Key points
-
Omega-3 fatty acids help maintain the integrity of the gut lining and support a healthy microbiome.
-
They also play a central role in liver metabolism, including fat regulation and inflammatory balance.
-
Because the gut and liver are directly connected, omega-3 intake influences the function of both systems.
-
A major 2025 global review led by Philip Calder found that approximately 76% of people worldwide do not consume enough omega-3.
-
This widespread gap may contribute to digestive dysfunction, inflammatory imbalance, and metabolic stress.
-
Oily fish such as sardines, mackerel, salmon, and anchovies are the richest dietary sources.
Introduction
Omega-3 fatty acids are among the most important nutrients for maintaining long-term health. While they are often associated with heart and brain function, their role in supporting gut integrity and liver health is equally significant — and frequently overlooked.
The gut and liver operate as an integrated system, often referred to as the gut–liver axis. This relationship influences digestion, inflammation, immune signalling, and hormone metabolism. When omega-3 intake is insufficient, both gut barrier function and liver resilience can be affected.
This is particularly relevant because modern diets provide far less omega-3 than the body requires for optimal physiological function.
A major global review published in Nutrition Research Reviews in 2025 concluded that most people worldwide do not consume enough of the key omega-3 fatty acids EPA and DHA. This is not a minor nutritional gap, but one that may have important implications for inflammatory regulation, gut integrity, and metabolic health.
What are omega-3 fatty acids?
Omega-3 fatty acids are essential fats, meaning they must be obtained through the diet because the body cannot produce sufficient amounts on its own.
The most biologically important forms are:
-
EPA (eicosapentaenoic acid)
-
DHA (docosahexaenoic acid)
These are found primarily in oily fish such as sardines, mackerel, salmon, and anchovies.
Omega-3 fatty acids are incorporated directly into the membranes of cells throughout the body, including those lining the gut and those within the liver. This influences how cells function, communicate, and respond to inflammatory signals.
In practical terms, omega-3 helps determine how resilient tissues are to stress and how effectively the body regulates inflammation.
Omega-3 intake is widely insufficient
The 2025 global review led by Philip Calder and colleagues found that approximately 76% of people worldwide do not meet recommended intake levels for EPA and DHA.
This pattern is also seen in the UK. Although official guidelines recommend around 450 mg per day (equivalent to two portions of oily fish per week), most adults consume considerably less.
This shortfall is not simply a dietary technicality. Over time, insufficient omega-3 intake may contribute to:
-
Increased inflammatory signalling
-
Reduced gut barrier resilience
-
Greater metabolic stress within the liver
-
Reduced ability to regulate immune responses effectively
Common reasons for low intake include:
-
Low consumption of oily fish
-
Modern dietary patterns lacking marine foods
-
Concerns about contaminants
-
Increased physiological demand during periods of inflammation, stress, or hormonal change
Omega-3 and gut health
Supporting the gut microbiome
The gut microbiome plays a central role in digestion, immune function, and metabolic regulation.
Omega-3 fatty acids help promote a more favourable microbial balance, including supporting the growth of beneficial bacterial species associated with anti-inflammatory activity.
This helps support:
-
Digestive efficiency
-
Immune regulation
-
Reduced inflammatory burden
From a functional perspective, omega-3 helps create an internal environment that supports microbial stability rather than inflammatory disruption.
Supporting the gut lining
The gut lining acts as a selective barrier, allowing nutrients into the bloodstream while preventing unwanted substances from entering.
Omega-3 fatty acids are incorporated into the cells that form this barrier, helping maintain their structure and function.
This is particularly important because when gut barrier integrity is compromised, inflammatory compounds and bacterial fragments can enter circulation, placing additional demand on the immune system and the liver.
Maintaining gut barrier integrity is therefore a key foundation for overall metabolic health.
Omega-3 and liver health
The liver is responsible for regulating metabolism, processing nutrients, and managing inflammatory signalling.
Omega-3 fatty acids support liver function in several important ways.
Supporting fat metabolism
Omega-3 helps regulate how fats are processed within the liver. It supports the use of fats for energy while helping reduce excess fat accumulation within liver cells.
This contributes to more efficient metabolic regulation.
Supporting inflammatory balance
Omega-3 plays a central role in regulating inflammatory signalling within liver tissue.
This helps protect liver cells from excessive inflammatory stress, allowing the liver to carry out its metabolic and regulatory roles more effectively.
Supporting cellular resilience
Omega-3 fatty acids are structural components of liver cell membranes.
Healthy cell membranes allow liver cells to respond appropriately to metabolic demands, regulate nutrient processing efficiently, and maintain overall functional stability.
The gut–liver connection
The gut and liver are physically and functionally connected via the portal vein, which carries substances absorbed from the digestive tract directly to the liver.
This means the liver is continuously exposed to signals originating from the gut.
When gut barrier integrity is strong, this system functions smoothly. When it is compromised, inflammatory signals reaching the liver increase, placing additional metabolic strain on the body.
Omega-3 fatty acids support both sides of this relationship by:
-
Supporting microbial balance
-
Maintaining gut barrier integrity
-
Supporting healthy liver metabolism
-
Helping regulate inflammatory signalling
This makes adequate omega-3 intake a key nutritional factor in supporting overall digestive and metabolic resilience.
Practical considerations
The richest dietary sources of EPA and DHA include:
-
Sardines
-
Mackerel
-
Salmon
-
Anchovies
For individuals who consume little or no oily fish, supplementation may be an effective way to support adequate intake.
This is particularly relevant for individuals experiencing inflammatory symptoms, digestive dysfunction, or metabolic stress, where omega-3 requirements may be higher.
Conclusion
Omega-3 fatty acids play a central role in maintaining the structural and functional integrity of both the gut and the liver.
They help regulate inflammation, support gut barrier resilience, promote a healthier microbiome, and support efficient liver metabolism.
Given that most people consume less omega-3 than recommended, improving intake represents one of the most important foundational steps in supporting long-term digestive, metabolic, and overall health.
Karen’s clinical insight
In practice, low omega-3 intake is a common contributing factor in individuals experiencing inflammatory symptoms, digestive dysfunction, or hormone-related imbalances. Supporting adequate omega-3 intake helps strengthen gut barrier integrity and reduce metabolic strain on the liver — both of which are essential for maintaining long-term health.