Premium

Grey seal milk is more complex than breast milk, new study reveals: Why is this significant?

The researchers found that seal milk comprises 332 different kinds of oligosaccharides, a type of sugar that contributes to the development and health of offspring

For the analysis, the scientists took samples from an Atlantic grey seal colony on a small island off the eastern coast of Scotland. (Photo: Wikimedia Commons)

Milk from grey seals is much more complex than that of other mammals, including humans, according to a new study. The analysis revealed that seal milk had 33% more sugar molecules than in breast milk, which was previously thought to be the most complex. Scientists say that the unique sugars in seal milk may one day be used to develop medicines for humans.

The study, ‘Seal milk oligosaccharides rival human milk complexity and exhibit functional dynamics during lactation’, was published in the journal Nature on Tuesday (November 25). It was carried out by researchers at the University of Gothenburg (Sweden).

How was the study carried out?

For the analysis, the scientists took samples from an Atlantic grey seal colony on a small island off the eastern coast of Scotland. Mother seals come to the spot every fall to give birth. They stay there for about 18 days — without going to water to hunt — until their pups are weaned.

Patrick Pomeroy, a biologist at the Sea Mammal Research Unit at the University of St Andrews (Scotland), told The New York Times, “Mums come ashore pretty hefty, and they leave pretty lean… The pup just balloons from being a tiny, little, scrawny bag of bones to being basically a spherical lump, well-padded out and very fluffy.”

What did the scientists find out?

The researchers found that seal milk comprises 332 different kinds of oligosaccharides, a type of sugar that contributes to the development and health of offspring. This is the largest number of oligosaccharides that scientists have found in any kind of milk. For comparison, human milk contains, on average, 100 oligosaccharides.

Also in Explained | Human activities & coastal habitat degradation: Why India’s sea cows are under threat

These sugars also play a role in “protecting against viruses and bacteria, cultivating the initial flora of the body’s microorganisms and promoting the development of the stomach and intestinal tract,” according to a report in Phys.org.

The researchers said that seal milk could be more complex than that of others, as grey seals are exposed to extreme environmental stresses and high exposure to external dangers. A complex milk would help protect their rapidly growing young.

Story continues below this ad

The findings are crucial because the newly discovered sugar molecules could be added to breast milk substitutes to strengthen the immune system in infants.

Daniel Bojar, a senior lecturer at the University of Gothenburg in Sweden and the study’s lead author, told Phys.org, “The study highlights the untapped biomedical potential hidden in understudied wild species. Our research group is the only one in the world to analyse milk sugars from these uncharacterized mammals using mass spectrometry at that depth.”