Discovering Coffee's Unique Health Benefits
By Michael Downey
Chronic liver disease and cirrhosis cause 35,000 deaths per year in the United States. Cirrhosis is the ninth leading cause of death in America, responsible for 1.2% of all US deaths.68 However, scientists have found that the risk of liver cirrhosis, and of dying from this disease, can be greatly reduced by coffee consumption.
Those drinking 4 cups of coffee daily exhibited a full 84% lower risk of cirrhosis, according to a study in the Annals of Epidemiology.69 This is consistent with an earlier 8-year study of over 120,000 people that found that each cup of coffee daily lowered the risk of dying from cirrhosis by 23%.70
Also, patients with hepatitis B or C have been shown to be less likely to develop nonalcoholic cirrhosis if they are also coffee drinkers.71
Alzheimer's disease becomes increasingly prevalent with aging, striking more than 40% of those over 84.72 Promising studies are finding that greater daily consumption of caffeinated coffee cuts the risk of both Alzheimer's18,73 and dementia74 later in life.
Scientists have discovered that long-term coffee intake exhibits a dose-dependent association with improved cognitive function and memory,75,76 and it protects primary neuronal cells.77
In fact, one mouse study has far-reaching implications for humans. Researchers found that moderate caffeine intake - equivalent to human consumption of 5 cups of coffee daily - began to reverse Alzheimer's damage in just 5 weeks.20
Although the mechanism by which coffee lowers the risk of cognitive decline is not known, a 2009 study on mice found that caffeine decreases levels, in both the blood and the brain, of amyloid-beta, a substance involved in the development of Alzheimer's.78 Later, a 2010 review of previous mouse studies found that caffeine - the equivalent of 5 cups of coffee daily in humans - decreases levels of beta- and gamma- secretase, proteins used in amyloid-beta production in the first place.20
Then, in 2011, scientists concluded that coffee may be the best source of the caffeine shown to protect against cognitive decline. The reason is that another unknown component in coffee appears to synergize with the caffeine to increase blood levels of a factor (granulocyte colony-stimulating factor, or GCSF) associated with improved cognitive function in Alzheimer's.79
Caffeinated coffee has also been associated with protection against Parkinson's disease, the second most common neurodegenerative disorder after Alzheimer's.80 A study of 29,000 individuals found that one to four cups daily decreased the risk of Parkinson's by 47% and 5 or more cups decreased the risk by 60%.81 Increasing granulocyte colony-stimulating factor using drugs like Neupogen® is demonstrating efficacy in animal models of established Parkinson's disease.82-85 Several other studies confirmed an inverse dose-dependent relationship - the greater the number of daily cups of caffeinated coffee, the lower the risk of Parkinson's disease.86-88
DNA damage is characterized as a physical abnormality within the genetic makeup of a cell, such as a break in a DNA strand. It usually occurs to greater extent within cells that frequently divide. DNA damage can lead to genetic mutations that cause cancer.89 And when DNA damage occurs within cells that divide less frequently, it can promote aging.89
It's difficult to avoid the many causes of DNA injury. Oxidizing agents produced by normal metabolic processes promote this type of damage. Also, DNA defects can be triggered by numerous external agents such as ultraviolet light, radiation, chemotherapy, industrial chemicals, and certain environmental chemicals such as polycyclic hydrocarbons, found in smoke.
Scientists have discovered a surprisingly simple way to help decrease DNA damage. Studies show that higher coffee consumption decreases levels of oxidative DNA damage,90,91 which in turn inhibits both cancer and aging.
A 2011 study confirmed coffee's DNA-related effect on cancer risk. The researchers found that regular coffee drinkers enjoyed a 13% decreased risk of cancers generally, and those who consumed high levels of coffee enjoyed an 18% decreased risk. Additionally, they enjoyed specific protection against prostate, breast, colorectal, pharyngeal, esophageal, hepatocellular, pancreatic, bladder, and endometrial cancers.92
How Do Coffee Compounds Work?
Despite coffee's powerful antioxidant punch, the mechanism for coffee's protection against a host of diseases may involve a lot more than a fierce battle between antioxidants and free radicals. Scientists are beginning to discover that coffee's phytochemistry also exerts direct biological actions on the body, which may underpin a web of indirect, protective effects against diseases from diabetes to cancer.93,94
Early studies suggest that the polyphenols in coffee (both caffeinated and decaffeinated) may modify key enzymes that improve intracellular signaling,95,96 the communication system that facilitates cellular actions such as tissue repair, immunity, and homeostasis. Poor cell signaling may be a factor in cancer, diabetes, and more. (A subsequent study suggested in 2008 that this cellular signaling effect could also explain coffee's inhibition of blood platelet aggregation and cardiovascular risk.97)
Then, in 2009, a study found that by modulating specific cell signaling pathways (known as ERK1/2 and JNK), the various polyphenols in coffee - especially chlorogenic acid - help prevent the degeneration of those human cells that are rich in lipids.98 Brain cells are lipid-rich and this may explain coffee's neuroprotective effect against cognitive decline and diseases of the brain.
Similarly, one study suggested that polyphenols - for which coffee is the prime dietary source - may affect cellular response and sensitivity by interacting with nuclear receptors.99 Receptors are molecules that pick up intracellular signals, determining whether a cell gets the right instructions to divide, die, or release molecules - thus regulating body functions to fight disease.
A 2006 review of animal and human studies found that coffee compounds raise levels of detoxifying enzymes that protect against DNA damage and - likely as a direct result - reduce the susceptibility of lymphocytes (white blood cells involved in immune response) to damage from reactive oxygen species (ROS).100 This may partly explain how coffee lowers the incidence of DNA damage and related diseases such as cancer.
One 2009 study on humans found that 3 cups of coffee daily for 3 weeks increased the number and metabolic activity of beneficial bacteria called bifidobacteria.101 These intestinal bacteria may explain one mechanism for coffee's benefits: bacteria can boost immunity, lower blood pressure, and increase mineral absorption.
In 2010, researchers discovered that the phenolics in 4-8 cups of coffee daily have the direct action of dampening inflammatory activity.66 Chronic low-level inflammation has been associated with diseases ranging from cancer to diabetes, as well as aging.
A 2011 randomized, controlled trial found that consumption of (caffeinated or decaffeinated) coffee produces specific improvements in the function of the liver and of adipocytes (fat-storing cells), both associated with a healthy metabolism. This provides further insight into the possible mechanisms behind coffee's benefits, because disrupted metabolic activity is a biological risk factor for a number of chronic diseases (including type 2 diabetes).102
In addition to the numerous other antioxidants in coffee, a 2011 study confirmed that caffeine itself is a potent scavenger of oxygenated free radicals.103 Caffeine was found in another 2011 study to work synergistically with other coffee antioxidants.104 However, caffeine may also work along direct cellular pathways unrelated to its antioxidant action.
Scientists determined in 2011 that caffeine protects the integrity of the blood-brain barrier - which suggests that caffeine may reduce the risk of some diseases by limiting the transport of blood-borne pathogens, drugs, cells, and other substances into the brain, where they might affect brain synapses. The team also found that caffeine defends against the specific blood-brain barrier dysfunction linked to Alzheimer's and Parkinson's disease.105
Although many people assume they should limit their coffee intake, a wealth of scientific research suggests that its wide-ranging health benefits increase with the amount consumed.
Numerous studies show that higher daily coffee consumption results in a lower risk of diabetes, cardiovascular disease, cancer, Alzheimer's, and a host of other chronic diseases, including obesity.
There are a number of phytochemicals, the most predominate being chlorogenic acid, that provide coffee's disease-protecting punch. Of interest is the additional ability of coffee polyphenols to exert direct biological actions on cells. For instance, daily coffee intake may modify key enzymes that improve intracellular signaling,95,96 which can protect against diabetes, cancer, and many other diseases.
The benefit is dose-related. Drinking just one cup of coffee a day - caffeinated or decaffeinated - can decrease the risk of developing diabetes by 13%.24 But 12 cups a day slashes the risk of developing diabetes by 67%.21
While traditional medicine fights an impossible battle against a tidal wave of diabetes, cancer, Alzheimer's, and other age-related diseases, extensive research suggests that coffee - far from being a guilty pleasure that should be limited - is an all-natural and inexpensive elixir. With the availability of new "polyphenol-retaining" coffees, moderate coffee drinkers can now obtain the myriad benefits that were once reserved only for so-called "heavy" coffee users.
There remain, however, a significant percentage of people who are sensitive to caffeine's stimulating effects on the central nervous system, or find they encounter heartburn and other digestive problems in response to ingesting even a cup of coffee. The new polyphenol-retaining coffee bean beverages are less likely to induce gastric upset.
For those who don't want to drink any coffee, there are now standardized chlorogenic acid supplements available that provide the high potencies of beneficial coffee compounds with only tiny amounts of caffeine.