Unfiltered Coffee Can Raise Cholesterol | The Most Dangerous Brewing Method Explained

 One cup wakes you up. Two cups keep you going. The bitter, aromatic taste is hard to resist. Among all the things that stimulate the brain and create mild dependence, coffee is arguably one of the healthiest. A morning cup, an afternoon cup, one more before work begins—this is everyday life for countless coffee lovers.

But what many people don’t realize is that choosing the wrong coffee—or brewing it the wrong way—can quietly work against your health. Certain types of coffee can actually raise total cholesterol and LDL cholesterol levels. The hidden culprit?
Unfiltered coffee.

Let’s start with a quick explanation of LDL cholesterol, often referred to as “bad cholesterol.” Unlike HDL (“good cholesterol”), which helps clear cholesterol from blood vessels, LDL transports cholesterol from the liver throughout the body. When LDL levels are too high, it can penetrate blood vessel walls, become oxidized, trigger inflammation, and gradually form plaques. These plaques narrow arteries and increase the risk of cardiovascular disease—earning LDL its reputation as a silent killer.

This helps explain a puzzling situation many people face: they eat low-fat, low-salt diets, exercise regularly, even limit eggs—yet their LDL cholesterol still comes back elevated on blood tests. Stranger still, some people see their levels return to normal months later. The reason?
They stopped drinking coffee.

The idea that “drinking coffee the wrong way can raise blood lipids” isn’t just internet rumor—it’s backed by solid scientific evidence. Studies show that brewing method makes a dramatic difference, and the key factor affecting cholesterol is whether the coffee is filtered.

Unfiltered coffee refers to coffee brewed without paper filters. This includes espresso from home or office machines, French press coffee, moka pot coffee, Turkish coffee, boiled coffee, and similar methods.

A meta-analysis of 14 randomized controlled trials found that compared with paper-filtered coffee, long-term consumption of about 900 ml of unfiltered coffee per day increased LDL cholesterol by an average of 17.8 mg/dL, translating into an estimated 11% increase in cardiovascular disease risk. These findings have been repeatedly confirmed by umbrella reviews in The BMJ and studies supported by the NIH. For people who already have high cholesterol, the effect is even more pronounced.

So where does the problem actually come from?
Not the milk in milk-based drinks—but coffee oils, which many people assume are beneficial.

Coffee bean oils contain two compounds that act behind the scenes: cafestol and kahweol. These diterpenes make up about 1% of coffee bean content. They are easily extracted by hot water, but they do not pass through paper filters. As a result, boiled or unfiltered coffee contains especially high concentrations.

These two compounds interfere with the body’s cholesterol regulation system by blocking the excretion pathways of bile acids and neutral sterols. When cholesterol that should be eliminated stays trapped in the body, LDL levels gradually rise.

The amount of these diterpenes varies dramatically by brewing method:

Unfiltered methods (moka pot, French press)

Office coffee machines / chain café coffee
Paper-filtered coffee (pour-over, drip coffee, filter bags)

Most office espresso machines use metal filters, which trap only part of the oils. In other words, they “filter—but not very well.” A Swedish study revealed that coffee from office machines contained 15–18 times more diterpenes than home-brewed paper-filtered coffee. Some espresso samples had cafestol levels as high as 2,447 mg/L. In contrast, boiled coffee filtered through paper saw these compounds drop from 939 mg/L to just 28 mg/L—a 97% reduction.

No need to panic—coffee lovers don’t have to give up their daily lifeline. Just remember two principles: moderation and the right brewing method.

Most of the documented risk comes from long-term consumption of 900 ml or more of unfiltered coffee per day. One regular cup a day is generally not a problem.

More importantly, choose safer brewing methods. Cold brew and paper-filtered coffee are the simplest and most affordable ways to reduce risk. They remove nearly all cafestol and kahweol, preventing LDL cholesterol from rising.

To wrap up, here are some practical tips:

• At home, choose pour-over or drip machines with paper filters

• At chain cafés, opt for cold brew—or ask if the coffee is paper-filtered

• In the office, consider pooling resources for pour-over gear, or stock filter coffee bags and paper filters

• If you really enjoy espresso or French press coffee, keep portions in check—no more than 900 ml per day (roughly two large cups)

Drink smart, and let coffee work with your health—not against it.