Coffee – Who can drink it and who should avoid it?

Coffee is one of those things – you either love it or hate it. You know if you like the taste or not (or if it’s just a reason to drink sugar and cream). You know how it makes you feel (i.e. your gut, your mind, etc.).

Not to mention the crazy headlines that say coffee is great, and the next day you should avoid it!

There is actual science behind why different people react differently to it. It’s a matter of your genetics and how much coffee you’re used to drinking.

NOTE: Coffee does not equal caffeine. Coffee contains between 50-400 mg of caffeine/cup, averaging around 100 mg/cup. Coffee is one of the most popular ways to consume this stimulant. But… a cup of coffee contains a lot of things over and above the caffeine. Not just water, but antioxidants, and hundreds of other compounds. These are the reasons drinking a cup of coffee is not the same as taking a caffeine pill. And decaffeinated coffee has a lot less caffeine; but, it still contains some.

Let’s look at caffeine metabolism, its effects on the mind and body, and whether coffee drinkers have higher or lower risks of disease. Then I’ll give you some things to consider when deciding if coffee is for you or not.

Caffeine metabolism

Not all people metabolize caffeine at the same speed. How fast you metabolize caffeine will impact how you’re affected by the caffeine. In fact, caffeine metabolism can be up to 40x faster in some people than others.

About half of us are “slow” metabolizers of caffeine. We can get jitters, heart palpitations, and feel “wired” for up to 9 hours after having a coffee. (This describes my mother, who would even avoid black teas, which have about 40-50 grams of caffeine.)

The other half is “fast” metabolizers of caffeine. (This describes my father, who would have an espresso after dinner.) They get energy and increased alertness and are back to normal a few hours later.

Me? I’m somewhere in the middle. Like most people, I can have a couple coffees before 2 pm, but not after or it will keep me up past my bedtime.

This is part of the reason those headlines contradict each other so much – because we’re all different!

The effects of coffee (and caffeine) on the mind and body

NOTE: Most studies look at caffeinated coffee, not decaf.

The effects of coffee (and caffeine) on the mind and body also differ between people; this is partly from the metabolism I mentioned. But it also has to do with your body’s amazing ability to adapt (read: become more tolerant) to long-term caffeine use. Many people who start drinking coffee feel the effects a lot more than people who have coffee every day.

Caffeine stimulates the central nervous system but the half-life varies between people and depends on a host of factors such as age, body weight, pregnancy status, medication and liver health. In most healthy adults, the half-life is 5 – 6 hours.

Here’s a list of these effects (that usually decrease with long-term use):

  • Stimulates the brain
  • Boosts metabolism
  • Boosts energy and exercise performance
  • Increases your stress hormone cortisol

Coffee does not dehydrate as is commonly believed. While caffeinated drinks may have a mild diuretic effect and cause the need to urinate (like most liquids), 550 mg of caffeine a day doesn’t appear to increase the risk of dehydration. (This is equivalent to five 8-ounce cups pf coffee.)

So, while some of these effects are good and some aren’t, you need to see how they affect you and decide if it’s worth it or not.

Coffee and health risks

There are a ton of studies on the health effects of coffee, and whether coffee drinkers are more or less likely to get certain conditions.

Here’s a quick summary of what coffee can lead to when consumed in excess for YOUR body:

  • Caffeine addiction and withdrawal symptoms lasting 5-7 days if consumption is stopped abruptly instead of tapered (e.g. a headache, fatigue, irritability, loss of concentration)
  • Increased sleep disruption
  • Tremors
  • Dry mouth
  • Dizziness
  • Blurred vision
  • Rapid heart rate and palpitations
  • Heartburn and stomach ache
  • Nausea and cold sweats
  • Pale and clammy appearance
  • Suppressed appetite

On the positive side:

  • May prevent gallstones
  • May relieve headaches
  • May suppress appetite (helpful for those who are overweight)
  • Increased energy
  • Enhanced physical performance
  • Reduced perception of muscle pain
  • Lower risk of Alzheimer’s and Parkinson’s
  • Lower risk of developing type 2 diabetes
  • Lower risk of certain liver diseases
  • Lower risk of death (“all-cause mortality”)
  • Mixed reviews on whether it lowers risks of cancer and heart disease

NOTE: What’s super-important to note here is that coffee intake is just one of many, many factors that can affect your risks for these diseases. Please never think regular coffee intake is the one thing that can help you overcome these risks. You are health-conscious and know that eating a nutrient-rich whole foods diet, reducing stress, and getting enough sleep and exercise are all critical things to consider for your disease risk. It’s not just about the coffee.

Should you drink coffee or not?

There are a few things to consider when deciding whether you should drink coffee. No one food or drink will make or break your long-term health.

Caffeinated coffee is not recommended for:

  • People with arrhythmias (e.g. irregular heartbeat)
  • People with high blood pressure
  • People with liver or kidney disease
  • People with gastroesophageal reflux disease
  • People who often feel anxious or depressed
  • People who have trouble sleeping
  • People who are pregnant
  • Children and
  • Teens

If none of these apply, then monitor how your body reacts when you have coffee. Does it:

  • Give you the jitters?
  • Increase anxious feelings?
  • Affect your sleep?
  • Give you heart palpitations?
  • Affect your digestion (e.g. heartburn, etc.)?
  • Give you a reason to drink a lot of sugar and cream?

Depending on how your body reacts, decide whether these reactions are worth it to you. If you’re not sure, I recommend eliminating it for awhile and see if you feel a difference.

NOTE: If you’ve been a heavy coffee drinker, you may wish to taper consumption over a week rather than stopping abruptly. For example, cut back to one or two cups of caffeinated coffee in the morning, and decaf the rest of the day before dropping coffee completely.


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How often do you drink coffee in a day? Does it have a specific effect on you? Let us know in the comments below.

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