DietMind and Body

All about Coffee

by Brian St. Pierre


Coffee is among the most consumed beverages in the world. Coffee needs to be treated with care and avoided altogether by those who metabolize it poorly, but can provide health benefits to some people.

With 90% of North American adults consuming caffeine daily, it is the world’s most consumed drug.

But is coffee really bad for us? Do we need to give up our beloved cuppa joe? And If it’s bad, why does it feel so good?

Coffee’s risks

Research on coffee’s safety is mixed, for several reasons:

  • People vary genetically in how well they can process caffeine and coffee.
  • Coffee interacts with many hormones and neurotransmitters in the body, such as cortisol, acetylcholine, and insulin. These relationships are complex, and often depend on timing, amount, and people’s individual makeup.
  • As a crop, coffee is typically grown and processed in smaller batches by smaller-scale farmers and producers. Variations in soil and climate, as well as later roasting and brewing technique, will change the taste and chemical makeup. It’s hard to standardize the exact chemical compounds in coffee from batch to batch.

So it’s hard to say definitively that coffee is “good” or “bad”; “healthy” or “unhealthy”.

What about my metabolism?

One reason that evidence on the health effects of coffee is so mixed is that people clear caffeine at different rates. Caffeine is broken down and cleared by the liver, and our genetic makeup shapes how quickly and effectively we can do this.

  • On one hand, “slow” metabolizers of caffeine don’t process caffeine effectively. These are people who are adversely affected by caffeine, get the jitters, and are wired for up to nine hours after consumption.
  • Others just get a boost in energy and alertness for a couple of hours; they are considered “fast” metabolizers of caffeine.

Thus, whether coffee is better or worse for you depends on how well and quickly you metabolize caffeine.

What about cortisol?

Cortisol is a hormone produced by the adrenal glands. It increases blood pressure, spikes blood sugar and prepares the body for “fight or flight” mode.

Coffee and caffeine tend to transiently increase cortisol levels; however, this depends on several factors, including when you drink coffee, how often you drink it, and whether you have high blood pressure.

Cortisol is normally high in the morning, so if you drink some coffee at 6 a.m. and 10 a.m., you should be fine, as cortisol is naturally elevated at that time of day anyway.  However, your body may not appreciate coffee as much in the afternoon or evening, when cortisol normally drops. At that point, consider tea or something decaffeinated.

Coffee’s benefits

Caffeine & dehydration

For years, fitness enthusiasts worried that coffee would dehydrate them. However, a recent review of 10 studies found that consuming up to 550 mg of caffeine per day (or about five 8-oz cups) does not cause fluid-electrolyte imbalances in athletes or fitness enthusiasts.

In another review, researchers concluded that consuming caffeine-containing beverages as part of a normal lifestyle does not lead to fluid losses exceeding the volume of fluid consumed (intake and output were roughly equal), nor is it associated with poor hydration status.

Take-home: Don’t drink coffee as your only beverage, and drink enough water, and you’ll be fine.

Coffee & performance

Let’s be honest — that first morning coffee can transform us from beast to philosopher (or at least, slightly more awake and nicer beast). Coffee, and more specifically its caffeine content, provide many noted mental and physical performance benefits.

Caffeine reduces our rate of perceived exertion, so it doesn’t feel like we’re working as hard as we actually are. People who regularly drink coffee perform better on tests of reaction time, verbal memory, and visuo-spatial reasoning.

Another study found that women over the age of 80 performed significantly better on tests of cognitive function if they had regularly consumed coffee over the course of their lifetimes.

Take-home: A little bit of coffee/caffeine before important tasks requiring alertness and energy can be a good thing.

Coffee, antioxidants & cancer

While dark chocolate and green tea gather a lot of acclaim for their antioxidant content, coffee actually outshines them both in this department.

In fact, the antioxidants in coffee may make up as much as 50-70% of the total antioxidant intake of the average American! (Which is not necessarily a good thing, because it means that there are a lot of vegetables not getting eaten…)

Despite some general worries about the health effects of coffee, coffee consumption is associated with an overall decreased risk of cancer.  In particular coffee consumption has been shown to be associated with a lower risk for oral, esophageal, pharyngeal, breast (in post-menopausal women), liver, colon, and aggressive prostate cancer.

When it comes to the prostate, researchers recently found that men who drank the most coffee (6 or more cups per day) were nearly 60% less likely to develop advanced prostate cancer than non-coffee drinkers.  Other research has shown that people who regularly consume two or more cups per day may have a 25% decreased risk of colon cancer.

Again, the research is mixed in part because of the variation in response to coffee.

Take-home: Coffee may lower your cancer risk, but don’t count on it as your only health strategy. And eat some vegetables already.

Summary & recommendations

Coffee’s not for everyone. And it’s not a magic bullet. Still, it seems to have significant health benefits for those who can tolerate it, including:

  • better athletic and mental performance
  • possibly lower rates of some types of cancer, neurodegenerative diseases, and Type 2 diabetes
  • possibly some prevention of premature mortality and cardiovascular disease

Most of the research on coffee is epidemiological. This means studies look at associations rather than cause and effect. Simply because coffee is associated with particular risks and benefits doesn’t necessarily mean that coffee causes all of these risks or benefits.

Just as with all foods (and nutrients for that matter), dosage matters. While some studies have found large intakes (5-6 cups) to have significant benefits, other research suggests that drinking that much coffee is counter-productive.

In general, it appears that drinking some coffee is good, but more might not be better, especially if you are a slow metabolizer.  For those who are greatly affected by coffee and caffeine, avoid it altogether or cut down your consumption.

Want a quick and easy test of your coffee consumption? Ask yourself how you feel physically, mentally, and emotionally a few hours after you drink some… as well as if you miss your daily dose.

Also, go black if possible. Pumping your coffee full of cream, sugar, and other exotic additives reduces any potential health benefits by adding unnecessary calories and artificial flavours and sweeteners. (And Frappucinos or chocolate covered coffee beans? C’mon.)

Taking all the data into consideration, it seems that your best bet is about 1-3 cups of coffee (8-24 oz) per day. This will maximize the benefits while minimizing the risk.

And keep this in mind…while there is positive data on coffee, these benefits don’t necessarily include things like energy drinks and caffeine pills.  There are many antioxidants and bioactive compounds in coffee that are interacting with its caffeine content to provide the benefits.  So, unfortunately, Red Bull doesn’t count.

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