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 Hans H. Stein at the University of Illinois knew he could help.
The new index, known as the digestible indispensable amino acid
score (DIAAS), parses out the digestibility of individual amino
acids making up proteins. And it relies on pigs, not rats, as
the preferred model for humans.
Stein has been evaluating nutrient digestibility, including
amino acids, in pigs for 30 years.
“The FAO determined the pig is the preferred model for humans
when you evaluate proteins, moving away from the rat, which had
been used for the last hundred years. They also recommended
human foods should be evaluated exactly the same way as we
evaluate feed ingredients for pigs. So, when I saw that I
thought, ‘Well, we know how to do this,’” says Stein, professor
in the Department of Animal Sciences and the Division of
Nutritional Sciences at Illinois. “We started doing some
research in this area and published the very first paper on
DIAAS values for proteins in 2014.”
His team has completed multiple studies since then, including a
new one published in the British Journal of Nutrition. In this
work, Stein and his co-authors show meat products, including
ribeye steak, bologna, beef jerky, and more, score above 100 on
the DIAAS chart, meaning their amino acids are highly digestible
and complement lower-quality proteins.
“If the protein quality is greater than 100, that means it can
compensate for low protein quality in another food. In
developing countries where people are eating a lot of maize or
rice, they are typically undernourished in terms of amino acids.
But if they can combine that with a higher-quality protein such
as a small amount of meat, then you have improved quality
overall,” Stein says.
Other meats, as well as dairy products, have already been shown
to have high DIAAS scores, but this is the first study to
evaluate cooked and processed meat products. Since cooking and
processing can affect proteins, Stein knew it was important to
feed the pigs the same form of meats that humans consume.
“We did feed ribeye steaks to the pigs,” Stein says. “They loved
it.”
Nine pigs were fed each of nine meat products for a week:
salami, bologna, beef jerky, raw ground beef, cooked ground
beef, and ribeye roast cooked medium-rare, medium, and
well-done. Researchers collected material from the ileum, part
of the small intestine, through a small surgically placed port
called a cannula. Amino acid digestibility and DIAAS scores were
calculated for various human age groups using this material.
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For all the meat products and age groups, DIAAS
values were generally greater than 100 regardless of processing,
although scores tended to be higher when calculated for older
children, adolescents, and adults than children between 6 months and
3 years of age.
“The reason for that is the amino acid requirement, and the
requirement for higher quality protein, is greater for younger
children because they’re actively growing. Adults don't necessarily
need a very high protein quality because their protein needs are not
very high, unless they are bodybuilders or nursing women,” Stein
says.
The results also showed bologna and medium-cooked ribeye steak
offered the highest DIAAS values in the study for the older
children, adolescents, and adults age group. That bologna, a highly
processed, low-cost meat product, offers high-quality protein could
come as welcome news for lower-income families.
Stein points out that meat proteins aren’t the only low-cost option.
His earlier research shows milk and other dairy products are
excellent sources of protein for children. And he plans to evaluate
fish, eggs, plant-based meats, and more products in the future.
The article, “Most meat products have digestible indispensable amino
acid scores that are greater than 100, but processing may increase
or reduce protein quality,” is published in the British Journal of
Nutrition
[DOI: 10.1017/S0007114520000641]. Authors include Hannah Bailey,
John Mathai, Eric Berg, and Hans H. Stein. Funding for the research
was provided by the National Cattlemen’s Beef Association.
The Department of Animal Sciences and the Division of Nutritional
Sciences are part of the College of Agricultural, Consumer and
Environmental Sciences at the University of Illinois.
[Source: Hans Stein
News writer: Lauren Quinn] |
