Among the various lipids of nutritional interest, two deserve special attention: Omega 3 and Omega 6.
They are two polyunsaturated fatty acids, respectively called linoleic acid or LA (18:2) and alpha linolenic acid or ALA (18:3).
These fatty acids are defined as essential , since – given the body’s inability to synthesise them independently – they must necessarily be introduced with the diet.
Once taken through food, these two nutrients are converted enzymatically into other polyunsaturated fatty acids (PUFA), called semi-essential and having specific metabolic functions.
In particular, linoleic acid is the progenitor of the omega 6 series fatty acids, while from alpha linolenic acid we get the omega 3 series analogues.
These metabolic pathways involve the intervention of two enzymatic complexes, capable of lengthening the carbon chain and increasing the number of double bonds.
Thanks to these enzymatic interventions the respective series of fatty acids are formed, belonging to the omega 6 series, if they derive from linoleic acid, and to the omega 3 series, if they derive from alpha-linolenic acid.
Main Omega-6 derivatives
The main omega 6 derivatives or essential seeds of linoleic acid are: gamma linolenic acid or GLA (18:3), diome-gamma-linoleic acid or DGLA (20:3) and arachidonic acid (AA, 20:4).
Besides being synthesised in the body, these fatty acids can be taken with food.
Good sources of omega 6 are oilseeds, the germ or embryo of cereals, legumes and pseudo-cereals, and their extracted oils.
Main Omega-3 derivatives
The main omega-3 derivatives or essential seeds, originating from alpha-linolenic acid metabolism, are: eicosapentaenoic acid or EPA (20:5) and docosahexaenoic acid or DHA (22:6).
The best food sources of omega 3 are cold sea fish, krill and algae.
The terms “omega 6” and “omega 3” refer to the position of the first double bond in relation to the methyl (terminal) portion of the molecule.
It is therefore no coincidence that omega, which is the last letter of the Greek alphabet, is included in their nomenclature.
Thus in omega 6 the first double bond is between the sixth and seventh carbon atom from the methyl group.
In Omega-3 the first double bond is between the third and fourth carbon, again starting from the methyl end.
The symbolism (xx:x) shows the number of carbon atoms of the fatty acid compared to the number of double bonds of the molecule; for example, linoleic acid (18:2) comprises 18 carbon atoms and has two double bonds.
Can the production of semi essential fatty acids be insufficient?
The body’s ability to synthesise omega-6 and omega-3 derivatives, like many other biological functions, declines with age.
Other conditions that can diminish it are: cortisone drug therapy, alcoholism, protein malnutrition, etc..
It is also important to remember that omega-6 and omega-3 compete for the use of the enzymes involved in their desaturation (desaturate), as they are common to both metabolic pathways.
An excessive intake of omega 6 (quite frequent) can compromise the formation of EPA and DHA from alpha linolenic acid.
In addition, it should not be forgotten that omega-3, in particular EPA and DHA, are deficient in most Western nutritional regimens.
This means that these two semi essential fatty acids must also be introduced, albeit in part, necessarily with food.
For adults, 250 mg EPA and DHA per day are sufficient. In case of pregnancy, breastfeeding and age 2 years or less, it becomes necessary to add another 100-200 mg of DHA.
What is the right ratio between omega-6 and omega-3?
The ratio of omega 6 to omega-3 in the Western diet is much higher than 10:1 while, to be ideal, it should be between 4:1 or 8:1.
To rebalance this ratio, it is essential to increase the consumption of fish, especially blue fish and the species living in the northern seas; food supplements containing fish oil, cod liver, krill and algae may be used.
Why is the relationship between omega-6 and omega-3 important?
The fatty acids in the omega 6 and omega-3 series are the precursors of the eicosanoids, which have become famous for the studies of Dr. Barry Sears and his famous dietary model, called the Zone Diet.
Without going into insidious biochemical details, eicosanoids are hormonal substances with local action or paracrine (prostaglandins, thromboxanes and leukotrienes) that regulate different functions and physiological parameters.
All omega 3s and some omega 6s support anti-inflammatory function, while other omega 6s (such as arachidonic acid) support pro-inflammatory function.
The levels and balance of fatty acids in the two series seem to be important for the prevention and treatment of coronary heart disease, hypertension, type 2 diabetes, immune and inflammatory disorders.
When to use omega-6 and omega-3 supplements?
Essential fatty acid dietary supplements should only be used in a state of deficiency, in case of doubt that it may occur or to take advantage of their positive effect on the metabolism.
Since omega 6 deficiency is more unique than rare, essential fatty acid supplementation is usually limited to omega-3.
In particular, the omega-3 series favours the intake of the most deficient and metabolically most active ones: EPA and DHA.
Naturally contained in fishery products and algae, they are highly concentrated in fish, fish liver, krill and algae oil.
The recommended dose depends on nutritional status, any physiological, special or pathological condition and age.
Generally, it is considered safe to take 1-5 g of omega-3 per day with supplements.
Properties and Effectiveness
What benefits have omega 3 and omega 6 shown in the course of studies?
Benefits on lipaemia
Essential fatty acids have a positive effect on lipaemia.
Omega 3 mainly reduce triglycerides, while omega 6 mainly improve the cholesterol profile.
Omega 3s play a very positive role on dyslipidemia triggered or aggravated by type 2 diabetes mellitus.
Benefits on blood pressure
Omega-3s reduce blood pressure, both in healthy subjects and subjects with primary hypertension.
Benefits on complications of hyperglycaemia and diabetes mellitus type 2
Besides dyslipidemia, omega-3s also plays a beneficial role on certain lesions because of chronic hyperglycaemia.
Benefits on inflammatory state, blood and circulation in general
In the right ratio and quantity, omega-3 and certain omega 6 are anti-inflammatory and lower the condition of systemic inflammation.
Omega 3s have a protective function on the endothelium, improve venous circulation and promote the elasticity of the capillaries.
They also prevent atherosclerosis, fluidise plasma and reduce platelet aggregation.
All these effects, combined with the impact on metabolic parameters, should reduce the possibility of cardio-cerebrum-circulatory events such as heart attacks and strokes.
Benefits on brain and eye development
In the foetus and child, omega-3s are needed (in higher than normal amounts) to allow nervous and eye development.
Benefits on brain activity
It’s mostly about old age. The omega 3 supplement can prevent mild cognitive impairment.
Omega-3s, especially the EPA, seem to play a crucial role in the fight against certain types of depression.
Benefits on sport
It seems that good omega-3 levels can prevent the onset of inflammatory discomfort to tendons, joints and muscles in endurance athletes who perform particularly long and intense sessions.
Doses and Mode of Use
How to use omega 3 and omega 6 supplements?
Omega 3 and omega 6 supplements should be taken orally.
They are mostly in the form of opercoli, capsules or oil.
The dose should be estimated according to individual needs, taking into account the nutritional status and in agreement with the doctor.
Usually only a few grams of active substance per day are sufficient (difficult to estimate for oils).
It is recommended to take essential fatty acid supplements to obtain 0.5-2.0% of total energy in the form of omega 3, and 4-8% in omega 6.
Remember that it is important to preserve these products suitably, shielding them from light, oxygen and heat, to keep their nutritional functions intact.
Side effects of omega 3 and omega 6 supplements are mainly related to overdose or individual hypersensitivity.
They may appear:
- Gastrointestinal discomfort: fish smells, eruptions, nausea, abdominal cramps, dyspepsia and diarrhoea.
- Blood clotting disorders are rarely found.
- Even more infrequent, and linked to hyper-dosage, are the conditions of systemic peroxidases.
When should Omega 3 and Omega 6 supplements not be used?
Omega 3 and omega 6 supplements should never be used in case of hypersensitivity or worse allergy to the ingredients.
In addition, it is recommended to avoid them during drug therapies that reduce blood clotting.
Precautions for Use
What do you need to know before taking omega 3 and omega 6 supplements?
First of all it is advisable to consult a nutrition professional to assess the need for a supplement based on omega 3 and omega 6 essential fatty acids.
Second, it is essential to read carefully the composition, side effects, contraindications and drug interactions.
Finally, although supplementation with these nutrients plays a beneficial role in many situations (pregnancy, breastfeeding, replacement diseases, etc.), it is essential to consult your doctor before taking them.