Your Coffee Addiction May Not Be a Bad Thing

Top Line 

Go ahead and grab another cup of coffee. Coffee consumption has potent antioxidant effects potentially improving liver health, improving insulin sensitivity, increasing cognitive function, decreasing risk of cognitive disorders, and decreasing risk of all-cause mortality. 


Why it Matters 

Frequent coffee consumption commonly gets a bad rap when in actuality, it has potential preventative health applications against conditions that affect millions of people worldwide. 


Key Takeaways 

  1. Coffee has protective effects on the liver by reducing inflammation and oxidative damage. Coffee may reduce the risk of liver cancer, liver disease, and metabolic disease. Chlorogenic acid found in coffee can improve insulin sensitivity. 
  2. Coffee consumption may improve cognitive function by increasing memory during passive tasks. Coffee consumption may reduce the risk of Alzheimer’s, Parkinson’s, and suicide. 
  3. Coffee consumption has been linked to decreased risk of all-cause mortality. 


If you’re part of the vast amount of people that drink coffee on a daily basis, you may be wondering what impact your addiction has on your health. Worldwide, caffeine is the most consumed psychoactive drug with effects on mood, arousal, and motor function (1). 


Caffeine is classified as an ergogenic aid, meaning it increases exercise performance (link to previous article). Coffee has vast health benefits acting on various tissues in the human body. While the exact mechanisms by which coffee elicits these positive health effects are unknown, there is compelling evidence to indicate these benefits exist. So next time it's early afternoon and you’re thinking about having another cup of coffee, go for it - and keep these in mind. 


Coffee and Liver Health 


The liver has a wide range of functions in the body. These include: producing bile, producing proteins for blood plasma, producing cholesterol and fat carrying proteins, breaking down nutrients from food, regulating blood clotting, clearing the blood of drugs and other poisonous substances, as well as countless more (2).  


Needless to say, optimizing your liver function and keeping it healthy is paramount to health. 

Damage to the liver over time can lead to inflammation and a host of health problems. Coffee consumption is beneficial for liver health by reducing inflammation. Subjects who drank more than two cups a day had half the risk of chronic liver problems compared to those that consumed less than one cup (3). 


Inflammation of the liver over time may lead to liver cancer. In a 2013 review, people who drank the most coffee had half the risk of liver cancer compared to those that drank the least (4). 


Among smokers, consumption of four or more cups of coffee a day was associated with a 92% reduced risk of developing liver disease (5). 


In a study involving chronic hepatitis C patients, four cups of coffee daily for a month resulted in a reduction of oxidative damage of the liver, correlated with increased telomere length (more on this later), which is perhaps one mechanism by which coffee exerts its health benefits. (6) 


Although researchers are not conclusive on the exact mechanisms by which coffee works, a 2013 meta analysis concluded that rates of liver cancer and metabolic syndrome may be improved by daily moderate consumption of filtered coffee intake (7). 


So if you want to keep your liver healthy, it might be best to swap out some alcoholic drinks and add in a morning cup of coffee, if you don’t already. 


Coffee and Brain Function

You may be the person or know someone that is groggy in the morning and can’t function until they have their morning coffee. This is due to the fact that coffee and caffeine affects cognition and mental state. 


Coffee’s effect on mood is largely dependent on the dose, arousal state of the user previous to consuming it, and if the user is habitual or not. 


Data from one study suggests that one cup of coffee (75mg of caffeine) every 4 hours can result in a pattern of sustained mood improvement throughout the day (8). 


Along with improving mood, coffee may potentially boost your cognitive function. If you're taking in information in your morning meeting passively, then caffeine seems to help memory retention (ex. Passive meaning recalling information presented). If the task is self learning related and requires intention, then it does not seem to have as much of an effect. Those beginning the tasks with suboptimal alertness (tiredness) seemed to have the most benefit. 


Aside from having an effect on cognitive function, coffee appears to have a positive effect on reducing the risk of cognitive diseases such as Alzheimer’s and Parkinson’s. 


As a result of the roasting process of coffee beans, a group of compounds called phenylindanes are produced. These compounds inhibit two protein fragments, beta amyloid and tau, that clump together in Alzheimer’s and Parkinson’s. Dark roast coffee has a higher quantity of phenylindanes than light roast (9).


In fact, a meta-analysis of risk factors for Parkinson's disease concluded that coffee drinks have a ⅓ lower risk of developing the disease than non drinkers (10). 


Another review indicated a 65% reduced risk of developing Alzheimer's from mid-life to late life with consumption of 3-5 cups of coffee per day (11). 


Even more, coffee consumption over the lifespan is associated with a reduced risk of suicide (12) . 


Although it's probably the buzz you’re after, improved mood, cognition, and decreased risk of developing cognitive disorders aren’t bad side effects to have. 


Coffee and Blood Glucose Control 


Diabetes is a disease that affects the body’s ability to regulate blood sugar levels affecting 10.5% of the US population (13). 


Approximately 88 million American adults, more than 1 in 3, have prediabetes and of those, 80% don’t know it (14). 


Physical activity has been inversely associated with diabetes risk, as exercise can increase insulin sensitivity (15). 


Along with physical activity, diet has a tremendous role in improving insulin sensitivity. 


Coffee has been shown to improve blood glucose control in both diabetics and normal individuals due to it containing an antioxidant called chlorogenic acid.


Chlorogenic acid works by potentiating insulin action in a similar way to the drug Metformin. Chlorogenic acid has hypoglycemic and anti-diabetic effects, stimulates insulin secretion, and improves glucose tolerance and insulin resistance. (16). 


A 2018 meta analysis of 30 studies revealed that coffee consumption is inversely associated with risk of type 2 diabetes (17). 


The data demonstrates that in addition to exercise and healthy lifestyle choices, coffee consumption can aid against the development of diabetes and pre-diabetes, as well as help those that have type 2 diabetes. 


Coffee, Longevity, and All Cause Mortality 


Coffee consumption is correlated with reduced risk of mortality. 


Granted while this is an observational study and can’t prove causation, over a ten year period, subjects who drank 4-6 cups of coffee per day had a 64% lower risk all cause mortality than those who did not drink coffee. 


There is also a relationship between coffee consumption and age. For subjects who were at least 45 years of age, drinking two extra cups of coffee per day was associated with a 30% lower risk of mortality (18). 


An umbrella review of multiple meta-analyses analyzing coffee consumption and health found that consumption of 3-4 cups a day versus none resulted in a reduced risk of all cause mortality, cardiovascular mortality, and cardiovascular disease (19). 


The exact mechanism by which coffee exerts its effect on mortality and longevity is unknown, although there is some speculation. 


Nucleic acids, the building blocks for our genes, break down into metabolites, which circulate in the blood and trigger an inflammatory process associated with human aging and chronic disease. 


Researchers found that incubating cells with caffeine along with these nucleic acid metabolites prevented the harmful effects of the metabolites on the cells. 


Groups of individuals with higher activation of inflammatory gene clusters had higher rates of high blood pressure, stiffer arteries, and more circulating free radicals, compared to the low activation group. 


Groups with lower activation of gene clusters had higher concentrations of caffeine and its metabolites in their blood. This is one potential mechanism that explains the link between coffee and longevity (20). 

Another possible mechanism by which coffee has an impact on longevity is through its impact on telomere length. Telomeres protect DNA during cellular division. Telomere length is a biomarker of aging, with shortening accelerated by oxidative stress. Higher coffee and caffeine consumption is associated with longer telomere lengths in female nurses, according to a study of 4780 women from 1976-2010 (21). 


An intervention study revealed that 500ml of dark roast coffee per day for four weeks compared to water intake alone had a protective effect on human DNA integrity in both men and women (22). 


While these findings aren’t pointing to coffee as a magic life enhancing elixir, they are notable and present an interesting area of future research. 


Potential Side Effects and Considerations 


While coffee seems to have clear health benefits, scientists aren’t convinced enough to prescribe it as medicine, and there are some risks to be aware of. 


Excessive short term consumption of coffee can lead to unwanted side effects such as irritability, insomnia, and anxiety, although these vary person to person. 


Some individuals report having symptoms of GERD with coffee consumption. If this is the case, tea is an alternative, and actually is higher in antioxidant content than coffee. 


A person's sensitivity to caffeine is largely controlled by genes affecting the CYP1A2 enzyme and thus varies person to person (23). 


Coffee contains a compound called cafestol, which has been shown to increase cholesterol levels (24). This compound gets caught in paper filters, so if high cholesterol is a concern, then it might be advisable to drink filtered coffee over other methods such as french press. 


Another factor to consider is the increased calorie content from additives like milk, cream, and sugar to coffee. A study analyzing 12 years of data of coffee drinkers found additives increased daily calorie consumption by 69 calories per day compared to those that drink black coffee. While this may not seem like a large amount, over time it may have a compounding effect on weight gain (25). 


Bottom Line: 


Your coffee addiction may not be a bad thing after all. Coffee consumption is associated with a reduced risk of all cause mortality, and has beneficial effects on liver function, metabolic health, and brain function. 


Andrew Malkiel, MSc 






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