Beta-palmitate is a structured triglyceride where palmitic acid is bonded to the middle position (beta/β-position – position sn-2) of the glycerol backbone
- In human milk nearby half of the calories are supplied by fat. About 98% is in the form of tri-glycerides containing 3 fatty acids attached to glycerol.
- The glycerol backbone offers three positions to bind fatty acids: two outer positions (alpha/α-positions – position sn-1 and sn-3) and one inner position (beta/β-position – position sn-2).
- In human milk, palmitic acid (C16:0) is the major saturated fatty acid, representing about 17–25% of the total fatty acids.
- The difference between human milk and infant formulas is the position of palmitic acid at the glycerol molecule. The unique placement of palmitic acid at the beta-position of the triglyceride in breast milk is different from most infant formulas.
- Infant formulas contain vegetable oils: palm oil provides palmitic acid. Palmitic acid from palm oil is predominantly attached to the alpha-positions of the triglycerides.
- During the digestion process of triglycerides (with help of the enzyme lipase), the fatty acids bound to the alpha-positions are released while the fatty acid in the beta-position remains attached (unhydrolysed). That means that after the enzymatic breakdown, 1-monoglyceride (glycerol with 1 fatty acid attached at the beta-position) is absorbed in the small intestine. The 2 free fatty acids (which come from the alpha-positions) can either be absorbed or react with other components.
- Studies show that palmitic acid is better absorbed in the beta-position as a mono-glyceride (human milk) than as a free fatty acid from the alpha-positions (infant formulas).
- Moreover, the location of palmitic acid in the beta-position improves the absorption of calcium in the small intestine.
- The free fatty acids have the tendency to form complexes with minerals such as calcium. These complexes, also known as calcium or fatty acids soaps, cannot be absorbed in the small intestine and are thus excreted in the faeces. This may result in harder stools, which can lead to pain and discomfort and constipation. Studies show that breastfed infants have lower amounts of faecal calcium soaps and softer stools than formula-fed infants.
- Presence of palmitic acid in the faeces means a needless loss of energy and available calcium for the infant. Calcium absorption in infants is especially important due to its critical role in bone development.