Glossary Detail

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name of the term: Omega-3 fatty acids

Short introduction

  • A triglyceride is composed of 1 glycerol molecule connected with 3 fatty acid molecules.
  • A fatty acid consists of a straight chain of an even number of carbon atoms (C), which each hold two hydrogen atoms (H). At one end, the chain has 3 H atoms (methyl-end) and at the other end a carboxyl group (COOH). The carboxyl group makes it an acid.
  • Fatty acids vary in carbon chain length and the number of double bonds in the chain.
  • Fatty acids can be saturated or unsaturated.
  • Saturated fatty acids are straight chains, saturated with hydrogen (H). Each C atom carries 2 H-atoms. These fatty acids have no double bond.
  • Unsaturated fatty acids have one or more double bonds between the C atoms (and in the place missing 2 H atoms).
  • • The double bond in unsaturated fatty acids produces a kink or bend in the molecule. Bending causes the molecule to stay fluid at room temperature. These kinks in the structure make the body cell membrane (layer that covers the cell) flexible and permeable, allowing nutrients to enter the cell and waste products to leave.
  • The number of double bonds classifies fatty acids as monounsaturated or polyunsaturated. The position of the first double bond classifies polyunsaturated fatty acids further.
  • Cis polyunsaturated fatty acids: >1 double bond between the C atoms.
    • ω-3 (omega-3/n-3: position of double bond = 3) fatty acids: including ALA and DHA. E.g.: α-linolenic acid (ALA) C18:3 and the long chain polyunsaturated fatty acids (LCPUFAs) eicosapentaenoic acid (EPA) C20:5 and docosahexaenoic acid (DHA) C22:6.
    • α-linolenic acid (ALA) is an essential fatty acid: it cannot be synthesised (produced) by the body; it needs to be supplied by food. 
  • Most people in the Western world do not get enough omega-3 fatty acids in their diet.

Main natural sources

Depending on the diet of the mother, these fatty acids are found in human milk. 

  • ALA: vegetable oils (flaxseed, linseed canola, soy, walnut), soybeans, pumpkin seed, chia seed, walnuts and tofu.
  • EPA and DHA: salmon, herring, mackerel, sardines. 

Main function

  • For normal growth and development.
  • For the developing brain, during pregnancy and early childhood and for life-long brain health. For cognitive (brain memory and performance) and behavioural development and function.
  • DHA is a major component (50%) of the retina (light-sensitive eye layer) and important for visual development.
  • In cell membranes, LCPUFAs have specific roles that contribute to immune cell responses. Studies show intake of LCPUFAs early in life can influence immune development.

Deficiency disease

  • Risk of cardiovascular diseases (heart attack, stroke) and atherosclerosis.
  • Signs and symptoms of an omega-3/omega-6 deficiency include: allergic or atopic tendencies (eczema, asthma, hay fever), visual symptoms (poor night vision, visual disturbances), attention problems (poor concentration, attention and memory problems), emotional sensitivity (depression, excessive mood swings, anxiety), disturbed sleep-wake cycle and decreased immunity (increased susceptibility to diseases and infection, poor wound healing).
  • In infants and children growth may be decreased. Studies in children show the negative impact on neurocognitive development – associated with impairment in cognitive (brain memory and performance) and behavioural performance.

DRIs (Dietary Reference Intakes) have not been established for EPA and DHA. Although there is no DRI, the National Academies have recommended that approximately 10% of the Acceptable Macronutrient Distribution Range (AMDR) for ALA (α-linolenic acid, C18:3, precursor EPA and DHA) can be consumed as EPA and/or DHA (life stage groups > 1 year).

Recommendations for ALA have been established.

Recommended daily intake

Latest Dietary Reference Intakes (DRIs)
Institute of Medicine (IOM)

Age categoryPer day
ALA / LA
Pregnancy
Lactation
1.4 g  / 13 g (AI)
1.3 g  / 13 g (AI)
Infants 6 – 12 months0.5 g / 4.6 g (AI)
Children
 1 – 3 years
 4 – 8 years
0.7 g /  7 g (AI)
0.9 g / 10 g (AI)
Males
 9 – 13 years
14 – 18 years
19 – 30 years
31 – 50 years
50 – 70 years
> 70 years
1.2 g / 12 g (AI)
1.6 g / 16 g (AI)
1.6 g / 17 g (AI)
1.6 g / 17 g (AI)
1.6 g / 14 g (AI)
1.6 g / 14 g (AI)
Females

9 – 13 years
14 – 18 years
19 – 30 years
31 – 50 years
50 – 70 years
> 70 years

1.0 g / 10 g (AI)
1.1 g / 11 g (AI)
1.1 g / 12 g (AI)
1.1 g / 12 g (AI)
1.1 g / 11 g (AI)
1.1 g / 11 g (AI)


AI = Adequate Intake.

Synonyms: Omega 3

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