read!

It might be possible to adjust caffeine levels in vivo by dietary means. It's certainly a good idea to be aware of food-drug interactions in relation to CYP1A2 (the liver enzyme mentioned in the article that breaks down most of the caffeine in the body). As mentioned, its action is inhibited by (for example) oral contraceptives -- extending the half-life of caffeine in the body from between 5 and 6 hours to well over 8 on average. Pregnancy does something similar.

Vit C increases the absorption of estrogen (CYP1A2 inhibitor). Echinacea also seems to inhibit CYP1A2. So if you're female and trying to stave off a cold while you're on the Pill, you can caffeinate super-easily for long periods of time on just a couple of espressos. Less sleep = more coffee the next morning. And lather, rinse, repeat.

Not a problem experienced by most on H-B

More dramatically, Fluvoxamine (SSRI anti-depressant) lowers the clearance of caffeine by 80%. Other CYP1A2-inhibitors (varying strengths) are supposed to include grapefruit juice, cumin, turmeric, sassafrass, and a group of vegetables including carrots, parsley, parsnips and fennel. Several other drugs are inhibitors, too. http://www.ildcare.eu/downloads/artseni ... ctions.pdf

Cruciferous veg like broccoli and cabbage are listed as inducers of CYP1A2, so plenty of them in the diet might help metabolize caffeine faster. Smoking speeds up caffeine metabolism. So does eating charbroiled (or smoked) meat, and St John's Wort. Perhaps if you're male, a smoker, popping a herbal mood-enhancer daily, and regularly eating well-cooked grilled meat with coleslaw while avoiding carrots, you might not caffeinate very easily at all.

I don't know how effectively this kind of information can be used to adjust body caffeine levels generically, given the differences between people, build-up of tolerances over time, and varying absorption rates of different substances, but the interactions are being researched more and more and it could be worth experimenting. I've upped my cruciferous vegetables at lunchtimes

Searching CYP1A2 plus caffeine clearance, food-drug interactions, inhibitors and inducers etc pulls up a host of articles on this subject. NB most lists of inhibitors and inducers are partial -- drug lists tend not to include many foodstuffs, and vice versa.

coffeedom wrote:The traditional espresso also tends to use slightly darker roasts like Illy or Segafredo, for example. These coffees will definitely have less caffeine per gram than third wave or Nordic types of roasts which don't go into second crack.

Taking a very rough average of a 1.5 oz shot and say a 16g dose, the caffeine range is probably closer to 90-140 mg per espresso beverage. With lighter coffees this could be a bit higher still. So probably 3-4 of these types of espressos would fall under the "safe" limit as discussed in the article.

Doesn't a darker roast for a given coffee have more caffeine by weight than a lighter roast? Caffeine is preserved through high levels of roasting, so in a given weight you're packing in more yummy caffeine-laden particles in your basket.

Doesn't a darker roast for a given coffee have more caffeine by weight than a lighter roast? Caffeine is preserved through high levels of roasting, so in a given weight you're packing in more yummy caffeine-laden particles in your basket.

This isn't exactly right. Roasted coffee has more caffeine by weight than green coffee. That is because the coffee drops from 11-13% moisture down to less than 3% during roasting, as most of the moisture evaporates once the bean temp exceeds 100C and goes into first crack. The bean density decreases before much happens with the caffeine. The difference in moisture between light and dark roasts is however very small as the moisture loss is long finished. Caffeine is relatively stable during the roast, but you can't add caffeine to the bean as it roasts. Rather, a slight amount is lost due to degradation once the bean temp gets high enough. After the drying phase, the amount of caffeine per gram can only go down, though not by much unless you go very deep into second crack.

On the other hand, roasted coffee has less caffeine by volume as the roast progresses and beans expand. But if you are weighing your shots, then the amount of caffeine of light versus dark roasts differs only slightly, with light roasts having slightly more.

Avoiding to espresso coffee: the science of quality, caffeine is a hydrolyzed compound, and the dose if caffeine is therefore directly related to the quantity of water used. This explains why espresso has a lower volume of caffeine than brewed coffee, even though espresso uses the same or sometimes a higher dose per serving.

Actually darker roasts are going to yield you more caffeine in the cup(but only if you are weighting your dose). Lets say their is 1mg of caffeine per bean, and your dose is 20 grams. Well 20 grams of light/med roast coffee might be 120 beans, but 20 grams of dark roast coffee might be 140 beans. So even if darker roasted coffee had less caffeine per bean (lets say .9mg per bean), it doesn't matter. Light/med roast 1mg x 120 = 120mg, dark roast .9mg x 140 = 126mg


If your going old school and just dosing and swiping then I have no idea.

It's a nice idea Dustin but your math is a bit ad hoc. After first crack you'll find that 140 beans of dark roast weighs about the same as 140 beans of light roast. This is simple conservation of mass. The only significant change to the mass of each bean occurs during the drying phase leading up to and into first crack when the bean's moisture evaporates. After that, a small amount of mass is burned off as smoke but the amount is insignificant until deep into second crack when things really start smoking.

What changes is the density of the bean as the bean expands during and after first crack. Between first crack and second crack the mass and the caffeine levels are relatively stable. Caffeine starts to break down when the internal bean temperature reaches 428F, so as the roast darkens toward second crack, we start losing caffeine, not gaining.

If you keep roasting darker and darker, you destroy the caffeine, though you also start losing a lot of mass as the beans turn to ash. Pretty much everything gets killed as you roast the beans into oblivion.

For most roasts, say between City and FC+, 20 grams of a specific coffee will be about the same number of beans (give or take) as the weight of each bean barely changes. However, the amount of caffeine in a FC or FC+ roast will be a little less than in a City or City+ roast, depending on how much above 428F the roast goes and for how long.