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What is omega 3? The key essential fatty acid for brain health

Omega 3 is a type of polyunsaturated fatty acid. It’s an essential fatty acid, which means that we can’t make it ourselves and need to get it from dietary sources. The three main types of omega 3 fatty acids are Docosahexaenoic acid (DHA), Eicosapentaenoic acid (EPA) and Alpha-linolenic acid (ALA). 

Omega 3 Eicosapentaenoic acid (EPA)

EPA is beneficial for a number of reasons. Its main function is as a precursor to chemicals called eicosanoids, which help to reduce systemic inflammation throughout your body. It's also been shown to support the heart, joint mobility, circulation, immunity, and mood.

Omega 3 Docosahexaenoic acid (DHA)

Omega 3 DHA’s main role is making up part of the structure of your cell membranes, particularly in the nerve cells in your brain and eyes. DHA accounts for about 8% of your brain's total weight, making it essential for brain and nervous system development and function, especially in babies and children. 

Omega 3 Alpha-linolenic acid (ALA)

Your body partially converts Omega 3 ALA to Omega 3 EPA and DHA, so it ultimately supports your health in the same ways EPA and DHA do. It can be hard for your body to convert ALA into the DHA and EPA, and it isn’t always converted in significant enough amounts. This is especially in relation to DHA.

Omega 3 benefits 

Omega 3 is vital for many different aspects of your health. It’s needed for developing the central nervous system and brain as well as playing a role in heart health, energy production, hormone health and keeping inflammation at bay. 

Omega 3 and heart health

Omega 3 EPA and DHA have been shown to contribute to normal functioning of the heart and normal blood pressure (1). It helps to lower triglycerides (2), which could potentially lead to fatty deposits in the artery walls, increasing the risk of a heart attack or stroke. This could be due to the anti-inflammatory properties of omega 3. Inflammation can damage the blood vessels which can then potentially lead to further cardiovascular problems (3).

Omega 3 and inflammation

Omega 3 can help to reduce inflammation by dampening inflammatory reactions, reducing levels of pro-inflammatory cytokines and eicosanoids. It’s also been shown to produce anti-inflammatory mediators called resolvins, protectins and maresins in the body (4) (5).

Omega 3 and brain health

The brain is around 60% fat, and 10-20% of that comes from Omega 3 DHA. DHA is an important building block for your cell membranes and your brain’s structure and development, therefore it’s especially key in pregnancy and childhood (6) (7).

Omega 3 and the immune system

Omega 3 can help in cases of an overactive immune system by dampening inflammatory responses, which are sometimes triggered by the immune system in reaction to an allergen or pathogen. Both Omega 3 EPA and DHA may also help to improve the function of immune B cells, a type of white blood cell that fights bacteria, viruses and fungi.

Omega 3 and vision

Omega 3 DHA is a key structural component of your retina, the part of your eye that recognises objects (11).

Omega 3 for bone and joint health

Omega 3s help increase the amount of calcium you absorb from your gut (12) and improve bone strength and collagen synthesis in your bones. As you age, your production of cartilage, the connective tissue that helps to cushion your joints, decreases, leaving you more vulnerable to joint pain and inflammation.

Small, randomised controlled trials have seen an increase in bone density in older people with osteoporosis when supplementing with Omega 3 EPA, compared with placebo groups, whose bone density decreased over time (13).

Omega 3 and sleep

Omega 3, specifically Omega 3 DHA, has been shown to support the release of melatonin, the sleep hormone, which plays a role in the circadian rhythm and sleep patterns. Omega 3 fatty acids can also regulate levels of stress hormones like norepinephrine (14).

Omega 3 and skin

Omega 3 supports healthy skin membranes, helping to repair any damaged cells or tissues and improving the strength of your skin as a result. Omega 3 DHA and EPA both benefit your skin by managing oil production (15) and can also help reduce swelling and inflammation (16).

Omega 3 and mood

Several studies suggest that omega 3 supplements can support mood (17) (18).

Omega 3 deficiency & depletion 

Unfortunately, most of us aren’t getting enough omega 3 in our diets for a number of reasons. Not consuming fish plays a big part in this. Lifestyle factors that may affect the metabolism of fats, such as smoking cigarettes, consuming alcohol, stress, or diabetes can contribute to low levels, as well as genetics, or immune system issues.

Additionally, the amount of omega 3 available in commercial products, such as eggs, fish and meat, are affected by some modern agricultural practices. Another factor is that we tend to have much higher levels of a different fatty acid called omega 6 in our diet. Omega 6 is still an essential fat, but when we eat more omega 6 than omega 3, it can cause inflammation, and this may be linked to conditions from arthritis to heart disease. Omega 3 and omega 6 work best when they are in a balanced ratio, close to 1:4. This is because omega 3 acids are anti-inflammatory whilst omega 6 acids are pro-inflammatory. Unfortunately, our modern diets often mean that we get far too many omega 6s, and not enough omega 3, having an omega 3 to omega 6 ratio of roughly 1:16. 

Processed foods, conventionally raised meat and caged eggs, which make up a lot of today's modern diet, are high in omega 6. Instead, we want to consume health-promoting foods such as organic grass-fed meat and animal products, and seeds like flaxseeds, hemp seeds, pumpkin seeds, sunflower seeds and pistachios.

Omega 3 deficiency symptoms

Omega 3 deficiency and depletion can manifest with the following symptoms:

  • Dry, rough skin, hair and nails
  • Dry, itchy or watery eyes
  • Frequent infections and poor wound healing 
  • Poor memory and difficulty paying attention 
  • Excessive thirst
  • PMS or breast pain
  • Infertility
  • Cardiovascular health problems
  • Joint pain or arthritis
  • Inflammatory health problems such as eczema or arthritis
  • Excessive mood swings, depression, anxiety and behavioural issues 
  • Poor sleep and night terrors 

Omega 3 RDA

It is recommended that we eat 2-3 portions of oily fish in our diet per week to provide our bodies with enough of these healthy essential oils. Oily fish is really good for us, but eating too much can have some health risks. This is because it can contain small amounts of pollutants that can build up in your body.

Pregnant or breastfeeding women need to sustain optimum levels of omega 3 to support healthy baby development, but there is a lower oily fish limit of two portions per week in order to reduce the risk of pollutants causing harm to a foetus or baby.

Vegans and vegetarians should focus on including plant sources of omega 3 like flaxseeds, walnuts and chia seeds. 

Omega 3 sources 

Omega 3 fatty acids are found in both marine and plant based foods and oils. 

Omega 3 foods

Sources of DHA and EPA include: 

  • Oily fish like salmon, mackerel, kipper, herring, sardines and fresh tuna
  • Shellfish
  • Seaweed
  • Omega 3 fortified products, such as milk, yoghurt, eggs and spreads

Your body can use EPA and DHA most efficiently, so they have the most direct health benefits. To minimise the impact of pollutants like heavy metals absorbed from fish, eat mainly small fish and if you do eat larger fish, like tuna, pair it with a natural chelating agent, like coriander.

Sources of ALA include: 

  • Seeds: chia seeds, flaxseeds, hemp seeds (and hemp seed oil)
  • Nuts: walnuts (and walnut oil), pecans, hazelnuts
  • Products made from soybeans like soybean oil and tofu, rapeseed oil 
  • Green leafy vegetables 

Omega 3 supplements

When choosing an omega 3 supplement, look for Omega 3 EPA and DHA on the label, as these are the most important types of omega 3s. Many omega 3 supplements often contain little, if any, EPA and DHA, so make sure your supplement contains these, and in good amounts. 

Omega 3 EPA and DHA are most often found in fish-based omega 3 products. Vegetarian options are available, but they usually only contain ALA. ALA oils are made from plant sources and contain both omega 3s and omega 6s. They don’t contain any EPA or DHA, the types of omega 3s that are active in your body. Your body can convert ALA into EPA or DHA, but this conversion process is quite inefficient. 


Individual situations and life stages require different amounts of omega 3. These include during childhood, pregnancy, breastfeed, those taking medication, immunocompromised and many others, so it is always best to speak to a health professional to get advice on the amount that might be right for you. 

In an ideal world, you would be able to get an optimal intake of omega 3 from food alone. Optimal intake of omega 3s is best achieved through a combination of dietary sources (nuts, seeds and 2-3 servings of oily fish per week) and supplementation to top up your daily intake.

It is important to mention that fish provides other important nutrients as well as omega 3, including protein, iodine, selenium, calcium, vitamins A and vitamin D, so eating fish in addition to taking an omega 3 supplement is important for a healthy, balanced diet.  


  1. Moderate consumption of fatty fish reduces diastolic blood pressure in overweight and obese European young adults during energy restriction

  2. Omega-3 fatty acids and hypertriglyceridemia in HIV-infected subjects on antiretroviral therapy

  3. Dietary fish oil decreases C-reactive protein, interleukin-6, and triacylglycerol to HDL-cholesterol ratio in postmenopausal women on HRT

  4. EPA and DHA reduce LPS-induced inflammation responses in HK-2 cells

  5. n-3 polyunsaturated fatty acids, inflammation, and inflammatory diseases

  6. Health benefits of docosahexaenoic acid (DHA)

  7. Essential fatty acids, DHA and human brain

  8. Supplementation of fish oil and olive oil in patients with rheumatoid arthritis

  9. Study on the use of omega-3 fatty acids as a therapeutic supplement in treatment of psoriasis 

  10. Use of cod liver oil during the first year of life is associated with lower risk of childhood-onset type 1 diabetes

  11. Docosahexaenoic acid is the preferred dietary n-3 fatty acid for the development of the brain and retina

  12. Calcium metabolism, osteoporosis and essential fatty acids

  13. Calcium, gamma-linolenic acid and eicosapentaenoic acid supplementation in senile osteoporosis

  14. Dietary factors and fluctuating levels of melatonin

  15. Healing fats of the skin: the structural and immunologic roles of the ω-6 and ω-3 fatty acids

  16. Diet and acne

  17. Omega-3 fatty acids in major depressive disorder

  18. A meta-analytic review of double-blind, placebo-controlled trials of antidepressant efficacy of omega-3 fatty acids




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