The health effects of coffee are not as clear-cut as some studies may suggest. Coffee is chemically very complex and its individual components affect us in different ways. Web Ars Technica summarized the current knowledge about the positive and negative effects of this popular drink on human health.
You have probably heard that drinking coffee is good for your health. Studies have shown that consuming an adequate amount of coffee is associated with many health benefits, including a lower risk of developing type 2 diabetes and some cardiovascular diseases. Although these associations have been proven many times, they do not actually prove that coffee reduces the risk of disease.
It’s complicated with coffee
Some sources state that consuming three to five cups of coffee a day is optimal for health, but in reality it is not that simple. Coffee contains many ingredients that can affect health in various ways. In addition to caffeine, it contains other substances and compounds that act on the human body.
- Alkaloids – In addition to caffeine, another important alkaloid contained in coffee is trigonelline. It is less studied than caffeine, but research suggests that it can have positive health effects – for example, it reduces the risk of type 2 diabetes.
- Polyphenols These compounds, which are found in many plants, including cocoa and blueberries, are beneficial to the heart and blood vessels. They can help prevent neurodegenerative diseases such as Alzheimer’s disease. Coffee contains mainly a group of polyphenols called chlorogenic acids.
- Diterpenes – Coffee contains two types of diterpenes – cafestol and kahweol – which form coffee oil, a natural fat released from coffee during its preparation. These substances may increase the risk of cardiovascular disease.
- Melanoidins – the compounds which are formed at high temperatures during roasting give the roasted coffee a color and a characteristic taste and aroma. They can also have a prebiotic effect, which means that they increase the amount of beneficial bacteria in the gut, and this is important for overall health.
The way coffee is grown, prepared and served can affect the content of individual substances and thus its health effects. For example, growing conditions can affect the amount of caffeine and chlorogenic acids – coffee grown at high altitudes will have a lower caffeine and chlorogenic acid content.
A number of factors affect it
It has also been shown that the two most common types of coffee beans – arabica and robusta – have different contents of caffeine, chlorogenic acid and trigonelin. However, neither type has been shown to be more beneficial or harmful to health.
The key is also how much the coffee is roasted. The stronger the roasting, the more melanoidins are formed (and the more intense the taste), but the chlorogenic acid and trigonelline content decreases. Instant coffee is the most commonly consumed type in the UK. It is usually freeze-dried. Research shows that instant coffee contains higher amounts of melanoidins than filtered coffee and espresso.
The chemical composition of coffee also affects the way it is prepared. For example, brewed coffee contains higher amounts of diterpenes compared to filtered coffee. Other factors also have an effect – for example amount of coffee, fineness of grinding, water temperature and cup size.
Chlorogenic acids reduce the risk of cardiovascular disease by improving arterial function. There is also evidence that they can reduce the risk of type 2 diabetes by regulating the sharp rise in blood sugar after a meal. On the other hand, diterpenes have been shown to increase lipoprotein levels, a type of cholesterol associated with cardiovascular disease.
Milk and sugar can also have an effect
Adding milk, cream, sugar and syrup will change the nutritional value. Not only does the calorie content increase, but so can it increase the intake of saturated fats and sugars. Both of these factors are associated with an increased risk of type 2 diabetes and cardiovascular disease and may counteract the beneficial effects of other substances in coffee itself.
There is also evidence that different people may react differently to some of these compounds. Regular drinking of three to four cups of coffee a day has been shown to create tolerance to the blood pressure-raising effects of caffeine. Genetics can also play an important role in how your body treats caffeine and other compounds.
Increasing evidence also points to the gut microbiome as an important factor in determining the health effects of coffee. For example, some research suggests that intestinal microbes play an important role in the metabolism of chlorogenic acid, and therefore can decide whether health will be beneficial or vice versa.
Although humanity has been drinking coffee for centuries and is currently the second best-selling commodity in the world after oil, we still do not know the answers to many questions about its impact on human health. Therefore, it continues to be the case that the consumption of this drink should follow the motto “less is sometimes more”.