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Omega-3 / Omega-6 Test

What are Omega-3 and Omega-6?

Omega-3 and Omega-6 are dietary fats known as polyunsaturated fatty acids. A healthy diet has a balance of both Omega-3 and Omega-6 fatty acids. The '3' and '6' refers to their chemical structure.

The three main Omega-3 fatty acids are:

  • alpha-Linolenic acid (ALA): important for the heart, nervous system, and immune system
  • Eicosapentaenoic acid (EPA): produces substances called eicosanoids that help to reduce inflammation and depression
  • Docosahexaenoic acid (DHA): helps brain development and function

Strictly, ALA is the only omega 3 considered to be an 'essential' fatty acid as it cannot be made in the body and must be obtained from foods. Some ALA can be converted to EPA and in turn to DHA.

The main Omega-6 fatty acids include:

  • Linoleic acid (LA)
  • gamma-linolenic acid (GLA)
  • Arachidonic acid (AA)

LA is an 'essential' fatty acid, as it also cannot be produced in the body and must be obtained from foods. LA is converted to GLA and then to AA.

Why are Omega-3 and Omega-6 important?

Omega-3 fatty acids are needed for the membranes surrounding cells in the body. They are also needed for providing energy, and for healthy functioning of blood vessels, heart, lungs, and immune system, and making hormones.

Of the Omega-3's,

  • EPA leads to the production of substances called eicosanoids that are anti-inflammatory, and help to reduce inflammation and depression.
  • ALA is important for the heart, nervous system, and immune system
  • DHA helps brain development and function

Omega-6 fatty acids provide energy and help with cell functioning.

Of the Omega-6's,

  • LA is pro-inflammatory, and therefore increases inflammation
  • GLA, on the other hand, may reduce inflammation and inflammatory diseases
  • AA leads to the production of eicosanoids that are proinflammatory but they also regulate the immune system.

Note that generally eicosanoids produced from EPA are anti-inflammatory, while those from AA can be harmful and lead to inflammation and inflammatory diseases.

What is the Omega-6 to Omega-3 ratio and its importance?

The proportions of these fatty acids - that being the ratio of Omega-6 to Omega-3 - in the body is very important. The Omega-6 to Omega-3 ratio should be from 1:1 to 4:1 for good health. This means that for every 1 to 4 grams of Omega-6 eaten, 1 gram of Omega-3 should be consumed.

The balance between these two Omegas is critical to your health because Omega-6 fatty acids can be harmful while Omega-3s are beneficial to health; Omega-6 fatty acids (LA and AA) contribute to inflammation while Omega-3 fatty acids help to reduce inflammation. This means that when Omega-6s are high and Omega-3s are relatively low, there can be an increase in chronic diseases that involve inflammatory processes, including rheumatoid arthritis, inflammatory bowel disease, cardiovascular disease, Alzheimer's disease, and diabetes.

What food sources provide Omega-3 and Omega-6?

Many foods such as nuts and eggs contain both Omega-3 and Omega-6 fatty acids, so typically more than one type of fatty acid is eaten in any food.

The main dietary sources of omega 3 include

  • ALA: flaxseed, chia seeds, hemp seeds, walnuts, soybean, and rapeseed oils
  • EPA/DHA: oily fish such as salmon, herring, mackerel, sardines, and anchovies, and breast milk

The main dietary sources of omega 6 include

  • LA: Most seed and vegetable oils, e.g., poppy seed, rapeseed, sunflower, safflower, palm, hemp, corn, wheat germ, and soybean
  • GLA: botanical seed oils, such as evening primrose oil and borage oil, and human breast milk
  • AA: organ meats, poultry, dairy products, and eggs

Unfortunately, many people in the Western world consume too much Omega-6 and too little Omega-3, with diets rich in refined vegetable oils (and foods cooked in them) and processed foods.

What are the effects of too much or too little Omega-3 and Omega-6?

Omega-3 deficiency can cause scaly skin and/or a red itchy skin rash, dry eyes, dry hair, depression, and stiff painful joints. However, Omega-3 supplements may have mild side effects including unpleasant taste, bad-smelling breath and sweat, gastrointestinal problems (e.g., indigestion, nausea, and diarrhoea), and headache.

Omega-6 deficiency is not usually a problem; indeed, the reverse is true. Many Western diets have an omega 6:3 ratio in the range of 10:1 to 20:1. When Omega-6s are relatively high, they may cause inflammation and increase the risk of chronic inflammatory diseases (see above). Omega-6 supplements may worsen breathing in people with lung disease and increase levels of triglycerides (a fat) in the blood.

Who should have their Omega-3 / Omega-6 tested?

An Omega-3 (EPA) deficiency and imbalance in the Omega-6 to -3 ratio are linked with serious health conditions, including heart attacks, stroke, lupus, arthritis, depression, attention deficit hyperactivity disorder, schizophrenia, Alzheimer's disease, obesity, diabetes, insulin resistance, asthma, and cancer. An Omega-6 deficiency may be indicated by conditions including arthritis, eczema, psoriasis, dry eye, diabetes, or tender breasts.

How to test for Omega-3 / Omega-6?

Fasting for 12 hours prior to the blood sample being taken is preferred (drink plenty of water).

The Omega-3 / Omega-6 test can be done from a few drops of blood collected in your own home. A self-collection pack, along with full instructions on how to collect the blood drops from a finger, is provided by The Online Clinic. Instructions must be read and followed carefully. A few drops of blood are taken from a little finger and collected in the collection tube. This is sent by post to a named laboratory for analysis. The test results are then sent to a doctor at The Online Clinic for interpretation. You can discuss the findings with the doctor, should you so wish.

What do Omega 3 and Omega 6 test results indicate?

Values reflecting your Omega-3 / Omega-6 test results will vary depending on your age and the laboratory analysing your blood sample. Your test results will estimate your Omega-6 to -3 ratio, and therefore determine whether you need dietary supplementation with either Omega-6 or -3, or whether your daily dietary supplement is providing too much or too little of these.

If you are advised to take Omega dietary supplements, you should tell your doctor about the medicines and dietary supplements you are taking. Supplements can interact with some medicines. Omega-3 and Omega-6 dietary supplements can interact with anticoagulants and cause bleeding. Omega-3 dietary supplements should not be taken by people with diabetes, or diseases of the heart, kidneys, liver, and pancreas without a doctor's approval. Fish oils can also affect the action of contraceptive pills. Omega-6 dietary supplements (GLA) may increase the effectiveness of ceftazidime (antibiotic) and anti-cancer treatments, immunosuppressive effects of cyclosporine (organ transplantation), and increase the risk of seizures with phenothiazines (schizophrenia).

What is a normal daily intake of Omega-3 and Omega-6?

Official standards for daily intake of the Omega-3 and Omega-6 have not been established, but some organisations provide guidelines.

An adequate daily intake of ALA is:

  • 0.5 grams/day for infants aged 0 to 12 months
  • 0.7 to 1.2 grams/day for children aged 1 to 13 years
  • 1.6 grams/day for males aged 14 years and older
  • 1.1 grams/day for females aged 14 years and older
  • 1.4 and 1.3 grams/day for pregnant and breastfeeding females

Should I take Omega-3 and Omega-6 dietary supplements?

Sufficient Omega-3 and Omega-6 fatty acids can be provided in the food and drink we consume, and therefore supplements should not be needed. While sufficient Omegas may be consumed, the intake of Omega-6 is frequently in excess relative to the intake of Omega-3. To balance this, Omega-3 supplements can be taken in the form of fish-based oils, such as cod liver oil and krill oil, and plant (algae)-based algal oil. Omega 6 supplements (GLA) include evening primrose oil and borage oil.

Rather than taking individual Omega supplements, it may be better to have a good balance of Omega-3 and Omega-6. These two fatty acids are often supplied with a third Omega fatty acid called Omega-9 in a combined Omega-3-6-9 supplement. The combination can increase your Omega-3 fatty acid intake and improve the Omega-6 to Omega-3 ratio, resulting in a healthy ratio of 4 (or lower) to 1.

How to maintain or achieve good Omega-3 and Omega 6 levels

To achieve a healthy Omega-6 to Omega-3 ratio (4 or lower to 1), your diet should include: eating oily fish twice a week, using Omega-3 rich oil (e.g., olive oil) in salad dressings, include Omega-3 fortified foods, and when cooking, and limiting refined vegetable oils (high in omega 6) and processed foods containing/cooked in them.

Reviewed by: Dr Loraine Haslam MBBS, DRCOG, DFSRH, LoC SDI, LoC IUT, MRCGP
GMC registration number: 4524038
Date: 4 October 2023
Next review: 3 October 2025
All UK registered doctors can have their registration checked on
The Medical Register at the GMC website.
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