Is drinking coffee really that bad for you?

Posted: Sunday, April 24, 2011

Growing up, I berated my mother for drinking coffee. When I was 16, I read a pamphlet on nutrition that labeled coffee as taboo. The idea that coffee was a source of ill health stuck with me until I tried a modern coffeemaker and a new gourmet-coffee fan was born.

Despite my own personal reconciliation with coffee, it remains controversial for many people and continues to get a bum rap. But why? What is it about coffee that often makes it seem a vice rather than a virtue? Among other sins, coffee is said to:

* Increase heart disease risk; Increase blood pressure;

* Be linked to pancreatic cancer;

* Cause dehydration;

* Leach calcium from the bones, causing osteoporosis.

To be fair, early research seemed to support many of these claims. However, some research done decades ago is not of the same caliber as that conducted today. Some studies were poorly designed, not accounting for coffee drinkers' other behaviors, such as smoking. Thus, researchers might have concluded, wrongly, that coffee causes heart disease.

As a dietitian, I see many clients who are confused and frustrated about food. They receive conflicting messages about nutrition from the mass media or from friends. These messages often lack context and/or history. Unfortunately for food, this results in a "good for you" or "bad for you" mindset.

Coffee and high blood pressure

Many clients have worried, for example, that coffee will cause high blood pressure. Blood pressure will increase after drinking a cup of coffee but returns to pre-coffee consumption levels within a couple of hours. If someone consumes coffee regularly, the blood pressure-raising effect wanes as the person adapts.

We might also ask: How much coffee causes sustained high blood pressure? Are we talking about a cup in the morning or a pot? If we don't define "moderate consumption" or put it into context, we might assume that a teacup's worth is the same as a Super Big Gulp.

The real question is whether long-term, moderate coffee consumption leads to high blood pressure. If you look at all the collected evidence, the answer is, it does not. Having said this, for those with high blood pressure or who are prone to developing it, reducing or eliminating coffee may be beneficial.

Coffee and hydration

A similar misconception is seen with coffee and hydration. The mantra in some fitness magazines goes something like this: "For every cup of caffeinated beverage consumed, drink an extra glass of water to prevent dehydration."

This is false. This myth started in the late '70s. One of the earliest studies that fueled this idea involved subjects being given either a drink of plain water or a drink containing 250 mg of caffeine (the equivalent of about 2.5 small cups of coffee), after both groups had abstained from consuming caffeine for three weeks. Researchers then collected urine output for 3 hours after consuming the caffeine. Since people urinated more immediately after consuming the caffeine drink, the researchers concluded that caffeine ultimately dehydrated the participants.

However, researchers didn't look at the long-term effects. They didn't monitor urine output for longer than 3 hours. While there is a small increase in urine output in the first couple of hours after caffeine consumption, the body compensates for this loss during the rest of the day by decreasing urine production.

To get a truer picture of water balance (or hydration status), researchers would need to compare the total amount of water consumed and the total water lost over a 24-hour period. The longer view would show that eventually, the body compensates for extra trips to the restroom.

We also now know that when someone is referred to as "caffeine naive" (new to caffeine consumption), they'll have a stronger response to whatever's being measured -- whether heart rate, blood pressure or urine output -- so the effect will be magnified. With regular consumption of coffee, however, caffeine's stimulatory effects often become less effective. Caffeine newbies might be sprinting to the bathroom while more experienced java ninjas might not feel a bladder flutter.

Coffee and antioxidants

So coffee isn't the demon beverage that will make your blood vessels explode. Does that make it a health food? Yes... and no.

Coffee is a complex beverage. Best known for its caffeine content, coffee also contains many other compounds that include antioxidants, such as phenols, also found in wine, green tea, apples, and chocolate. "Antioxidants" is a fancy word for compounds that protect our cells and tissue from the ravages of oxidation.

Oxidant production is a part of life. Oxidative chemicals are produced as part of our metabolism, as we breathe oxygen and digest food for energy. These compounds can also be produced from pollutants like smog, smoking, alcohol, and sunlight. Fortunately, we're protected by two sources of antioxidants: those our bodies produce and those we get from food.

Here's an idea of how coffee might be beneficial. The Journal of the American Medical Association performed a systemic review -- an examination of the combined results of many different studies -- that found habitual coffee consumption was associated with a lower risk for Type 2 diabetes. The antioxidants may protect the cells of the pancreas that produce insulin from damage, essentially extending their warranty so they can keep doing their job. Or, this lowered risk may be due to one of coffee's other compounds, such as chlorogenic acid. Chlorogenic acid as been shown to help reduce blood levels of glucose (blood sugar).

There's equally impressive research showing coffee may protect against Parkinson's disease, dementia, and cardiovascular disease. However, it's still not clear how this works. We know that coffee contains antioxidants, and that it does have some health benefits, but we aren't completely clear which constituents of coffee are responsible.

Should we drink to our health?

Many studies suggest that we have to drink a lot of coffee to reap the benefits. For instance, the systemic review on coffee and Type 2 diabetes found that the protective effects seemed to require an intake of about 5-7 cups per day -- probably not realistic or desirable for many people. Is there a point where the increasing amounts of caffeine outweigh any potential benefit? The jury is still out.

Thus, it's probably still best to follow governmental guidelines on caffeine consumption:

* For adults, the upper limit is about about 400 to 450 mg per day, or about the amount found in three to four 6-ounce (177 mL) cups per day.

* Women who are pregnant or nursing don't have to eliminate caffeine entirely. Up to 300 mg per day is considered safe.

* For children, the intake limit is 45 mg per day for ages 4-6, 53 mg per day for ages 7-9, and 85 mg per day for ages 10-12. (But really, do you want caffeinated children on your hands?)

Coffee is among the world's most popular beverages. While it's been unfairly vilified over the years, more recent research demonstrates that coffee is not to be seen as a vice. As with all things, coffee is to be enjoyed, if not revered, in moderation and guilt free.

Doug Cook is Naturally Savvy's Preventative Health Expert. He is a Registered Dietitian/Nutritionist and Certified Diabetes Educator. NaturallySavvy.com is a website that educates people on the benefits of living a natural, organic and green lifestyle.

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