Healthy Andy

A study published in the Journal of the American Medical Association suggests that drinking green tea can help you live longer.  Many studies in the past have examined the specific health benefits of either green tea, or the active antioxidants in green tea, but this study examined the actual consumption of tea and compared it to mortality rates in Japanese adults.

The Ohsaki National Health Insurance Cohort Study

This study began back in the ’90s in Japan, following over forty thousand adults over the age of 40 without any history of major chronic disease (heart disease, cancer, that sort of nasty stuff).  Individuals were followed up on over the course of the next eleven years to see how many had died from any cause. Participants filled out a questionnaire that asked some basic questions about daily nutrition habits, including the consumption of green tea.  This makes this study very similiar to the Nurse’s Health Study, a study that has followed over 100,000 nurses over the course of decades (except, since it’s an American study, they don’t specifically ask about green tea).

For the Ohsaki study, participants were asked if they drank green tea never, occasionally, 1-2 cups per day, 3-4 cups per day, and 5 or more cups per day.  The authors noted that the typical “cup” of green tea is about 100 milliliters (about 3.5 ounces).

By the way, one of the nice things about this study is, the researchers took the time to see if their questionnarie was at all accurate.  They picked a sample of people and had them do a more comprehensive food diary for three days on four seperate occasions.  They found that there was a moderate to strong correlation between reported intake and actual intake.

The Results: Green Tea Makes You Live Longer

After accounting for potentially confounding variables like age or physical activity, the researchers found that the more green tea people drank, the less likely they were to die from any cause.  The effect was obviously most noticeable in the 5 or more cups of tea per day group; if you used non-tea drinkers as a baseline, the hazard ratio was 0.88 for the 5 cups a day drinkers.  This means that for every 1 non-tea drinker, 0.88 tea drinkers died… which basically means green tea makes you live longer.

The effect was even MORE pronounced among women; the hazard ratio was 0.77 for the heavy tea-drinkers.  So for every 100 non-tea drinkers who died, only 77 tea drinkers died of any cause.  The researchers followed these effects for eleven years.

Then, they took a look at more specific causes of death (they reviewed data for seven years for this). They found that green tea consumption significantly reduced the risk of death from cardiovascular disease, but didn’t reduce the risk of death by cancer.  After looking even closer into the data, they found that when it came to cardiovascular disease, the greatest protection was from stroke.  Once again, the effect was most pronounced in women, who had a 42% less chance of death by stroke if they were drinking 5 or more cups per day of green tea (compared to one or less).

This shouldn’t be a big shock to readers of this website- we’ve talked before about how antioxidants make arteries more elastic and pliable (and therefore healthier).  Since strokes are caused by either blockage or rupture of an artery in the brain, healthier arteries are going to be less prone to those kinds of problems.  And I don’t know about you, but I have no deep and burning desire to experience a stroke, so I’m going to keep drinking green tea and live longer than I would have otherwise!

Stay healthy!

By the way, the full text of this study is available online for free at this link:  http://jama.ama-assn.org/content/296/10/1255.long

We’ve all heard the phrase “stress kills”, but how?  What are the effects of stress on the human body?

Ever since the 50′s, a guy named Selye paved the way for scientific research into the biological effects of stress on an organism.  He identified a number of nasty effects that emotional stress can inflict on the human body.  In order to explain them most easily, first we have to go over a little bit of the nuts and bolts of how your nervous system works.  Don’t worry, it won’t hurt.

Stress And Health Is All About The Autopilot

First off, your Central Nervous System (CNS for short), which is your brain and spinal cord, coordinate all of the zillions of activities going on in your body at any particular time.  Some of those activities are big and voluntary… such as going for a jog.  Some are subtle and automatic, meaning we don’t have to think about doing them. 

Digestion is a good example.  You don’t have to actually think through each and every chemical reaction to break down your breakfast burrito, and thank goodness for that, but most of us really suck at chemistry.

Since neurologists like to give things big names, they decided to divide the nervous system up into stuff you do voluntarily, and stuff you do involuntarily (or automatically).  The automatic part of the nervous system they named the “Autonomic Nervous System“.  Why not the “Automatic Nervous System”?  Because that doesn’t sound anywhere near as impressive when you’re trying to show off to your friends, that’s why.

Those darn neurologists didn’t stop there.  Once we started learning a lot more about the stress response and how various critters, including humans, respond under stress, they divided the automatic part of the nervous system into two more divisions:  the sympathetic and parasympathetic.

Those are big words that really just stand for fairly simple concepts.  It’s important to understand the difference, however,  because that’s what’s going to explain the effects of stress on the human body.

Parasympathetic:  Feed and Breed

Bascially speaking, the parasympathetic nervous system (let’s just call it “feed and breed” from now on, it will be easier) is the mellowed-out version of you, physiologically speaking.  All the various maintenance issues of the body are handled in this version of your autopilot nervous system.  Digestion gurgles along, wounds get healed, tissues are repaired, your immune system is at its best, and reproductive functions are all a go. 

You can think of it in terms of keeping house if you like.  In Feed and Breed mode, the house gets cleaned, the trash gets taken out, and the lawn gets mowed.  There is peace in the valley.

Sympathetic:  Fight or Flight

The opposite end of the spectrum is the sympathetic nervous systerm, also called “Fight or Flight” mode (you may have heard this term before).  This is your body in warfare mode.  You are under attack, and everything in your body is shifted over to giving you every single edge possible for immediate survival.

Anything and everything that isn’t about fighting like crazy or running like the wind shuts down.  In other words, digestion, reproduction… all those things from Feed and Breed mode get the big OFF switch, and instead, vision improves, skeletal muscles (your big mover muscles like your arms and legs) get a  boost, and you’re essentially one big old adrenaline boost.

It’s an evolutionary survival mechanism.  Remember, things weren’t always so (relatively) calm and peaceful for us.  Back in the Stone Age, violence was commonplace.  If you go walking down the trail and a huge bear jumps out and wants to eat your face, you want every fiber of your being devoted to running away or fighting your way out.  Digestion?  Who cares about that?  It isn’t much good to be digesting your food nicely, if YOU are now being digested by the bear.

Chronic Effects of Stress

Of course, in the good old days, those stress episodes only lasted for a few minutes.  Pretty quickly, the situation resolved in one way or another… either you got away from the bear, or you were dead.  Either way, the stress response was over.  And, so, your body could then switch back into Feed and Breed mode once the threat was gone (well, assuming  you lived).

And there’s the kicker.  The stress response is only supposed to last a brief stretch of time.  The majority of the time, you should be chugging along in Feed and Breed mode, keeping your body nicely maintained, with little brief bursts of Fight or Flight to get you through the occasional ugliness.

But in our modern world, that isn’t how it works.  Our stresses are chronic, and so the effects of stress on our body compounds over time.  If you’re always in Fight or Flight mode, the house never gets cleaned (going back to our keeping house metaphor).  The dishes pile up in the sink, the trash overflows out the trash can and onto the floor, the lawn gets all overgrown and nasty and the neighbors start eyeballing you for bringing down property values all around the neighborhood.

Or, more literally, our body can’t do all the many, many maintenance chores that are necessary to keeping the machine running smoothly.  And so, we start to fall apart, little by little, because we’re stuck in Fight or Flight and can’t get back to Feed and Breed.

Parts is Parts, and Stress is Stress

Hang on there, Healthy Andy, you say.  I’m not being chased by bears.  That’s stupid.  I’ve never even seen a bear.  So how can you say my stresses are chronic?

Simple.  Your body responds to all stresses the same.  Positive or negative, physical or emotional, it doesn’t matter… you pop into Fight or Flight mode. 

So no, we don’t get chased by bears any longer, which is nice, but we do have things like jobs, and mortgages, and families, and all kinds of other sources of emotional stress that never seem to let up.  And since our stress is chronic, the effects of stress follow suit.  We get sick more easily.  We have trouble focusing.  We have trouble having kids.

Ever notice a couple who keeps trying and trying and trying to have kids, and they’re practically going nuts because it just isn’t happening, and finally they just throw their hands up and give up.  Two weeks later, there’s a bun in the oven.

Well, sure.  Because before, they were all riled up and stressing themselves out.  Remember, one of the effects of stress is to depress reproductive function, because that’s Feed and Breed stuff, and not Fight or Flight.  A fantastically fertile uterus never saved ANYONE from a charging bear.

And since our body doesn’t know any better… because it doesn’t think, it responds… you get two stressed out people who are stressed out because they can’t concieve BECAUSE they’re stressed out.  Once the stress goes away, Feed and Breed kicks back in, and suddenly yet another couple is out shopping for car seats.

It’s Not Absolute

I’ve kind of made it sound like there’s a big switch, with Feed and Breed on one side and Fight or Flight on the other, and never the two shall meet.  Well, it’s a little more complicated than that.  While one does tend to cancel the other out, it’s not an all or nothing sort of thing.

Instead, you sort of blend into stress, along a continuum.  So instead of a switch, it’s more like a dial, with STRESS on one side and MELLOW on the other, and the more intense the stress, the more the dial gets turned in that direction.  That’s a crude metaphor, but you get the idea.

And really, I haven’t gone into a lot of the specific physiological responses, like cortisol release, because frankly, this is already a really long article.  However, now you have a good basic understanding of the effects of stress on the human body and why stress and health are so closely related.

Your body needs down time to recover from Fight or Flight, so give yourself a break from time to time and stay healthy!