A new study in Nature shows grey seal milk contains the highest known diversity of oligosaccharides, surpassing even human breast milk.

Key Findings on Grey Seal Milk

• Researchers analysed milk from Atlantic grey seals in Scotland and found exceptional biochemical complexity linked to the species’ extreme breeding conditions.
• Unique Qualities 
• • Seal milk contains 332 oligosaccharides, the highest recorded in any mammal.
  • These sugars are 33% more diverse than those in human breast milk.
  • Rapid pup growth within 18 days of nursing is supported by this high-energy, immune-boosting milk.
• Scientific Significance: Complexity likely evolved due to harsh environments and the need to protect vulnerable pups.
  • Newly identified sugars could help improve infant formulas, enhancing immunity and gut development.

What Are Oligosaccharides?

• Oligosaccharides are complex carbohydrate molecules composed of short chains of sugars, naturally present in many mammalian milks.
• Biological Role of Oligosaccharides
• • Support immune defence by blocking harmful viruses and bacteria.
  • Aid in establishing the infant gut microbiome.
  • Promote development of the stomach and intestinal tract.
  • Act as prebiotics, feeding beneficial microbes essential for early-life health.
• Human Milk: These are called human milk oligosaccharides (HMOs) and they are the third most abundant solid component in breast milk after lipids and lactose.
  • More than 200 different types of oligosaccharides have been identified in human milk.

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About “Atlantic Grey Seal”

• Introduction: The term is a misnomer, as grey seals are strictly North Atlantic species, not found in the Antarctic region.
• Habitat: They inhabit temperate and subarctic waters across the western and eastern North Atlantic.
• Distribution
• • Western Atlantic: Labrador to Nova Scotia.
  • Eastern Atlantic: British Isles, Iceland, Norway, Baltic Sea.
• Diet: They feed mainly on benthic and demersal fish, along with other coastal prey.
• Behaviour and Reproduction: Grey seals are gregarious and polygynous, with late-winter breeding and intense maternal care lasting about 18 days.
• IUCN Status: They are classified as Least Concern, with several populations recovering due to reduced hunting pressures.

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