Omega-3: why your body needs them and where to find them

There is a good chance you are not getting enough omega-3 without realising it. According to ANSES, the majority of French adults consume two to three times less EPA and DHA than recommended levels. This silent deficiency does not cause dramatic symptoms, but it gradually affects essential functions: heart health, mental clarity, inflammation regulation and even weight management.

Our modern diet is largely responsible for this imbalance. We consume a lot of omega-6, found in refined vegetable oils, processed foods and intensively farmed meats. Omega-6 and omega-3 compete in the body for the same metabolic pathways. A ratio that heavily favours omega-6 promotes a chronic low-grade inflammatory state, which sits at the heart of many modern diseases.

Understanding what omega-3 are, where to find them and how to eat enough is one of the most impactful dietary decisions you can make. No expensive supplements or complex diets are needed: a few concrete adjustments to your plate are enough to make a real difference.

Omega-3s are polyunsaturated fatty acids that our body cannot produce in sufficient quantities on its own. They must be obtained through diet, which makes them so-called essential fatty acids. There are three main forms, each with a distinct role and bioavailability.

ALA (alpha-linolenic acid) is the plant-based form of omega-3. It is found in flaxseeds, walnuts and rapeseed oil. ALA can theoretically be converted into EPA and DHA by the body, but this conversion is very limited: it ranges between 5 and 15% depending on the individual. This means relying solely on plant sources to meet your EPA and DHA needs is often insufficient.

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the marine forms of omega-3, directly usable by the body. EPA plays a major role in reducing inflammation and supporting cardiovascular health. DHA is the primary structural component of the brain and retina: it makes up 30 to 40% of the fatty acids in the cerebral cortex. Both are found mainly in oily fish, seafood and marine algae.

The effects of omega-3 on cardiovascular health are among the most thoroughly documented in nutrition science. Meta-analyses covering tens of thousands of patients have shown that regular intake of EPA and DHA reduces blood triglycerides by 15 to 30%, slightly lowers blood pressure, and reduces the risk of cardiovascular events in at-risk individuals. These effects are attributed to the ability of omega-3 to thin the blood, reduce clot formation and improve endothelial function.

For the brain, DHA is literally the building material for your neurons. A diet low in omega-3 is associated with reduced cognitive capacity, less stable mood and an increased risk of depression. Studies have shown that populations who regularly eat oily fish have significantly lower rates of depression than those whose diets are poor in omega-3. The connection with stress and hormones is direct: a better-nourished brain regulates emotions more effectively, which reduces emotional eating.

One of the most important effects of omega-3 is their anti-inflammatory action. They serve as precursors to molecules called resolvins and protectins, which signal the body to stop an inflammatory response. This property is central to understanding their impact on many chronic conditions linked to inflammation. It also explains why omega-3 are central to the recommendations of an anti-inflammatory diet.

Oily fish are by far the most concentrated source of EPA and DHA. Salmon, mackerel, sardines, herring and anchovies top the list. A serving of 150 grams of canned sardines provides around 1.5 grams of EPA+DHA, which comfortably covers daily recommendations. What makes canned fish so practical is that it is affordable, widely available and easy to incorporate into any meal.

On the plant side, ground flaxseeds, chia seeds and walnuts provide significant amounts of ALA. One tablespoon of flaxseed oil contains around 7 grams of ALA. These sources are valuable for diversifying intake, particularly for people who do not eat fish. Rapeseed oil, common in French kitchens, is also a useful source of ALA for dressings and low-temperature cooking.

Algae deserve a special mention: they are the original source of marine omega-3, since oily fish are rich in EPA and DHA because they feed on algae. Algae oil supplements exist and are an excellent alternative for vegetarians and vegans. On the plate side, good fats like avocado and oilseeds contribute to a balanced lipid profile, even if their omega-3 content remains modest.

Omega-3 deficiency is difficult to identify without a blood test, because its signs are diffuse and easily attributed to other causes. Dry and dull skin, hair lacking shine, persistent fatigue and painful joints can all be signals of insufficient essential fatty acid intake. Difficulty concentrating and unexplained mood swings are also part of the clinical picture.

Certain profiles are more exposed to this imbalance. People who eat little or no fish are most at risk. Vegetarians and vegans, whose diet is naturally free of preformed EPA and DHA, should pay particular attention to their intake. Pregnant and breastfeeding women have increased DHA needs for foetal and infant brain development. Older adults, whose capacity to convert ALA declines with age, form another at-risk group.

One often-overlooked element is the impact of the gut microbiome on fat absorption. A poorly functioning gut or dysbiosis can reduce the assimilation of polyunsaturated fatty acids, even when dietary intake seems adequate. Taking care of your gut flora is therefore an indirect but real condition for optimising your body's use of omega-3.

Incorporating more omega-3 into your diet does not require overhauling your habits. The target recommended by ANSES is around 250 mg of EPA+DHA per day for a healthy adult, which in practice means eating two portions of oily fish per week. Baked mackerel on Tuesday, sardine salad on Friday: that is a simple and effective baseline.

For people who cook little or dislike fish, small habits add up quickly. Adding a spoonful of ground flaxseeds to yoghurt or a smoothie provides ALA without changing the taste of the meal. Replacing sunflower oil with rapeseed oil for dressings noticeably improves the omega-6/omega-3 ratio. Keeping a stock of canned sardines or mackerel in the cupboard means a complete meal can be ready in five minutes.

If you practise intermittent fasting, the quality of your meals during your eating window matters even more. A diet rich in omega-3 helps reduce inflammation and supports body composition by preserving muscle mass during an energy deficit. Polyunsaturated fatty acids pair particularly well with quality proteins to create satisfying, nutritionally dense meals.