The question title says it all: My colleague wanted to try my coffee, so he grabbed one bean of coffee (roasted) and chewed it up.

After several minutes, he claims, that it has positive effects on him (feels "juiced up)

Obviously, I am wondering now: Is it just placebo effect, or is there any possibility to feel this after chewing up only one bean?


First I want to draw a comparison between how much caffeine is in a coffee bean versus a cup of coffee, a cup of tea, or a double espresso.

In a standard cup of coffee, there is approximately 150 mg of caffeine. In a cup of black tea, steeped for 3 - 5 minutes there is approximately 50 mg of caffeine. In a double espresso there is approximately 60 - 90 mg of caffeine depending on the roast, grind, extraction time, etc.

In one dark roasted espresso bean there is approximately 6 mg of caffeine according to this source.

If a person is extremely sensitive to caffeine, they would probably be able to feel the effect of 6 mg of caffeine. However, if someone is a coffee drinker, the likelihood that this caffeine is actually affecting them is very unlikely.

If your friend never ingests soda, coffee, tea, or caffeine in any form then he may have felt some of the effects. In my opinion, the majority of the way your colleague was feeling was probably a placebo effect.

Edit: Coming back to this answer, I neglected to mention the effect of the taste of the coffee bean. Taste and aroma can powerfully affect and stimulate the brain. Due to the relatively strong taste resulting from chewing up a roasted coffee bean, this may have also contributed to the reported feeling of stimulation.

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  • 3
    The placebo effect can have a great effect on the coffee drinker. How many times have you seen the caffeine addict express great relief after finally taking that first sip in the morning? – Robert Cartaino Feb 2 '15 at 17:39
  • Your assertion about the caffeine levels vs bean roast is incorrect. Three beans roasted to three levels will all have roughly the same amount of caffeine. However, the more darkly roasted bean will have more caffeine by weight. Caffeine is not lost during the roasting process, water is, so the weight of a bean may change, but the amount of caffeine does not. – Suspended User Feb 2 '15 at 18:57
  • @ChrisinAK Ok. I am open to this. Can you explain to me how more caffeine is in a light roast brew versus a dark roast brew then? I would like to understand and change my post accordingly. – Patrick Sebastien Feb 2 '15 at 18:59
  • It depends on how you measure the coffee. The melting point of caffeine is higher than the temperatures beans reach while roasting, so caffeine is not destroyed. Beans do lose moisture however, during the roast process, so the darker you roast, the less weighty the bean becomes for the same amount of caffeine. So by weight, darker beans will contain more caffeine. However, most people don't measure their coffee by weight, they measure by volume when making a pot of coffee. – Suspended User Feb 2 '15 at 19:04
  • @ChrisinAK I did some research and you are correct. I will edit my post accordingly. – Patrick Sebastien Feb 2 '15 at 19:23

This paper from the BC government states that 3 chocolate covered coffee beans have 36mg of caffeine.

This study used doses of 0.3 mg per kg of body mass per hour, and noticed that the caffeine levels saturated exponentially.

Information on the Effective Dose (ED) of caffeine, has been surprisingly hard to find. Although I did find papers that refer to 100mg as a "low dose" or as a "baseline dosage".

It is difficult to arrive at a recommended ordinary consumption quantity, or a standard “dose,” since caffeine is present in various consumer goods at widely differing levels. Some sources suggest that one-hundred milligrams, whether delivered into the bloodstream by liquid or solid, is useful as a base-line single dosage.[18] Though caffeine content can differ markedly even within a product category, (for example, the amount of caffeine present in “real-world coffee” can range from seventy-five to two-hundred-fifty milligrams per serving), the rough quantity of caffeine in the most commonly ingested products is well known.[19]

A standard six ounce cup of drip-brewed coffee contains roughly one-hundred milligrams of caffeine, whereas a similarly sized cup of brewed tea contains roughly seventy milligrams.[20] Espresso, a common ingredient in many of today’s popular specialty coffee drinks, contains closer to one-hundred milligrams of caffeine per liquid ounce.[21] A conventional twelve ounce can of soda contains approximately fifty milligrams of caffeine, though specialty sodas such as “Jolt Cola” contain closer to seventy milligrams.[22] Milk chocolate contains roughly six milligrams of caffeine per ounce.[23] In the most common over-the-counter drugs, “Anacin” and “Excedrin” tablets contain thirty-two milligrams of caffeine each, while “Vivarin” contains two-hundred milligrams per tablet.[24]

More noteworthy than the specific quantity of caffeine in conventional consumer products is the quantity of each product ingested on a daily basis. While the customary six ounce cup of coffee may contain one-hundred milligrams of caffeine, the ordinary serving sizes of “Starbucks” coffees are twelve, sixteen, and twenty ounces each.[25] More than half of all adult Americans “drink an average of three and a half cups of coffee a day, in addition to tea, cola, chocolate and over-the-counter caffeine-containing drugs.”[26] If potential problems with adult caffeine consumption are an issue to be considered, the caffeine intake of children is even more important, because “the potency of caffeine on a human body depends on the body’s weight.”[27] Some sources suggest that “[t]he highest exposure to caffeine from soft drinks on a mg/ kg / day basis is among young children,” especially children under the age of six.[28]

It seems unlikely that he would feel the effect of eating a single bean.

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I'm sure it's possible. I myself feel the effect of chewing on a single bean.

The reason has to do with the different way we absorb caffeine when chewed rather than brewed.

When drinking coffee, the caffeine has to be digested and absorbed through your stomach lining, duodenum, or small intestine (I'm not sure which.)

On the other hand, when chewing on a bean, the caffeine is directly absorbed by your mouth into the bloodstream. Therefore even a single bean, which may have 1/10 or less caffeine than a cup, will give you a boost. It will give it sooner, usually while you're still chewing on it, but it will go away sooner too. (Unless you eat a large number of beans. Don't do that.)

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  • Welcome to Coffee SE, feel free to take the tour. – MTSan Apr 10 '16 at 2:58
  • AFAIK, there is nothing wrong with eating a large number of beans by someone who is tolerant to caffeine. – Acumenus Jul 7 '16 at 6:01

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