We have an expensive espresso coffee machine that produces excellent coffee. As native Northern Europeans we drink large cups of coffee. The other day I took the effort of trying to calculate the amount of caffeine in one cup of coffee. The machine has three coffee choice button (apart from a number of buttons also providing different varieties of coffee with hot milk). They provide a ristretto, an espresso, and a strong coffee with increasing volumes of coffee down the buttons. We use the bottom coffee button with the coffee strength set to high and always press it twice to get a double coffee of 250 mL. Now based on data provided for caffeine content in coffee expressed from an espresso machine averaging about 2,000 mg/L, the amount of caffeine in the cup can be calculated to be around 500 mg. That is a lot.
The European Food Safety Authority (EFSA) in a recent opinion stated that a cup of coffee with 200 mg of caffeine is fine but daily intake of caffeine should be restricted to 400 mg. We exceed this exposure with only one cup of coffee. What could be the implications?
The detrimental effects
It might not all be good.
I recently had a question about coffee and iron absorption. Looking at a recent scientific report it was clear that coffee inhibit iron absorption. A cup of coffee within an hour of an iron rich meal reduced iron absorption by at least 40%. So it is not a good idea to finish a meal with a cup of coffee in case you suffer from iron deficiency. In this case it probably doesn’t matter that much if the cup contains 200 mg or 500 mg of caffeine.
It is also not a good idea to have a late cup of coffee just before going to bed. Large amount of caffeine can disturb sleep patterns and cause insomnia. On the benefit side, caffeine enhances alertness and mood, and increases performance, but that is probably not what you want when going to bed. This effect is most probably influenced by the amount of caffeine consumed so a 500 mg caffeine cup should definitively be avoided before sleep.
Caffeine may also aggravate pre-existing health conditions such as migraines and heart arrhythmias and it can promote anxiety and panic attacks, especially in high doses and in those with pre-existing anxiety disorders. That doesn’t sound very encouraging except that regular coffee consumption will blunt such effects. And we have our daily dose.
So it might be fine.
The beneficial effects
And there is the other side.
The simple act of drinking caffeinated coffee seems to be able to reduce the risk of colon cancer returning after surgery and subsequent death. A clinical trial examined outcomes in patients with stage III colon cancer who were treated with surgery and various chemotherapies. All 953 patients reported their intake habits for 128 foods, including caffeinated coffee, decaffeinated coffee, and nonherbal tea, during and 6 months after chemotherapy.
The benefit was strongest in the heaviest drinkers of caffeinated coffee. Patients who consumed at least four cups of coffee a day or about 460 mg of caffeine were 52% less likely to have their cancer return or to die than noncoffee drinkers. Patients who drank fewer cups of caffeinated coffee also saw a benefit, but the degree of risk reduction tapered as the average number of cups per day dropped. In other words, there was a dose-response effect.
If you aren’t affected by colon cancer there might be more good news. Various studies in recent years have suggested that coffee protects against the development of breast cancer and skin cancer, and protects against the recurrence or progression of prostate cancer.
Among postmenopausal women, heavy coffee consumption is associated with a lower incidence of estrogen receptor (ER)-negative breast cancer. In a study involving about 6,000 females there was a small decrease of 20% in overall breast cancer risk associated with coffee consumption of more than 5 cups/day compared with 1 or fewer cups/day. However, among the heavy coffee drinkers there was a strong reduction of close to 60% in risk for ER-negative breast cancer.
Coffee may reduce the risk of developing basal cell carcinoma of the skin, according to new prospective data from more than 110,000 healthcare professionals who participated in two large, surveillance studies. Study participants who drank more than 3 cups of caffeinated coffee a day had a 17% reduction in their relative risk of basal cell carcinoma compared with individuals who drank less than 1 cup per month. However, no association was found between consumption of coffee and either squamous cell carcinoma or melanoma.
Drinking 4 or more cups of coffee a day was associated with a lower risk for prostate cancer recurrence and progression, according to a prospective study of a cohort of 630 prostate cancer patients. The study authors found that men who drank that much coffee daily had a 59% reduced risk for prostate cancer recurrence and/or progression, compared with those who drank 1 or fewer cups per week.
So maybe not too much coffee after all
It all sounds great but note that as prospective and observational studies the findings only reveal correlations and are not proof of causation. There are many such studies with dubious results.
However, being an optimist I think I stick to my daily large cup of coffee and hope for the best, ignoring the EFSA advice for now.