Chemically synthesisedbetaine products that claim similar bio-efficacy to natural betaine, such as betaine hydrochloride (HCl), have been shown in recent studies to show significant differences in performance. The differences were particularly pronounced when osmolytic functionality was compared. For betaine to function as an efficient osmolyte in vivo, it is important that it dissolves in water rapidly and completely. Comparative studies have shown that natural betaine is approximately three times more soluble and that it dissolves in water more than twice as rapidly as betaineHCl. The low water solubility of betaineHCl can reduce cellular uptake of the betaine component, reducing its ability to function as an osmolyte and methyl donor. Betaine HCI's high chloride content can also disrupt cellular water balance and interfere with betaine's key osmolytic function, leading to wet litter and poorer performance. Further studies using an in vitro intestinal cell model have shown that betaineHCl negatively influenced the gut barrier, significantly reducing transepithelial electrical resistance values and reducing the ATP content of cells when compared to natural betaine. Weak cellular tight junctions between gut epithelial cells can lead to movement of antigens across the gut barrier to provoke a damaging and energetically costly inflammatory response. BetaineHCl also increased cell inflammation compared to both the control and natural betaine groups, as indicated by significantly higher cytokine IL-8 production.