Coffee, the world’s most consumed beverage, is a complex combination of many bioactive molecules, including polyphenols, caffeine, lipids, nicotinic acid, chlorogenic acid, carbohydrates, calcium, potassium, and magnesium. Is coffee good for you? there are several health benefits of coffee, the components of coffee have anti-inflammatory and antioxidant effects on human health. Consumption of these bioactive compounds has beneficial effects and helps in the prevention of many diseases. Chlorogenic acids in coffee are known to possess anticarcinogenic properties [1, 2].

It is reported that annually, more than 500 billion cups of coffee are sold worldwide [3, 4].

The good impact of coffee on human health has been recognized long ago and in the 16^th century, it was noticed that coffee accelerates the digestion process and increases heart rate. Researches carried out on coffee has reported positive effects of coffee on the human body.

1. Consumption of Coffee decreases risk of type 2 diabetes.

Many studies have suggested evidence that consumption of coffee is linked with a reduced risk of diabetes type 2. In 2002, the first cohort study investigated the effect of ingesting approximately 7 cups every day with no consumption of coffee. The results showed that participants who used to drink 7 cups daily had a 50% lower risk of diabetes type 2 than those who did not drink coffee at all [5].

Studies have reported an inverse relationship between consumption of coffee and the risk of having type 2 diabetes, one of the most serious global health concerns in the current century. According to literature-based evidence, consumption lowers the risk of type II diabetes by 23-67% [6].

A potential association has been found between drinking coffee and reduced prevalence of impaired glucose tolerance, insulin sensitivity, and hyperglycemia [7, 8].

An important finding stated by many studies conducted shows promising effects of both decaffeinated and caffeinated. In a randomized controlled trial, the effect of caffeinated and decaffeinated coffee was observed over the course of 16 weeks of consumption of both. The study found both to be protective against deterioration of glucose tolerance in the human body [9].

2. Protective effect of Coffee consumption on Alzheimer’s disease.

Caffeine is a psychoactive and neuro stimulating substance and is known for maintaining the brain’s cognitive functions in aged individuals.

Several studies have investigated the association of coffee intake with decreased risk of dementia/ Alzheimer’s disease in humans.

A population-based study of participants of the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) investigated the effects of drinking 3-5 cups at midlife on the risk of Alzheimer’s disease later and in life. The follow-up of the participants showed a decreased risk of getting dementia/AD by 65% [10].

A study conducted in Japan reported that individuals who consumed 3 cups every day had a lower prevalence of silent brain restriction in middle age, which consequently reduced the risk of dementia in older age [11].

Caffeine present in coffee is reported to be a protective factor against dementia and Alzheimer’s disease through molecular Aβ-related mechanisms by many studies performed on mice [12].

3. Lowers risk of stroke in women.

In a 24 years, follow-up study of 83,076 women in the U.S, long-term consumption of coffee was assessed and it was concluded that intake has no link with increased risk of stroke in women, in fact, it modestly decreases the risk of stroke [13].

A population-based cohort study in Sweden concluded that women who consume more than one cup every day have a decreased risk of stroke compared to those who consumed less than one cup daily. The study suggested that women with low or no consumption of coffee are at an increase of stroke [14].

In a meta-analysis of prospective studies, it was stated that per day intake of 1-6 cups was inversely associated with risk of stroke and an average consumption of 3-4 cups daily reduced the risk of stroke by 17% [15].

4. Habitual coffee consumption may lower the risk of heart failure.

Consumption of 3 cups daily is found to be associated with a 19% and 16% decreased risk of mortality from cardiovascular disease and coronary heart disease respectively, compared with the non-drinkers [16].

According to a study, moderate coffee drinkers might be at a lower risk of coronary heart diseases (CHD) because of the beneficial compounds found in coffee that have a protective effect against CHD [17].

5. Intake of coffee may reduce certain types of cancers

Cancer is the most difficult disease to overcome and a major global health burden with a very higher rate of morbidity and mortality.

It is reported by many studies that coffee consumption is associated with a decreased risk of many types of cancers including oral, liver, pharynx, colon, and prostate cancers. It is considered a healthy beverage for the prevention of colorectal cancer and it decreases its risk by up to 26%. The biologically active compounds in coffee including caffeine, chlorogenic acid, and cafestol may have anti-tumor effects and are considered to be anticarcinogenic [18].

In six cohort studies, an inverse association was observed between the occurrence of the digestive system (oral, pharynx) cancer and coffee consumption [19, 20, 21, 22, 23, 24]. All of the studies performed were large prospective investigations on different populations. In one of the large cohort studies of 968,432 men and women from the US, it was found out that consumption of caffeinated coffee lowered the risk of oral/pharyngeal cancer mortality.

In a meta-analysis of 1,534,039 participants from 13 published articles, it was concluded that intake of coffee or caffeine might reduce the incidence of endometrial cancer (EC), which is a type of gynecologic cancer. The reduced risk of endometrial cancer varied and decreased by 5% for consumption of 1 cup each day while for one cup of caffeinated coffee, the risk reduced up to 7%, and for decaffeinated one, it lowered the risk up to 4% [25].

6. Higher coffee consumption may reduce the risk of Parkinson’s disease.

Caffeine’s neuroprotective effect has been observed in many studies. A large prospective study with 30 years of follow-up of more than 8000 Japanese-American men aged from 45 to 68 years revealed that higher consumption of coffee is associated with a notable decrease in the prevalence of Parkinson’s disease [26].

The inverse relationship between intake of coffee and risk of developing PD is supported by many research studies and it was observed that the major role in this relationship is played by caffeine present in the coffee. In a large population Health Professionals' Follow-Up Study (HPFS) and Nurses' Health Study (NHS), the reduced risk of PD was found only in the consumption of caffeinated coffee and not in intake of decaffeinated coffee [27].

7. Moderate coffee consumption may be associated with lower risk of mortality.

Yes, you read it right. Drinking coffee has a non-linear relationship with the risk of mortality.

Many studies have been performed to find out the relation between intake of coffee and mortality risk in humans. In a large prospective cohort Nurses’ Health Study (NHS) and Health Professionals Follow-up Study, it was found out that consumption of 1-5 cups was associated with a lower risk of mortality compared to non-coffee drinkers. A higher intake of coffee was not associated with the risk of mortality in humans [28].

In a population-based prospective study, a dose-dependent response of coffee was studied in relation to mortality from chronic liver diseases. According to the study, one cup consumption of coffee on a daily basis reduced the risk of death by 15% while consumption of 4 cups daily decreases the death risk by 71% [29].

8. Can elevate your mood.

There is vast literature available assessing the effects of caffeine on behavioral changes of human beings. Several studies have indicated the significant positive effects of coffee on the mood and performance of the human body. It has been reported in the literature that 200 to 250 mg of caffeine can boost up mood which can last up to 3 hours [30].

Caffeine, the active ingredient of coffee can influence the alertness and sleepiness of the human body too. It is found to be postponing the onset of sleep even with a low dose of 100 mg while a dose of 300 mg can potentially enhance daytime alertness [31].

9. Coffee consumption improves physical activity

In cross-sectional research on Australian women, daily consumption of 1-2 cups was associated with higher physical activity and the participants felt less likely to be tired and more energetic with a daily intake of coffee.

Caffeine present in the coffee promotes physical activity in middle-aged women by minimizing fatigue and feeling of tiredness [32].

Caffeine has been used by many athletes to increase their performance in sports. Scientists have extensively studied the effect of caffeine on athlete’s performance and it is reported that a moderate dose of 3-6 mg/kg potentially enhances performance in trained athletes. The International Olympic Committee ruled12 μg of caffeine per ml of urine was a permissible limit for athletes [33].

 It is obvious how fatigue and mood can impair a person’s ability to participate in any physical activity, intake of caffeine increases the feeling of vitality and reduces the feeling of fatigue in an individual, thus improving performance.

10. May induce weight loss.

Caffeine, the active ingredient of coffee has been used for obesity management. It is known that caffeine through several mechanisms can induce weight loss and burn body fat. A meta-analysis of several randomized controlled trials demonstrated that consumption of caffeine may reduce BMI, weight, and body fat [34].

 In a cross-sectional study of 2129 men and women, consumption of coffee was significantly associated with losing weight and weight loss maintainers stated a potentially higher intake of coffee compared to the general population [35].

Obesity is currently a global health problem and is associated with many other health problems, especially in developed countries. It affects the quality of life and increases the risk of mortality. The primary treatment available for obesity is weight loss. A study evaluated the outcome of caffeine intake treatment with calorie shifting diet in 60 overweight and obese females and concluded that caffeine treatment combined with calorie shifting diet might be an implicit approach to weight loss [36].

11. Coffee may benefit liver health.

The liver is a vital human organ performing a lot of functions and damage to the liver could be fatal for an individual. Coffee has been considered to exhibit hepatoprotective properties and several experimental studies have been performed to investigate the effect of coffee on liver health. It has been found in many pieces of research that consumption of coffee is inversely associated with liver cirrhosis and a reduced risk of hepatocellular carcinoma (HCC). In a meta-analysis of 16 cohort studies, it was found that people who drink coffee have a significantly reduced prevalence of cirrhosis than those who did not consume coffee. It has been found to be associated with improved outcomes with hepatitis C virus (HCV) and non-alcoholic fatty liver disease (NAFLD) [37, 38, 39].

Coffee impacts positive effects on liver enzymes, consequently improving liver steatosis and fibrosis causing a decrease in the risk of chronic liver diseases such as cirrhosis and HCC [40].

Some studies have reported that regular consumption of coffee is linked with a reduced rate of liver disease progression in patients with Hepatitis C Virus (HCV) [41].

12. Coffee is a major source of Antioxidants.

Itis a mixture of many biologically active compounds, some of those compounds exhibit significant therapeutic antioxidants, anticancer and anti-inflammatory effects. It is reported in several studies that the beneficial effects of coffee are due to its high antioxidant activity [42].

The compounds that induce antioxidant activity in coffee are the chlorogenic, caffeic, ferulic, and n-coumaric acids present in it [43].  

It has been found that strong antioxidants are present in roasted coffee and many studies have been carried out to investigate the association between roasting and high antioxidant activity of coffee [44].

13. Reduces the risk of depression.

The relationship between intake of coffee and its impact on depression is not well-studied. However, some researches have been carried out to find the association between coffee consumption and its effect on human mental health.

The first research investigating the effect of consumption of coffee on depression was a prospective study of 2232 middle-aged men and it was concluded that coffee consumption may reduce the risk of depression [45].

Another large prospective cohort study of 50,739 women from the United States found out that with increased consumption of caffeinated coffee, the risk of depression decreases [46].

14. Coffee is a nervous system stimulant.

Caffeine present in coffee is considered to be a central nervous system stimulant and the most abundantly used psychoactive substance worldwide. It is used by many people to improve work performance and also for social activities.  

Coffee has been reported to enhance human cognitive performance including learning, memory, thinking, and problem-solving abilities. In a study conducted in 2001, it was reported that intake of a 150 mg dose of caffeine improves cognitive performance for approximately 10 hours [47].

A randomized controlled study of 160 caffeine-naïve participants concluded that caffeine improved consolidation of long-term memories in humans [48].

15. Coffee consumption might reduce gout in men.

In a 12 year prospective study, it was found out that long-term or habitual consumption of coffee was associated with a lower risk of gout [49].

The inverse relation of coffee intake with incidence of gout is supported by many mechanisms: the compounds present in coffee influence insulin resistance which has a strong positive relationship with hyperuricemia, thus decreased insulin resistance due to consumption of coffee influences into a decreased risk of hyperuricemia and gout [50].

Is Coffee Consumption is good or bad?

This is one of the most controversial topics of the current era and needs more research before jumping into a final word about the good or bad influence of coffee on human health.

Coffee is one of the most popular beverages worldwide and has many health benefits proven scientifically. It is composed of many bioactive compounds which are good for human health.

The benefits of these bioactive compounds have been proven in many studies and coffee is an essential part of the diet in many countries. Coffee is considered to be a driving force for humans as it has an alerting effect on the human brain and its various functionalities. Its consumption is increasing in middle-aged people as it grows in popularity.

Caffeine present in coffee has a wide safety profile and is considered to be not posing any hazard to human health by the American Food and Drug Administration. However, apart from this, various studies have reported harmful effects of coffee too when taken in high doses.

It is concluded in many studies that coffee might reduce the risk of depression and induce alertness and wakefulness, on the other hand, several studies have reported that high doses of coffee might induce anxiety and tenseness [51].

Coffee is a major component of the daily diet in many countries, it has various essential nutrients including vitamin B2, Vitamin B3, Vitamin B5, and Vitamin E and every cup of coffee you take adds up to these nutrients in the body. The micronutrients present in coffee include sodium, potassium, magnesium, and manganese. Several meta-analyses of prospective cohort studies have been performed to find out the relationship between consumption of coffee and all-cause mortality caused by coronary heart disease, cancer, metabolic disease, and neurological disease.

According to a recent meta-analysis, a 10% lower risk of mortality is associated with ingestion of the highest dose of seven cups of coffee per day, however, the largest reduction in relative risk was linked with an intake of three cups of coffee per day [52].

Conclusion:

Coffee has amazing benefits for human health, it is not only a beverage but also a mixture of essential nutrients.

The scientific community has been performing several prospective experimental analyses to prove the health benefits of coffee in several life-threatening diseases including cardiovascular diseases (, neurological disorders, certain types of cancers, liver disorders, and some gastrointestinal conditions.

Consumption of coffee in moderate amounts is considered to be safe and more likely to benefit human health. It improves the physical performance of an individual and boosts alertness.

It can keep you awake for longer periods and will not let sleepiness takes you over. It has positive effects on mood and improves cognitive functions of the brain. The central nervous system is one of the most common active sites of caffeine.

It has been reported that sportsmen use caffeine prior to their sports activity to enhance their physical performance. Compounds present in coffee protects vital organs of the human body due to their anti-inflammatory properties and can protect the human body from many chronic diseases such as diabetes.

Consumption of coffee lowers the risk of liver cancer by 40% and also reduces the risk of prostate cancer and colorectal cancer by 15%. It is because the antioxidants present in it influence carcinogenic metabolism in the body and also blocks mutations.

With so many beneficial effects on human health, many studies have reported its adverse effects too. High intake of coffee is reported to be associated with several health risks including elevated blood pressure, increased anxiety, loss of appetite, and can cause insomnia and restlessness in an individual.

It can also affect pregnant women and their fetuses in a negative way if ingested in higher doses (i.e. more than one cup a day).

Therefore, with all the scientific evidence and controversial statements about the beneficial and harmful effects of coffee on human health, it can be concluded here that consumption in moderate amount will pose a lot of good effects on an individual’s health and high intake should be avoided to stay out of any adverse effect caused by it. Our bodies can get a lot of benefits and will be protected from so many dangerous health problems if we habitually take it within moderate limits.

Besides this, many investigations have been carried out to study the effects of caffeinated and decaffeinated coffee on human health and the research is still ongoing to find out important factors that lead to positive and negative effects of coffee on the human body.