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Lipids

Lipids. FUNCTIONS OF FAT. Energy storage unlimited Insulation and protection Absorption and transport of fat-soluble vitamins & fat-soluble antioxidants eg lycopene, beta carotene Essential fatty acids (EFA) Adds flavour and texture to food Promotes satiety. Body stores of fat.

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Lipids

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  1. Lipids

  2. FUNCTIONS OF FAT • Energy storage unlimited • Insulation and protection • Absorption and transport of fat-soluble vitamins & fat-soluble antioxidants eg lycopene, beta carotene • Essential fatty acids (EFA) • Adds flavour and texture to food • Promotes satiety

  3. Body stores of fat • Fat occurs as triglycerides in the body • Dietary fat is stored in adipose (fat) cells located in depots on the human frame • The type of FAs in our body stores are a reflection of the type of fat we eat (i.e SF, PUFA or MUFA)

  4. Lipids Definition: Group of compounds that are not soluble in water

  5. Types of lipids • Fat = solid at room temperature • Oil = liquid at room temp. • Triglycerides (fats and oils) • Sterols (cholesterol, plant sterols) • Phospholipids (lecithin)

  6. Triglycerides • Glycerol and 3 fatty acids (FA) Saturated (SFA) Unsaturated Monounsaturated (MUFA) Polyunsaturated (PUFA) • Fats and oils contain a mix of FAs • FA’s classified by no. of carbons in chain, no. dble bonds & position of first dble bond. • Thus according to the predominant type of fatty acids in the fat listed above

  7. Omega - 3 Linolenic acid (EPA, DHA) Omega - 6 Linoleic acid Omega - 9 Oleic acid Most Western diets have larger amount of omega 6 Polyunsaturated margarines have a high content of omega 6 Essential fatty acids

  8. Phospholipids • Important part of cell membranes • Help transport FAs and cholesterol in the blood

  9. Sterols • Synthesised by the liver and present in animal foods • Essential for production of hormones (estrogen, testosterone and adrenal) • Precursor for bile acids NB - advertising of low cholesterol products

  10. Trans fatty acids (TFA) • Unsaturated fats – PUFA or MFA • Occur naturally in butter, milk, beef • Also formed during manufacture of margarine, when liquid vege oil are hydrogenated (hardened) to turn them into a semi-solid spread • Changes chemical structure from cis orientation to trans

  11. TFA (2) • Raise blood cholesterol like SFA • NZ intake low compared to US • Some margarines/spreads are now trans free <1% or around 12-18% TFA content • Butter 5% TFA content

  12. DIGESTION OF FATS • 50-100g triglycerides • 4-8 g phospholipids • 300-450mg of cholesterol • STOMACH • Fat floats and is not digested • SMALL INTESTINE • Bile binds water and fat so digestive enzymes can hydrolyse the fats

  13. DIGESTION OF FATS • Triglycerides • hydrolysed to glycerol with 2 fatty acids => glycerol with 1 fatty acid • Phospholipids • hydrolysed to Glycerol + phosphate and 2 fatty acids Triglycerides, Cholesterol & Phospholipids • Assembled into lipid transporters called chylomicrons and delivered to lymph and blood • Cholesterol • Transported to liver and cells or transformed into bile and stored in gall bladder

  14. Storage of fat • Adipose cells • Many TG’s in one cell => lots of energy • In energy demand: • TG’s hydrolysed to glycerol and FA’s, transported to cells and hydrolysed further to energy, CO2 & H2O • Fat fragments combine with CHO fragments & completely oxidised to CO2 & H2O/ • BODY FAT CANNOT BREAK DOWN COMPLETELY UNLESS CHO IS PRESENT AT THE SAME TIME.

  15. DID YOU KNOW!!! • Kiwis are the highest per capita consumers of ice cream in the world; munching through 27 Litres each person, per year. • Reprinted with permission from the March 2007 Issue of Healthy Food Guide

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