Infant formula more like human breast milk

A major component of breast milk is triacylglycerol, which aids absorption of key nutrients by the infant gut, but few infant formulas contain anything like it. The fat used in most infant formulas is derived from plants, which have a different chemical structure to the fat produced by mothers in their human milk.

Now a team from Rothamsted Research have found a way to modify the biochemical pathways of plants so they can produce an oil that mimics the chemical structure of human milk fat.

The infant formula market is currently estimated to use nearly half a tonnes of vegetable-derived fat per year.

According to lead researcher Dr Peter Eastmond, applying metabolic engineering technology to oil-producing crops, or even oil-producing microorganisms, might provide a new source of cost-effective, human milk fat substitute for infant nutrition.

While some milk formulas already contain triacylglycerol that mimics the structure of human milk fat, these human milk fat substitutes (HMFS) are expensive to make, and the process generates solvent waste and uses palm oil.

Costs are one of the main reasons why HMFS are found in only about 10% of infant formulas, particularly premium products formulated and marketed for ease of digestion.

While breast milk is the best and first choice for infant nutrition, the team hope their breakthrough could lead to improvement in all grades of formula for babies who need it.

“In human milk fat, saturated fatty acids are attached to the middle point of the central ‘backbone’ of the triacylglycerol molecule, giving it a distinctive structure, and evidence from several clinical trials has suggested that this assists nutrient absorption in the infant gut. However, the fat used in most infant formulas is derived from plants, where these saturated fatty acids almost always bond to the ends of the ‘backbone’ instead,” Dr Eastmond said.

Writing in the journal Proceedings of the National Academy of Sciences, the team report making triacylglycerol where more than 70% of the saturated fatty acids are in the crucial ‘middle’ position, compared with less than 3% in the unmodified plant — a more than 20-fold increase.

“We have engineered the metabolism of a plant so the fat it produces has the structure found in human milk, not vegetable oil,” Dr Eastmond said.

“Several oilseed crops could be candidates for HMFS production, such as sunflower and oilseed rape.”

Image credit: ©stock.adobe.com/au/Andrey Kiselev