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Is coffee good or bad? The answer is not that simple. Some individuals may benefit from coffee’s health properties and the others will mostly experience negative and detrimental health consequences.
You probably have heard some people saying that drinking four cups per day makes them feel good, and others complain that it takes only one coffee to make them jittery, aggressive, unable to sleep or to have other symptoms such as chest pains.
The opinions on the health effects of coffee are divided, and the information available online either promotes the health benefits of coffee or warns about its negative side effects.
The truth is that the effects of coffee should be determined on individual bases, after considering benefits and side-effects, level of sensitivity, and specific medical conditions that coffee may either worsen or improve.
This article describes evidence based health benefits as well as the negative effects of various daily amounts of coffee. Using the following information you can determine whether coffee is good or bad for you.
What is in coffee?
Coffee contains more than a thousand compounds, many of which exert important effects on the body, either on their own or in synergy with each other.
One cup of coffee contains a small quantity of minerals and vitamins, but since moderate users drink about 4-5 cups per day (400mg of caffeine), these amounts contribute significantly to the overall daily nutrient intake.
The image below shows the total amounts of micronutrients for four servings of two of the most popular coffees: espresso and brewed coffee in a plunger.
Please note that the amounts vary depending on factors such as the type of coffee or the method of preparation as shown in this example. The last two columns display the recommended daily allowance of these nutrients for comparison.
Data taken from USDA food database.
Importance of caffeine in coffee
Coffee contains caffeine (about 100mg per serving) which is a stimulant drug that affects the nervous system and has an impact on hormones.
It is the most potent ingredient in coffee and has the biggest influence on how our body reacts to coffee.
Before answering the question if coffee is good or bad for you, it is also essential to consider the following points:
- Caffeine allergy (extremely rare). However, if you show common allergic reactions, such as hives or anaphylaxis, you should avoid caffeinated drinks.
- Caffeine sensitivity is determined by each individual’s genetic make-up and dictates how well we can handle this drug. Being caffeine-sensitive or a slow caffeine metabolizer restricts how much coffee you can handle. Negative rather than positive health effects occur as a result of caffeine intake. On the other hand, fast caffeine metabolizers, those that can quickly break down and excrete caffeine, experience a wide range of health benefits.
- Caffeine tolerance. If you are not highly sensitive to caffeine, it is possible to build up tolerance to caffeine. This means that after a few days of consuming the same daily dosage, symptoms, such as increased energy, euphoric feeling, increased focus and disturbance in sleep, tend diminish and even disappear. In some extreme cases, you can build your tolerance to the point of overconsumption and high dependency (caffeinism), which has detrimental results on your health.
- Caffeine overdose may occur regardless of sensitivity level. It depends on the combination of the dose and your level of sensitivity. To avoid overdosing, learn what is a safe dosage for you.
Is coffee addictive?
Coffee is often described as an addictive beverage, since it contains caffeine and it seems to be hard to quit. Caffeine, although a drug, is not addictive.
When is coffee bad for you?
7 potentially harmful effects of coffee.
Harmful effects of coffee specific to caffeine (see full article..):
Drinking caffeinated coffee is not recommended if you are a slow caffeine metabolizer, or have allergy to caffeine.
Caffeine may have adverse effects on some people. It may cause:
- loose stools (large doses),
- worsening of reflux symptoms in people that suffer from GERD (although not as much as other constituents in coffee),
- indigestion in obese individuals,
- increase in blood pressure in hypertensive or highly caffeine sensitive people,
- increase the risk of heart attack in slow metabolizers,
- anxiety and nervousness,
- disruption in energy levels throughout the day and affect your sleep,
- increase the risk of infertility (large doses),
- miscarriages, especially in women who are slow caffeine metabolizers (large doses),
- increase the risk of fibrocystic breast disease in women in the breast cancer risk group,
- hot flashes and night sweats in postmenopausal women.
Potential harmful effects of drinking coffee
- Coffee and cancer
Earlier this year California introduced mandatory warnings on labels that warn customers about acrylamide present in coffee, which the State lists as a carcinogen.
The fact is that coffee contains an insignificant amount of this toxin, especially in comparison to other common foods such as potato chips, breakfast cereals, cookies or French Fries. Acrylamide has been linked to cancer in rodents but not in humans.
- Coffee contributes to acid reflux in people who suffer from (or are prone to) GERD
Gastroesophageal reflux (GERD)* is often caused by the transient relaxation of the lower esophageal sphincter (LES). LES is a muscle between the stomach and the esophagus that ideally only opens when you swallow food.
If this muscle is relaxed, stomach acid may be pushed up to the esophagus burning its delicate lining. In people who suffer from GERD, this sphincter relaxation occurs more frequently and is easily triggered by some foods, especially coffee. (8)
Decaffeinated coffee, however, has significantly less impact in individuals with reflux disease. (9)
It doesn’t mean, however, that caffeine is the causing factor. Decaffeinating coffee removes several other constituents of coffee that have been shown to worsen reflux more significantly than caffeine. (read more..)
*Different spelling of (e/oe)sophagus
GERD – gastro – esophageal reflux (U.S, Canada)
GORD – gastro – oesophageal reflux (U.K, Australia)
- Coffee is bad for your heart if you are a slow caffeine metabolizer
Slow metabolizers have an increased risk of a non-fatal heart attack when they drink 2-3 cups of coffee per day (200-300mg caffeine). Those who drink 4 cups of coffee have 4 times more risk of heart attack comparing with those that drink 1 cup per day.
- Coffee may increase the risk of ovarian cancer
Postmenopausal women who drink five or more caffeinated coffees per day have a higher risk of developing ovarian cancer. It is thought that the increase in risk is due to interaction of some components of coffee with caffeine. (10)
- Breast cancer and fibrocystic breast disease
No correlation was found between breast cancer and coffee in one study (11).
Please note that some studies show the association of caffeine intake with a higher risk of fibrocystic breast disease in women who are at the higher risk of developing breast cancer. (12)
- Coffee can contain diterpenes: cafestol and kahweol which increase blood lipids
Cafestol and kahweol (called diterpenes) are potent cholesterol-raising agents contained in coffee.Filtered and instant coffees contain the least amount of these compounds, since the filtering process traps the diterpenes.
The highest levels of diterpenes per cup are found in Turkish coffee, French press, espresso and boiled coffee consumed in Scandinavia.
Please note that there is evidence that cafestol and kahweol have anti-cancer properties and are good for the livers’ health. (16)
- Health effects of additives taken with coffee
When coffee is consumed with any other additives besides water, it may have an additional impact on health, especially with the average daily amounts of coffee (4-5 cups).
Adding sugar to coffee increases greatly the calorie intake and adds high amount of fructose, augmenting the risk of metabolic syndrome.
Drinking coffee with milk may cause lactose intolerance symptoms in some individuals and add to the calorie intake.
Non-dairy creamers contain all sorts of unhealthy ingredients, such as hydrogenated soybean oil, high-fructose corn syrup and monosodium glutamate.
When is coffee good for you?
12 health benefits of coffee
Most health benefits are achieved by the majority of the population with an intake of 3-5 coffees per day.
Many health benefits of coffee can be attributed to caffeine. The positive effects are associated mostly with fast caffeine metabolizers. If you are sensitive to caffeine, however, these benefits may not apply.
Health benefits of coffee related to caffeine (see full article..):
- improves learning capacity, alertness and mood;
- helps to burn fat during exercise;
- decreases the risk of gout;
- improves heart health, if you are a fast caffeine metabolizer;
- reduces the risk of depression and suicide;
- reduces the risk of developing dementia, Alzheimer’s and Parkinson’s disease;
- reduces the risk of type 2 Diabetes Mellitus;
- has protective properties in liver diseases;
- increases physical performance in athletes.
Health benefits of coffee
- Coffee reduces gout incidence and flare-ups in some people
The consumption of coffee is associated with a lower incidence of gout and may reduce gout flare-ups in some people.
This positive effect is due to coffee’s (not necessarily caffeine’s) ability to decrease uric acid in the blood. (Note: the consumption of tea is not associated with decreased uric acid). (17, 18, 19) A large observational study showed that intakes of 4-5 coffees per day, have a 40% lower risk of gout and of at least 6 cups per day a 59% lower risk, when compared with zero intake. (20)
However, there are some claims stating that consuming large amounts of coffee can cause an increased risk of recurrent gout attacks and flare-ups, but they are not confirmed by studies.
- Coffee consumption doesn’t increase the risk of cancer, and possibly lowers the risk of some cancers
Coffee consumption is not linked to the risk of cancer mortality. (21)
Studies on coffee and colorectal cancer are somewhat conflicting although more studies show positive effects.
One large systematic study review has found no association between caffeinated coffee and colorectal cancer in men and women. This means that it neither increases nor decreases the risk of cancer in the colon or rectum. (22) Another more recent large study, however, found that individuals who drink caffeinated coffee have a lower risk of developing colon cancer, specifically proximal tumors, while decaffeinated coffee drinkers show lower risk in both colon and rectal cancers. (Tea has shown no association with colorectal cancer risk). (23)
Individuals who had two cups of decaffeinated coffee daily showed a 52% lower incidence of rectal cancer compared to those who never consumed decaffeinated coffee.
Coffee consumption is significantly related to a decreased risk of liver cancer, although it is not known which compound or synergy of compounds have these protective properties.
Skin cancer – Melanoma
Two recent large studies have shown a reduction of risk of cutaneous melanoma. It was found that four or more cups of caffeinated coffee per day decreased the risk of melanoma by up to 25%, but decaffeinated coffee hasn’t shown a significant reduction of this risk.
No association between coffee and gastric cancer was found in a large systematic review and meta-analysis. (28)
Acrylamide has no association with cancer in humans.Acrylamide has no association with cancer in humans.Acrylamide has no association with cancer in humans.
- Coffee and multiple sclerosis (MS)
Studies on the association between coffee and MS are inconclusive. However, the most recent study (2016) showed that a high intake of caffeinated coffee is related to around 30% lower risk of multiple sclerosis. It is thought to be due to caffeine’s neuroprotective properties, and its ability to suppress pro-inflammatory cytokine production. More studies are needed, however, to confirm the findings of the caffeine involvement. (29)
- Coffee hydrates rather than dehydrates
Drinking coffee was previously thought to have diuretic effects due to its caffeine content. However, many studies have disproved this belief and showed that coffee has rather hydrating effects due to its liquid content. (read more..)
- Coffee and heart disease
For fast caffeine metabolizers (medium to high caffeine users), long term intake of between 3-5 cups daily of coffee shows the biggest reduction of risk of cardiovascular disease (CVD). Consumption of large amounts of coffee was not associated with increased risk of CVD. (30, 31) Fast metabolizers also show a 22% lower risk of heart attack by having 2-3 cups of coffee per day (200-300mg caffeine).
- Coffee reduces risk of Alzheimer’s
- Coffee reduced risk of dementia
Drinking 3-5 cups of coffee per day is associated with a decreased risk of developing dementia by 65%. Caffeine, antioxidant capacity and increase of insulin sensitivity is believed to cause these effects. However, more studies are needed. (34, 35)
- Coffee reduces risk of Parkinson’s disease
- Coffee and Diabetes 2
Individuals with type 2 diabetes have a reduced risk in overall mortality, and mortality associated with cardiovascular disease (CVD) and coronary heart disease (CHD). (44)
A large study found that the risk of developing type 2 diabetes mellitus was 35% lower for those who drink at least 6 cups of coffee per day and 28% lower for those who drink 4-6 cups, comparing to those who consumed less than 2 cups per day. (45)
Another study, only considering the male population, found that those that consumed 6 or more cups of coffee per day had a 54% lower risk in developing type 2 diabetes mellitus compared to those who didn’t drink coffee at all. (46)
- Coffee reduces risk of Liver diseases
Individuals with chronic liver diseases are encouraged to drink at least 3 cups of coffee per day, since it has positive effects on liver health. It is believed that the synergy of multiple compounds in coffee provides the liver some protective properties.
Coffee intake showed protective properties against alcoholic and non-alcoholic cirrhosis and reduced the risk of mortality from cirrhosis.
Coffee intake also lowers the rate of developing hepatocellular carcinoma, improves antiviral therapy in hepatitis C patients, and reduces the severity of non-alcoholic fatty liver disease symptoms and the risk of developing liver cancer. (47, 48, 49)
By contrast, decaffeinated coffee, tea and cola-drinks have not been associated with these protective properties. Therefore, it is believed that these properties are due to the synergy of caffeine with other coffee compounds. (50)
- Coffee reduces risk of depression and suicide
Several observational studies show that caffeinated coffee is associated with a decreased risk of depression and that suicide risk associated with depression is lower in individuals with a higher consumption of coffee.
An amount of 4-5 coffees per day is the most optimal in risk reduction and is associated with 20% lower risk of developing depression and 53% lower suicide risk. However, the risk is 58% higher with a usage of at least 8 cups of coffee per day compared to moderate coffee drinkers. (51, 52, 53, 54)
Please note that these are only observational studies which don’t actually prove that coffee causes the reduction of the risks of depression and suicide.
- Coffee and Mortality rate
Large studies show that regular and long term coffee consumption is associated with a lower incidence of deaths from all causes, specifically due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections.
The exact reasons are unknown but it is thought to be associated with the more than 1000 compounds contained in coffee, including caffeine and antioxidants, such as polyphenols.
The optimal daily amount of coffee for both men and women is 4-5 coffees per day. This intake guarantees a 12% decrease in death risk in men and 15% in women. (55)
The risk of all-cause mortality and mortality associated with cardiovascular diseases is slightly reduced in decaffeinated coffee drinkers. (56)
Is decaf coffee good for you?
What is decaffeinated coffee?
Decaffeinated (decaf) coffee is made from coffee beans that have had most of the caffeine removed with organic solvents, water or carbon dioxide.
The process of decaffeination doesn’t remove all the caffeine from coffee, although the remaining amounts are very small (3% or less). (57)
Small amounts of antioxidants are also lost through the decaffeination process, although the overall antioxidant contents still remain very high.
According to the FDA guidelines, decaffeinated coffee must have 97% of the caffeine removed. However, since coffee beans may have varied contents of caffeine, decaf coffees may have different caffeine levels too.
The amount of caffeine ranges from none to 13.9mg per 16oz serving in decaffeinated coffees and from 3 to 15.8mg per shot in decaffeinated espresso.
During the process of decaffeination, a small percentage of antioxidants is removed, resulting in about 15% less antioxidant activity compared to standard coffee. (58)
Most studies are done using regular coffee. This most likely because this is what most coffee drinkers have, and because caffeine is its most potent component.
Many health benefits of decaffeinated coffee are believed to be due to the high amounts of antioxidants which may have protective properties in cardiovascular diseases, cancers and type 2 diabetes.
From the studies mentioned above, the association between decaffeinated coffee was found with:
- Reduced risk of gout
- Reduced risk of rectal and colon cancer
- Reduced risk of type 2 Diabetes
- Although studies generally show no association with Parkinson’s, Alzheimer disease and dementia (it is thought to be due to the effects of caffeine), some observational studies show that there may be some connection between high amounts of antioxidants. More studies are needed.
- Lower incidence of death from all causes, heart, respiratory, stroke, injuries, accidents, diabetes and infections. More studies are needed to find out which constituents of coffee are responsible.
- Reduced risk of liver cancer, although it is not known what compounds are responsible.
- Hydrating properties due to liquid contents.
Negative effects of decaffeinated coffee
- Reflux, although much lower risk than in regular, caffeinated coffee.
Decaffeinated coffee is better than regular coffee for these individuals:
- With high sensitivity to caffeine;
- Sufferers of reflux;
- Pregnant women;
- When taking medications which interact with caffeine
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NUTRITION FACTS VS NUTRITION MYTHS
You will find a summary of the most common nutrition myths and evidence-based nutrition facts here.