Live Better, Live Longer; The New Studies That Reveal What's Really Good---and Bad---for Your Health

832019 Live Better Live Longer The New Studies That Reveal Whats Really Good---and Bad---for Your Health

httpslidepdfcomreaderfulllive-better-live-longer-the-new-studies-that-reveal-whats-really-good-and 112



Note to Readers

Medicine is an ever-changing science and as new research or clinical experience in-

creases our knowledge it may change diagnosis and treatment The authors have checkedwith sources believed to be reliable in their efforts to provide information that is generally

in accord with the standards accepted at the time of publication The information in this

book is not intended as a substitute for advice from your doctor It is impossible to list ev-

ery risk or bene1047297t associated with diagnostic tests medications lifestyle changes and

herbal and alternative medicines and individual experiences may vary Individual readers

are solely responsible for their own health care decisions the authors and the publisher do

not accept responsibility for any adverse effects individuals may claim to experience

whether directly or indirectly from the information contained in this book

The fact that an organization or Web site is listed in the book as a potential source of

information does not mean that the authors or publisher endorse any of the informationthey may provide or recommendations they may make

983124983112983119983117983105983123 983108983125983118983118983109 983106983119983119983115983123

An imprint of St Martinrsquos Press

983116983113983126983109 983106983109983124983124983109983122 983116983113983126983109 983116983119983118983111983109983122 Copyright copy 2010 by Drs Sanjiv Chopra and Alan Lotvin

with David Fisher All rights reserved Printed in the United States of America For infor-

mation address St Martinrsquos Press 175 Fifth Avenue New York NY 10010

wwwthomasdunnebookscom

wwwstmartinscom

The Library of Congress has cataloged the hardcover edition as follows

Chopra Sanjiv

Doctor chopra says medical facts and myths everyone should know Sanjiv Chopra and

Alan Lotvin with David Fishermdash1st ed

p cm

Includes bibliographical references and index ISBN 978-0-312-37692-5

1 Medicine Popular 2 MedicinemdashMiscellanea 3 Medical misconceptions

I Lotvin Alan II Fisher David III Title

RC82C4638 2011

616mdashdc22

2010038890

ISBN 978-0-312-37693-2 (trade paperback)

Originally published under the title Doctor Chopra Says

First St Martinrsquos Grif1047297n Edition March 2012

10 9 8 7 6 5 4 3 2 1



Often I begin my lectures by asking everyone in the audience who

has at least two cups of coffee most days to raise their hands

Usually the majority of people do so Then I ask how many of them

have at least four cups a day and fewer hands are raised Finally I askhow many of them average six or more cups of coffee a day In response

there is always some ner vous laughter and rarely more than a few

hands raised Thatrsquos when I surprise my audience ldquoGood for yourdquo I tell

those few people ldquoYoursquore doing your liver a big favorrdquo

Coming from me a liver specialist that is high praise indeed

In the past drinking too much coffee supposedly had been linked

to a variety of health problems including heart attacks birth defects

pancreatic cancer osteoporosis and miscarriages We do know that

coffee can cause insomnia tremors and it can raise blood pressure and

increase urination But more recent evidence indicates that rather than

being dangerous coffee may also offer substantial bene1047297ts including

protection against heart disease Type 2 diabetes liver cirrhosis Par-

kinsonrsquos disease cavities colon cancer prostate cancer and even sui-

cide It is known to bring relief for asthma increase endurance and

concentrationmdashsome major league baseball players are known to drink

as many as six cups of coffee during a gamemdashand increase the absorp-

tion of other medications It can be used to treat headachesmdashpopular

1 Is Coffee Truly

a Lifesaver



6˙

Food and Drink

over-the-counter pain medications contain as much caffeine per pill as a

large cup of joe And contrary to conventional wisdom it appears to lower

the risk of being hospitalized for an ar-

rhythmia What is most surprising is

that so few people realize how much

value there is in a cup of coffee Or

in fact several cups of coffee

According to legend in about

1000 983137983140 the shepherd Kaldi from the province of Kaffa in Ethiopia

noticed that the sheep in one pasture were far more active than thosein the nearby herds The cause of that he determined were the odd

ldquocherriesrdquo they were eating He tried one himselfmdashand felt its energiz-

ing effects Soon the local monks were using this fruit to help them

stay awake at night Eventually coffee was exported to Yemen and the

1047297rst known coffeehouse opened in Istanbul in 1471 Initially the con-

servative religious leaders of the Middle East forbade it because of its

stimulating abilities but eventually it spread throughout Europe andbecame a popular and pro1047297table beverage By 1675 there were more

than 3000 coffeehouses in England

The health bene1047297ts of coffee have been debated for centuries Cof-

fee has been blamed for everything from infertility to causing rebellions

In 1674 for example English women complained that this ldquonauseous

Puddle-water has Eunucht our Husbands they are become as

impotent as Agerdquo

But while many people still believe coffee can be dangerous nu-

merous large studies indicate that drinking coffee actually provides

considerable protection against sev-

eral serious diseases andmdashthis is

even more remarkablemdashmany people

should be drinking more coffee not

less

While most medical studies begin with a speci1047297c premise to be

tested considerable information can be gleaned from statistical analy-

sis of information collected with no speci1047297c goal One of the largest of

What is most surprising is

that so few people realize

how much value there is in a

cup of coffee

Many people should be

drinking more coffee

not less



Is Coffee Truly a Lifesaver˙

7

those observational collections was compiled by the Kaiser Perman-

ente Medical Care Program KP had been founded during World War

II as a prepayment medical plan for employees of Kaiser Shipyards

and expanded coverage after the war In the 1960s according to cardi-

ologist Dr Arthur Klatsky an investigator at that companyrsquos research

division ldquoKaiser Permanente began a study to determine which [medi-

cal] tests were worth doing and which tests were not This involved

setting up a computerized database to store information from health-

checkup examinations Although the computers were rudimentary

the database made it possible to perform a study of heart attack pre-dictors matching a wide diversity of known risk factors The study was

conceived by Dr Gary D Friedman as basically a search for new heart

attack predictors

ldquoCounting all history queries and measurements there were about

500 items and some of them would prove predictive of heart attacks

One was that abstinence from alcohol predicted a higher risk from

heart attacks compared to light or moderate drinkers That was not apre-study hypothesis and it led us to further explore alcohol and

health I was able to obtain grant money to create a new data base

about alcohol habits from 1978 to 1985 It consisted of about 129000

people from a multi-ethnic group We used that data base to look at

subsequent medical eventsmdashfor example hospitalization or death from

a speci1047297c cause like heart disease or cancer We published the

alcoholndashheart attack study in 1974rdquo

Another study from the same database 1047297rst published in 1992 and

updated in 2006 reported an inverse relationship between coffee and

liver cirrhosis Coffee lowered the blood level of liver enzymes aston-

ishingly the study found that the more coffee people drank the less

chance they would develop alcoholic cirrhosis Each cup daily ac-

counted for a 20 percent reduction in risk For example alcohol drink-

ers could reduce the chance of cirrhosis by 80 percent by drinking

four cups of coffee daily

The reason for this is not known ldquoEpidemiology doesnrsquot determine

mechanismsrdquo explained Dr Klatsky ldquoit usually shows only associations



8˙

Food and Drink

I was surprised at the strength of the apparent protection When you

see something that is reduced 60 70 80 percent that is a very major

reduction risk Thatrsquos what we found in the relationship between

heavy coffee drinking and the likelihood of developing cirrhosis Itrsquos

very important to mention that the best way to reduce the risk of alco-

holic cirrhosis is to limit alcohol intake not to cover heavy drinking by

taking coffee

ldquoI wish we knew a lot more about the coffee-cirrhosis link We wish

we knew what type of coffee people drink whether they put cream or

sugar in it whether they 1047297lter it whether itrsquos caffeinated or decaffein-ated but all we know is the number of cups per day We did a sub-

sample of about 10000 people and people who drink a lot of coffee

generally four or more cups a day almost always drink caffeinated

coffeerdquo

Personally Dr Klatsky states he has ldquotwo cups of coffee in the morn-

ing and sometimes a cup at noon but otherwise it keeps me awake

Threersquos my maximumrdquoThe curious bene1047297ts of coffee reported in this study may possibly

extend to other diseases affecting the liver In August 2007 the jour-

nal Hepatology reported that 10 different studies conducted in

Europe and Japan showed that people who drink coffee have a sig-

ni1047297cantly reduced chance of developing liver cancer The studies in-

cluded about 240000 people including 2260 suffering from liver

cancer and showed that people who drank at least several cups of cof-

fee every day had less than half the chance of being diagnosed with

liver cancer than study participants who drank no coffeemdashthe odds

dropped by 23 percent with each daily cup As in Dr Klaskyrsquos study

there was no attempt made to determine the reason for this decline in

liver cancer thatrsquos the type of work done in laboratories by scientists

though there is some speculation that coffee causes liver enzymes to

become stronger

It has been my experiencemdashand this is anecdotal evidencemdashthat

coffee lowers liver enzymes which is quite desirable prevents liver 1047297-

brosis (scarring) reduces the rate of hospitalization from chronic liver




9

disease and reduces the risk of eventually developing liver cancer We

know that coffee is insulin sensitizing there are people whose pan-

creas produces suf1047297cient insulin but for some reason it does not have

its desired target effect Coffee sensitizes cells to insulin so that it

does have the necessary effect Another recent study from the Har-

vard School of Public Health Beth Israel Deaconess Medical Center

showed that coffee drinkers have high levels of plasma adiponectinmdash

thatrsquos important because low levels of plasma adiponectin have been

linked with aggressive liver disease And 1047297nally four cups of coffee a

day has been shown to reduce the incidence of very painful gout by asmuch as half

This impact on insulin may have another vitally important bene1047297t

While previous studies had failed to 1047297nd a link between coffee drink-

ing and prostate cancer a National Institutes of Healthndash funded study

published in 2009 followed 50000 male health professionals for two

decades and found that men who drank six or more cups of caffein-

ated or decaffeinated coffee daily reduced their chances of developingadvanced prostate cancer by 60 percent men who had four or 1047297ve

cups saw a 25 percent reduction and drinking up to three cups pro-

vided a 20 percent lower risk compared to people who did not drink

coffee

While the reasons for this impact are not known one of the au-

thors of the study Harvardrsquos Kathryn Wilson speculated ldquoCoffee has

effects on insulin and glucose metabolism as well as sex hormone lev-

els all of which play a role in prostate cancerrdquo

If thatrsquos all it did it would still be remarkable but there is a rapidly

growing body of evidence that it has other real bene1047297ts No one can

patent coffee not even Starbucks so studies about the effects of cof-

fee have to be conducted by large public- oriented groups Researchers

at the Harvard School of Public Health and Brigham and Womenrsquos

Hospital conducted their own 125000-person study from 1980 to

1998 which revealed another impressive bene1047297t of coffee People who

drink coffee regularly can signi1047297cantly reduce their risk of Type 2 or

adult-onset diabetes The results were impressive Men who drank six



10˙

Food and Drink

or more cups of caffeinated coffee daily reduced their risk for this ter-

rible disease by more than 50 percent women who drank the same

amount reduced their risk by almost 30 percent

Those 1047297ndings were con1047297rmed by a meta-analysis conducted at

Australiarsquos University of Sydney A team of international researchers

examined 18 studies involving more than 450000 participants and

their meta-analysis found ldquoEvery additional cup of coffee consumed

in a day was associated with a 7 percent reduction in the excess risk of

diabetesrdquo

In both of these studies it really was quantity that mattered In theworld of coffee quality is in the cup of the holder The philosopher

Voltaire was purported to drink as many as 50 small cups of coffee a

daymdashand died in 1778 at age 83 While that certainly seems extreme

in the Harvard study those people who consumed fewer than four

normal-size cups daily reduced their risk of contracting Type 2 diabe-

tes only by about 2 to 7 percent But adults who routinely had four or

1047297ve cups reduced their risk by 30 percent And six or more cups Anextraordinary 50 percent Oddly that study showed that for women

drinking 1047297ve or more cups a day provided no additional bene1047297ts Like

the Australian study the Harvard study did examine the difference

between caffeinated and decaffeinated coffee and found that for men

drinking four or more cups daily of decaffeinated coffee reduced the

risk of developing diabetes by 25 percent and for women by 15 per-

cent so clearly there are bene1047297ts no matter what type of coffee you

drinkmdashas long as you drink a lot of it

Further con1047297rming this link was an 11- year study beginning in

1986 conducted at the University of Minnesota examining the rela-

tionship between coffee and diabetes in postmenopausal women

Women who drank six or more cups of any type of coffee were 22 per-

cent less likely to be diagnosed with diabetes than women who drank

no coffee Surprisingly especially to those people who believe the me-

dicinal value of coffee is derived from its caffeine content women

who drank six or more cups of decaffeinated coffee reduced their risk

by 33 percent The present theory about why there has consistently




11

been a difference in the bene1047297ts of heavy coffee intake in men and

women is that womenrsquos hormones or more often hormone-replacement

drugs in postmenopausal women mitigate the effect

Another analysis this one conducted by Harvard with researchers

working with colleagues from the Universidad Autoacutenoma de Madrid

investigated the link between coffee

and strokes in women Because cof-

fee does stimulate the heart there

has been a supposition that too much

coffee might cause heart problemsFor that reason it was long believed

that drinking a substantial amount

of coffee could be very dangerous In

fact this study showed exactly the

opposite effect Using data from the Nursesrsquo Health Study in which

83000 women regularly completed food frequency questionnaires

including about coffee consumption for 24 years researchers discov-ered that women who drank two or three cups of coffee a day reduced

their risk of stroke by 19 percentmdashand the more coffee they drank the

greater the reduction Women who did not smoke reported even greater

bene1047297ts nonsmoking women who drank four or more cups of coffee a

day reduced their risk by an amazing 43 percent This level of risk re-

duction is on par with the impact of some of the best-selling drugs in

the world

Although the reasons for this are not known there is some very

interesting associated data It turns out that these bene1047297ts are not as-

sociated with caffeinated tea or soft drinksmdashand people who drank at

least two cups of decaffeinated coffee did show a reduced risk for

stroke According to epidemiologist Esther Lopez-Garcia one of the

directors of the study ldquoThis 1047297nding supports the hypothesis that com-

ponents in coffee other than caffeine may be responsible for the po-

tential bene1047297t of coffee on stroke riskrdquo This is an important point

Coffee like wine has hundreds of component chemicals including po-

tassium magnesium vitamin E and antioxidants It is naiumlve to believe

Because coffee does

stimulate the heart there

has been a supposition that

too much coffee might

cause heart problems In

fact this study showed

exactly the opposite effect



12˙

Food and Drink

that only one of those substances is some sort of magic bullet Research-

ers in the University of Sydney diabetes study reached the same conclu-

sion pointing out ldquoOur 1047297ndings suggest that any protective effects of

coffee are unlikely to be solely effects of caffeine but rather as has

been speculated previously they likely involve a broader range of chemi-

cal constituents present in these beverages such as magnesium lignans

and chlorogenic acidsrdquo

A companion study to the Nursesrsquo Health Study published in the

Journal of Internal Medicine in 2008 followed more than 40000 male

health professionals for 18 years and concluded that men who drank1047297ve cups of coffee a day reduced their risk of dying from heart disease

by 44 percent In fact men who drank more than 1047297ve cups of java

every day were 35 percent less likely to die from any cause while women

who drank between four and 1047297ve cups reduced their risk of mortality by

26 percent

According to a Swiss study that reduced risk is seen even in people

who have suffered heart attacks The Stockholm Heart EpidemiologyProgram enrolled more than 1300 men and women who had a con-

1047297rmed heart attack between 1992 and 1994 Eight years later those

patients who normally drank between one and three cups of coffee

daily reduced their risk of death by a third over those people who aver-

aged less than a cup a day while those participants who consumed

four to 1047297ve cups reduced their risk of suffering a fatal heart attack al-

most by half

While it has long been accepted that people with heart arrhythmia

should avoid coffee another Kaiser Permanente long-term prospective

study published in March 2010 reported just the opposite People who

drank at least four cups of coffee daily were almost one-1047297fth less likely

to be admitted to a hospital with a heart rhythm disturbance than

non-coffee drinkers Dr Klatsky and colleagues analyzed data col-

lected from more than 130000 people over a seven- year period and

found that the reduced risk extended to the various types of rhythm

disturbance Dr Klatsky admitted that ldquoThis [study] is going to sur-

prise people I think conventional wisdom is that coffee can cause




13

palpitations and it can cause rhythm problems I think though that

conventional wisdom is not always right and the data that were avail-

able before this study do not support the idea that moderate amounts

of coffee provoke rhythm problemsrdquo

Dr Klatsky pointed out that ldquowersquore not going to recommend that

people drink coffee to prevent rhythm problemsrdquo but that people who

drink a moderate amount of coffee can be reassurred they are not in-

creasing their risk of signi1047297cant heart rhythm problemsrdquo

There may well be even more bene1047297ts to drinking a lot of coffee

Both the Kaiser Permanente study and the Nursesrsquo study indicatedthat heavy coffee drinkers were less likely to commit suicide and

men but not women had a reduced risk for Parkinsonrsquos disease In

2000 the Journal of the American Medical Association reported that

a federally funded study of 8000 Hawaiian men found that those

who didnrsquot drink coffee had double the risk of getting Parkinsonrsquos

than men who drank four ounces to four cups of coffee a day While

these links are not as statistically compelling as the reduction in cir-rhosis or diabetes theyrsquore certainly worth considering Again no one

knows precisely why this is true but it is known that in Parkinsonrsquos

patients the cells that produce the chemical dopamine have stopped

working and caffeine increases the production of dopamine in the

brain

Every year I spend four weeks attending on the hepatology ser vice

at Beth Israel Deaconess Medical Center a major teaching af1047297liate of

Harvard Medical School For the last several years Irsquove been telling

every student resident and fellow on our liver ser vice to ask all our

patients how much coffee they drink And what Irsquove heard over and

over is that none of these patients with severe liver disease drinks cof-

fee Itrsquos remarkable how consistent that has been But one year on my

last day a resident approached me smiling broadly and said ldquoDr Cho-

pra Irsquove 1047297nally got a patient who drinks coffeerdquo

ldquoTell me about himrdquo I said

ldquoThis was a patient admitted with cellulitis He drinks four cups of

regular coffee a dayrdquo



14˙

Food and Drink

When I took my own history I asked him ldquoPlease tell me about

tea and coffeerdquo

ldquoI donrsquot drink teardquo he said ldquoBut I love coffeerdquo I asked him if he drank

regular or decaf ldquoRegularrdquo I asked him how many cups he drank every

day ldquoFour cupsrdquo What size ldquoUsual sizerdquo Then I asked one more ques-

tion ldquoHow long have you been drinking coffeerdquo

And matter-of-factly he responded ldquoEver since my liver transplantrdquo

Well no wonder coffee hadnrsquot prevented his disease I then asked

ldquoDid someone tell you to drink coffee after your transplantrdquo

He shook his head ldquoNo but after my transplant I suddenly had thisincredible urge to drink coffeerdquo

Personally I love coffee and drink about four or 1047297ve cups a day

Usually with skim milk or black but no sweetener My collaborator Dr

Lotvin drinks between three and 1047297ve cups of black coffee daily Once

I was asked to compare the bene1047297ts of drinking coffee to exercising in

patients with Type 2 diabetes After thinking about it for a moment I

said ldquoTheyrsquore both quite bene1047297cial It seems to me that the best thingto do is run to Starbucksrdquo

But before you run out and start chugging coffee by the pot please

remember that coffee does have some negative effects on a lot of

people It can keep you awake at night It may be dangerous for people

with serious cardiac arrhythmias It can worsen heartburn and also

the symptoms of irritable bowel syndrome It can raise your blood

pressure and make you irritable And some studies have shown that

drinking two or more cups a day does increase the risk of a miscar-

riage for pregnant women and may result in lower-weight babies But if

you can drink a considerable amount of coffee without any repercus-

sions some very good studies indicate you may well be adding an ad-

ditional layer of protection against some very dangerous diseases If

you intend to start drinking start slow have half a cup If there is no

problem have a full cup See how you feel And if it doesnrsquot affect you

go ahead have another cup



Note to Readers

Medicine is an ever-changing science and as new research or clinical experience in-

creases our knowledge it may change diagnosis and treatment The authors have checkedwith sources believed to be reliable in their efforts to provide information that is generally

in accord with the standards accepted at the time of publication The information in this

book is not intended as a substitute for advice from your doctor It is impossible to list ev-

ery risk or bene1047297t associated with diagnostic tests medications lifestyle changes and

herbal and alternative medicines and individual experiences may vary Individual readers

are solely responsible for their own health care decisions the authors and the publisher do

not accept responsibility for any adverse effects individuals may claim to experience

whether directly or indirectly from the information contained in this book

The fact that an organization or Web site is listed in the book as a potential source of

information does not mean that the authors or publisher endorse any of the informationthey may provide or recommendations they may make

983124983112983119983117983105983123 983108983125983118983118983109 983106983119983119983115983123

An imprint of St Martinrsquos Press

983116983113983126983109 983106983109983124983124983109983122 983116983113983126983109 983116983119983118983111983109983122 Copyright copy 2010 by Drs Sanjiv Chopra and Alan Lotvin

with David Fisher All rights reserved Printed in the United States of America For infor-

mation address St Martinrsquos Press 175 Fifth Avenue New York NY 10010

wwwthomasdunnebookscom

wwwstmartinscom

The Library of Congress has cataloged the hardcover edition as follows

Chopra Sanjiv

Doctor chopra says medical facts and myths everyone should know Sanjiv Chopra and

Alan Lotvin with David Fishermdash1st ed

p cm

Includes bibliographical references and index ISBN 978-0-312-37692-5

1 Medicine Popular 2 MedicinemdashMiscellanea 3 Medical misconceptions

I Lotvin Alan II Fisher David III Title

RC82C4638 2011

616mdashdc22

2010038890

ISBN 978-0-312-37693-2 (trade paperback)

Originally published under the title Doctor Chopra Says

First St Martinrsquos Grif1047297n Edition March 2012

10 9 8 7 6 5 4 3 2 1























1 Is Coffee Truly

a Lifesaver



6˙

Food and Drink





























less







cup of coffee



not less




7












attack predictors























8˙

Food and Drink







taking coffee






coffeerdquo
















become stronger







9



















coffee
















10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo



















































1 Is Coffee Truly

a Lifesaver



6˙

Food and Drink





























less







cup of coffee



not less




7












attack predictors























8˙

Food and Drink







taking coffee






coffeerdquo
















become stronger







9



















coffee
















10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo































6˙

Food and Drink





























less







cup of coffee



not less




7












attack predictors























8˙

Food and Drink







taking coffee






coffeerdquo
















become stronger







9



















coffee
















10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo
































7












attack predictors























8˙

Food and Drink







taking coffee






coffeerdquo
















become stronger







9



















coffee
















10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo































8˙

Food and Drink







taking coffee






coffeerdquo
















become stronger







9



















coffee
















10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo
































9



















coffee
















10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo































10˙

Food and Drink









diabetesrdquo



























11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo
































11






















the world











Because coffee does









12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo































12˙

Food and Drink














26 percent








most by half














13




















brain















14˙

Food and Drink


tea and coffeerdquo
































13




















brain















14˙

Food and Drink


tea and coffeerdquo































14˙

Food and Drink


tea and coffeerdquo





























Live Better, Live Longer; The New Studies That Reveal What's Really Good---and Bad---for Your Health

Documents

Transcript of Live Better, Live Longer; The New Studies That Reveal What's Really Good---and Bad---for Your Health