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Minggu, 17 Agustus 2014


by J.E. Block M.D., Phd, FACP

Coffee is consumed as a leisurely relaxing beverage with potential health benefits and a slight concern of harm. But what is the benefit and does it outweigh the risk?  I have been researching the answer for over fifty years. Now I think I have the solution! Coffee has over a thousand chemicals, many formed during the roasting process. The bioactive componds are “boiled down to” caffeine, the Diterpenes (Cafestol and Kahweol) found in the oils, the healthy polyphenols (notably chlorogenic acid), some minerals (a little magnesium and even less potassium) and minimal vitamins. A healthy aspect of coffee is the wonderful aroma, which lasts a few minutes after it is brewed. This is due to aromatic hydrocarbons in the coffee that are rapidly vaporized. In experiments with laboratory rats, it was discovered that coffee aroma orchestrated the expression of more than a dozen genes and changed their protein expression, in ways that reduced the stress of sleep deprivation. Seventy-five percent of coffee’s flavor is smell alone. The grounds remove 85% of heavy metals (lead, copper, mercury, cadmium, and zinc) from tap water! They may also capture other heavy metals. Moreover, there are three preparations of coffee that are commonly consumed and worthy of discussion; boiled, unfiltered coffee, filtered coffee.

Caffeine is the most commonly consumed psychoactive drug in the world, and some of its behavioral effects may resemble those produced by cocaine and amphetamine. Coffee accounts for about 75% of the adult intake of caffeine in the United States, although this will change among younger adults with the growing popularity of energy drinks.

The caffeine content of coffee varies greatly, depending mainly on the beans, and how they’re roasted. The average in an 8 oz. cup is about 100 mg. (Tea has about half as much caffeine as coffee). Decaffeinated coffee has some caffeine left, but only 2 to 4 mg in an 8 oz. cup. The lethal dose of caffeine is 10 grams, an equivalent to the amount in 100 cups of coffee.

Caffeine is primarily metabolized by the liver enzyme cytochrome P450 1A2 (CYP1A2). The form of the SNP rs762551 indicates a person speed of the CYP1A2 metabolism of caffeine. Tobacco and marijuana accelerate its metabolism. People with the slower version of the CYP1A2 enzyme, who drank at least three cups of coffee per day, are more likely to experience some negative effects. These include raising blood pressure, making arteries stiffer, jitteriness, insomnia, adrenal fatigue, heartburn, significantly increase risk of heart attack by increasing levels of homocysteine, insulin, and cholesterol. Habitual use may cause some of these influences to wear off. Fast metabolizers have a reduced risk of the above list of negative effects! Caffeine is absorbed in the stomach and small intestine and then distributed throughout the body, including the brain. In that it is fat soluble, it enters our cells almost immediately. The amount circulating in the blood peaks 30 to 45 minutes after it’s ingested and only small amounts are around eight to 10 hours later.

Caffeine has multiple targets in the body. It is a performance enhancer, boosting the strength of muscle contraction and offsetting some of the physiological and psychological effects of physical exertion. In the brain, caffeine achieves many of its effects by blocking the activity of adenosine, a neurotransmitter that affects almost every bodily system.  One of the primary actions of adenosine is to make us tired or sleepy. Caffeine, by blocking the uptake of adenosine, keeps us from feeling the effects of fatigue.  As a consequence of its blockade of adenosine receptors, caffeine also affects most of other major neurotransmitters, including dopamine, acetylcholine, serotonin, and, in high doses, norepinephrine.  By affecting these, it is able to deliver a major boost to our capacities even when we are well-rested, something that could not be explained by the inhibition of adenosine alone.   By increasing the transmission of dopamine, caffeine improves our mood, arousal, pleasure, thinking, and protects brain cells from age and diseases like Alzheimers and Parkinsons.  By increasing the activity of acetylcholine, caffeine increases long-term memory.  Raising and adjusting serotonin levels, caffeine relieves depression, makes us more relaxed, alert, and energetic, and relieves migraines.

The Polyphenols which are antioxidants in coffee has been shown to prevent free radicals from causing cell damage. A recent study showed that coffee, high in lipophilic antioxidants and chlorogenic acid lactones, protected primary neuron cell cultures against hydrogen peroxide-induced cell death.  Other studies have indicated that coffee constituents other than caffeine, to include phenolic compounds (chlorogenic acids, hydroxycinnamic acids), and chemicals formed from Maillard reactions, like melanoidins, have the antioxidant properties. Most of the antioxidants are lost in the roasting process. Recently, procedures to extract these before roasting and add them back afterwards have been developed. This has boosted the antioxidant level by 90%.

Coffee prevents and/or decreases gallstones, rheumatoid arthritis, migraine headaches, over-hydration, and symptoms of viral disease. It will also improve diabetic control and increases caloric burn during exercise (if consumed right before a workout). Studies show a lower risk for some cancers that include liver, colon, uterine, prostate and breast. Coffee drinking is associated with lower levels of enzymes that indicate liver damage and inflammation. Coffee decreases the incidence of both a fatty liver and cirrhosis and improves response to treatment of hepatitis C. Cafestol and Kahweol, substances found in unfiltered coffee, are responsible for the liver benefits.

The waxy substances in coffee are called diterpenes which are a plant derived organic compound. The two main types in coffee are Cafestol (pronounced CAF-es-tol) and Kahweol (pronounced KAH-we-awl). They are present either as oily droplets or in the grounds floating in the coffee. However, a paper filter traps most of the Cafestol and Kahweol, so coffee that’s been filtered has little, if any, medical effect on cholesterol levels or liver cancer issues. An interesting study published in 2011 showed that of all the filtering methods the so-called sock method, which uses a cotton-nylon cloth and/or a metal mesh were almost as effective as a paper filter at trapping Cafestol. The concentration of these two compounds depend on the type of coffee; arabica beans contain both Cafestol and Kahweol, whereas robusta beans contain half as much Cafestol and hardly any Kahweol. In arabica beans, they may be present in up to 1% of the total volume of the beans. Espresso contains more dipterpenes, but because it is consumed in smaller amounts, it may not have much of a health impact.

Cafestol raises serum cholesterol much more than Kahweol does, but Kahweol is more protective to the liver and more anti-cancer than Cafestol. Both compounds are extracted by hot water but are retained by paper and to a lesser degree by other filters. This explains why Scandinavian boiled coffee, Turkish coffee, and French press (cafetière) coffee contain relatively high levels of Cafestol and Kahweol (6-12 mg/cup), while filtered coffee, percolated coffee and instant coffee contain low levels (0.2-0.6 mg/cup).

Coffee filters were first invented in the early 1900s by a housewife in Dresden, Germany. Melissa Bentz wanted to brew coffee that wasn’t bitter tasting. She invented the filtered drink by pouring boiling water over a round piece of blotting paper folded to hold coffee grounds, letting the paper filter out the grounds as the liquid flowed into a metal cup she set below. This simple concept is still used today.

Filters remove coffee dregs from the finished product. The benefit of removing coffee grounds right after brewing coffee is that it prevents over brewing. Over brewing causes coffee to taste burnt and bitter. This masks the delicious coffee aroma and makes the coffee less enjoyable. Luckily, many varieties of coffee filters are available to assist in making premium coffee at home.

There are three different types of filters to choose from: paper, permanent and cloth. Paper filters are meant for one-time use and are disposed of after brewing. They are better in that they remove oily components (Diterpenes) much more than the cloth or wire mesh filter.

Although each paper filter costs pennies, a new one (or two) is used for each batch of coffee so that cost adds up. Since permanent filters can be used for years, using a daily paper version is nearly always the more expensive option. Packs of 40 generally cost $2-3 dollars. Permanent ones cost anywhere between $8-30 dollars and can be used for considerably longer after the initial investment.

Cafestol, a compound found in coffee, elevates cholesterol by hijacking its receptor in the intestinal pathway critical to its regulation. This is from research at Baylor College of Medicine and published in the journal, Molecular Endocrinology. Cafestol is the most potent dietary cholesterol-elevating agent known. Cafestol affects the signal in the cholesterol pathway.The discovery of a specific gene called fibroblast growth factor 15 or FGF 15 opened the door to understanding how Cafestol affects the farsenoid receptor X or FXR in the intestine. FXR was first identified as a bile acid receptor. It is part of the body’s own way of regulating levels of cholesterol. Both in vivo and in vitro research found that in the intestine, Cafestol activates FXR and induces FGF15, which reduces the effects of three liver genes that regulate cholesterol levels. 

To make a healthy cup of coffee is no secret. It should be brewed one cup at a time. I use a Keurig coffeemaker. I also purchased a Melitta paper filter kit and use two paper filters per cup. My earlier study showed that using two paper filters not only took out the harmful Cafestol, but allow me to use one third less coffee and brew as equally potent a beverage.

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