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Fruits and Veggies Limit Inflammatory Protein

Posted Oct 01 2008 8:02pm
(Hat tip: Binstock)
Fruits and Veggies Limit Inflammatory Protein (with recipe)
Janet Raloff

Over the past few years, many studies have linked an increased risk of
debilitating illness—such as heart disease or diabetes—with chronically
elevated blood concentrations of a protein typically associated with
inflammation. In many cases, people with the indicated illnesses didn't
even have a particularly level of inflammation. The good news: A new trial
finds that eating plenty of fruits and vegetables reduces concentrations
of the worrisome protein.

[fot] INFLAMATION QUENCHER? The fresh veggies in this, Janet's Carrot
Salad, are among those strongly associated with decreasing the body's
production of a protein known as CRP. Because this protein usually
connotes inflammation, the new findings suggest that carrots might offer a
dietary route to moderating potentially harmful, chronic inflammation.
Raloff

In the new trial, researchers recruited people to eat a low-produce diet
for a month and then increase that dietary component. The inflammation
marker—C-reactive protein (CRP)—was slightly elevated in the participants
while they ate few fruits and vegetables, says study leader Bernhard Watzl
of Germany's Federal Research Center for Nutrition, in Karlsruhe. He
points out that the recruits were not suffering from major infections but
that some were overweight. A host of studies has demonstrated that body
fat can trigger chronic inflammation (SN: 2/28/04, p. 139: Available to
subscribers at http://www.sciencenews.org/articles/20040228/bob9.asp).
Whatever the source of CRP, research has linked artery-clogging
atherosclerosis—and risk of heart attack—to excess blood concentrations of
the protein (SN: 4/20/02, p. 244: Available to subscribers at
http://www.sciencenews.org/articles/20020420/fob4.asp).

The study found that when the participants changed from a diet low in
produce to one high in such foods, they experienced a significant drop in
blood CRP. However, no statistically significant relationship emerged
between blood concentrations of any immune cell or of other components of
the immune system and the number of servings of fruits and vegetables
people had eaten.

Watzl says his team had actually been expecting to find that feeding
adults large quantities of fresh produce would rev up their immune
systems. The study was exploring the connections among diet, immune system
effects, and cancer risk. Earlier work by his team had suggested that
people eating little produce have weakened immune defenses against cancer.

The new findings, however, suggest a different potential explanation,
involving inflammation, for why people who eat the most fruits and
vegetables typically have the lowest incidence of cancers of the breast,
lung, and gastrointestinal tract.

Are carrots the answer?

Watzl's team recruited 63 healthy, nonsmoking men to take part in a
2-month study. All were around age 30, had similar body-mass indexes, and
reported no history of taking vitamin supplements.

During the study's first 4 weeks, the men were instructed to eat normally
except for their fruit and vegetable intake. The trial limited consumption
of these foods, or juices made from them, to just two servings per day.
One serving of solid food was 100 grams (3.5 ounces). A serving of juice
was 200 milliliters (6.8 ounces).

During the next 4 weeks, the volunteers were told to consume no fruits,
veggies, or juices except those provided by the researchers. The
participants were divided into three groups that received two, five, or
eight servings of these foods per day.

The most startling impact of getting eight servings of produce and juice
per day was a drop in blood CRP. In men going from two servings to eight
servings per day, CRP concentrations fell by one-third. No statistically
significant change occurred in men going from two to five servings.

"Our intervention study is the first to show that [blood] CRP
concentrations can be modulated by the consumption of vegetables and
fruits," the authors report in the November American Journal of Clinical
Nutrition.

The researchers attribute the CRP decrease in the eight-servings-per-day
group to increases in the men's consumption of foods rich in the
carotenoids alpha- and beta-carotene—plant pigments with antioxidant
properties. Although carotenoids impart color to a host of red, orange,
and yellow fruits and vegetables, alpha-carotene—at least in the German
diet—traces primarily to the consumption of carrots, Watzl notes. He says
his new data suggest that carrots may largely explain the CRP benefit.

Recruits may have been too well nourished

Several studies in recent years have shown that eating carotenoid-rich
foods, such as tomato juice or carrot juice, can stimulate the immune
system. To gauge that effect in the current study, the researchers
measured, at the beginning and end of each phase of the new trial, blood
concentrations of white blood cells and several immune-system chemicals.
However, concentrations of neither the cells nor chemicals varied
significantly during the trial.

Watzl concludes that the reason his team found no impact of the
high-produce diet on any of the men's immune systems is probably because
eating fruits and vegetables will stimulate the immune system only in
people whose diets are below some critical threshold in certain
plant-based compounds.

Alas, he notes, "our subjects were quite well nourished." Dietary history
data for the men showed most had been routinely consuming 350 milliliters
of fruit juice daily prior to taking part in the new study.

"In my opinion," Watzl says, "the reason that we didn't see major changes
in immune function is likely related to very high concentrations of
vitamins, like vitamin C, and carotenoids in the [recruits'] blood" when
they entered the study. In fact, the men's vitamin C concentrations didn't
notably drop in the lowest-fruits-and-veggies group until about 8 weeks
into the trial, he says, suggesting a person would have to eat a
low-produce diet far longer than that to seriously deplete his or her
stores of such nutrients.

Indeed, Watzl points out, a constant frustration to nutrition researchers
is that most people who volunteer to take part in their studies are "too
healthy or have too high an intake of certain nutrients" to reflect the
population generally, much less people who are poorly nourished.

"In this study," the nutritionist notes, "we did not really restrict the
intake of carotenoid-rich vegetables" severely: The lowest intake of
produce or juices was two servings per day. That's why Watzl's aim in his
next study is look at carotenoid impacts after "extended periods of
carotenoid depletion."

Janet's Carrot Salad

If carrots fight CRP, then this could be just the side dish to keep that
inflammation marker in check. So, we are again providing the recipe for
this year-round favorite in my household. The salad can be hot or not,
depending on whether you choose to add a dash of Tabasco sauce. Adults
tend to appreciate the unexpected kick far more than kids do.

I tend to be a little heavy-handed with the condiments, but for each pound
of peeled and grated carrots, mix in at least:

* 1/2 cup dried parsley
* 1/2 cup dried or fresh mint (mince fresh leaves and keep the stems out)
* 6 tbs. garlic powder (or to taste)
* 6 tbs. powdered cumin (or to taste)
* Salt and freshly ground black pepper (to taste)

Then blend in olive or canola oil (canola has less saturated fat), about
1/3 cup. Also add at least 1/4 cup of freshly squeezed lemon juice. Stir
thoroughly.

This salad tastes best when prepared an hour ahead of time and set out at
room temperature, so the flavors can meld. It keeps up to 5 days in the
refrigerator.
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