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The Importance of the Right Essential Fatty Acids

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Essential Fatty Acids are 'Essential'

Essential fatty acids or EFAs, are fatty acids that humans and other animals must ingest for optimal health because the body requires Essential fatty acids but can't make them from food. The term refers to fatty acids required for biological processes, and not those that only act as fuel.

There are only two EFAs: alpha-linolenic acid, an omega-3 fatty acid, and linoleic acid.

Some researchers consider gamma-linolenic acid (omega-6), lauric acid (saturated fatty acid), and palmitoleic acid (monosaturated fatty acid) conditionally essential.

Because your body can not synthesize EFAs, EFAs must be obtained by eating certain foods and taking dietary supplements regularly.

 

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In the body, essential fatty acids serve multiple functions. In each of these, the balance between dietary ω-3 and ω-6 strongly affects function.

  • They are modified to make
    • the classic eicosanoids (affecting inflammation and many other cellular functions)
    • the endocannabinoids (affecting mood, behavior and inflammation)
    • the lipoxins from ω-6 EFAs and resolvins from ω-3 (in the presence of aspirin, downregulating inflammation.)
    • the isofurans, neurofurans, isoprostanes, hepoxilins, epoxyeicosatrienoic acids (EETs) and Neuroprotectin D
  • They form lipid rafts (affecting cellular signaling)]
  • They act on DNA (activating or inhibiting transcription factors such as NF-κB, which is linked to pro-inflammatory cytokine production)

Essentiality

Between 1930 and 1950, arachidonic acid and linolenic acid were termed 'essential' because each was more or less able to meet the growth requirements of rats given fat-free diets. Further research has shown that human metabolism requires both ω-3 and ω-6 fatty acids. To some extent, any ω-3 and any ω-6 can relieve the worst symptoms of fatty acid deficiency. Particular fatty acids are still needed at critical life stages (e.g. lactation) and in some disease states. In nonscientific writing, common usage is that the term essential fatty acid comprises all the ω-3 or -6 fatty acids. Conjugated fatty acids like calendic acid are not normally considered essential. Authoritative sources include the whole families, without qualification.[8][9][10] The human body can make some long-chain PUFA (arachidonic acid, EPA and DHA) from lineolate or lineolinate.

Traditionally speaking the LC-PUFA are not essential. See (Cunnane 2003)[11] for a discussion of the current status of the term 'essential'. Because the LC-PUFA are sometimes required, they may be considered "conditionally essential", or not essential to healthy adults.

A 2005 study has shown evidence that gamma-linolenic acid, GLA has been shown to inhibit the breast cancer promoting gene of Her2/neu.[12]

Biologist Ray Peat has claimed there are flaws in the studies showing the need for n-3 and n-6 fats. He further claims that EFA deficiencies have sometimes been reversed by adding B vitamins or a fat-free liver extract to the diet. In his view, 'the optional dietary level of the "essential fatty acids" might be close to zero, if other dietary factors were also optimized.'[13] However, these views are contrary to the scientific consensus.

A deficiency of essential fatty acids results in scaly dermatitis, hair loss, and poor wound healing.[citation needed]

Essential fatty acids should not be confused with essential oils, which are "essential" in the sense of being a concentrated essence.

Significant Sources of EPA and DHA

•    Cold water fatty fish (salmon, trout, sardine, mackerel, herring)
•    Shellfish (shrimp, mussels)
•    Marine algae
•    Krill

Food sources

Almost all the polyunsaturated fat in the human diet is from EFA. Some of the food sources of ω-3 and ω-6 fatty acids are fish and shellfish, flaxseed (linseed), hemp oil, soya oil, canola (rapeseed) oil, chia seeds, pumpkin seeds, sunflower seeds, leafy vegetables, and walnuts.

Essential fatty acids play a part in many metabolic processes, and there is evidence to suggest that low levels of essential fatty acids, or the wrong balance of types among the essential fatty acids, may be a factor in a number of illnesses, including osteoporosis.[14]

Plant sources of ω-3 contain neither eicosapentaenoic acid (EPA) nor docosahexaenoic acid (DHA). The human body can (and in case of a purely vegetarian diet often must, unless certain algae or supplements derived from them are consumed) convert α-linolenic acid (ALA) to EPA and subsequently DHA. This however requires more metabolic work, which is thought to be the reason that the absorption of essential fatty acids is much greater from animal rather than plant sources (see Fish and plants as a source of Omega-3 for more).

The IUPAC Lipid HandbookPDF (370 KiB) provides a very large and detailed listing of fat contents of animal and vegetable fats, including ω-3 and -6 oils. The National Institutes of Health's EFA Education group publishes 'Essential Fats in Food Oils.' This lists 40 common oils, more tightly focused on EFAs and sorted by n-6:3 ratio. Stuchlik and Zak, 'Vegetable Lipids as Components of Functional Food'PDF (139 KiB) list notable vegetable sources of EFAs as well as commentary and an overview of the biosynthetic pathways involved. Users can interactively search at Nutrition Data for the richest food sources of particular EFAs or other nutrients. Careful readers will note that these sources are not in excellent agreement. EFA content of vegetable sources varies with cultivation conditions. Animal sources vary widely, both with the animal's feed and that the EFA makeup varies markedly with fats from different body parts.

How Do We Know EFAs Are So Essential?

If either LA or ALA are missing in the diet because a person chooses to eat a fat-free diet or they select fats that are low in one or the other, the health of body cells deteriorates, and deficiency symptoms develop. Historically, rats that were fed fat-free diets failed to reproduce, grow normally, or remain healthy. At first, these issues were thought to be due to Vitamin E deficiency (a fat-soluble vitamin), but where then discovered to be due to lack of omega-6 fat. In humans, signs of omega-6 LA deficiency include dermatitis, poor wound healing, loss of hair, and infertility. Thankfully, all of these outcomes are reversible.

No distinct disease occurs in humans when omega-3 ALA is missing in the diet, but, as mentioned, these fatty acids are required for proper vision and central nervous system development and functioning.  They also compete with pro-inflammatory products of omega-6 mediators in the body and produce an anti-inflammatory state in the body.  Finally, people who consume plentiful omega-3s from seafood and flax have been observed to have reductions in body fat and increases in the ability to use carbohydrate as a fuel (improved insulin sensitivity).

Starting in the 1900s, the North American dietary fat consumption drastically changed. With new industrial processes and a greater demand for food to feed a rapidly growing population, we shifted from eating fats in their natural state to those in packages and pre-prepared forms. We also became highly scared of saturated fats, like those in butter and tropical oils, and so turned to margarines and refined vegetable oils.

Fatty fish also became less popular because we thought fat was deadly, so we choose less-nutritious white fishes and low-fat versions of poultry and meat (and, of course, we had to cover them in breading and high-sugar sauces). Finally, because we were eating so much beef and chicken, these animals had to fed grain-based diets instead of naturally grazing on grass - there was not just enough pasture to keep up.  

All of these food changes has lead our current population to have a diet heavily-based on omega-6 fats, with very few omega-3s. The margarines, fish, beef, pork and poultry we eat now are all dominant in omega-6 linoleic acid (LA). In turn our dietary ratio of omega-6 to 3s is much different than our healthier ancestors: it’s been estimated that we currently eat an omega-6 to omega-3 ratio of 15-20:1, compared to 1:1 many years ago (when heart disease was not the #1 killer at such young ages).

During evolution, omega-3 fatty acids were found in most all foods consumed: meat, wild plants, eggs, fish, nuts and berries. But now the picture has changed and our health has suffered. True, other factors come into play, like lack of physical activity and excessive sugar intake, but dietary fat imbalance plays an important role.

The problem with excessive omega-6 fats is that in the body are many:

  • Omega-6 LA competes with the normal metabolism of omega-3 ALA to EPA and DHA, so that much less can be made in the body through the normal omega-3 pathway.
  • Omega-6s drastically reduce incorporation of omega-3 EPA and DHA into cell membranes when they are consumed in the diet (normally, EPA and DHA would be placed into membranes).
  • Omega-6 fats in the body are highly susceptible to free-radical attack and produce compounds such as oxidized LDL cholesterol which contribute to atherosclerosis.
  • When consumed as part of a normal diet, omega-6 ALA is converted to pro-inflammatory products (prostaglandins, thromboxanes, leukotrienes) which contribute to plaque formation on arteries, allergic responses, increased blood pressure, and tumor growth. Omega-3s have the opposite effect:
  • Basically, many current common diseases can be linked back to excess omega-6s in our food supply, which leads to chronic inflammation. The solution then is to reduce our intake of these fats and increase our intake of omega-3s. But remember: a balance is important  and some omega-6s are still essential.

What Is The Ideal Omega-6 To Omega-3 Ratio?

In today’s society, it’s practically impossible to get a 1:1 ratio of omega-6s to 3s as we did in the past. Also, EFA experts do not recommend we strive for this since we have more of a requirement for omega-6s than we do 3s, and not all omega-6s are bad. Thus, for disease prevention and optimal body processes, a 6:1 ratio, or somewhat less, is ideal. Therefore, in a typical diet containing about 60 grams of total fat and 20 grams of PUFA,  you’d  aim for at least 4 grams of omega-3s, which you can easily get from food and supplements.

Making Omega-3 Fatty Acids

When people consume LA or ALA these fatty acids can be converted to other important omega-6 and omega-3s in the body, but this doesn’t always occur effectively.  Omega-6 LA is often easily transformed to omega-6s known as gamma-linoleic acid (GLA) and arachidonic acid (AA). GLA is considered a good fat to have in our bodies, but AA is mostly not – it depends on the situation you’re looking at though.

The most important conversion process for our health and well-being is the creation of special omega-3 fats known as EPA (eicosapentanoic acid) and DHA (docosahexanoic acid) from ALA.  High levels of EPA and DHA in our cells is very beneficial for lowering our risk of diseases, preventing cancer, avoiding depression and correcting attention deficit disorders.  Also, DHA is very important for visual acuity and development of the brain. Unfortunately, for most humans, the conversion of ALA to EPA and DHA is not an efficient process. It has been estimated that  only 5-10% of ALA is converted to EPA and 2-5% is converted to DHA; considering how little ALA is in the diet to begin with, this is barely anything at all. Part of the reason minimal ALA is converted to EPA and DHA is that the body prefers to burn it as a fuel – studies with humans have shown that as much as 34% ALA is breathed off as CO2 (via metabolism). Thus, for optimal intake of EPA and DHA we should aim to eat these food sources regularly instead on relying on our body to make them for us:

And technically, since EPA and DHA can be made in the body from ALA, they’re not essential. But since we are very limited in what we are able to synthesize and these fats are an important part of healthy cell membrane functioning, they are crucial for everyone.

Bottom Line on EFAs

Overall, omega-3s are fats that everyone should include in their diets right now;  they’re one fat you shouldn’t be afraid of, but rather, should seek out for optimal health.

Resources:

  • Whitney Ellie and Rolfes SR Understanding Nutrition 11th Ed, California, Thomson Wadsworth, 2008
  • Enig Mary G. Know your Fats Bethesda Press 2005 
  • Burr, G.O., Burr, M.M. and Miller, E. (1930). "On the nature and role of the fatty acids essential in nutrition" (PDF). J. Biol. Chem. 86 (587). http://www.jbc.org/cgi/reprint/97/1/1.pdf. Retrieved 2007-01-17
  • Anderson BM, Ma DW. Are all n-3 polyunsaturated fatty acids created equal? Lipids Health Dis. 2009 Aug 10;8:33.
  • Biochemical and Physiological Aspects of Human Nutrition. Martha H. Stipanuk,ed. 2000. WB Saunders Co.
Last modified on Friday, 16 December 2011 19:05
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