A study, exploring mammal milk's potential as a substitute for human milk oligosaccharides (HMOs) in infant formula, found that goat milk oligosaccharides were the most suitable substitute, closely resembling the structure of HMOs in several ways.
It’s well established that human breast milk is the gold standard of infant nutrition. This is partly due to its high concentration of human milk oligosaccharides (HMOs), accounting for roughly 20% of the milk's carbohydrate content.
What makes HMOs so special is still largely unknown, but one thing is for sure: they play a significant role in establishing a healthy microbiome in infants.
According to Dr Regina Karim, global senior science manager at H&H Group, despite being non-digestible carbohydrates with no direct nutritional value, HMOs act as prebiotics, supporting the growth of beneficial bacteria in the gut. In turn, HMOs strengthen the gut barrier's function, acting as decoy receptors that prevent pathogens from attaching to the gut. Instead, pathogens get trapped by HMOs and are flushed away, providing a crucial immunity protection function.
While the benefits of HMOs are clear, breastfeeding is not always a viable option, and many turn to infant formulas to provide essential nutrition to babies.
This has spurred many researchers and companies across the food and beverage industry to explore alternatives and HMO replications. Namuh and Ginkgo Bioworks, for example, are working to develop HMOs using precision fermentation, while a team of scientists from the University of California discovered a way to genetically engineer plants to produce HMOs.
These HMO advancements could change the future of infant nutrition, yet one of the biggest hurdles to achieving this on an industrial scale is that synthetically producing HMOs is costly and complex.
A review, published in the Comprehensive Reviews in Food Science and Food Safety Journal, by a team from the College of Food Science and Engineering at Northwest A&F University in Xianyang, China, explored the possibilities of obtaining milk oligosaccharides (MOs) from other mammals as potential substitutes for HMOs in infant formula. The MOs of six mammals – goat, cow, yak, camel, donkey, and pig – were compared to HMOs to determine which one, if any, was the most suitable as a human milk substitute.
The team found that goat milk oligosaccharides (goat MOs) were the most suitable natural alternative to HMOs, as they share similar functional and structural properties. The researchers also argued that goat MOs can be viably extracted from goat milk on an industrial scale.
To determine that goat MOs were the most suitable substitute for HMOs in infant formula, the team conducted a comparative analysis focused on the biological, functional, and industrial aspects of the mammal’s MOs.
Cow’s milk has been a staple ingredient in infant formula for decades. This is largely due to its availability on the market, making it more accessible and cost-efficient for companies in the infant nutrition space. The researchers also argue that, in comparison to goat milk, cow milk has a higher allergenic potential (cow milk allergy affects around 2-3% of infants globally).
In addition, the team found that for oligosaccharide content, goat milk outperformed cow, yak, camel, donkey, and pig milk. The oligosaccharide profile of goat MOs is richer and more closely related to HMOs, thus they concluded that goat milk served as a more suitable and safer alternative for infant formula development.
A comparison between the structure, composition, and function of goat MOs and HMOs determined that while human milk contains around 247 types of MOs, goat milk contains around 78, and cow milk contains only 50.
HMOs were present in high concentrations in human milk: between 20-23 g/L in colostrum (the milk produced by a mother in the first few days after giving birth) and 5-15 g/L in mature milk. In comparison, MOs were found at a much lower concentration in goat milk: 2000-2,400 mg/L in colostrum and 60-350 mg/L in mature goat milk.
While low compared to HMOs, the concentrations in goat MOs were higher than those found in mature cow and sheep milk, 30-60 mg/L and 20-40 mg/L respectively.
The most abundant HMO in human milk is 2’-fucosyllactose (2’-FL), which makes up approximately 20 to 40% of the total HMOs contained in colostrum. Goat milk contains 2’-FL, but at a significantly lower concentration.
Goat milk was also found to contain NeuGc, a sialylated oligosaccharide, which has been shown to have the potential to support immune function and brain development. Of note, while HMOs contain the sialylated oligosaccharide, NeuAc, NeuGc is nearly absent, thus adding to the functional potential of goat MOs.
The team also noted that the acidic oligosaccharide content in goat milk was more like human milk, than other MOs.
But how feasible is it to use goat milk oligosaccharides in infant formulas on an industrial scale?
According to the researchers, one method may be more suitable than others for extracting this nutrient from goat milk: membrane separation technology.
The technology essentially works as a filter: employing membranes with varying pore sizes to separate components of the milk based on their particle size.
For the extraction of MOs, after an initial purification process, ultrafiltration membranes remove large molecule components like proteins and fat globules from the milk. The filtered solution is then passed through a rigorous ultrafiltration membrane or nanofiltration membrane, which removes the majority of the lactose.
For further purification chromatography membranes combined with fluorescence detection analysis may be used.
The team noted that using a physical membrane separation method could ensure the properties and the structure of the goat MOs are maintained.
One major challenge is that compared to cow milk, goat milk tends to yield a lower volume of oligosaccharides, which could lead to higher production costs for goat MO-based products. Additionally, the oligosaccharide content in goat milk is about half that of human milk, which means that efficient extraction processes would be essential to maximise yields.
While challenges related to yield and cost persist, the team argued that the current advancements in membrane separation technology mean the method of extraction could become increasingly viable on an industrial scale.
The researchers also considered goat MO’s potential beyond infant formula, noting that due to the oligosaccharides' role in gut health and their prebiotic effects, there is potential for their incorporation into a range of functional food and beverages.
The team states that the addition of goat MOs in functional foods has demonstrated probiotic effects, which can positively impact intestinal health, and immunity, alongside preventing dental cavities, reducing blood lipids, and regulating blood sugar levels.
The researchers also found use cases for goat MOs in pet food, an industry that is a growing market for functional ingredients. Common uses could include immune and digestive health, safeguarding intestinal health, and upping the nutritional quality of pet food.
