Overview 

Is caffeine harmful or good for my health?  What if I’m pregnant or have a specific health condition?  If I am going to drink caffeinated beverages, how much should I drink?  These questions and more are addressed below in quick and clear highlights from a recent research review in the prestigious New England Journal of Medicine.  (“Coffee, Caffeine, and Health” by Rob M. van Dam, Ph.D., Frank B. Hu, M.D., Ph.D., and Walter C. Willett, M.D., Dr.P.H.).

 

Four key takeaways about caffeine:

1. Drinking caffeinated coffee (the main source of caffeine in adults in the UK and Ireland) does not increase the risk of cardiovascular diseases and cancers, according to a large body of evidence reviewed.

2. Drinking a moderate amount of coffee daily has been consistently associated with a reduced risk of several chronic diseases[JB1] .

Let’s unpack that finding a bit.  A “moderate” amount of coffee here means 3 to 5 standard cups of coffee (at 8 ounces / 235 ml each) per day. So, it’s important to consider that a “medium” or “regular” size in most popular coffee shop chains is much larger than a standard.  For example, Costa’s medium – which was reduced in size last year – still is the equivalent of 1.5 “standard” cups.

 

3. Since high caffeine intake can have various negative effects, the following limits have been recommended.

• 200 milligrams of caffeine (not to be confused with milliliters of coffee) per day for pregnant and lactating women (about 1 cup of brewed coffee). 

• 400 mg of caffeine per day for adults who are not pregnant or lactating (about 2 standard cups of brewed coffee).

• Because sensitivity to caffeine and ability to break it down vary so much from person-to-person, more or less might be appropriate depending on the individual.

 

Here’s a handy guide to caffeine concentration, since the concentration of caffeine varies between and even within types of caffeinated beverages.

 

4. Caffeine and coffee should not be recommended by doctors as preventative medicine, given available evidence; but, for adults who are not pregnant or lactating and do not have specific health conditions, moderate consumption of coffee or tea can be part of a healthy lifestyle.

 

A DEEPER DIVE INTO THE CAFFEINE REVIEW

Caffeine is the world’s most popular “psychoactive agent”.  While that may sound a bit sinister - like a detective gone wrong in a Netflix thriller - it simply means that caffeine is a chemical that affects the nervous system, including the brain, causing temporary changes in the way we see the world around us, feel about it, and behave in it.   But you already knew that.  The world seems a different place after that first cup of tea or coffee in the morning.

 

Sugar and spice and...

But, like most things, knowing the effects of caffeine is a bit complicated.  Getting qualified medical and/or nutritional guidance is recommended.

 

First of all, bear in mind that most people take in caffeine as part of a beverage or food.  So, it’s not just the caffeine that can cause health effects.  This goes beyond the more obvious effects of added sugar or milk or of the often long list of additives in fizzy drinks.

 

For example, drinking unfiltered coffee - such as from a French press - can raise overall cholesterol levels (thanks to diterpene cafestol).  So, not drinking as much unfiltered or espresso-based coffee may help to keep overall cholesterol in check.

 

On the other hand, coffee contains hundreds of plant-based chemicals (including polyphenols) and other compounds (including minerals) that can have more positive health effects.  Such effects include a reduction in damage to cells from poor diet, the environment, and stress (often referred to as oxidative stress); improvement in gut health; and metabolism of glucose and fat.

 

A different stoke for different folks

Another factor making things complicated is that caffeine affects different people in different ways. 

Typically, it takes an adult’s body 2.5 to 4.5 hours to break down and eliminate just half of the caffeine ingested.  That means it can usually take 10 to 23 hours for some people to totally rid themselves of caffeine.  But it can take much less or more time for others.   So, people who find that caffeine taken later in the day reduces the amount or quality of sleep should reduce their caffeine or take it earlier in the day.

 

Smoking speeds up the process of clearing caffeine from the system but pregnancy slows it down a lot, especially in the third trimester. 

Caffeine affects people very differently and some of this is inherited through our genetic makeup. 

But medications can also cause caffeine’s effects to be drawn out for longer.  On the flip side, caffeine can also change the way that medications affect us.  These medications include “several quinolone antibiotics, cardiovascular drugs, bronchodilators, and antidepressant agents”, so your doctor should take caffeine consumption into account when necessary.

 

Sleep, alertness, and reaction time when you drink caffeine.

In moderate amounts (40 to 300 mg), caffeine can help to make a person more awake, alert and quicker in reacting.  It also can improve alertness during long, dull tasks such as “working on assembly line, long-distance driving, and flying aircraft”.   Doing one’s taxes, too.  While the effects are most needed when one is tired, caffeine can’t help make up for the effects of long-term sleep deprivation. 

Caffeine can help relieve pain when added to commonly used pain relief medications, following guidance from a medical professional.

 

Sleep and anxiety

Of course, taking caffeine, particularly later in the day, can make it harder to sleep and can reduce the quality of one’s sleep. And it also can cause anxiety.  This is especially true with:

·      more than 200 mg (one standard cup of brewed coffee) at a time,

·      more than 400 mg per day, and

·      in sensitive persons, including those with anxiety or bipolar disorders.

Again, the differences between the effects on sleep and anxiety from person to person are large.

 

Dehydration

High caffeine intake can send us on more trips to the loo to urinate, too.  But those who regularly take under 400 mg of caffeine per day over longer periods have not been found to have more difficulty staying hydrated.

 

Quitting Caffeine

The important roles that tea, coffee, and other caffeinated beverages play in social and cultural life around the globe can be a factor that makes quitting more difficult for those who try.  But there are also withdrawal effects, including headaches, fatigue, decreased alert-ness, and depressed mood, as well as influenza-like symptoms in some cases.  The worst of these symptoms usually comes 1 or 2 days after quitting and can last for more than a week.  This period and the symptoms can be reduced by gradually weaning one’s daily dose.

 

Energy drinks and shots

Consuming caffeine through energy drinks and shots may have worse effects than other beverages with caffeine:

• These are popular among children and adolescents who may be more susceptible to the effects of caffeine;

• People often consume these a lot of these drinks in relatively short periods of time, not previously having formed a tolerance to caffeine;

• Consumers often don’t know how much caffeine they contain when consuming them;

• The caffeine may have compounded effects with other elements of the energy drinks; and 

• They are often combined with alcohol consumption or strenuous physical activity such as dancing for long periods.

People consuming energy drinks should pay attention to the caffeine content and not take more than 200 mg of caffeine at a time or combine with alcohol.  Effects of high doses of energy drinks or shots and in combination with alcohol have led to adverse cardiovascular, psychological, and neurologic events, including death.