Animal molecule found in meat and drugs 'could damage health'

The non-human sugar is also present in meat and could help explain dietary associations with heart disease and cancer, say scientists.

Sialic acids are found in all mammals and coat the surfaces of cells, allowing them to interact with their companions and the surrounding environment.

At the same time the sugars are targets for infectious diseases such as influenza, malaria and cholera.

Humans lack one type of sialic acid that is found in many other mammals, including our close relatives chimpanzees and gorillas.

When the animal version, known as Neu5Gc, finds its way into the human body it triggers an immune response that can have a damaging inflammatory effect in some individuals, said the researchers.

The US scientists found that many modern biotech drugs derived from animal sources – some of which are used to treat inflammatory disorders – are contaminated with the sugar.

"It's reasonable to suggest that for some patients who have problems with some drugs, this may be part of the reason why," said Professor Ajit Varki, who led the research published in the journal Nature Biotechnology.

Prof Varki, from the University of California at San Diego, said: "Sialic acids are required for survival, but they're also used to attack you. They are crucial for things like brain plasticity and kidney function, but lots of pathogens (harmful agents) attach to them, and some even coat themselves with these sugars to avoid detection."

Previously it was believed that healthy human immune systems were untroubled by non-human sialic acid.

"Now we know that to be untrue," Prof Varki added. "It's part of our diet, and especially abundant in red meat.

" We all develop antibodies to Neu5Gc, but this immune response varies greatly in people."