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Fatty Acids

What are fatty acids?

Naturally occurring fatty acids usually contain 2-28 carbon atoms, each with one or two hydrogen atoms attached, a methyl group (CH3) on one end and a carboxylic group (COOH) on the other one.

Fatty acids belong to fats, which belong to lipids.

In foods, fatty acids usually appear in combination with glycerol as triglycerides and only in small amounts as free fatty acids, which are not bound to other molecules.

Chart 1. A List of Fatty Acids in the Human Diet

SHORT-Chain
FA (SCFA)
MEDIUM-Chain
FA (MCFA)
LONG-Chain
FA (LCFA)
VERY LONG Chain
FA (VLCFA)
SATURATED FA
  • Acetic (C2:0)
  • Propionic (C3:0)
  • Butyric (C4:0)
  • Isobutyric (C4:0)
  • Methyl-butyric (C5:0)
  • Valeric (C5:0)
  • Isovaleric (C5:0)
  • Caproic (C6:0)
  • Caprylic (C8:0)
  • Capric (C10:0)
  • Lauric (C12:0)
  • Myristic (C14:0)
  • Palmitic (C16:0)
  • Stearic (C18:0)
  • Arachidic (C20:0)
  • Behenic (C22:0)
  • Lignoceric (C24:0)
  • Cerotic (C26:0)
  • Montanic (C28:0)
  • Melissic (C30:0)
  • Lacceroic (C32:0)
  • Geddic (C34:0)
  • Hexatriacontylic (C36:0)
MONO-UNSATURATED FA
  • Omega-7
  • Palmitoleic (C16:1n-7)
  • Cis-vaccenic (C18:1n-7)
  • Omega-9
  • Oleic (C18:1n-9)
  • Eicosenoic (C20:1n-9)
  • Erucic (C22:1n-9)
  • Nervonic (C22:1n-9)
POLY-UNSATURATED FA
  • Omega-9
  • Eicosatrienoic or mead (C20:3n-9)
TRANS
FA
  • Elaidic (C18:1)
  • Brassidic (C22:1)

Chart 1 legend: FA = fatty acid; Cn is the number of C atoms; The number after the colon means the number of the double bonds (saturated fatty acids have zero); the number after “n” tells at which C atom the first double bond appears.

Essential Fatty Acids

Essential fatty acids are necessary for the human life and health, but they cannot be produced in the human body, so you need to obtain them from food. There are two essential fatty acids [1]:

All other fatty acids can be produced in your body, so you do not need to get them from foods.

Essential Fatty Acid Deficiency

Essential fatty acid (EFA) deficiency is rare; it most commonly occurs in infants fed with diets low in EFA [3].

The main causes of essential fatty acid deficiency are [1,2]:

  • Feeding infants with skim milk formula
  • Chronic fat malabsorption in cystic fibrosis
  • Severe malnutrition
  • Low-fat diet (<5% energy from fats)

Symptoms of essential fatty acid deficiency include dry scaly rash, soft nails, slow wound healing, increased susceptibility for infections, short-term memory loss, difficulty concentrating,  fainting, decreased visual acuity, sexual dysfunction and impaired growth in children [1,2].

Diagnosis of essential fatty acid deficiency can be made by finding increased eicosatrienoic acid : arachidonic acid ratio (>0.2) in the blood [1].

Treatment of essential fatty acids deficiency may include consuming walnut oil, which is high in both linoleic acid (LA) and alpha-linolenic acid (ALA) [2] or a combination of sunflower or corn oil (high in linoleic acid) and oily fish or fish oil supplements, which are high in eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA) (which are produced from ALA in the body and are responsible for the main effects of ALA).

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