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Omega 3 & omega- 6; long-chain polyunsaturated fatty acids (lc-puf as)

Omega-3 & Omega-6 ; Long-chain polyunsaturated fatty acids (LC-PUFAs)

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Omega 3 & omega- 6; long-chain polyunsaturated fatty acids (lc-puf as)

  1. 1. )
  2. 2. Food classification
  3. 3. Background and Chemistry • Fat is the most energy dense macronutrient and has important functions, not only as a source of energy but also as a crucial component of cell membrane structure, healthy brain and nervous system function. • The quality of fat consumed is therefore very important, particularly in early life, pregnancy and lactation.
  4. 4. Classification of fats Fats are classified into 4 categories as follows: 1. On the basis of chemical composition 2. On the basis of fatty acids 3. On the basis of requirement 4. On the basis of sources
  5. 5. Classification: On the basis of requirement 1. Essential fatty acids • Fatty acids which are essential to be taken in our diet because they cannot be synthesized in our body. Linoleic, linolenic and arachidonic acids. 2. Non-essential fatty acids • Fatty acids which can be synthesized by the body and which need not be supplied through the diet. Palmitic acid, oleic acid and butyric acid.
  6. 6. Classification: On the basis of fatty acids • 1. Saturated fatty acids • 2. Unsaturated fatty acids I. Monounsaturated fatty acid (MUFA): II. Polyunsaturated fatty acid (PUFA): A. Omega-3: α-linolenic acid (ALA); eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). B. Omega-6: linoleic acid (LA); Arachidonic acid (ARA – derived from LA)
  7. 7. Classifications of polyunsaturated fatty acids • Based on the length of their carbon backbone, they are sometimes classified in two groups: • Short chain polyunsaturated fatty acids (SC- PUFA), with less than 18 carbon atoms. • long-chain polyunsaturated fatty acids (LC- PUFA) with more than 18 carbon atoms.
  8. 8. polyunsaturated fatty acids • The PUFAs linoleic acid (LA) and α-linoleic acid (ALA) are essential fats, meaning that they must be regularly supplied from external dietary sources as they cannot be synthesized by the human body. • LA and ALA undergo metabolic conversion • Arachidonic acid (ARA – derived from LA) and • Eicosapentaenoic acid and Docosahexanoeic acid (EPA & DHA respectively – derived from ALA). • Some physiological functions are directly attributable to these LC-PUFA's while other functions and biological effects require the formation of their active lipid metabolites (eicosanoids & docosanoids).
  9. 9. long-chain polyunsaturated fatty acids (LC-PUFA) • LC-PUFAs can be further metabolised into short-lived lipids known as eicosanoids & docosanoids which influence physiological systems and clinical outcomes. • Their effects on human health depend on the type of eicosanoid produced and can influence both positive and negative health outcomes. • For example an excessively increased ratio of omega-6 (n-6) to omega-3 (n-3) fatty acids has been suggested to promote inflammation and inflammatory-related diseases through the production of n-6-derived proinflammatory eicosanoids.
  10. 10. Eicosanoids • Eicosnaoids include several families: prostaglandins, prostacyclins and thromboxanes as well as leukotrienes and hydroxl fatty acids. • Eicosanoids are involved in platelet aggregation, chemotaxis and cell growth.
  11. 11. Docosanoids • Docosanoids include resolvins, protectins and maresins. • Docosanoids are actively involved in physiological processes similar to eicosanoids, and more specifically, in the regulation and resolution of inflammatory processes, in which n-3 LC-PUFAs play an important anti-inflammatory role.
  12. 12. Physiological Roles of LC-PUFAs Energy supply Membrane Structure and Function of in the brain and retina & platelet Influence immune response, cell differentiation & growth and regulate gene transcription. Influence vascular, neural and immune function
  13. 13. Dietary Sources • While fish is considered one of the best sources of omega-3 LC-PUFA, it is by no means the only source.
  14. 14. Dietary Sources • Fish • Marine species, especially from cold waters, contain high amounts of LC-PUFA’s . • A recent systematic analysis, of more than 1.5 million individuals representing 113 out of 187 countries (82% of the world's population) found that more than 80% of the world's population has a mean omega-3 seafood intake below the recommended levels of 250 mg/d for adults.
  15. 15. Meat • The fatty acid composition of meat depends primarily on the type of animal. • In ruminants, such as cows, more than 90% of the unsaturated fatty acids are hydrogenated to saturated fatty acids in the rumen. • Beef therefore, contains higher amounts of saturated fatty acids than the meat of non-ruminant animals. • The content of LC-PUFA's and their precursors is considerably lower compared to the LC-PUFA content of oily fish. • ARA is the LC-PUFA that is most predominantly present in meat.
  16. 16. Eggs and Milk • Egg yolk consists of approximately 30% fat, mostly saturated (SFA) and monounsaturated fatty acids (MUFAs), but also a considerable amount of LA. • Milk fat also consists mostly of SFA's and MUFA's and only contains small amounts of PUFA’s. • There are no appreciable contents of LC-PUFA's in cows’ milk and other dairy products.
  17. 17. Plants • Plants store energy as oil in their seeds. • The FA composition of seed oils varies widely and typically one FA dominates. • Plant-derived foods are not sources for LC-PUFA's, but for the precursor fatty acids linoleic acid and α-linolenic acid.
  18. 18. Health Benefits in Infants • LC-PUFAs are thought to have many health benefits both in the short and long-term. • While it is difficult to pinpoint direct cause and effect, studies suggest LC-PUFAs may improve visual acuity, cognitive development and allergy outcomes as well as support immune function and improve markers of cardiovascular disease.
  19. 19. Cognitive Development • Breastfeeding is associated with an advantage of 2.2 IQ points adjusted for maternal IQ. • It has been hypothesized that the observed difference in cognitive outcomes between breastfed and formula fed infants may be attributable at least in part to the provision of n-6 and n-3 LC-PUFA's that are present in breastmilk but not in conventional infant formula. Health Benefits
  20. 20. Allergy and Immune Function • It has been hypothesized that PUFA status in infancy may have a protective effect on the development of allergies. • Results from observational studies show a clear association between low DHA content of breastmilk and an increased risk of atopic disease in the infant. Health Benefits
  21. 21. Visual Acuity • Development of visual acuity in infancy reflects nervous system development, and not refractive errors that are correctable with eyeglasses. • Breastfed infants having received DHA-enriched complementary foods had more mature visual evoked potentials at 9 and 12 months of age compared to the control group. Health Benefits
  22. 22. LC-PUFA in Breastmilk and BMS • Fat is the largest contributor to the caloric content of breastmilk and is the most variable concentration of all macronutrients . • Concentration varies between women as well as between feeds and is influenced by stage of lactation, total milk volume and maternal nutrition.
  23. 23. • Infant intake of LC-PUFA’s and their precursors is derived from maternal diet or body stores. • Additionally, LC-PUFA metabolites are formed in relatively small amounts from endogenous PUFA conversion. • Studies show that 30% of linoleic acid (LA) present in breastmilk was derived from dietary sources and 1.2% ARA originated from endogenous conversion of LA.
  24. 24. • Sufficient dietary intake is also important to ensure adequate intake in infants. Supplementation with preformed LC-PUFA’s has been shown to increase their concentrations in breastmilk in very short periods of time. • Supplementation of DHA in lactating women for 14 days demonstrated that approximately 20% of DHA was secreted into breastmilk indicating that dietary DHA is an important determinant of DHA content in breastmilk. • Physicians should counsel mothers to ensure sufficient dietary LC-PUFA intake in order to support optimal infant growth and development.
  25. 25. LC-PUFA and Lactational Changes Over Time • The composition of fatty acids in breastmilk change over time. • The proportions of both n-6 and n-3 LC-PUFA’s decrease considerably within the first month of lactation with ARA decreasing ~ 38% and DHA by as much as 50%. • This decrease does not necessarily imply a drop in total LC-PUFA supply as total milk fat increases over time, therefore the total amount of LC-PUFA’s secreted into breastmilk remain relatively stable.
  26. 26. • After the large changes seen in DHA and ARA concentration during the first month concentrations remain relatively stable up to 12 months of age. • DHA supply from breastmilk was determined to be approximately 50 mg/day during the first three months of life, dropping to around 33 mg/day by six months. • These values are significantly lower than the advised intake of 100 mg/day and highlight the potential benefits of DHA supplementation. • While ARA content also decreased over the first six months, supply was considered to be adequate.
  27. 27. Recommended LC-PUFA Intake for Lactating Mothers • Sufficient maternal intake of DHA is important for lactating women to ensure that infants receive the high amount of LC-PUFA required for the rapidly developing central nervous system. • To ensure an adequate supply of DHA to infants and to maintain maternal DHA status it is recommended that lactating mothers consume at least 200-300 mg/day of DHA .
  28. 28. • A daily supply of 200 mg DHA results in a breastmilk content of 0.3%, providing the infant with a total daily supply of 100 mg DHA. • To achieve nutrient recommendations women should consume a minimum of two portions of fish per week, including at least one portion of oily fish. • Women who do not eat fish are encouraged to take good quality fish oil supplements.
  29. 29. LC-PUFA Content of Breastmilk Substitutes • LC-PUFA enriched formulae are common worldwide. • Most formulae contain 0.2-0.4% DHA of total FAs and 0.35-0.7% of total FAs as ARA. • These values are based on worldwide averages of DHA and ARA in breastmilk as well as on expert recommendations on adequate intakes.
  30. 30. Changing LC-PUFA Requirements in Infancy • In the absence of firm evidence to define reference nutrient intakes for newborns and young infants, breastmilk may serve as a model to define appropriate ARA and DHA intakes,
  31. 31. • International authoritative bodies have proposed adequate intakes (AI's) for older infants from 6-24 months as there is insufficient evidence to set dietary reference intakes (DRI's) for infants and children. • Beyond this age, advice for children should be consistent with advice for the adult population (i.e. 250 mg/day EPA+DHA or 1-2 portions of oily fish per week).
  32. 32. LC-PUFA Requirements in Infancy
  33. 33. Complementary Feeding • In Complementary Feeding, delaying the introduction of fish does not appear to reduce the risk of allergy development. • However, it can lead to a significant reduction of n-3 LC-PUFA intake which in turn may contribute to adverse health outcomes. • In fact, studies have shown that, following the introduction of complementary foods, ARA and DHA intake for infants in both low and high income countries often lies below nutrient intake recommendations.
  34. 34. • In low income countries, traditional complementary foods are low in LC-PUFA's, putting infants at increased risk of suboptimal LC-PUFA intake. • This is of particular concern when the infant is not breastfed and/or if the lactating mother has very low intakes of LC-PUFA's herself. • A study estimating DHA and ARA intakes in low income countries for children aged 6-36 months found median intake of 48.9 mg and 64 mg/day respectively. • On average, infants were only receiving half of the recommended daily intake of DHA.
  35. 35. THANKS FOR YOUR ATTENTION

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Omega-3 & Omega-6 ; Long-chain polyunsaturated fatty acids (LC-PUFAs)

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