Prof. Dr. Werner Seebauer is Dean of Studies – Association of German Preventologists, Head of Preventive Medicine Department of Institute of Transcultural Health Sciences (European University Viadrina) and Head of Preventive Medicine – NESA (The New European Surgical Academy).
Since 2000, prof. dr. Werner Seebauer worked only in preventive medicine, after ten years spent at the Frankfurt University Hospital. He is also involved in the medical professionals training for nutrition and prevention.
MediHelp International contributes to the medical science development and is actively involved in the international social responsibility advocacy.
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Coffee is one of the world's most common prepared beverage, alongside tea
The earlier warnings related to the increase of certain risks, such as cancer risks and heart disease, were based on correlations that roasting the coffee beans, among others, produce acrylamide, as a cancerogenic substance, and on the other hand, in certain forms of preparation a connection with the increase in LDL cholesterol is suspected.
The following article shows when and how coffee can increase risks, and why it usually can be convincingly said that it does not increase disease risks but lowers some disease risks.
Reduction of certain cancer risks
Acylamide is carcinogenic, but over coffee, when adequately prepared, it is not usually given the effective amounts (more on that below in the article). Higher levels of acrylamide are more likely to be added via chips, fries, toasted bread, gingerbread, and other toasted biscuits.
Numerous study evaluations show evidence that coffee reduces various forms of cancer.
With 3-4 cups of coffee per day (one cup equals approx. 140 ml), a reduction of 29% in uterus cancer was found. For postmenopausal breast cancer, the study evaluations calculated a risk reduction of 2% per 2 cups of coffee intake; before the menopause, there was no relation to a risk reduction.
Also in liver cancer and chronic liver disease study evaluations saw a risk reduction by coffee. For the intake of an additional cup of coffee per day, a risk reduction of 16% was calculated.
Further analyses from the meta-analysis of the studies from 1966 to 2012 even showed that the risk of liver cancer in coffee drinkers was up to 40% lower than in people who do not drink coffee at all. One benefit was that the effect on the liver enzymes reduced liver cirrhosis and thus the development of cancer. Since not all studies are equally useful and other factors play a role, such a result is merely a guide that indicates that coffee has a positive impact, along with other factors. Almost always both harmful and protective effects on the organism depend on a combination of several factors.
In addition to acrylamide, furans are also produced when roasting coffee beans, which are also considered harmful at a higher dose. The doses in coffee are low and do not produce acutely measurable toxic effects, but due to the summation effects with many other toxins from everyday life, all pollutants should be reduced wherever possible. The coffee powder brewed over filter paper is the best way to keep the furans lower in this regard. The coffee preparations from capsules for coffee machines are significantly more disadvantageous in terms of furans and acrylamide (also instant powder coffee contains more acrylamide).
In a further context, there is a correlation between coffee consumption and the risk reduction of diseases such as type 2 diabetes mellitus, diseases of the cardiovascular system and Parkinson's disease.
Coffee contains many different phytochemicals, of which a spectrum may have antioxidant, anti-inflammatory and thus anticancer effects.
The International Agency for Research on Cancer (AICR) and other societies, according to hundreds of studies, attribute a benefit to coffee today and no risk if certain factors are considered (see below).
Up to 6 cups of coffee consumed throughout the day did not show any risk increases related to cancer or cardiovascular disease. But pay attention: Too hot drunk coffee (over 65 ° C) may increase cancer risk.
Whether in particular, the hot temperature causes the disadvantage is not understood; In hot tea, such relationships have not been described. Drinking coffee not too hot does not increase risks either.
Beware in certain situations
Pregnant women, people with insomnia and people with high blood pressure or cardiac arrhythmia may also drink coffee, depending on the times, but the decaffeinated variant would be recommended.
Pregnant women can usually enjoy up to 3 small cups of unsweetened coffee throughout the day, but less might be better.
Also in the context of a migraine, some people have to pay attention to potentially unfavorable effects of caffeine.
Topic LDL cholesterol
It has been observed in clinical studies that coffee increase the LDL cholesterol levels in some people with blood lipid metabolism disorders and elevated lipid levels (hyperlipidemia).
This effect seems to be mainly due to substrates in the oily fraction of coffee (such as Diterpene, Cafestol, etc.), which arise when brewing ground coffee beans with hot water. Such diterpenes and the cafestol, however, largely remain in the coffee paper filter, which is why this type of preparation is recommended.
Other types of preparation, such as those in the Scandinavian countries, or methods such as "French Pressed Coffee" or "Turkish Coffee" contain much higher amounts of Cafestol.
Espresso is at the cafestol level in the middle. The best, as emphasized, the paper filter method.
The topic of high blood pressure and diabetes
There is no obvious association with high blood pressure and caffeine from coffee or tea. Nevertheless, any hypertensive person who does not get his high blood pressure better through other activities (weight reduction, physical activity, if necessary drug therapy, etc.) should look at whether a decaffeinated coffee may bring benefits.
The same is true of diabetics who have high blood sugar levels. There, too, they should see if decaffeinated coffee might bring benefits (of course, their coffee should always contain no added sugar). As mentioned, pure coffee otherwise reduces type 2 diabetes risk.
The caffeine content in the coffee depends on the type of coffee and the roasting as well as the particle size of the coffee powder and, of course, on the dilution by water. The brewing method (type and duration) also influences the caffeine content.
As a rough orientation you can estimate*:
- A cup of coffee (125-140ml) has about 67 - 112mg of caffeine. By the way, it is similar to strong brewed black tea.
- A cup of espresso (50 ml) has about 50-60 mg of caffeine.
- A glass of Cola (200ml) usually contains between 10-40 mg of caffeine.
- A cup of common black tea (140 ml) contains 20-50mg of caffeine; green tea has lower caffeine or theophylline levels and the effects are delayed.
* according to the federal food key 1995 - Kirschbaum et al. 2001
From 200 mg of caffeine, it may be more likely to cause motoric disturbance (restlessness). However, the effects are subject to habituation effects, which with prolonged use even higher doses are more tolerated.
Pregnant women have a significantly slower metabolism and thus degradation time of caffeine; In adults, about half of the caffeine in the blood is broken down after 5 hours (metabolic half-life).
Does coffee degrade the water balance of the organism ("liquid predator")?
For a long time, it was assumed that coffee takes more water from the body than it supplies because higher doses of caffeine also increase kidney circulation and excretion of urine. Increased renal circulation and kidney filtration is a positive effect and the water balance of the organism is also not negative as assumed (no dehydration promotion and poorer fluid supply) if not too high quantities were drunk.
Several studies from recent years have shown that caffeine intake of at least 250 to 300 mg (approximately 2 to 3 cups of coffee) in a short time window led to a short-term increase in urine production, thus increasing the excretion of water and sodium, above which the organism loses more water. However, the water balance was not seriously disadvantaged and the otherwise recommended throughout the day hydration is the water balance within the day balanced again (this is not just to make with coffee). Besides, it is observed that persons who regularly drink caffeinated coffee or tea, the urine-enhancing effect is reduced, and various compensation mechanisms compensate the increased water and sodium excretion.
Coffee can very well contribute to the total fluid intake, in as much as regular moderate coffee consumption (3-4 cups per day)* also consumes other beverages and water-containing foods. During the day at least 1.5 liters of liquid (such as water, mineral water, unsweetened fruit, and herbal teas) should be drunk.
* The same statements can be made as to black and green teas.
A glass of water beside the coffee is not necessary, but in any case often advantageous because the fluid intake of people is usually suboptimal or even often far too low.
In summary, recommendations:
- Coffee has several positive effects in terms of health promotion or reduction of certain disease risks, such as some types of cancer, type 2 diabetes, cardiovascular and liver diseases. However, the coffee should not be drunk too hot and the paper filter method with longer slow brewing has advantages.
Since too hot drunken coffee (over 65 °C) seems to increase the risk of cancer, and freshly brewed coffee is usually hotter, it should first be cooled slightly or drunk with the addition of a little cold water or a little cold milk.
- The additives to coffee should better not contain the heavily sugared variants, cream, artificial flavor additives, or something similar.
- Pregnant women and people with insomnia as well as high blood pressure or cardiac arrhythmias should drink better coffee only in smaller quantities or decaffeinated.
Pregnant women can generally enjoy up to 3 small cups (125 ml) of unsweetened coffee safely throughout the day. However, since caffeine pass the placenta, and the effects on the fetus, which is very sensitive to it, can be difficult to study, pregnant women should better drink only one cup of coffee (125 ml) per day if it is not decaffeinated.
- In the case of insomnia, everyone should check for themselves at what interval before going to bed caffeinated drinks should not be drunk. From 200mg of caffeine is usually an excitatory effect and the metabolic half-life of caffeine degradation is in adults with an intact caffeine metabolism about 5 hours.
- Brewing coffee openly through filter paper is the best way to reduce harmful substances and risk factors - even better are the protective effects with a little longer heat input (30 minutes).
- With about 3 cups of coffee per day, there is usually no negative water balance of the organism. In any case, it is advantageous to pay attention to plenty more unsweetened fluid intake throughout the day (water, fruit tea, vegetable juices - with enough exercise even diluted fruit juices).
- The "healthy" coffee does not include sweetened types like Frappuccinos, and other types of the mix, some of which have become common in coffee houses; some of which contain up to 500 kcal per drink. The coffee should be pure filter coffee without sugar sources or other flavor additives. Low milk quantities are okay.