Pet supplement formulators looking to do more than just dissolve an active ingredient got a practical introduction to lipid excipient science at the National Animal Supplement Council Annual Conference, where Nick DiFranco, senior marketing manager for Gattefossé USA, made the case that the right lipid chemistry can meaningfully improve how well a supplement actually works in the body.
"Lipids can act as both solubilizers as well as offer access to in vivo benefits that you don't get with other technologies," DiFranco said. "They can overcome in vivo barriers and challenges, and they allow you to access enhanced absorption pathways in the body because of their natural origin."
What are lipid excipients?
Lipid excipients are ingredients derived from dietary oils, which are the same kinds of fats found in everyday food. Because the body recognizes them as food, it processes them through normal fat digestion, which turns out to be a useful property when delivering supplements.
The physical behavior of a lipid, whether it's a liquid or solid at room temperature, how well it mixes with water, how the body absorbs it, depends on the length and shape of its fatty acid chains. Shorter chains behave differently than longer ones, and that difference can be used strategically in formulation.
To make sense of the wide range of available lipid excipients, DiFranco pointed to the hydrophilic lipophilic balance, or HLB, scale, which is essentially a spectrum running from oily substances on one end to water-friendly ones on the other.
"If you combine different ingredients, you can create formulations that utilize the best of the oily side, the best of the aqueous side, and allow you to formulate challenging molecules," he said.
Why lipids do more than dissolve
Most common formulation approaches focus on getting an active ingredient to dissolve. But dissolving and absorbing are two different things, DiFranco said, and that distinction matters.
"Just because you can solubilize your ingredient doesn't mean it's going to be absorbed and have a beneficial effect," he said. "That's where lipids come into play."
Because the body treats lipid excipients like dietary fat, digesting them triggers a process that produces microscopic structures, called mixed micelles, that essentially act as carriers. Those carriers keep the active ingredient in a form that's ready to be absorbed and shuttle it to the intestinal wall where absorption happens.
The type of fatty acid in the lipid determines which absorption route gets used. Shorter-chain fats, the kind found in MCT oil, can temporarily widen the gaps between intestinal cells, letting more of the active ingredient through. DiFranco noted this is the same mechanism used in some oral formulations of GLP-1 compounds like Ozempic.
Longer-chain fats can direct an active ingredient into the lymphatic system instead of the bloodstream, which allows it to bypass the liver entirely. That may be advantageous for ingredients that the liver would otherwise metabolize before they can be used by the body.
DiFranco used CBD as an example. In one study, researchers compared a standard MCT oil formulation to a more sophisticated lipid system using longer-chain chemistry. Without changing the active ingredient or the manufacturing process, the more targeted lipid system produced nearly three times the absorption.
"How often do we really think deeply about what the chemistry is, and if we can be getting more out of that ingredient by using the right chemistry?" he said. "That's a powerful example."
Getting pets to actually take it
Better absorption is only useful if the animal will consume the product. DiFranco acknowledged that some of the best-performing lipid chemistries, particularly the shorter-chain MCT-type ingredients, have a smell and taste that cats and dogs find off-putting.
One workaround is encapsulating those ingredients in a soft gel or capsule so the animal never tastes them. For chewable formats, lipids can be used to coat active ingredient particles, physically blocking bitter or unpleasant flavors from reaching taste receptors. Two common approaches are fluid bed coating, which sprays a melted lipid over the particles, and high-shear coating, which uses friction rather than heat, a gentler option for heat-sensitive ingredients, said DiFranco.
"Palatability and acceptance are important criteria that we have to consider," he said.
