Essential Fatty Acids
What is there to Know?
Definition
Essential fatty acids ( also known as AGEs or EFAs) are lipids .
Types
Essential fatty acids belong to two families: omega 3 (ω3 or n-3) and omega 6 (ω6 or n-6).
Only two fatty acids are actually essential (that is, they must necessarily be introduced with the diet): α-linolenic acid (omega 3) and linoleic acid (omega 6). From these, the human body is able to obtain five other derivatives that are metabolically more active or otherwise functional :
- Omega 3: Alpha Linoleic Acid, Docosahexaenoic Acid or DHA (22:6 ω3) and Eicosapentaenoic Acid or EPA (20:5 ω3).
- Omega 6: Linoleic acid, Gamma linolenic acid or GLA (18:3 ω6), Diomo-gamma-linolenic acid or DGLA (20:3 ω6) and Arachidonic acid or AA (20:4 ω6).
Functions
Essential fatty acids perform functions that are, to say the least, fundamental to health; consequently their lack, excess or altered balance between them can cause undesirable effects.
The most relevant functions are:
- They build cell membranes
- They balance the production of eicosanoids (superhormones that mediate inflammation, with a promoting or suppressing action, based on the specific eicosanoid)
- Promote metabolic balance ( blood pressure , cholesterol , triglycerides , blood sugar , etc.)
- They protect (even if sometimes indirectly) the heart and brain from vascular pathologies ( atherosclerosis , thrombi , emboli )
- They support neurological development
- They protect the nervous system from aging
- They support visual function
- They optimize the embryonic development and growth of the child
- They appear to be involved in the reduction of major depression etc.
Sources
The foods that contain the most essential fatty acids are: fishery products (especially from cold seas), algae , krill , many oilseeds , fat fleshy fruits and the germ of starchy seeds .
Ratio: Excess and Enzymes
Relationship
The ratio of essential fatty acids is a very important factor.
Even if it is often underestimated, this ratio represents a criterion of nutritional balance that is fundamental to say the least.
We must not forget that all nutrients have a metabolic impact on the body; even lipids are no exception, on the contrary, fatty acids are among the most industrious molecules in this sense.
Researchers have found important correlations between the pathogenesis of various disorders and the alteration of the relationship between the two essential fatty acids in the diet.
Excess
With this premise, we would be led to believe that the more essential fatty acids one eats, the better; this is only partially true!
First of all, polyunsaturated fatty acids are very sensitive to oxidation and peroxidation. Eating too many of them, in addition to increasing the portion of energy fats , runs the risk of promoting oxidative stress in the body (which many try to compensate for by increasing their intake of vitamin E ). On the other hand, this occurrence is mainly connected to the unreasonable abuse of specific food supplements , lacking adequate antioxidant protection or of poor quality ( rancidity ).
Furthermore, certain omega 6s are involved in the synthesis of eicosanoids which promote inflammation; this means that if taken in excess they could promote systemic inflammation.
Enzymatic competition
Omega 6 and omega 3 fatty acids have enzymatic processes in common.
Since omega 6 are naturally more abundant in the contemporary Western diet, omega 3 are “metabolically penalized”.
These are the fundamental reasons why an optimal ratio between omega 6 and omega 3 has been established.
Actual Consumption and Suggested Values
In 1996
According to the LARN of 1996 (Levels of Recommended Intake of Nutrients for the Italian population, published by the Italian Society of Human Nutrition – SINU), the average effective ratio between omega 6 and omega 3 in the diet was 13:1, which corresponded to a overall energy percentage of 6% on daily caloric consumption .
This means that the Italian population introduced approximately 5.54% of daily calories in the form of omega 6 and 0.46% in the form of omega 3 (values referring to the total energy share).
In addition, in the same edition it was recommended to take:
- In infants (6 months – 1 year): approximately 4.5% of total daily calories in the form of omega 6 and 0.2-0.5% in the form of omega 3, with a recommended ratio of 22.5/ 9:1 (total 0.5 g/day)
- In children (1-3 years): approximately 3% of total daily calories in the form of omega 6 and 0.2-0.5% in the form of omega 3, with a recommended ratio of 15 to 6:1 (total 0.7 g/day)
- For all others: about 1-2% of total daily calories in the form of omega 6 and 0.2-0.5% in the form of omega 3, with a recommended ratio of 4:1 (total 1 or 1 .5 g/day).
Analyzing these data, it seems clear that the total intake of essential fatty acids falls well within the recommendations; however the ratio is clearly skewed.
Today
The most recent version of LARN focuses more on the distribution of omega 3, suggesting specific values based on the type of molecule:
- In infants (6 months – 1 year): the share of omega 3 has increased up to 0.5-2.0%, of which at least 250 mg/day in the form of EPA and DHA + another 100 mg/day of DHA . Omega 6s are contained in a measure of 4-8%. In all, essential fatty acids make up 5-10% of total calories.
- The same in children from 1 to 2 years.
- For adults and the elderly : a quota of omega 3 up to 0.5-2.0% is recommended, of which at least 250 mg/day in the form of EPA and DHA. Omega 6s are contained in a measure of 4-8%. In all, essential fatty acids make up 5-10% of total calories.
- In pregnancy and breastfeeding : a quota of omega 3 up to 0.5-2.0% is recommended, of which at least 250 mg/day in the form of EPA and DHA + another 100-200 mg/day of DHA. Omega 6s are contained in a measure of 4-8%. In all, essential fatty acids make up 5-10% of total calories.
How to fix it
The dietary interventions necessary for nutritional correction could be summarized as follows:
- Drastic reduction of the omega 6 intake (in particular of linoleic acid) contained in sunflower seeds , wheat germ , sesame , walnuts , soybeans , corn , olives , therefore in the relative oils.
- Significant increase in the intake of omega 3 (alpha linolenic, eicosapentaenoic and docosahexaenoic fatty acids), whose food sources are:
- Oils and meats from oily fish (especially rich in eicosapentaenoic and docosahexaenoic)
- Chia , kiwi , perilla , flax , cranberry seeds ; walnuts and walnut oil , hemp oil , flax oil, canola oil , canola oil, and soybean oil (especially high in alpha-linolenic acid).
NB : some foods are excellent sources of both essential fatty acids, therefore, in order to correct the balance of the two lipids, it would be advisable to prefer the “purest” food sources of omega 3.
Respecting the recommended rations of essential fatty acids might seem like a difficult undertaking to say the least; fortunately, it is possible to optimize the ratio between omega 6 and omega 3 by increasing the consumption of oily fish (up to 2-3 portions per week), algae and food supplements , even without reducing the overall intake of omega 6.
| Ratio ω6/ω3 in some commonly used oils | |
| Linseed oil | 1:4 |
| Rapeseed oil | 2:1 |
| Hemp oil | 3:1 |
| Soybean oil | 8:1 |
| Olive oil | 9:1 |
| Wheat germ oil | 10:1 |
| Peanut oil | 62:1 |
| Sunflower oil | 71:1 |
Fair Ratio: Why?
The answer to this question is complex and very articulated. In summary, the right ratio between omega 6 and omega 3:
- Promotes the homeostasis of lipemia
- Improve blood pressure regulation
- GUARANTEES the balance of endogenous EICOSANOIDS .
Inflammatory and anti-inflammatory eicosanoids
Omega 3s are precursors of PG1 and PG3 type eicosanoids, therefore they perform an antiplatelet , vasoprotective and antithrombotic function; on the contrary, certain omega 6s are also precursors of the proinflammatory and prothrombotic PG2 eicosanoids.
In other words, PG2 eicosanoids (those potentially in excess because they derive from omega 6) FAVOR THE INITIATION of inflammation, while PG1 and PG3 eicosanoids (those probably in defect because they derive from omega 3) FAVOR THE REGRESSION of inflammation.
It is mandatory to specify that ALL eicosanoids (PG1, PG2 and PG3) are molecules essential for the correct functioning of the organism; however, the tendency to CHRONIC inflammation (potentially aggravated by the excess of certain omega 6) represents an important risk factor for autoimmune diseases ( rheumatoid arthritis , recto – ulcerative colitis , Crohn’s disease , etc.) and can aggravate some pathologies metabolic disorders, increasing cardiovascular risk .
Ultimately, maintaining the right ratio between omega 6 and omega 3 guarantees the homeostatic balance of the eicosanoids, facilitating the prevention of chronic systemic inflammation and reducing the risk of autoimmune and cardio -vascular diseases.
Did you know that…
Recent studies carried out in vivo suggest that the ratio between essential fatty acids does NOT play as decisive a role as was assumed by interpreting the results obtained in vitro.
This means that you first need to worry about REPLACING saturated and trans fats with SIMILAR amounts of unsaturated acids.
In fact, as part of a diet low in saturated and trans fats, an intake of omega 6 equal to 5-10% of total calories (in particular of linoleic acid) seems to have a protective effect against coronary risk .
On the other hand, the experiments carried out on the impact of various fatty acids can lead to not only different but even opposite results.
A recent investigation has shown an inverse correlation between omega 6 and inflammation, highlighting a prevalence of anti-inflammatory activity in vivo, i.e. the exact opposite of what was suspected by observing the results in vitro.
The explanation could lie in the type of omega 6 used or in other still poorly understood metabolic variables.
