Optimising omega-3 absorption

If we want to reap the full benefits of the omega-3s we take, we must seek to optimise our digestion.

 While we advocate as a general rule that ‘you are what you eat’, the fact is that you are what you ‘digest, absorb and metabolise‘.

If you’re investing in your health by supplementing with premium omega-3 fatty acids, you’ll want to ensure you are absorbing all the potential goodness they offer! Poor absorption will not only be a waste of money but will prevent you feeling the full benefits of your chosen supplement.
In this section we bring you practical advice straight from our nutritionists – follow these tips and you’re on your way to maximising your omega fat absorption. For those who are interested in exactly how fat absorption works and, more specifically, how different forms of omega-3 are digested, we detail the science too. We feel everyone would be better off understanding the role of dietary co-factors – nutrients which support and enhance complex fatty acid metabolism digestion. Ideally you’ll incorporate more of these into your diet – benefiting not just from maximising your omega-3 absorption but increasing your intake of valuable phytonutrients and antioxidants too.

Dr Nina Bailey

Head of Clinical Nutrition

Nina Bailey AX0A1440“The concept of taking a ‘one-a-day’ (albeit a rather large and difficult to swallow capsule in most cases) may seem attractive and convenient, but if you are swamping your body with omega-3 in one large dose, you may not be getting the best from your product. Digestion is improved when omega-3 supplements are taken with food, but to get the ultimate health benefits from EPA and DHA when using them therapeutically, it is best to split the dosage up and take capsules with several meals instead of ingesting them all at once. By split dosing, we improve the bioavailability and provide the body with manageable amounts of omega-3 throughout the day, ensuring a constant supply for optimal anti-inflammatory outcomes.

Sophie Tully

Nutrition Education Manager

Sophie Tully AX0A1445“Omega-3 fats elicit their health benefits following release from our cell membranes, where they are incorporated after ingestion through the diet and supplements. Studies show that it takes at least three months for the EPA and DHA in our cells to reach optimum levels (known as the omega-3 index) in response to supplementation. At this point the amount of omega-3 being incorporated into the cells is still rising, even when taking doses of more than 2g per day. Thus if you are taking your Igennus supplements for a specific health reason it is important to take the recommended dose, for at least three months.”

Kyla Williams

Nutrition Technical Advisor

Kyla Williams AX0A1436“To optimise the absorption of omega-3, give your digestion a helping hand by taking supplements with food. If they repeat on you, take supplements just before a meal containing fat. The bile and enzymes produced when you eat a meal will help to breakdown the fat, and consuming a meal already containing fat will support the digestion process by helping to transport the omega 3 fatty acids to the parts of the body required, such as the brain.”

The process of breaking down and utilising the fatty acids found in fish oil can be varied, depending on the type of fat consumed. The type of oil is determined by its chemical structure. There are three main forms of omega-3 fat found in supplements, including triglycerides (TG, the natural form of fish oil), ethyl-esters (EE, the concentrated form of fish oil) and phospholipids (PL, derived from krill oil). TGs, in their natural form are generally associated with standard fish body or fish liver oil. The more recently developed re-esterified triglyceride (rTG) takes the EE form of omega-3 and reconverts it back to its natural TG form. This not only allows the delivery of concentrated omega-3, but ensures that absorption is optimised.

There are numerous studies comparing the absorption of these different forms, measured by their ability to raise the omega-3 index (the % of EPA and DHA in our red blood cell membranes) based on a standard manufacturer-recommended dose. rTG has proven to be the most effective, followed by EE, then TG and finally PL from krill oil.

How fat is absorbed

The absorption of dietary fats is a complicated process that requires many steps including the transport of fat from the diet into the intestine cell, and then from the intestine cell to the lymphatic system and then to the blood.

Triglycerides from standard fish oil

Typically, fats in most food sources are found in their natural triglyceride (TG) form. These fats are comprised of three fatty acids (such as omega-3 EPA and DHA) linked to a molecule of glycerol. Without glycerol, free fatty acids can rapidly oxidise and therefore the glycerol backbone helps to naturally stabilise the fat molecules and prevent breakdown and oxidation. The addition of antioxidants such as vitamin E and encapsulation of oils also prevent fatty acids from oxidising.

Digestion of triglycerides

Digestion of fats requires the chemical breakdown of large molecules to smaller molecules. As TG molecules are too big to travel across cell membranes into the cells of the intestine, after consumption, bile and the enzyme lipase breakdown dietary fat in the small intestine. The lipase enzyme breaks the TG molecule into two free fatty acids and a monoglyceride (one fatty acid combined to the glycerol), which are then able to cross the membrane and enter the cells of the small intestine where they are reassembled again as TGs.

Once the TGs are reformed, they join with other fats and proteins to form carrier molecules called chylomicrons. Chylomicrons enable fats to move within the water-based solution of the bloodstream, allowing the TGs to be transported out of the cells of the small intestine through the lymphatic system (a transport network of clear fluid called lymph) and finally into the blood, where they are then delivered to various part of the body. The type of protein present in the outer lipid layer of these structures determines which cells in the body they will be delivered to.


Fatty acids in ethyl-ester form are used to deliver high concentrations of omega-3 in a smaller volume of oil, to achieve therapeutic doses in fewer capsules. Ethyl esters are derived by reacting free fatty acids (such as omega-3 EPA) with ethanol. The fatty acids are removed from their natural glycerol backbone and then linked (esterified) with a molecule of ethanol.

Once this high concentration of omega-3 is achieved, it is also then possible to restructure the fat back to the natural triglyceride form, by re-attaching the fatty acids to the glycerol backbone, called re-esterified triglycerides.

Digestion of ethyl-esters

The digestion of ethyl-EPA fish oils is slightly different to TG due to the lack of a glycerol backbone. In the small intestine, it is again the pancreatic enzyme lipase that breaks the fatty acids from the ethanol backbone; the fatty acid-ethanol bond is more resistant to lipase compared to TGs, therefore slowing this process, and producing free fatty acids plus ethanol. The free fatty acids are then taken up by the cells of the small intestine but must then be reconverted to TGs in order to form chylomicrons, then leave the cell, enter the lymphatic system and then the blood.

Human Digestive System

The speed of absorption of omega-3 fatty acids in TG form is faster, but these oils tend to be far less concentrated than ethyl-ester oils. Split doses of ethyl-ester fatty acids assists the absorption especially when taken with a fat-containing meal.

As a result, the bioavailability may be compromised unless the supplement is taken with a fatty meal to ensure the presence of a glycerol ‘pool’ required for the free fatty acids to reform as TG; taking EE supplements with a high fat meal can improve bioavailability by as much as 13 fold. In addition, without glycerol, EE are more susceptible to oxidation than TG, so it is important to include an antioxidant such as vitamin E to protect the oil.

Whist at first glance, EE supplements may sound like they have potential absorption complications, it is worth noting that EE is  most commonly used in large intervention studies and the generic form of choice for pharmaceutical products such as Vascepa (the pure EPA product used in the USA for triglyceride management). Although it is now recognised that rTG has superior bioavailability and is more stable than EE, the pharmaceutical forms of EE can take several years to bring to market and cannot simply be modified once they are licensed medicines.

After absorption, EPA is used by the body for a variety of functions including being used directly as energy, to help form lipoproteins (fat molecule transporters which carry cholesterol), to be made into the phospholipids that form cell membranes, to form fatty acid esters or remain as triglycerides stored in fat (adipose) tissue.


A major component of the structure of cell membranes, phospholipids are both water- and fat-soluble. One of the richest sources of phospholipids is from krill oil.

Phospholipids are comprised of two fatty acids joined to a phosphate group (such as choline) and a glycerol molecule. The fatty acid positioning (or ‘space’) is limited on the glycerol molecule. Generally, one of the fatty acids will be a saturated fat and the other an unsaturated fat such as a monounsaturated fat, or a polyunsaturated fat such as EPA or DHA. Simply put, EPA and DHA have to compete with other fatty acids, including omega-6 fats, for this space. As such, omega-3 in phospholipid form results in a low concentration of omega-3 EPA.

Digestion of phospholipids

As phospholipids are hydrophilic (water-soluble), the digestion of phospholipids (PL) does not fully depend on the bile and pancreatic enzymes. Individuals with digestive malabsorption issues may therefore be able to digest phospholipids more easily.

Whilst the structure of the fatty acids in krill are the key feature attributed to its high bioavailability, the amount of EPA and DHA provided by krill oil is in fact the lowest of all the omega-3 sources! Indeed, the concentration of omega-3 as both EPA and DHA found in krill oil is so low, that taking omega-3 in the form of krill oil is not only unlikely to provide a therapeutic dose but in addition, the presence of DHA impedes upon the ability to produce a therapeutic level of EPA in excess of DHA.

Which omega-3 form is best?

Using a triglyceride fish oil is adequate for anyone looking for general wellbeing support, but since the concentrations of EPA and DHA are not high, the health benefits derived from standard fish oil will not be significant. For more intensive support, an ethyl-ester form of EPA will allow very high doses of EPA to be achieved as concentration can be as high as 90% (compared to 18% in a standard triglyceride fish oil). High concentration is important because this influences absorption and facilitates the targeting of benefits specific to a certain active (for example EPA). Purification and esterification also reduce to a minimum the volume of unnecessary fatty acids, waste products and impurities within the oil. Re-esterified triglyceride EPA concentrates EPA oil to a very pure form, like ethyl-EPA, but minics the natural triglyceride form to offer both high concentration and superior bioavailability.

Unlike lower concentration standard fish oil supplements, Igennus 70-90% EE and rTG supplements enable therapeutic blood plasma levels of EPA to be achieved. When taking EE omega-3, absorption can be enhanced by taking capsules with foods containing fat. For therapeutic use in specific health conditions, rTG is the gold standard – thus, it is also more expensive but has been proven to raise the omega-3 index to a greater extent and more rapidly than any other form of omega-3 – as with Pharmepa Restore.

The effective absorption and utilisation of omega fats by the human body is dependent on the presence of certain enzymes. These enzymes act as catalysts in the omega-3 & -6 conversions, as well as the conversion into anti-inflammatory eicosanoids – vital hormones including prostaglandins and leukotrienes.

Dark green leafy vegetables in colander

Green vegetables are a wonderfully rich source of phytonutrients and antioxidants – load up your plate!

To ensure that these enzymes and enzyme-mediated conversions function properly, certain vitamins and minerals need to be present in the body, known as ‘co-factors’. Co-factors supply the body with the nutrients to enhance the effectiveness of omega fatty acids in the brain and body, providing important anti-inflammatory, immune- and blood-regulating substances, which increase our wellbeing. The most important co-factors for omega-3 metabolism are:

  • vitamins: B6, B12, biotin, niacin, folic acid
  • minerals: zinc, magnesium and selenium.

In order to enable your body to get the most from your omega health supplement, or indeed any omega fatty acids from your diet, it is important to eat foods rich in these co-factors. Good sources are raw fruit and vegetables, nuts (not roasted!) and grassfed meat. Try to eat as many different types of vegetables as possible on a daily basis, ensuring that you include darker green leafy vegetables such as kale, broccoli or cavolo nero, which also supply you with beneficial phytonutrients such as chlorophyll.