Research Shows That SN-2 DHA Is More Easily Absorbed And Crucial For Infant Development

Fatty acids (FA) are the main energy source in breast milk and are of great significance for the development of infants. FAs with sn-2 positional preference are an important component of triacylglycerol because they have better usability. This study quantified the FAs profiles of total and sn-2 positions in colostrum, transitional, and mature breast milk samples from 103 healthy volunteers.

Multicomponent analysis showed significant differences in FA profiles among different lactation periods due to relative percentages less than 1%. Linoleic acid (LA) is mainly located in the sn-1,3 position of TAGs, and is more common in Chinese women's milk than in Western women. Most breast milk does not meet the LA requirements in infant formula/ α- Standard for the proportion of linolenic acid. FAs related to brain development, mainly sn-2 in TAGs, are enriched in colostrum. Capric acid and lauric acid are enriched in transitional and mature breast milk, and capric acid exhibits sn-1,3 selectivity in TAGs. This study will contribute to the development of infant formula containing TAG that is more similar to breast milk.

Docosahexaenoic acid (DHA) is a 22:6 ω- 3 fatty acids (FA) are abundant in the membrane of human brain cells, and due to their unique structure and multiple double bonds, they contribute to the normal development of neural and retinal tissues throughout human life. DHA deficiency in the developing brain of fetuses, newborns, and children is often associated with neuropathology (such as cognitive impairment and anxiety) and visual function related disorders. DHA also plays an important role in maintaining cognitive function and emotional performance in adulthood.

DHA has traditionally been enriched through consumption α- Linolenic acid（ α- LNA; 18: 3 ω- 3) The diet and marine food such as fish and algae are obtained. However, the individual's α- The efficiency of converting LNA into DHA is often insufficient to meet daily needs, especially for pregnant women and patients with liver or maple syrup urine diseases. On the other hand, due to the agricultural revolution and the food industry, modern diets have shifted from being rich in the ocean or α- LNA's oil (flaxseed oil, etc.) turns to be rich in ω- 6 fatty acid oils (such as soybean oil, palm oil, and corn oil) and saturated fats, ω- The intake of 3 fatty acids decreases, and the DHA concentration in breast milk further decreases. Therefore, some suggest adding pre formed DHA from fish oil, algal oil, or high DHA structured lipids (SL) to food. Research has shown that mothers who consume a pre formed DHA diet accumulate much more DHA in their milk compared to those who are purely vegetarian. The DHA in vegan milk is mainly composed of plant oils ω- 3. Fatty acid synthesis.

Usually, DHA is esterified to different positions (sn-1, 2, or 3) in the triacylglycerol (TAG) molecule, depending on various food sources. After oral administration, TAGs are hydrolyzed by sn-1,3-specific pancreatic lipase to form sn-2 monoacylglycerols (MAGs) and free fatty acids (FFAs). Sn-2 MAG is then well absorbed through the intestinal mucosa and is preferentially used for the biosynthesis of TAG or phospholipids (PL; an important component of brain cell membranes). On the contrary, no specific absorption was observed in FFAs hydrolyzed from the sn-1 and sn-3 positions.

Therefore, compared to randomly distributed TAGs with DHA, TAGs with DHA located at the sn-2 position are more advantageous in absorption and utilization. Similarly, the absorption efficiency of sn-2 DHA MAG is significantly higher than other derivatives, such as DHA diacylglycerol (DAG) and DHA ethyl ester. However, currently most DHA recommendations and supplements do not pay attention to its location distribution, only focus on the total daily intake.

Given that the positional arrangement of DHA in the TAG and PL structures affects its pharmacological and nutritional benefits for human brain development and maintenance, it is necessary to provide a background on the distribution of DHA in common fats and oils, as well as the benefits of a high sn-2 DHA lipid diet for the brain. There are four main types of DHA lipids from natural sources: sn-2 DHA TAG, DAG, and MAG in fish and algae oil, as well as sn-2DHA PL in krill oil and egg yolk.

The normal development and maintenance of central nervous system function are related to the accumulation of docosahexaenoic acid (DHA) in the brain; ω- The amount of 3 fatty acids is highly correlated. DHA incorporated at the position of lipid sn-2 is well absorbed by the intestinal mucosa and effectively utilized in the body. However, modern consumers' direct intake of DHA has decreased, with saturated fat or ω- The increased intake of 6 fatty acid oils leads to behavioral and neurophysiological deficiencies. The multiple bidirectional pathways in this axis provide new insights into the interaction between DHA supplementation, gut microbiota, and brain health. In order to obtain high sn-2DHA in the diet, it is recommended to increase the specific activity of lipase and optimize the purification process to produce sn-2DHA lipids in a more effective and economical manner. These types of diets will be beneficial for sn-2 ω- Individuals with a strong demand for lipids, such as infants, children, pregnant women, and lactating women.

Reference:

[1] Jin J, Jin Q, Wang X, et al. High sn-2 docosahexaenoic acid lipids for brain benefits, and their enzymatic syntheses: A review[J]. Engineering, 2020, 6(4): 424-431. （https://www.sciencedirect.com/science/article/pii/S2095809920300400）

[2] Qi C, Sun J, Xia Y, et al. Fatty acid profile and the sn-2 position distribution in triacylglycerols of breast milk during different lactation stages[J]. Journal of Agricultural and Food Chemistry, 2018, 66(12): 3118-3126. (https://pubs.acs.org/doi/abs/10.1021/acs.jafc.8b01085)