It may become possible to artificially produce “breast milk” using the power of plants .
Recently, researchers at the University of California, Berkeley (UCB) have succeeded in genetically engineering plants to produce special sugars called human milk oligosaccharides (HMOs), which are found in real human breast milk .
HMOs are highly nutritious sugars, but until now they have been difficult to produce artificially, and although powdered milk contains similar nutrients, it contains almost no HMOs.
However, by obtaining these sugars from plants, it is hoped that it will be possible to produce powdered milk with ingredients closer to the real thing , as well as to develop more nutritious breast milk for adults .
Why is “human milk oligosaccharide” good for your body?
Currently, approximately 75% of the world’s infants drink “infant formula ,” or “powdered milk,” as a supplement
to breastfeeding during the first six months of life .
Although formula provides essential nutrients for growing infants, it is currently not possible to replicate the same composition as breast milk.
Among these , human milk oligosaccharides (HMOs) are considered to be particularly difficult to artificially produce .
To begin with, even though they are all called “sugar,” not all of them are made the same.
The simplest are “monosaccharides,” represented by glucose and fructose, which are the smallest units of carbohydrates that cannot be broken down further.
Next, when two monosaccharides are combined, they become “disaccharides,” such as sugar and lactose.
Oligosaccharides are formed when several to ten monosaccharides are linked together, and human milk oligosaccharides (hereafter referred to as HMO) are one type of oligosaccharide .
When more monosaccharides are combined together, they become polysaccharides.
Needless to say, the more monosaccharides that are linked together, the more complex the structure is and the more difficult it is to produce artificially.
On the other hand, the more complex the sugar’s structure, the slower it is digested and absorbed by the body, and therefore the higher its health value.
(Glucose and fructose, which are found in large amounts in sweets and juices, are quickly digested and absorbed, causing blood sugar levels to rise rapidly.)
HMOs, which are found in high concentrations only in human breast milk, are also very important for infant health.
The biggest reason for this is the “prebiotic effect” of HMOs.
Prebiotics are substances that are indigestible, such as oligosaccharides and dietary fiber.
When we eat resistant foods, they are not broken down or absorbed in the stomach or small intestine, but are carried intact to the large intestine, where they become food for the microorganisms that live symbiotically there, providing functions such as regulating the intestinal environment, suppressing the rise in blood sugar levels after meals, and preventing obesity .
In infants, HMOs also exert a prebiotic effect, promoting the growth of beneficial gut bacteria and helping to reduce the risk of dangerous intestinal infections.
However, although it is possible to artificially produce HMOs, mass production is difficult, and they are not yet suitable for industrial use.
Currently, there are methods for producing HMOs using E. coli, but they only produce small amounts and produce toxic by-products that are very costly to remove .
As a result, there are very few powdered milk formulas that contain HMOs, and even if there are any, they are quite expensive.
The research team therefore attempted to develop a completely new method for artificially producing HMOs.
The main role was chosen for this project to be “plants . ”
How on earth do we get plants to make HMOs?
Genetically engineer plants to produce “human milk oligosaccharides”!
Patrick Shih, one of the researchers, explained why they chose to use plants:
“Plants are amazing organisms that can take sunlight and carbon dioxide from the atmosphere and produce sugar .
Moreover, plants do not just produce one type of sugar, but a wide variety of sugars, from simple to complex.
“Plants already have the basic system in place to make these sugars naturally, so we thought why not apply it to artificially produce human milk oligosaccharides (HMOs) .”
The team used the Australian native plant Nicotiana benthamiana , a close relative of tobacco , to genetically modify the plant .
What makes HMOs unique are the complex molecular structures that link the monosaccharides together .
Previous research has revealed that this molecular structure found in HMOs is involved in the action of specific enzymes.
So the team genetically engineered N. benthamiana plants so that they could genetically express this particular enzyme.
As a result, the genetically engineered N. benthamiana successfully produced HMOs with the same molecular structure as the original .
What’s more, N. benthamiana has succeeded in producing all three major groups of HMOs, according to Collin Barnum of the team .
(Human milk oligosaccharides does not refer to a single type of sugar, but is a general term for a diverse group of polysaccharides. For this reason, they are often written as HMOs.)
The three groups are one with a branched molecular structure and two with unbranched molecular structures (see diagram below).
“To our knowledge, this is the first time anyone has been able to simultaneously produce all three HMOs from a single organism,” Burnham said.
The team also calculated the cost of producing HMOs on an industrial scale from genetically modified plants and found that it is likely to be cheaper than the current E. coli-based method.
In response to this, Shi spoke about his outlook for the future:
“Imagine being able to artificially produce human milk oligosaccharides in one factory.
This would allow the human milk oligosaccharides to be extracted while grinding up the plant and added directly to milk powder.
There are still many challenges to actual manufacturing and commercialization, but this is a big goal we are aiming for.”
In addition, it is believed that HMOs produced by plants are not only useful for babies, but also for the development of plant-based milk for adults (milk extracted from plants; unlike cow’s milk, it does not contain lactose or cholesterol).
In the near future, we may see “breast milk for adults” on supermarket shelves .