The science of nutrition must is just awash with paradoxes, here are a
few.
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Diet and disease--the Israeli paradox: possible dangers of a high
omega-6 polyunsaturated fatty acid diet.
Yam D, Eliraz A, Berry EM.
Department of Membrane Research and Biophysics, Weizmann Institute of
Science, Rehovot, Israel.
Israel has one of the highest dietary polyunsaturated/saturated fat
ratios in the world; the consumption of omega-6 polyunsaturated fatty
acids (PUFA) is about 8% higher than in the USA, and 10-12% higher
than in most European countries. In fact, Israeli Jews may be regarded
as a population-based dietary experiment of the effect of a high
omega-6 PUFA diet, a diet that until recently was widely recommended.
Despite such national habits, there is paradoxically a high prevalence
of cardiovascular diseases, hypertension, non-insulin-dependent
diabetes mellitus and obesity-all diseases that are associated with
hyperinsulinemia (HI) and insulin resistance (IR), and grouped
together as the insulin resistance syndrome or syndrome X. There is
also an increased cancer incidence and mortality rate, especially in
women, compared with western countries. Studies suggest that high
omega-6 linoleic acid consumption might aggravate HI and IR, in
addition to being a substrate for lipid peroxidation and free radical
formation. Thus, rather than being beneficial, high omega-6 PUFA diets
may have some long-term side effects, within the cluster of
hyperinsulinemia, atherosclerosis and tumorigenesis.
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THE FRENCH PARADOX
When the situation in France is compared to that which is observed in
the United States, we see that only a minority of the French
population follows low-calorie diets.
Further, the average French diet contains 30% more fat than the
average American diet, and the French exercise very little or not at
all. Yet, the weight of the average French citizen is considered ideal
and France has one of the lowest rates of cardiovascular disease in
the world, with only Japan having a slightly lower rate.
This positive situation is presently being undermined in the youth
population of France. Young people under the age of 25 have adopted
American style eating habits, consuming much fast foods and sweet soft
drinks.
Numerous recent studies have shown this type of diet to be unnatural
and unhealthy. More importantly the traditionally accepted dieting
principles have proven to be completely in error.
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An Obesity Paradox
CUTLER, Calif., March 4, 2004
(AP) Farm worker Iris Caballero often has a hard time keeping the
refrigerator and cupboard stocked with food. Yet, she's overweight and
diabetic.
She is a classic example of a modern-day paradox: as reliable access
to healthy food declines, the likelihood of being overweight goes up.
The working poor like Caballero often have no time for cooking, little
money to buy fresh vegetables, and a long walk to the closest
supermarket with a good produce section.
"We have been pretending that it is easy to replace a diet of soft
drinks and fast food with home-cooked meals, fresh fruits and
vegetables," said Adam Drewnowski, a University of Washington
epidemiology professor who has studied the problem.
The problem is pronounced in what seems an unlikely place —
California's Central Valley, where much of the nation's produce is
grown. The valley also has some of the highest poverty rates.
Although being overweight is usually associated with eating too much
rather than with hunger, a growing body of research is showing that
the people who have gained the most weight in the last decade tend to
have the lowest incomes, and often go without the kind of food or the
amount they need.
Caballero's neighborhood mini-market in the isolated farming town of
Cutler offers a full array of processed foods in colorful packages —
and battered apples selling for 50 cents.
"Many people can't afford to eat the produce they pick," said
Drewnowski, who also heads a center for public nutrition. "These
people are obese, frankly, because they have no money, and some diets
are cheaper than others.
"The message has been to blame people — 'you're not choosing well,
you're not educated enough.' We forget there are people whose choices
are severely limited by finances and time allocation."
Caballero understands those limits and their consequences. During
harvest season, she picks the grapes and oranges in the groves that
surround this small town of Cutler. Fruit is available, and money is
too. The family eats relatively well.
During winter, jobs are scarce, so Caballero feeds her husband and
three children the cheapest food she can get: potatoes, bread,
tortillas.
For Caballero, who has been diabetic since she was 19, the sugar-and
fat-laden offerings of her local market are more than unhealthy:
they're dangerous. Obesity is a leading risk factor for diabetes, an
incurable condition in which the body can't break down sugars in the
blood.
Cutler Elementary, which Caballero's children attend, has so many
diabetic kids that teachers recently had an emergency workshop on how
to handle blood sugar highs and lows. This in a school where 100
percent of the kids qualify for free school lunches.
After a 15-year-old diabetic student became blind — one of the
consequences of untreated diabetes — the school sought help. Now,
Caballero and other farmworker mothers attend a free nutrition class
that considers their culinary traditions, low budgets and lack of
time.
The women come because they know that the cheapest, fastest, most
filling meal — the burger and soda that look so good at the end of a
long day in the fields — is not the healthiest for their families.
In the class, one of at least 10 groups Dolores Vallejo teaches each
week, the Spanish-speaking mothers learn to read English-language
labels. Vallejo points out that "high fructose corn syrup," "sucrose"
and "dextrose" all mean azucar — sugar. She shows them several quick,
inexpensive, low-fat recipes their families might enjoy, like
vegetable chili.
Unfortunately, most public health programs don't address such issues.
As processed foods rich in sugar and fat have become cheaper than
fruits and vegetables, the poor in particular are paying a high price
with obesity rates shooting up, followed by diabetes.
This is happening even as conditions associated with malnutrition —
like anemia, caused by an iron deficiency in diets lacking leafy
greens- continue to plague poor children, said Jay Battacharya, a
health economics expert at Stanford University's medical school.
Walking out of the nutrition class, Caballero and the other mothers
said they appreciate the tips on healthy eating. But they still have
to scrape to pay extra for real fruit juice instead of the punch they
now know is mostly sugar and water. And they still have to walk four
miles, often with their children, to and from the nearest supermarket,
where fresh produce is plentiful and less expensive.
Along the state highway linking Cutler to the supermarket in Orosi, a
new sidewalk has just been laid — a testament to the women's efforts
to feed their families better.
"I want to feed my family better food," said Irene Flores, a
farmworker with three children who stores large sacks of beans to eat
during the winter. "My husband was asking me to buy lettuce, because
he likes salads. How can I buy it at almost $2 a head?"
******
A Swiss Paradox?
Janet Raloff
Gstaad, Switzerland, has gained renown for its challenging ski trails
and celebrity sightings. Come summer, however, the area's slopes host
cows, not skiers. It now appears that milk from those cows produces
cheeses rich in some heart-healthy nutrients.
Mention omega-3 fats and most people think of fish. Indeed, oily fish
from cold ocean waters offer an especially rich source of these
heart-healthy fats, which is why the American Heart Association
recommends including fish in your diet.
Where and on what Bossie grazes appears to make a big difference in
heart-healthiness of cheeses made from her milk, a new study finds.
USDA/Ken Hammond
However, some plants also produce omega-3 fats in abundance. The
carbon-chained backbone of these plant fats tend to be shorter than
the 20- and 22-carbon version typical of fish oils, so the omega-3
fats are different. On the other hand, chemical reactions in the body
can elongate some plant fats to fishy lengths. Moreover, even at 18
carbons, the plant-derived alpha-linolenic-acid (ALA) omega-3 can
contribute to heart health, research has shown.
In general, cheeses are fatty foods. However, Jürg H. Beer of the
Canton Hospital in Baden, Switzerland, and his colleagues now report
finding that cheeses produced in alpine areas around Gstaad hold a
more heart-healthy mix of fats than do cheeses made from the milk of
cows grazing at lower altitudes. Not only were alpine cheeses highest
in omega-3 fats, such as ALA, but they also had relatively low
concentrations of saturated fats and arachidonic acid, a fatty acid
that can promote inflammation in the body. As an unanticipated
benefit, cheeses made from the milk of grass-fed alpine cows exhibited
the highest concentrations of the unusual trans fatty acid, conjugated
linoleic acid, that a number of studies have linked with cancer
prevention.
Beer acknowledged to Science News Online that even alpine cheeses
"can't compete with fish" as a source of omega-3 fatty acids. The
plant-derived omega-3s aren't as abundant nor as consistently of the
preferred length as the fatty acids from fish are. However, Beer
notes, for people concerned about mercury contamination of fish or who
just like cheese, alpine varieties appear to be a heart-healthy
choice.
Beer's team reports its new findings in the Jan. 6, 2004 Circulation.
The alpine answer to the French paradox?
Over the years, many studies have highlighted a conundrum: Though the
typical French diet contains large amounts of butter, cream, and other
foods rich in typically artery-clogging saturated fats, the French
incidence of fatal heart attacks is low. To tease out why,
epidemiologists have probed other aspects of the regional cuisine. At
present, the leading candidate to explain what has come to be known as
the French paradox is wine—a beverage that's a Gallic favorite and
rich in heart-sparing antioxidants.
Beer notes that alpine regions also have developed a reputation for
longevity—something the locals attribute to their dairy-rich diet.
Realizing that the grass-fed livestock might be grazing on
omega-3–endowed plants, the internist decided to collaborate with the
Federal Institute of Technology in Zurich to profile the fats in
various cheeses.
Altogether, the researchers sampled 12 alpine cheeses from the Gstaad
region, 7 commercially made English Cheddars, 6 cheeses from cows
whose diets had been supplemented with omega-3–rich linseeds, 7
commercially made Emmentalers (what North Americans refer to as Swiss
cheese), and 8 alpine cheeses made from the milk of cows that had
received silage corn. The alpine cheeses are traditionally hard
cheeses, unlike typical Emmentalers or Cheddars.
The researchers observed a trend. Cheeses from the milk of purely
grass-fed alpine cows had the best fat profile, followed by cheeses
from silage-fed alpine cows and linseed-supplemented cows. Lowest in
omega-3 fatty acids were the Emmentalers and then the Cheddars.
Grass-based alpine cheese contained four times as much of the plant
omega-3 ALA as did the Cheddar, more omega-3 fats in general, three
times as much conjugated linoleic acid, and 20 percent less of the
saturated fat palmitic acid.
"Surprisingly," Beer's team notes, cheese from the milk of cows
getting the linseed omega-3 supplement contained only half as much ALA
as did cheeses from grass-fed alpine cows. Emmentalers contained only
40 percent as much of this omega-3 fatty acid as alpine cheeses did.
Most people living in industrialized countries consume an average of
55 grams of cheese per day, the researchers say. That much Cheddar
would supply 62 milligrams of ALA daily—a mere 22 percent as much as
an equivalent amount of alpine cheese. In other words, just swapping
one cheese for the other could increase daily ALA consumption by 210
milligrams. The Swiss researchers cite data from a 1999 Harvard study
indicating that increasing the ALA content of the U.S. diet by 210
milligrams per day might cut the population's risk of fatal heart
attacks by 15 to 20 percent.
To test whether the ALA-rich alpine cheeses actually translate into
beneficial changes in heart risk for people, Beer's team has begun a
year-long study with local volunteers. If alpine cheeses indeed prove
heart healthy, the researchers say they'll next try to answer the
important questions of what aspects of climate, altitude, and
livestock diet contribute to the dairy products' unusual fat profile.
*******
The Mexican Paradox
by Sue Widemark
Many of us have heard of the PIMA paradox - this is the fact that
whereas the American PIMA Indians are the most obese population in the
United States, their genetically similar sister tribe which moved down
to Mexico, suffers no obesity at all! What is the difference? First,
the Mexican PIMAs eat a high carbo, low fat diet and second, they have
no cars or other modern conveniences so they get about 22 hours of
hard labor each week. For example, it's not uncommon for the Mexican
PIMA children to RUN to a school six miles away. For diversion, the
adults, having no TV or cars, endulge in active running games. People