Neu5Gc is naturally found on cell surfaces in most mammals but not
in humans. It is a non-human sialic acid sugar molecule common in red meat
that increases the risk of tumor formation in humans.
Neu5Gc is also prevalent
in pig organs, with concentrations increasing as the organs are cooked, revealed a
study by researchers from the UC Davis School of Medicine and Xiamen
University School of Medicine.
‘Neu5Gc is also prevalent in pig organs, with concentrations increasing as the organs are cooked, revealed a study.’
The research, published in Glycoconjugate Journal
suggests that Neu5Gc may pose a significant health hazard among those who regularly consume organ meats from pigs. It gets incorporated into human cells by eating meats, organs
and some dairy products.
Previous studies have shown when Neu5Gc is incorporated into human
tissues, the immune system recognizes it as a foreign threat, producing
antibodies to counter it. Repeated consumption of these meats then
causes chronic inflammation, which has been known to increase risks of
tumor formation. Neu5Gc has been linked to cancer as well as
cardiovascular and other inflammatory diseases, including some bacterial
The UC Davis and Xiamen University study is the first to find Neu5Gc
in substantially higher levels in pig organs, including the spleen,
lungs, heart, kidney and liver, than in skeletal muscle, which cooking
of the meat exacerbates.
"We were rather surprised that organ meats from pigs have alarmingly
high levels of Neu5Gc," said co-author Frederic A. Troy II, professor
and chair emeritus in the Department of Biochemistry and Molecular
Medicine and adjunct professor at Xiamen University School of Medicine.
"Although we do not know quantitatively what levels trigger an
immune response, if you're going to eat organ meat, you're going to have
a potentially greater risk of certain inflammatory diseases," he said.
The risk of Neu5Gc toxicity is particularly high in China and other
countries where people tend to consume large amounts of organ meat. In
the U.S. and other western nations where there has been a rise in the
culinary "nose-to-tail" movement in recent years, more chefs are cooking
all parts of animals. Given the results from this study, the authors
urge people to be cautious about the types of meats they ingest.
Troy and colleagues recently reported high levels of the free form
of another sialic acid, Kdn, in breast, cervical, liver, lung, throat,
ovarian and uterine cancers. They also showed that a polymeric form of
Neu5Ac, a polysialic acid, is a metastatic factor when expressed on the
cell surfaces of a number of human cancers.
For the current study, the researchers assessed the levels of three
sialic acids - Neu5Ac, Neu5Gc and Kdn - located at the end of sugar
chains frequently attached to glycoproteins and gangliosides in cellular
Glycoproteins, such as polysialylated neural cell adhesion molecules
(NCAMs), have many functions during brain development that modulate
cell-cell adhesive interactions involved in synaptogenesis, neural
plasticity, myelination and neural stem cell proliferation and
differentiation. Gangliosides serve as markers for cellular recognition
and modulate axon-myelin interactions, axon stability, axon regeneration
and modulate nerve cell excitability.
The researchers measured sialic concentrations in pig spleens,
kidneys, lungs, hearts, livers and muscle at three, 38 and 180 days
(adult) of age. Compared to skeletal muscle, the concentrations of
Neu5Gc were high in all organs, particularly heart, spleen, kidney and
lungs. Cooking increased sialic levels in most organ tissues.
Though the study was conducted in pigs, these results have ramifications for organ meat from other animals.
"The basic, fundamental biochemical pathways for synthesis and
metabolism of the sialic acids are essentially identical processes
common in all evolutionary species from 'bacteria to brains'," Troy said.
"Therefore, the translational aspect of our findings to other mammalian
species is essentially a given from a biochemical perspective."
In contrast to mice and rats, neonatal pigs are genetically closer
to humans, and share similar physiology and anatomical structures with
human infants. Importantly, the piglet brain more closely resembles the
human brain in anatomic structure and developmental growth patterns,
The study also sheds light on the developmental biology of
sialylation, as the molecular mechanisms regulating the age-related
developmental expression and function of the sialic acids are poorly
"Our new findings show that there are clear changes in levels of
these sialic acids in young and adults pigs as a function of aging, a
finding that is neither well understood nor has been previously
reported," he said.
While it's long been known that sialic acids have higher
concentrations in animal meats, no one had ever precisely measured their
concentrations in specific organs. To some degree, this was a result of
"This study would not have been possible if not for the high
sensitivity afforded by LC mass spectrometry," Troy noted. "This advance
in structural analysis thus allows studies that could not have been
done five or 10 years ago."