What is bioavailability for omega-3 fatty acids?

Bioavailability is the proportion of a nutrient that enters the bloodstream and becomes available for the body to use or store. For omega-3 fatty acids, bioavailability determines how effectively EPA and DHA are absorbed and used to support functions such as heart health, brain function, and the body’s inflammatory response. A supplement with poor bioavailability forces the consumer to take more to reach the same effect or delivers less benefit than the label suggests.

Researchers measure bioavailability through pharmacokinetic studies, which track the concentration of an ingredient in the blood over time after a single dose. For omega-3s, that means measuring EPA and DHA in blood plasma at set intervals to see how much is absorbed and how long it stays in the system. The area under the curve, the AUC of the concentration-versus-time graph, is the key indicator of how much of the dose the body actually took up.

How do the different omega-3 forms compare?

Omega-3 supplements reach the market in several chemical forms, and each behaves differently in the body. Fish oil is the most common source and contains EPA and DHA, available in both liquid and capsule forms. Krill oil delivers omega-3s in phospholipid form, which may improve absorption and add antioxidants. Algae oil is the preferred vegan source of DHA and some EPA, typically supplied in triglyceride form. Beyond the source, the fatty acids themselves are bound in one of three ways.

Ethyl esters are a processed form in which fatty acids are attached to ethanol and are commonly found in concentrated omega-3 supplements. Triglycerides are the natural form found in fish and other dietary fats, familiar to the body’s digestive processes, and absorbed efficiently. Free fatty acids are omega-3s in their unbound form, and they offer the most efficient absorption because they skip a digestive step that the other two forms require.

The form is not a labeling detail. It sets the ceiling on how much EPA and DHA the body can absorb from a given dose.

Why are free fatty acids absorbed more efficiently?

Free fatty acids are absorbed more efficiently because they do not require enzymatic breakdown before the body can take them up. Ethyl esters and triglycerides both arrive at the intestine in a bound state and must be cleaved by digestive enzymes before absorption can begin. That enzymatic step depends on conditions that are not always present.

Ethyl ester absorption is the slowest of the three. Before the fatty acids can cross the intestinal wall, they must be released from the ethanol backbone by hydrolysis of pancreatic lipase. Triglyceride absorption is moderate. Triglycerides also need enzymatic breakdown, hydrolyzing into a monoglyceride and free fatty acid. Still, because they are the natural form found in dietary fats, the body handles them efficiently once the process is underway. After absorption, the fatty acids are re-esterified into triglycerides inside the enterocyte, packaged into chylomicrons, and transported into circulation.

Free fatty acid absorption is rapid. No hydrolysis is required, so the fatty acids cross the enterocyte cell wall directly without waiting for enzyme activity. AvailOm^® delivers EPA and DHA in this exact form, which is why it bypasses the rate-limiting step that constrains ethyl ester and triglyceride products.
 

What does the clinical data show?

A randomized, three-way crossover study found that the AvailOm^® lysine-free fatty acid formulation delivered significantly higher uptake of EPA and DHA than an ethyl ester comparator, both combined and individually. Twenty-one healthy subjects—10 men and 11 women with an average age of 41.7 years and a mean body mass index of 23.0—completed the study, each ingesting equal amounts of EPA and DHA in each product form.

The fold differences were substantial. Against the ethyl ester form, AvailOm^® showed 9.33-fold higher bioavailability of EPA and DHA over the first 12 hours and 8.09-fold higher over 24 hours. Against the triglyceride form, AvailOm^® showed 1.57-fold higher bioavailability over 12 hours and 1.44-fold higher over 24 hours. Peak concentration and time to peak also favored the lysine-free fatty acid form over the ethyl ester.

These results build on an earlier study by Manusama and colleagues, and together the two confirm that EPA and DHA delivered as a lysine-free fatty acid salt reach the bloodstream more completely than the same omega-3s delivered as ethyl esters or triglycerides.

Why does the fasting state matter for absorption?

The absorption gap between forms widens when the digestive system contains little fat. Under fasting conditions, the body produces fewer enzymes and bile needed to cleave ethyl esters and triglycerides, so absorption of these forms is limited until a fatty meal is present. Because AvailOm^® does not require that cleavage step, it is absorbed efficiently regardless of what else is in the stomach.

That makes AvailOm^® a strong fit for several consumer groups whose absorption of conventional omega-3 forms is compromised. People on a low-fat diet, people who take supplements on an empty stomach, and people who simply do not pair their supplements with a fatty meal all see greater benefit from the free fatty acid form. The advantage extends to people with reduced bile activity and people with an inflamed gut, where bile salt availability is hampered and conventional omega-3 absorption suffers most.

Fasting is a specific use case, but the superiority of the free fatty acid form is also expected in the nonfasting state, where the difference may be less pronounced when the supplement is taken with higher fat intake. For a formulator, this means AvailOm^® supports a label and usage story that does not depend on the consumer remembering to take the product with food.

What does higher bioavailability mean for a formulation?

Higher bioavailability enables the same concentrations of EPA and DHA to exert a stronger effect in the body, giving formulators room to design more effective and consumer-friendly products. A dose that the body absorbs more completely can support efficacy claims without escalating the amount of active in every serving, and it removes the dependence on a fatty meal that undercuts so many omega-3 supplements in real-world use.

AvailOm^® pairs that absorption advantage with a powder format that solves the handling problems of liquid omega-3s. As a single-entity, free-flowing powder, it is directly compressible into tablets and readily miscible with other powdered ingredients for capsule filling, opening the door to next-generation combination products that liquid fish oil cannot support. The bioavailability and the format work together to create a more absorbable omega-3 that also formulates cleanly into the dosage forms consumers prefer.

Which omega-3 form should you formulate with?

Formulate with the free fatty acid form when absorption matters, which is to say, almost always. The chemical form of an omega-3 ingredient sets the ceiling on how much EPA and DHA a formulation can actually deliver, and the free fatty acid form clears the enzymatic hurdle that slows ethyl esters and triglycerides. AvailOm^® from Evonik delivers EPA and DHA as a free fatty acid in a solid omega-3 lysine complex, with clinical data showing markedly higher bioavailability than both comparator forms and a clear advantage for consumers who take their supplement without a fatty meal. For formulators who need their label claim to translate into a real dose in the bloodstream, the form is where that begins. Connect with a ChemPoint specialist to talk through AvailOm^® for your next omega-3 formulation.