Sialic Acid in HMOs: Boosting Cognitive Health and Supporting Healthy Aging

February 28, 2025

Sialic acid is a vital nutrient that supports brain health, immune function, gut microbiome balance, and healthy aging. Incorporating it into your diet or through targeted supplementation can help unlock its full potential for lifelong wellness.

Content Outline

What is sialic acid?
- Sialic acid structure
The health benefits of sialic acid
How to get more sialic acid in your diet
Takeaway: The power of sialic acid for health and longevity

What is sialic acid?

Sialic acid is a naturally occurring sugar that’s critical for many biological processes. It’s commonly located on cell surfaces throughout the human body and participates in cellular communication, immunity, and brain health and function[i].

Sialic acids are part of a unique family of compounds called sialylated glycans and as well as cell membranes, they are also abundant in human milk where they are known to support the development of the infant brain and immune system.

Although sialic acid is known for its benefits in infants, emerging research suggests it may have important benefits for adults, particularly for healthy aging[ii]. By better understanding sialic acid’s role in the body, we can explore how boosting its levels may benefit our overall health and resilience as we age.

Sialic acid structure

Sialic acid is a subset of an ancient family of alpha-keto acid monosaccharides with a 9-carbon backbone, also known as nonulosonic acids[iii].

Source: (Chen & Varki, 2010)[iv]

There are many derivatives of sialic acid, including glycolipids or glycoproteins but the most common form in humans is N-acetylneuraminic acid or Neu5Ac.

The sialic acid structure gives the molecule versatility and allows it to interact with several biological systems. For example, it can protect cells by forming a physical barrier against pathogenic microbes[v] and promote important processes such as cellular repair and regeneration.

The health benefits of sialic acid

The structural diversity of sialic acid means it has several biological functions, including:

antiviral activity
antioxidant activity
anti-adhesion activity
anti-inflammatory properties
improved cognitive function
enhanced bone growth
prebiotic effects

In short, sialic acid is a powerhouse molecule that supports many key aspects of health, from brain development to immunity to healthy aging.

Supports brain development and cognition

Sialic acid is crucial for brain health, especially during infancy and early childhood. Sialic acid helps to form connections between nerve cells, enhancing learning and memory. However, more emerging research suggests that sialic acid may also maintain cognitive function as we age and may even have some protective benefits against neurodegenerative conditions, such as Alzheimer’s Disease[vi].

Strengthens immune function

Sialic acid has a pivotal role in defending the body against invaders. It can function as a decoy, bind to pathogens, and create a barrier to stop harmful invaders from interacting with your cells and potentially making you sick.

Additionally, sialic acid can regulate immune responses and reduce inflammation that may contribute to the development of chronic disease and aging[vii].

Promotes healthy aging

Sialic acid may play a pivotal role in promoting healthy aging in cells by supporting the repair of cell membranes which can be damaged by oxidative stress and inflammation.

Sialic acid may also counteract chronic low-grade inflammation, often called ‘inflammaging’, a major contributor to many age-related conditions, such as arthritis and heart disease.

Promotes gut health

Sialic acid also has important roles within the gut. For example, the main source of sialic acid in the human gut is mucin, a protein that’s the main component of mucus, a gel-like substance that lines the intestinal mucosal layer. This layer within the colon acts like a physical barrier between the gut and the rest of the body.

The sialic acid found on the mucosal surfaces comes from the diet, such as human breast milk, dairy products, and eggs, and can be integrated into the surface glycans lining the gut through metabolic processes.

Because sialic acid is found at the end of the mucin glycan it can directly interact with gut microbes and has an important role in interactions between the host and its microbial community[viii].

Furthermore, sialylated human milk oligosaccharides (HMOs) – HMOs with a sialic acid molecule added to the end - such as 3’-sialyllactose (3’SL and 6’sialyllactose (6’SL) which are natural prebiotics that support the growth and activity of beneficial gut bacteria and promote health.

How to get more sialic acid in your diet

So, we’ve elaborated on some of the many beneficial functions of sialic acid, but how can we get more of it to take advantage of its health-promoting qualities?

Well, there are various natural ways to increase your sialic acid levels, particularly through your diet and supplementation. In animal studies, consuming a protein-bound sialic acid source during early development was shown to enhance learning and the expression of genes associated with learning[ix].

Further studies have shown that sialylated HMOs may protect against the cartilage degradation that’s synonymous with the progression of osteoarthritis[x].

Here are some of our top tips for naturally increasing your sialic acid intake and why you may want to consider some key supplements to target various aspects of your health.

Natural food sources of sialic acid

Some foods naturally contain sialic acid, making them a convenient and excellent choice if you want to enhance your dietary intake with little effort.

Dairy products: Milk and other dairy products, including whey protein, can contain sialic acid. However, the amount of sialic acid can depend on the breed of cow but can range from 1.68 to 3.93 g/kg[xi].
Eggs: Egg yolk is particularly rich in sialic acid, containing approximately 10 times the amount that the egg white contains.
Edible birds’ nest: A Chinese delicacy produced by the swiftlet, a small bird native to Southeast Asia. The nests are made by hardened saliva that has been regurgitated by the birds and are a major feature in Chinese medicine because they are packed with nutrients including glycoproteins and sialic acid as well as iron, calcium, zinc, and magnesium[xii].
Organ meats: Some organ meats like kidneys, can contain sialic acid. However, the consumption of these may be controversial because some research has found that a non-human sialic acid called Neu5Gc can increase the risk of tumour growth with its concentration increasing when the meat is cooked[xiii].

3’-SL and 6’-SL supplements

Although the above foods can provide small amounts of sialic acid, they may not always be sufficient enough to produce the health benefits you are seeking. Instead, a more effective way to increase sialic acid levels could be through supplements, like those containing 3’-SL and 6’-SL. These are specialized forms of sialic acid that naturally occur in human breast milk and are renowned for their role in nourishing the beneficial gut microbes and promoting healthy aging.

Some of the benefits of 3’-SL and 6’-SL supplements include:

Gut microbiome modulation: 3’-SL and 6’-SL act as prebiotics and selectively feed some of the healthy bacteria in your gut, like A low abundance of this genus is found in people with specific health conditions like irritable bowel syndrome (IBS) and type 2 diabetes[xiv].
Cognitive function: Animal studies demonstrate that sialylated HMOs can enhance cognitive performance because they can increase gangliosides, fatty compounds important for cellular communication, in the brain through the provision of sialic acid.
Brain health: Sialylated HMOs can increase the production of short-chain fatty acids (SCFAs) by probiotic bacteria, contributing to brain health. For example, an increased production of butyrate could protect against cognitive decline[xv] and reduce neurodegeneration[xvi].
Bone health: Research shows that 3’-SL is a positive regulator of bone homeostasis, promotes bone formation, and alleviates bone loss in osteoporosis mouse models[xvii].

You can increase your consumption of sialylated HMOs, like 3’-SL and 6’-SL with our SuperHMO Prebiotic Mix and SuperHMO Synbiotic, available from our shop.

More lifestyle tips for healthy aging

Many of the benefits of sialic acid and sialylated HMOs are associated with healthier aging and longevity. You can maximize the benefits of sialic acids by pairing it with other health habits, such as:

eating balanced, nutrient-dense foods that support cellular health like fruits, vegetables, whole grains, healthy fats, and proteins
getting regular exercise to promote gut health, lower inflammation, and prolong movement and joint health
managing stress with relaxation techniques, activities, and hobbies and prioritising sleep

You can find out more about healthy aging with our ‘7 ways to slow aging’ blog.

Takeaway: The power of sialic acid for health and longevity

Sialic acid is crucial for supporting brain function, and immune health, and modulating the gut microbiome while promoting healthy aging. You can incorporate natural food sources and supplements like the SuperHMO Prebiotic Mix to harness its benefits and enhance your overall wellness and promote vitality and longevity.

Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome.