by Sally Squires
Washington Post Staff Writer
February 27, 2001
The soda industry
pays schools millions in its efforts to sell to
students. But research suggests kids who drink a lot of
soft drinks risk becoming fat, weak-boned, cavity-prone
Americans drink more soda pop than ever before.
These popular beverages account for more
than a quarter of all drinks consumed in the United States. More
than 15 billion gallons were sold in 2000. That works out to at
least one 12-ounce can per day for every man, woman and child.
Kids are heavy consumers of soft drinks, according to the U.S.
Department of Agriculture, and they are guzzling soda pop at
unprecedented rates. Carbonated soda pop provides more added sugar
in a typical 2-year-old toddler's diet than cookies, candies and ice
cream combined. Fifty-six percent of 8-year-olds down soft drinks
daily, and a third of teenage boys drink at least three cans of soda
pop per day.
Not only are soft drinks widely available everywhere, from fast food
restaurants to video stores, they're now sold in 60 percent of all
public and private middle schools and high schools nationwide,
according to the National Soft Drink Association.
A few schools are even giving away soft
drinks to students who buy school lunches.
As soda pop becomes the beverage of choice among the nation's young
- and as soda marketers focus on brand-building among younger and
younger consumers - public health officials, school boards, parents,
consumer groups and even the soft drink industry are faced with
How healthful are these
beverages, which provide a lot calories, sugars and caffeine
but no significant nutritional value?
And what happens if you drink a
lot of them at a very young age?
Beginning tomorrow, representatives of
the soft drink industry, concerned that public opinion and public
policy may turn against them, will stage a three-day "fly-in" to
lobby Congress to maintain soft drinks sales in schools - and to
educate lawmakers on the "proper perspective" on soft drink use.
The industry plans to counter a U.S.
Department of Agriculture proposal, announced in January, that would
require all foods sold in schools to meet federal nutrition
standards. That would mean that snack foods and soft drinks would
have to meet the same standards as school lunches.
Some state legislators are already taking steps to limit soft drink
sales to youngsters. In Maryland, a bill introduced by Sen. Paul
G. Pinsky (D-Prince George's) would prohibit sales of soft
drinks and other non-nutritious foods in schools until after 3 p.m.
Current law says vending machines can't be turned on until after the
final lunch period.
Nearly everyone by now has heard the litany on the presumed health
effects of soft drinks:
But does drinking soda pop really cause
Even the staunchest critics of soft drinks say finding the
scientific bottom line on soda pop can be maddeningly tricky.
"It's hard to pull out the health
effects of soft drinks from the whole diet," says Michael
Jacobson, executive director of the Center for Science in the
Public Interest and author of a critical report on soft drinks
called "Liquid Candy: How Soft Drinks Are Harming Americans'
"There are relatively few studies on
sugars. And some studies don't distinguish between naturally
occurring sugars and refined sugars."
To help separate fact from fiction, the
Health section reviewed the latest scientific findings and asked an
array of experts on both sides of the debate to weigh in on the
Be forewarned, however: Compared with
the data available on tobacco and even dietary fat, the scientific
evidence on soft drinks is less developed.
The results can be a lot like soft
drinks themselves, both sweet and sticky.
One very recent, independent, peer-reviewed study demonstrates a
strong link between soda consumption and childhood obesity.
One previous industry-supported,
unpublished study showed no link. Explanations of the mechanism by
which soda may lead to obesity have not yet been proved, though the
evidence for them is strong.
Many people have long assumed that soda - high in calories and
sugar, low in nutrients - can make kids fat. But until this month
there was no solid, scientific evidence demonstrating this.
Reporting in The Lancet, a British medical journal, a team of
Harvard researchers presented the first evidence linking soft drink
consumption to childhood obesity. They found that 12-year-olds who
drank soft drinks regularly were more likely to be overweight than
those who didn't.
For each additional daily serving of
sugar-sweetened soft drink consumed during the nearly two-year
study, the risk of obesity increased 1.6 times.
When lead author David Ludwig and
his colleagues parsed the data to examine those possibilities,
neither explanation panned out.
Drinking soda proved to be,
"an independent risk factor for
obesity," says Ludwig.
The soft drink industry quickly took
steps to dispute the findings.
Although the study included 548
ethnically diverse youngsters attending four public schools in
Massachusetts, the NSDA knocked the research for including too few
Caucasian kids: About two-thirds of participants were white,
compared with 75 percent of the total U.S. population and 88 percent
of Massachusetts residents.
The industry response also cited an earlier study conducted by
Georgetown University's Center for Food & Nutrition Policy that
showed overweight children consumed about 14 ounces of carbonated
beverages per day - only about two ounces more than kids of normal
body weight. The Sugar Association paid for part of the Georgetown
study, which was presented last April at the Experimental Biology
2000 meeting, but it has not been published in a peer-reviewed
Obesity experts, on the other hand, called the Harvard findings
important and praised the study for being prospective. In other
words, the Harvard researchers spent 19 months following the
children, rather than capturing a snapshot of data from just one
day. It's considered statistically more valuable to conduct a study
over a long period of time.
But even those who lauded the Harvard report still underscored the
"It's only a single study, and it
needs to be repeated," says William H. Dietz, director of the
division of nutrition and physical activity at the U.S. Centers
for Disease Control and Prevention (CDC) in Atlanta.
If soft drinks do prove to contribute to
obesity, how might this happen? Is it simply a matter of drinking in
too many calories?
Again, the jury is out, and there are several competing theories.
But there are some tantalizing clues suggesting that excess calories
alone can't explain the problem. The Harvard team also conducted a
meta-analysis - a number-crunching examination of similar research
conducted over the past 25 years - to explore this question.
They concluded that drinking sugary
calories doesn't register with the brain the same way that eating
calories does. In other words, the brain seems to get confused by
these sugary liquid calories that pass quickly through the stomach;
they do not seem to trigger feelings of satiety in the same way
calories from foods do.
Absent a signal that calories have been
consumed via soft drinks or sweetened fruit juices, the stomach does
not tell the brain to quit eating at the current meal or to eat less
at the next meal. In this way, the thinking goes, excess pounds are
Ludwig found that schoolchildren who drank soft drinks consumed
almost 200 more calories per day than their counterparts who didn't
down soft drinks. That finding helps support the notion, he says,
"we don't compensate well for
calories in liquid form."
The soft drink industry doesn't buy that
"Childhood obesity is the result of
many factors. Blaming it on a single factor, including soft
drinks, is nutritional nonsense," noted Richard Adamson, NSDA's
vice president for scientific and technical affairs.
On this point, the obesity experts tend
"There are no data from the Harvard
study that allow us to make an estimate of what proportion of
obesity might be accounted for by changes in soft drink
consumption," says the CDC's Dietz.
"It's unlikely that we will be able
to tie the obesity epidemic to any single change in the way we
live. It is much more complex than that."
Though the soft drink industry admits that soda contributes to tooth
decay, most data suggest it is just one of several contributors, and
a less important one in developed countries than elsewhere in the
world. In the United States, cavities have decreased while soda
consumption has increased.
Here's one health effect that even the soft drink industry admits,
grudgingly, has merit.
In a carefully worded statement,
the NSDA says that,
"there's no scientific evidence that
consumption of sugars per se has any negative effect other than
But the association also correctly notes
that soft drinks aren't the sole cause of tooth decay.
In fact, a lot of sugary foods, from fruit juices to candy and even
raisins and other dried fruit, have what dentists refer to as "cariogenic
properties," which is to say they can cause tooth decay.
Okay, so how many more cavities are soft drink consumers likely to
get compared with people who don't drink soda? This is where it gets
A federally funded study of nearly 3,200 Americans 9 to 29 years old
conducted between 1971 and 1974 showed a direct link between tooth
decay and soft drinks. (Numerous other studies have shown the same
link throughout the world, from Sweden to Iraq.)
But here's the rub:
In the last 25 years, tooth decay in
the United States and other developed countries has actually
declined - at the same time that soft drink use and obesity have
The scientific explanation for this
phenomenon appears to come from a number of studies.
One of the most illustrative is a 1994
British study of tooth decay among 12-year-olds in 90 countries.
Conducted by statisticians at the University of Reading, the study
found that throughout the world, dental decay rises
proportionally with sugar consumption.
But when researchers examined data from
29 industrialized nations, there was no evidence of a link between
sugar and tooth decay.
"These results suggest," the
researchers reported in the British Dental Journal, "that in
addition to sugar, other factors" - including improved diet,
fluoridated water and even genetics - play an important role in
reducing tooth decay.
But sugar isn't the only ingredient in
soft drinks that causes tooth problems.
The acids in soda pop are also notorious
for etching tooth enamel in ways that can lead to cavities.
"Acid begins to dissolve tooth
enamel in only 20 minutes," notes the Ohio Dental Association in
a release issued earlier this month.
The stimulant properties and dependence potential of caffeine in
soda are well documented, as are their effects on children.
While health advocates argue that
childhood use of caffeine can lead to dependence later in life - and
that regular doses of caffeine can have negative effects on brain
development - there is no conclusive science to demonstrate this.
Ever tried going without your usual cup of java on the weekend? If
so, you may have experienced a splitting headache, a slight rise in
blood pressure, irritability and maybe even some stomach problems.
These well-documented symptoms describe
the typical withdrawal process suffered by about half of regular
caffeine consumers who go without their usual dose, according to
Kenneth S. Kendler, professor of psychiatry and human genetics
at Virginia Commonwealth University (VCU) in Richmond.
Research on caffeine's effects in children is more limited, but it
suggests that kids also experience caffeine dependence and
withdrawal. At the University of Minnesota, child psychiatrist
Gail Bernstein and her colleagues gave 8- to 12-year-old
children the equivalent of two to three cans of Diet Coke daily for
13 days. Then they substituted caffeine-free soft drinks without
telling the children and measured withdrawal symptoms.
During a computerized test 24 hours later, the children showed
significantly decreased attention, a classic symptom of withdrawal,
The soft drink industry agrees that caffeine causes the same effects
in children as adults, but officials also note that there is wide
variation in how people respond to caffeine. The simple solution,
the industry says, is to choose a soda pop that is caffeine-free.
All big soda makers offer products with either low or no caffeine.
That may be a good idea, though it raises the question of whether
soda machines in schools should be permitted to offer caffeinated
beverages or at least be obligated to offer a significant proportion
of caffeine-free products. It also raises the question of how one
determines a product's caffeine content. Nutrition labels are not
required to divulge that information.
If a beverage contains caffeine, it must
be included in the ingredient list, but there's no way to tell how
much a beverage has, and there's little logic or predictability to
the way caffeine is deployed throughout a product line.
Okay, so most enlightened consumers already know that colas contain
a fair amount of caffeine. It turns out to be 35 to 38 milligrams
per 12-ounce can, or roughly 28 percent of the amount found in an
8-ounce cup of coffee. But few know that diet colas - usually chosen
by those who are trying to dodge calories and/or sugar - often pack
a lot more caffeine.
A 12-ounce can of Diet Coke, for
example, has about 42 milligrams of caffeine - seven more than the
same amount of Coke Classic. A can of Pepsi One has about 56
milligrams of caffeine - 18 milligrams more than both regular Pepsi
and Diet Pepsi.
Even harder to figure out is the caffeine distribution in other
flavors of soda pop. Many brands of root beer contain no caffeine.
An exception is Barq's, made by the Coca-Cola Co., which has has 23
milligrams per 12-ounce can. Sprite, 7-Up and ginger ale are
But Mountain Dew, the curiously named
Mello Yellow, Sun Drop Regular, Jolt and diet as well as regular
Sunkist orange soda all pack caffeine.
Caffeine occurs naturally in kola nuts,
an ingredient of cola soft drinks.
But why is this drug, which is known to
create physical dependence, added to other soft drinks?
The industry line is that small amounts are added for taste, not for
the drug's power to sustain demand for the products that contain it.
Caffeine's bitter taste, they say, enhances other flavors.
"It has been a part of almost every
cola - and pepper-type beverage - since they were first
formulated more than 100 years ago," according to the National
Soft Drink Association.
But recent blind taste tests conducted
by Roland Griffiths at Johns Hopkins Medical Institutions in
Baltimore found that only 8 percent of regular soft drink consumers
could identify the difference between regular and caffeine-free soft
The study included only subjects who reported that they drank soft
drinks mainly for their caffeine content. In other words, more than
90 percent of the self-diagnosed caffeine cravers in this small
sample could not detect the presence of caffeine.
That's why the great popularity of caffeinated soft drinks is driven
not so much by subtle taste effects as by the mood-altering and
physical dependence of caffeine that drives the daily
And the unknown could be especially troublesome for the developing
brains of children and adolescents. Logic dictates that when you are
dependent on a drug, you are really upsetting the normal balances of
neurochemistry in the brain. The fact that kids have withdrawal
signs and symptoms when the caffeine is stopped is a good indication
that something has been profoundly disturbed in the brain.
Exactly where that leads is anybody's guess - which is to say there
is little good research on the effects of caffeine on kids'
Animal studies demonstrate that phosphorus, a common ingredient in
soda, can deplete bones of calcium.
And two recent human studies suggest that girls who drink more soda
are more prone to broken bones. The industry denies that soda plays
a role in bone weakening.
Animal studies - mostly involving rats - point to clear and
consistent bone loss with the use of cola beverages. But as
scientists like to point out, humans and rats are not exactly the
Even so, there's been concern among the research community, public
health officials and government agencies over the high phosphorus
content in the US diet. Phosphorus - which occurs naturally in some
foods and is used as an additive in many others - appears to weaken
bones by promoting the loss of calcium. With less calcium available,
the bones become more porous and prone to fracture.
The soft drink industry argues that the phosphoric acid in soda pop
contributes only about 2 percent of the phosphorus in the typical US
diet, with a 12-ounce can of soda pop averaging about 30 milligrams.
There's growing concern that even a few cans of soda today can be
damaging when they are consumed during the peak bone-building years
of childhood and adolescence. A 1996 study published in the Journal
of Nutrition by the FDA's Office of Special Nutritionals noted that
a pattern of high phosphorus/low calcium consumption, common in the
American diet, is not conducive to optimizing peak bone mass in
A 1994 Harvard study of bone fractures in teenage athletes found a
strong association between cola beverage consumption and bone
fractures in 14-year-old girls. The girls who drank cola were about
five times more likely to suffer bone fractures than girls who
didn't consume soda pop.
Besides, to many researchers, the combination of rising obesity and
bone weakening has the potential to synergistically undermine future
health. Adolescents and kids don't think long-term.
But what happens when these
soft-drinking people become young or middle-aged adults and they
have osteoporosis, sedentary living and obesity?
By that time, switching to water, milk or fruit juice may be too
little, too late.