More evidence that vitamin K helps maintain
strong bones comes from a new look at data from 888 elderly men and women
participating in the Framingham Heart Study between 1988 to 1995. Those who
reported the lowest daily vitamin K intakes in 1988 had experienced
significantly more hip fractures by the 1995 examination than those reporting
the highest intakes. There was no relationship between bone mineral density and
vitamin K intakes, however.
Dark-green leafy vegetables, like spinach and
broccoli, are rich in vitamin Kknown chemically as phylloquinone. One
serving of spinach or two servings of broccoli provide four to five times the
Recommended Dietary Allowance of 65 to 80 micrograms daily. The lowest intakes
in this study averaged 56 micrograms; the highest 254 mcg.
The new findings support others reported in
1999. Analysis of data from more than 72,000 women in the Nurses' Health Study
showed that low vitamin K intakes increased risk of hip fracture.
Researchers at the ARS-funded center in
Boston collaborated on the new study with researchers from the Hebrew
Rehabilitation Center for Aged Research and Training Institute, Harvard Medical
School and others. They reported their findings in the American Journal of
Clinical Nutrition, 2000 (vol. 71, pp. 1201-1208).
Sarah L. Booth, (617) 556-3231,
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University, Boston, MA
People who already eat a low-fat diet to
reduce cholesterol might lower it more by consuming products with high levels
of plant sterols. That's what happened when the 53 men and women in a study
consumed low- and reduced-fat salad dressing containing soybean sterols as part
of a low-fat diet.
Cholesterol reductions nearly doubled in the
volunteers when they consumed 2.2 gramsabout one-half teaspoonof
soybean sterols daily for three weeks of the six-week study. A typical American
diet provides approximately 0.25 gram of plant sterolless than one-eighth
the study levelper day.
A number of fat-based foods on the market,
such as margarines, have been enriched with plant sterols. While their
potential benefits have been studied for decades, this study was unique in
examining the sterols as an ingredient in low-fat foods and as part of a
tightly controlled low-fat diet. It was partly funded by Lipton. The sterols
are similar in structure to cholesterol and most likely lowered the volunteers'
cholesterol by limiting its intestinal absorption.
The volunteers began the study with their
levels of "bad" (LDL) cholesterol in the mildly elevated range. The
low-fat diet alone reduced their total and "bad" cholesterol levels
7.3 and 8.4 percent, respectively. With the sterols, reductions were nearly
double: 14.1 and 18.2 percent.
Curiously, cholesterol dropped in five of the
53 volunteers only when they got the sterol esters. Many people with high
cholesterol don't respond to a low-fat diet and rely on cholesterol-lowering
drugs. The question is: Could dietary plant sterols also help these
Joseph T. Judd or
David Baer, (301) 504-9014,
Beltsville Human Nutrition Research
Center, Beltsville, MD
Tiny, premature infants did just fine when
given an intravenous feeding containing far less glucose than in current
solutions. Researchers found that the 5-day-old preemies were able to make
their own glucose using amino acids and fats added to the feeding solution as
glucose replacements. This means the amount of glucose in the intravenous
solution could safely be reduced. And that would cut the risk of high blood
glucose levels without increasing the risk of glucose levels dipping too low.
Healthy, full-term babies are able to break
down their glycogen, fat and protein stores to make glucose. But very premature
infants are born before these stores develop. So they are given extra glucose
to prevent a brain-damaging drop in their blood glucose levels and to meet
their energy needs. That often produces high blood sugar, however.
When this happens, they lose precious sugar,
water and salts through the urine, putting them at risk for dehydration and
electrolyte imbalances. Excess glucose can also affect the amount of carbon
dioxide premature infants produce, exacerbating problems for those with lung
To test their metabolic capacity, the
researchers cut the glucose infusion rate by 75 percent in 20 very premature
infants while providing amino acids and a fat emulsion. Despite this reduction,
blood glucose levels remained in the normal range for all infants throughout
the 8- to 12-hour study period.
Tracers showed that the majority of the
glucose the infants produced was derived from the fat and amino acids in the
intravenous solution, confirming that they could use their own metabolic
pathway to make glucose when needed. Background on this research can be found
in Diabetes, 1999 (vol. 48, pp. 7991-800).
Agneta Sunehag, (713) 798-6725,
Children's Nutrition Research Center at
Baylor College of Medicine, Houston, TX
Results are in: Adults love the taste of ARS'
reduced-sugar, low-fat milk shakes. The shakes have less than half the sugar
and only about 10 percent of the fat in commercial shakes. The new drinks are a
remake of a low-sugar variety developed in the 1970s for USDA's School Lunch
Kids weren't crazy about them, however. Last
fall, ARS opened its doors to about 600 youngsters who taste-tested the
chocolate shakes. Some comments: "not sweet enough," "there's an
aftertaste," and "taste like cereal." An agency scientist is
working under a cooperative agreement with Devine Foods, Inc., in Philadelphia,
Pa., to refine the shakes and further develop them as a commercial
The shakes are based on ARS' technology and
contain Devine's patented composition, which reduces fat and calorie content.
Fiber content is about 2 to 2.2 percent, which qualifies the shakes as a good
source of fiber. A 10-ounce shake has as much calcium, vitamins, and minerals
as a serving of milk but has fewer calories. It also has significantly less
Richard Konstance, (215) 233-6600,
Eastern Regional Research Center,
Now there's a laboratory test that
simultaneously detects Salmonella and a deadly form of E.
coliO157:H7. Developed and validated by ARS scientists, the new test
uses a technique called fluorescent polymerase chain reaction (PCR) to detect
the two foodborne pathogens. Evaluations so far show that the test detects
between one and 10 bacterial cells in cultured samples of meat and feces.
The samples are cultured for 6 to 16 hours
prior to performing PCR, which requires only 4 hours. This makes the new test
several hours faster than standard culturing techniques now used to detect
these two pathogens. Researchers validated the test by checking artificially
contaminated beef and chicken as well as cattle feces. The test would be just
as accurate on pork.
The meat processing-industry, which
slaughters more than $50 billion worth of livestock annually, could use this
technology to meet current federal regulations that mandate zero tolerance for
visible fecal contamination and for E. coli O157:H7. Each year, about
40,000 reported cases of salmonellosis and 73,000 estimated cases of diarrheal
illness due to O157:H7 occur in the United States.
Vijay K. Sharma, (515) 663-7279,
National Animal Disease Center,
A change in the way U.S. dairy cows are fed
may give consumers one more healthful reason to drink milk. Cows grazing
pastures, or fed diets containing vegetable oil, produced five times more of a
cancer-fighting compoundconjugated linoleic acid (CLA)than cows fed
conventional diets. The human body doesn't produce CLA on its own, but the
compound is available through foods such as whole milk, butter, beef and
An ARS dairy scientist increased CLA levels
in milk from cows fed typical confinement rations by adding whole soybean and
linseed oils to a typical corn-alfalfa diet. This boosted the CLA content in
the cows' milk to levels obtained from grazing, the researchers reported in the
Journal of Dairy Science, 2000 (vol. 83, pp. 1016-1027). The findings
may also increase interest in grazing for dairy cows. Currently, only 10 to 12
percent of U.S. dairy cows are grazed.
Laboratory animals given CLA in their diets
have shown a reduction in several types of cancers and a slower progression of
atherosclerosis, a contributor to heart disease. Today, human studies of CLA
are under way at several research institutions.
Larry Satter, (608) 264-5353,
U.S. Dairy Forage Research Center,
Is the form of selenium in broccoli more
potent against cancer than other food forms of the element or than selenium
salts, as some reports suggest? A series of rat studies confirms those reports.
ARS nutritionists dramatically reduced early stages of colon cancer in rats by
feeding the animals broccoli grown in a high-selenium medium.
Broccoli stores selenium as an amino acid
called selenium methyl selenocysteine. Humans and animals simply snip the end
off this amino acid to produce the anticancer agent called methyl selenol. The
form of selenium prevalent in grains and some meats requires several chemical
conversions to produce methyl selenol. Selenium saltsthe forms used in
some supplementsconvert more readily. But it's only one step for the form
in broccoli to get there.
Using test rats, the researchers confirmed
that these differences in selenium metabolism translated to differences in risk
of colon cancer. First, they pitted broccoli having several thousand times the
selenium normally found in the vegetable against the selenium salt selenate.
After beefing up the rats' selenium levels for several weeks, they injected the
animals with a potent carcinogen. High-selenium broccoli always resulted in
fewer precancerous lesions than selenate. And the number of precancerous
lesions decreased as the dose increased.
Then the scientists confirmed the
findings using a different saltseleniteand a higher dose of
selenium. They also challenged the animals with a much more potent carcinogen.
Although many more precancerous lesions occurred, the rats fed high-selenium
broccoli had half as many as the animals getting selenite. The findings will
appear in the September issue of the Journal of Nutrition.
For more information, contact
John W. Finley or
Cindy D. Davis, (701) 795-8353,
Grand Forks Human Nutrition Research
Center, Grand Forks, ND
A new specialty fruit for the
SouthSpring Satinis now available to nurseries. A cross between a
plum and apricot, this new cultivar is the first plumcot well adapted to the
medium-high chill areas of the South. Plumcots developed in California haven't
done well in the South.
Spring Satin produces beautiful,
white flowers that bloom in mid-March. In central Georgia, the large,
high-quality fruit ripen in late Maya time of year when high-quality
fruit is in limited supply. When fully ripe, the short-fuzz plumcots have a
very good flavor. They are about two inches in diameter, with reddish-black
skin and yellowish-red flesh. This unique cross is tolerant of major plum
diseases that make commercial production difficult.
Trees will be available
commercially this winter, but consumers will have to wait to try Spring Satin.
The trees take about three years to start producing fruit for large-scale
William R. Okie, (912) 956-6405,
Fruit and Tree Nut Research Laboratory, Byron, GA
Back to Contents
Two-fifths of the U.S. population may be
carrying a gene mutation that reduces risk of heart disease in menperhaps
by as much as 30 percentaccording to a study of nearly 3,000 men and
women in Framingham, Mass. The mutation, known as B2, is common in all
populations studied but previously had not been shown to reduce heart disease
B2 keeps blood levels of the good HDL
cholesterol high. And it keeps the size of the HDL particles larger, which also
reduces risk. About 40 percent of the study volunteers had at least one B2
mutant among the gene pair. The men with even one B2 had higher HDL and larger
HDL particles than those with no mutation. HDL averaged 7 percent higher in the
men with a single mutant and 10 percent higher in the men carrying two B2s.
The finding supports clinical evidence that
for every 1 percent increase in HDL, cardiovascular disease and death drop 2 to
3 percent. Risk of cardiovascular disease among the nearly 3,000 volunteers was
30 percent lower among the men with at least one B2 mutant, the researchers
reported in Arteriosclerosis, Thrombosis and Vascular Biology, 2000
(vol. 20, pp. 1323-29). Study leaders at the ARS-funded Boston center
collaborated with researchers at several institutions.
Women carrying the mutant also had higher HDL
levels and larger HDL particles. But their risk of cardiovascular disease was
not significantly different from women with the more common B1 genes. That may
be due to women's natural hormonal protection before menopause.
Jose M. Ordovas, (617) 556-3102,
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University, Boston, MA
Fried in shortening, chocolate-glazed, and
filled with cream or jelly, doughnuts are a guilty pleasure. But ARS scientists
are hoping to ease consumer guilt by reducing the oil content of
doughnutsa breakfast favorite that generates $4-5 billion in annual
In preliminary trials, doughnuts made from
dough containing modified rice starch and other ingredients absorbed as much as
70 percent less oil during frying than traditional, all-wheat doughnuts.
Compared to all-wheat doughnuts, which had 24 to 26 grams of oil, some of the
wheat-rice flour doughnuts had about 8 grams.
When mixed in with wheat flour, the
rice-based ingredients help reduce oil uptake by making the dough more tender,
consistent and moist. Though less oily, the doughnuts' taste, texture and other
sensory properties are comparable to traditional cake doughnuts. Reduced-oil
doughnuts are just one of many potential spin-offs that may benefit rice
growers and consumers alike.
Frederick Shih, (504) 286-4354,
Regional Research Center, New Orleans, LA
Correcting a critical shortage of the body's
most potent antioxidantglutathionepromises to reverse
life-threatening complications that kill millions of malnourished Third-World
children each year. Findings of this study also could help answer a
long-standing question: Why do two very different malnutrition
syndromesone often lethal, the other very easy to treatdevelop
among children living in the same famine-stricken area?
About half of all malnourished children
develop the more serious syndrome called kwashiorkor. Although these children
might not appear very wasted, they are difficult to treat, slow to recover and
suffer death rates as high as 25 percent. By contrast, children with marasmus.
exhibit the stick-thin, big-bellied syndrome that most people associate with
severe malnutrition, but they quickly respond to treatment and nearly always
Researchers suspected that many of the
symptoms of kwashiorkor stemmed from oxidative cell damage caused by a shortage
of gluathione. Their suspicions were confirmed in a study conducted at the
University of the West Indies, Jamaica, and reported in the American Journal
of Physiology, Endocrinology and Metababolism, 2000 (vol. 278: E405-412).
Children admitted to the hospital with
kwashiorkor had much lower glutathione levels and synthesis rates and higher
levels of compounds that signal oxidative cell damage. The problem was traced
to a critical shortage of two amino acids: cysteine, which is required for
glutathione synthesis, and methionine, which the body can convert into
The next phase of the study, in which
children diagnosed with kwashiorkor are given cysteine supplements, is already
yielding positive results. Glutathione synthesis rates and blood levels are
being restored within one week. But the real test will be whether cysteine
supplementation improves the children's recovery and survival rates.
Farook Jahoor, (713) 798-7084,
Children's Nutrition Research Center at
Baylor College or Medicine, Houston, TX