Coffee beans contain a complex array of compounds that contribute to the beverage’s flavor and diverse biological effects. Among these are diterpenes, a class of organic molecules responsible for some of coffee’s most notable health impacts. The two primary diterpenes found in coffee are cafestol and kahweol. Their presence in your daily cup depends entirely on how the coffee is prepared, as they influence both lipid metabolism and cellular defense mechanisms. Understanding the role of these specific molecules provides insight into how coffee consumption affects health.
What Diterpenes Are and Where They Originate
Diterpenes are lipid-soluble molecules, meaning they are oily substances concentrated within the fat or oil fraction of the coffee bean. Both cafestol and kahweol are pentacyclic diterpene alcohols, with kahweol differing from cafestol by possessing an extra double bond in its chemical structure. When coffee beans are roasted and ground, these compounds remain embedded in the oils, ready to be extracted by hot water during brewing.
The concentration of these compounds varies significantly between the two major species of coffee bean. Arabica beans, which account for the majority of global production, contain substantial amounts of both cafestol and kahweol. In contrast, Robusta beans typically contain about half the level of cafestol and almost no kahweol. Since these molecules are fat-soluble, they are readily suspended in the brew’s water as microscopic oil droplets, which is why the brewing process itself is the main factor determining how much reaches the final cup.
Physiological Effects on the Human Body
The effects of coffee diterpenes in the body are mediated primarily by cafestol, which is the more potent of the two molecules. The physiological response to these compounds involves a direct interaction with the body’s mechanisms for regulating cholesterol, while also offering some protective qualities.
Negative Effects
Cafestol is widely recognized as the most effective cholesterol-elevating compound in the human diet. Its consumption leads to an increase in serum cholesterol levels, with a particularly strong effect on low-density lipoprotein (LDL) cholesterol, often called “bad” cholesterol. Research has shown that consuming as little as 10 milligrams of cafestol per day can elevate cholesterol levels by approximately 5 mg/dL. This effect is entirely dose-dependent, meaning the more cafestol consumed, the greater the rise in circulating cholesterol.
The mechanism behind this elevation involves the liver’s metabolic pathways. Cafestol acts as an agonist, or activator, of the farnesoid X receptor (FXR), a nuclear receptor that plays a fundamental role in bile acid and cholesterol regulation. Activation of FXR by cafestol suppresses the activity of cholesterol 7 alpha-hydroxylase (CYP7A1), the enzyme that performs the rate-limiting step in converting cholesterol into bile acids. By reducing the liver’s ability to clear cholesterol by converting it to bile acids for excretion, cafestol effectively forces more cholesterol to remain in the bloodstream.
Potential Positive Effects
Despite the concerns related to cholesterol, coffee diterpenes also demonstrate several beneficial biological activities. Kahweol, in particular, exhibits properties that are anti-inflammatory and neuroprotective in laboratory models. Both cafestol and kahweol have been studied for their potential to enhance the body’s natural defense systems.
These diterpenes appear to boost liver detoxification functions by inducing specific enzymes, thereby helping the body neutralize certain toxins and carcinogens. They have also been linked to an increase in the production of glutathione (GSH), a powerful antioxidant used by the body to combat oxidative stress. Kahweol has also shown preliminary promise in studies related to bone health, suggesting it may inhibit the process of osteoclastogenesis, which involves the breakdown of bone tissue.
How Preparation Methods Influence Diterpene Levels
The single most important variable determining the amount of cafestol and kahweol in a cup of coffee is the presence or absence of a paper filter. Since diterpenes are oily, they are easily retained by the cellulose fibers of a paper filter, which acts like a physical barrier. This filtration mechanism significantly lowers the concentration of diterpenes that pass into the final beverage.
Brewing methods that do not use a paper filter result in the highest diterpene concentrations. These unfiltered methods include French press, Scandinavian boiled coffee, Turkish coffee, and Moka pot preparations. Boiled coffees, such as the Scandinavian or Turkish styles, are typically the highest in cafestol, followed closely by French press coffee. Espresso, while highly concentrated, typically delivers an intermediate dose of diterpenes due to the small volume of a standard serving.
Conversely, methods relying on a paper filter produce brews with negligible diterpene content. Standard drip coffee makers and pour-over techniques, such as Chemex or V60, effectively remove almost all the diterpenes from the final cup. Instant coffee also contains very low levels of diterpenes because the manufacturing process involves significant filtration and processing. This makes filtered coffee the preferred choice for individuals who are concerned about controlling their intake of cholesterol-elevating compounds.