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Coffee: A Most Enigmatic, Ubiquitous Beverage

Legend has it that coffee was discovered by a goat herder around 850 AD in what is now Ethiopia. It soon spread around the globe and is currently consumed by billions of people every day. But as the drink gained in popularity, it also gained a bad rap. From claims that coffee led to illegal sex in the 1500s, or that it caused impotence in the 1600s, to the more recent belief that it stunted your growth, history has not been kind to coffee.

In recent years, rumors have been replaced by scores of scientific studies. But reading through the research can be dizzying, as you’ll often come across a conclusion that directly opposes another you just read. In fact, it’s unlikely that any single study would yield enough evidence to convince us about the health effects of coffee one way or another. So some scientists instead focus compiling these disparate findings into mega-studies called meta-analyses. Eventually, the meta-analyses became so numerous that scientists started aggregating those into what are known as umbrella reviews to see if they could glean any general wisdom about coffee’s effects.

Two umbrella reviews were published last year (here and here), and their findings flew in the face of centuries of coffee gossip. The verdict was that coffee drinking is linked to lowered risk of myriad diseases like type 2 diabetes, heart disease, a few types of cancer, liver disease, Parkinson’s, Alzheimer’s and depression—not too shabby. Above all, coffee drinkers were less likely to die early from any cause. And with the possible exception of drinking it while pregnant, there were no negative effects to speak of.

“The key message is that with the evidence that we have up to date, we can say that coffee can be part of a healthy diet,” says nutritional epidemiologist Giuseppe Grosse at the University of Catania in Italy and lead author of one of the umbrella reviews.

Grosso also notes that the verdict could change. That’s because, for all of the studies out there, there’s still a whole lot we don’t know about the effects of coffee on our health. Here are some of the lingering questions that researchers are digging into.

What have genes got to do with it?

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Although studies are beginning to converge on the benefits of coffee, it’s hard to ignore the often-opposing findings. A major culprit has been that pesky variable of genetic diversity among study participants, which surprisingly, is rarely considered.

Take the gene CYP1A2, which encodes an enzyme of the same name that breaks down caffeine. One variant of this gene produces an enzyme that does the job quickly—at least for those who inherit two copies of it from their parents. People who inherit the other form of the gene are slower to process caffeine, so it hangs around in their bloodstream for longer. It turns out that whether you’re a fast or slow metabolizer helps to determine the toll that glugging coffee will take on your body.

Heart attacks are a prime example. For a long time, drinking coffee was thought to raise the risk of heart attack. But when researchers sequenced the CYP1A2 genes of coffee drinkers, they found that the risk was only heightened for those with the slow caffeine metabolism version of the gene.

Marilyn Cornelis, a geneticist at Northwestern University who led the study, has since searched far and wide across the genome, and zeroed in on additional genes that, like CYP1A2, help govern how the body processes caffeine. She’s still on the hunt for more.

“Very few studies have actually accounted for genetic variation,” says Cornelis. This omission may explain many of the inconsistent findings reported both in scientific journals and in the news. “What’s kind of cool now is that you look at these more recent studies they finally at least note the limitation of not including that variation.”

What makes coffee good for you?

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Although coffee is often equated with caffeine, the two are not synonymous. A seemingly simple cup of coffee is actually a complex blend of more than a thousand chemical compounds, including caffeine, chlorogenic acids and diterpenes.

Peter Martin, the founder of the Vanderbilt University Institute for Coffee Studies, says now that people are starting to accept that coffee has health benefits, the next logical question for scientists to ask is: How?

“Mechanistically, we don’t quite know how increased rates of coffee consumption can reduce rates of things like Alzheimer’s disease, various forms of cancer, depression, and Parkinson’s disease,” he says.

The answers may be as numerous as the diseases in question. Caffeine seems to be responsible for protecting coffee drinkers against Parkinson’s, for instance, but when it comes to guarding against type 2 diabetes, you’re just as well off if you prefer decaf. Clearly, there’s more to it than caffeine alone.

Many of the compounds found in coffee are antioxidants. That means they protect our cells by disarming dangerous molecules called reactive oxygen species (ROS), which can damage our DNA and proteins. “It’s easy to assume it’s a general mechanism, such as antioxidants, that works for practically every disease,” says Martin, but these antioxidant effects are probably just one piece of the puzzle.

How much coffee should you drink?

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Coffee may have health benefits, but how many cups should you be knocking back on a daily basis?

Once again, part of the answer may lie in your genes. Those stretches of DNA that control how your body processes caffeine may explain why some people feel fine after six cups, whereas others will get jittery and anxious after just one. “I think it’s important to find out what subgroups of the population should not be consuming coffee or limit their caffeine intake,” says Marilyn Cornelis.

Fortunately, we are naturally equipped to regulate our coffee consumption to some extent, according to Cornelis’ research. She discovered that people tend to adapt their coffee-drinking habits to reach their own caffeine sweet spot—the point at which they feel good but not jittery.

Nonetheless, recent headlines have touted 3 to 4 cups per day as optimal. That number was linked to the best outcomes for multiple diseases in one of the big review articles published last year.

Taking that number as a one-size-fits-all guideline is problematic because, aside from ignoring genetic differences, there is also the issue of what ‘a cup of coffee’ means chemically. It could mean a big cup or a small cup, instant coffee or fresh brewed, and a light, medium, or dark roast. Each version of a cup contains different levels of biologically important chemicals like caffeine, yet most of what we know about coffee and health still comes from studies that measure coffee consumption in terms of cups.

How does coffee impact pregnancy?

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Just about every aspect of health impacted by coffee-drinking deserves deeper study, but one in particular stands out.

“I would nominate the effect of caffeine on pregnancy as probably the most serious and tough problem to figure out,” says David Schardt, a senior scientist at the Center for Science in the Public Interest.

March of Dimes recommends that pregnant women limit themselves to 200 mg of caffeine per day, which is roughly the amount in one big cup of coffee. But they preface that number with an admission: “We don’t know a lot about the effects of caffeine during pregnancy on you and your baby. So it’s best to limit the amount you get each day.”

It’s true that little is known on the topic, and for good reason. When it comes to pregnancy, researchers rely on observational studies, which are often plagued by hidden factors that are not part of the study but still sway the results. That’s because randomized controlled studies—considered the gold standard of medicine—are out of the question for pregnant women, says Schardt.

“You would never randomly assign pregnant women to consume caffeine or not because if it turns out to be harmful, that would be unethical,” he says.

Saddled with lower-quality data, scientists have found that drinking coffee while pregnant may be linked to low birth weight, preterm birth, and pregnancy loss. Caffeine can pass through the placenta, where it gets broken down slowly because the fetus’ version of the caffeine-processing enzyme CYP1A2 doesn’t work as hard. That means when a pregnant mother drinks caffeine, the fetus gets prolonged exposure to the chemical. Still, with mainly observational data to go on, it’s hard to pin down if and how caffeine ultimately affects pregnancy.

(All images by Tevs Iuliia/Shutterstock)

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Health

What Magnetic Fields Do to Your Brain and Body

(Credit: pippeeContributor/Shutterstock)

There’s no escaping magnetic fields—they’re all around us. For starters, the Earth itself is like a giant magnet. A spinning ball of liquid iron in our planet’s core generates the vast magnetic field that moves our compass needles around and directs the internal compasses of migrating birds, bats, and other animals. On top of that, ever-industrious humans have produced artificial magnetic fields with power lines, transport systems, electrical appliances, and medical equipment.

We may not be able to see, hear, feel, or taste the magnetic fields that surround us, but some may wonder whether they can still exert effects on our bodies and brains. This question becomes more pertinent, and the answers more tantalizing, as the strength of the magnetic field in question gets cranked up.

Everyday Exposure

A magnetic field arises whenever a charged particle, like an electron or proton, moves around. Since the electric currents running through blenders, hairdryers, and wires in the walls of our homes consist of flowing electrons, they all generate magnetic fields. Through these sources, the average person is exposed to magnetic fields reaching 0.1 microtesla in strength on a daily basis. By comparison, the Earth’s magnetic field, which we are always exposed to (as long as we remain on the planet’s surface), is about 500 times stronger. That means the magnetic force penetrating your body as you lounge around your home or spend a day at the office is decidedly insignificant.

From time to time, a scientific study finds a link between living near high-voltage power lines and illness. Heightened risk of childhood leukemia is the most commonly cited potential health consequence, but whether or not the risk is real has been hard to pin down. One glaring issue is that scientists have yet to figure out the mechanism by which such weak magnetic fields—which are still in the microtesla range for homes next to power lines—could adversely affect the human body. In 2010, the International Commission on Non-Ionizing Radiation Protection concluded that the evidence that living near power lines increases the risk of the deadly blood cancer “is too weak to form the basis for exposure guidelines.”

(Credit: VILevi/Shutterstock)

An MRI machine. (Credit: VILevi/Shutterstock)

What’s the Threshold?

Meanwhile, a team of scientists at the Utilities Threshold Initiative Consortium (UTIC) has been busy working to figure out the threshold at which the human body shows a physiological response to a magnetic field. According to Alexandre Legros, a medical biophysicist at the Lawson Health Research Institute and Western University in London, Ontario and a UTIC scientist, the smallest magnetic field that has reliably been shown to trigger a response in humans is around 10,000 to 20,000 microtesla. But crucially, to produce the effect, the field cannot be static like Earth’s magnetic field; rather, it must change directions over time. When these strong, direction-shifting magnetic fields get directed at a human, small electrical currents begin to pulse through the body. Above that threshold, the currents can stimulate super-sensitive cells in the retina, known as graded potential neurons, giving the illusion of a white light flickering even when the affected person is in darkness; these visual manifestations are known as magnetophosphenes.

The 10,000-microtesla threshold is well above the strength of any magnetic field encountered in everyday life. So in what situations might magnetophosphenes occur?

Medical Magnets

“There’s only one circumstance in which you may perceive magnetophosphenes,” says Legros: “If you’re in an MRI [magnetic resonance imaging] machine and moving your head fast.” An MRI scanner is essentially a big magnet that produces a powerful magnetic field of around 3 tesla (or 3 million microtesla) — millions of times larger than the fields we’re normally exposed to. But because it’s a static magnetic field, MRI scanners don’t exert any noticeable effect on the body. That would change, however, if the patient inside the scanner were to rapidly move his or her head back and forth. “Moving quickly induces a time-varying field, so by doing that you are inducing currents in different structures of your brain,” says Legros. Those currents may lead to nausea, loss of balance, a metallic taste in your mouth, or in some cases, magnetophosphenes.

On par with the magnetic field of an MRI is the one produced by a medical procedure known as transcranial magnetic stimulation (TMS). But unlike MRI, which makes detailed pictures of the inside of the body, the purpose of TMS is to stimulate the brain. That task requires an electric current, which is why TMS relies on a magnetic pulse rather than a static magnetic field. When this pulse is delivered via an electromagnetic coil placed against the scalp, the resulting current jolts a particular part of the brain with the aim of treating neurological diseases like depression.

Out-of-this-World Magnetic Fields

The magnetic fields associated with MRI and TMS are the strongest that a human might realistically be exposed to. Still, they are “hilariously puny” compared to those found beyond our planet, says Paul Sutter, an astrophysicist at Ohio State University and chief scientist at the COSI Science Center in Columbus, Ohio. At the extreme lies the aptly-named magnetar, which is a rare type of neutron star with a magnetic field one thousand trillion times stronger than Earth’s.

An artist's impression of a magnetar. (Credit: ESO/L. Calçada/Wikipedia (CC BY 4.0))

An artist’s impression of a magnetar. (Credit: ESO/L. Calçada/Wikipedia (CC BY 4.0))

If any human ever got close to a magnetar, they would quickly find themselves in dire straits. “Strong magnetic fields can start to do surprising things,” says Sutter. At the atomic level, the strong magnetic field would move all of the positive charges in your body in one direction and the negative charges the other way, he explains; spherical atoms would stretch out into ellipses and soon they would start to resemble thin pencils. That drastic change in shape would interfere with basic chemistry, causing the normal forces and interactions between atoms and molecules in the body to break down. “The first thing you would notice is your entire nervous system, which is based on electrical charges moving throughout your body, is going to stop working,” says Sutter. “And then you basically dissolve.”

Sutter guarantees that our local neighborhood — which he defines as a radius of a few hundred light-years around Earth — has been surveyed and certified magnetar-free. None of these exotic objects are approaching us, and none of the massive stars nearby are likely to turn into magnetars when they die. The nearest magnetar is a safe distance of tens of thousands of light-years away. So, at least for the time being, we can rest easy and take comfort in our planet’s own meager magnetic field.

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Health

The Aftermath of Michael Jackson’s Antigravity Lean

The infamous lean.

In Michael Jackson’s 1987 music video “Smooth Criminal,” the legendary performer leans forward 45 degrees from a straight-up position — and comes back. It’s a feat that seemingly defies both physics and physiology, and the move has become another element of MJ’s aura of mystery.

Some type of cinematic or mechanical trick must be responsible, since most people can manage only a 20-degree forward tilt before toppling headlong. Yet Jackson performed the move live on tours around the world for years.

Lean In

In a study published this week in the Journal of Neurosurgery, three scientists examine the so-called Antigravity Lean, not from a physics but from a physiological perspective. The three neurosurgeons, all at the Postgraduate Institute of Medical Education and Research in Chandigarh, India, combine in the article their knowledge of Jackson with data on spine biomechanics.

It’s been known for years how Jackson defied gravity. His shoes had a slot that slid onto a bolt in the floor, allowing him to perform the dramatic lean.

Bending forward is limited by the erector spinae muscles, which act like cables to support forward bends up to 20 degrees, though some dancers can achieve 30 degrees, the paper says. When near the max of a bend, you can feel the strain on the Achilles’ heel as the ankles become the fulcrum for balance. People soon return to vertical or catch themselves from falling headlong.

Though Jackson’s 45-degree bend is not physically possible without trickery, the King of Pop still needed incredible core strength and leg muscles to pull it off, the authors write. Not just anyone can lock their shoes into the floor and become Michael Jackson, it seems.

“Several MJ fans, including the authors, have tried to copy this move and failed, often injuring themselves in their endeavors,” the researchers write.

Figure A shows the Antigravity Tilt (a 45-degree forward bend) and the normal limit that most people can bend forward. Jackson used shoes with a slot that slid onto a bolt in the floor. Figure B shows the shift when the body’s fulcrum is the hip and when it’s the Achilles’ tendon. (Illustration courtesy of Manjul Tripathi)

Figure A shows the Antigravity Tilt (a 45-degree forward bend) and the normal limit that most people can bend forward. Jackson used shoes with a slot that slid onto a bolt in the floor. Figure B shows the shift when the body’s fulcrum is the hip and when it’s the Achilles’ tendon. (Illustration courtesy of Manjul Tripathi)

Tough Act to Follow

Jackson’s sleight of foot inspired generations of dancers who push the limits physically. This has resulted in spinal stresses not previously seen by neurosurgeons.

This is not to point the finger at Jackson. But it does suggest the reality that injuries can occur that might require implant spinal surgery, the article says, something potentially devastating to a dancer.

But it’s not all bad news — neurosurgeons have gained a lot of new information on how to treat spinal cord injuries in recent years, something that could be in part thanks to MJ’s envelope-pushing dance moves.

“The King of Pop has not only been an inspiration but a challenge to the medical fraternity,” Tripathi says.

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Health

Your Emergency Contact Does More Than You Think

(Credit: Shutterstock)

You know when you’re filling out your medical paperwork and it asks for your emergency contact? Sure, the process might be annoying, but that emergency contact could actually be put to good use by researchers.

Since many of us use a family member, those contacts can help scientists create family trees. And they can also be used for genetics and disease research, according to a study released Thursday in Cell. Discovering what diseases are inheritable can be a laborious and expensive process — patients must be recruited and researchers must clearly determine patients’ phenotypes (physical traits that include eye color, height, and overall health and are often influenced by your genes).

To make that process easier researchers from three major New York medical centers generated family trees from millions of electronic medical records to create a database.This is the first time electronic health records have been used to trace ancestry and it’s the largest study of heritability using such records.

The More You Know

The researchers identified 7.4 million relatives with an algorithm that matched names, addresses and phone numbers from three medical centers. They found 500 inheritable phenotypes in the data just by looking at test results and observations in health records. The traits included diseases affecting skin, blood and mental health.

The data can help determine the heritability level of many common diseases. For example, researchers found that having an increase of HDL (good) cholesterol is 50 percent heritable, while LDL (bad) cholesterol is only 25 percent heritable. The study’s findings were consistent across the participating medical centers and published studies.

Previous heritability research primarily documented Caucasians of northern European descent, according to the study’s first author Fernanda Polubriaginof, but this research is much broader.

“This dataset will allow us for the first time to compute whether there are differences in other races and ethnicities,” said Polubriaginof in a news release.

Future studies could look at medical records for the hereditary contribution of any trait. Due to privacy issues, patient identifiers were removed for the data, which can only be used for research at the moment. Though, with patient consent, emergency contacts could be put to important use in the future.

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