Topic 2 - Warm-up Quiz PDF

Topic 2 – Warm-up Quizz Cholesterol is a… a) Fatty acid b) Triglyceride c) Sterol & Atoms normally not found in triglycerides are… a) Hydrogen b) Oxygen & c) Nitrogen The normal recommended intake of lipids (%energy) are: a) 20% & b) 30% c) 10% saturated fatty acid Which...

Topic 2 – Warm-up Quizz Cholesterol is a… a) Fatty acid b) Triglyceride c) Sterol & Atoms normally not found in triglycerides are… a) Hydrogen b) Oxygen & c) Nitrogen The normal recommended intake of lipids (%energy) are: a) 20% & b) 30% c) 10% saturated fatty acid Which compound The increased is not found consumption ofintotal thefats lipidhas fraction: been blamed as the major reason for a) the increase in obesity Daidzein a)b) true Beta-carotene simple angars than the lipids are b)c) false & Vitamin K I – Some Definitions Lipids: A mixture of water insoluble compounds, of both liquid and solid fats and additional compounds such as cholesterol, phytochemicals… Fats: Usually solid compounds, soluble in organic solvents, not in water, mostly triglycerides. In relation to nutrition, these are mostly of animal origin. Oil: A mixture of lipids that is liquid at room temperature. In relation to nutrition, these are mostly vegetable oils (Exceptions: coconut oil/butter). a -tainsmoresaturated as en solid Triglycerides (IUPAC: triacylglycerides): Mixtures of esters of fatty acids and glycerol, constituting the majority of dietary fats/oils. Fatty acid: a hydrocarbon with a carboxylic (acidic) function (COOH). ↳ to and ten form the sterified glyceral Trighycrids  II – Categories of Lipids Constitution of a fatty acid: ⑨ Carboxylic acids with hydrocarbon chains containing 4 to 36 carbons. o Almost all natural fatty acids have an even number of carbons (normal biological synthesis of C2 units). & Those with uneven number of C atoms often originate from bacterial metabolism. & Most natural fatty acids are unbranched. De 22 very long chain FA short ones are ↳ water soluble very => vein absorption et long hipdos more II – Categories of Lipids What’s in it ? Lipids Triglycerides : Free fatty acids Lipid soluble compounds: Other saponifiable & Saturated: no double bonds between compounds: carbons in the chain. Vitamins (D, E, K, A) & Monounsaturated: one double bond Sterols: e.g. cholesterol between carbons in the alkyl chain. Phytosterols (e.g. Phospholipids stigmasterol) (e.g. lecithin) & Polyunsaturated: more than one double bond in the alkyl chain. Unpolar polyphenols: Sphingolipids e.g. curcumin (e.g. ceramides) Carotenoids Waxes (esters of Terpenes alcohols and fatty acids)  II – Categories of Lipids- Fatty acids Most predominant II – Categories of Lipids Saturated Fatty Acids: apolar polar side side Chocolate fat: Text - mostly of animal fat origin - higher melting point compared to unsaturated fatty acids (ordered linear structure) - mostly C16:0 (palmitic acid), C18:0 (stearic acid) - free rotation around bonds  II – Categories of Lipids Mono-unsaturated Fatty Acids: oleic acid Double bond at 9th position from apolar end: -9 (9Z)-Octadec-9-enoic acid delta -> from the carboxylic end of the molecule Note: when counting from carboxyl-end: cis-Δ9-Octadecenoic acid - lower melting point due to bended structure (less linear, less ordered) - mostly in plant oils trans molecule fatty acids - no free rotation around double bond !! II – Categories of Lipids Polyunsaturated Fatty Acids: a) Numbering in delta system: 18:2 (Δ9,12), omega 6 b) Trivial name: linoleic acid, 20:5 (Δ5,8,11,14,17), c) Omega classification : Eicosapentanoic acid (EPA), -6 fatty acid an omega-3 fatty acid - lower melting point due to bended structure (less ordered) - mostly in plant oils and in fish oils (EPA, DHA) - no free rotation around double bond !! Unsaturated fatty acids: found in colder environment (otherwise e.g. fish would “freeze” solid.  II – Categories of Lipids Which are the essential fatty acids ?? Essential Fatty Acids - Functions: - 2 essential fatty acids: Linoleic acid and linolenic acid !! 18:3 (Δ9,12,15), -linolenic acid, 18:2 (Δ9,12), an  -3 fatty acid Linoleic acid, an omega-6 fatty acid These fatty acids cannot be formed by the human body from saturated fatty acids or monounsaturated fatty acids The body can only prolong and unsaturate from the carboxylic end, and not beyond carbon 9 and 10 ! RDA -requirement for humans: A high ratio of omega 3:6 has been -17/12 g linoleic acid/d (m/f) suggested to reduce CVD risk. -1.6/1.1 g linolenic acid/d (m/f) Recommended: 1:2. Status: 1:10 II – Categories of Lipids Essential Fatty Acids - Functions: Eicosanoid formation: important for inflammation (upregulation). Maintaining cell membrane fluidity (especially unsaturated FA). Endocannabinoids: mood, behaviour : arachidonoylethanolamide, 2-arachidonoyl glycerol; Lipoxins (from - 6) and resolvins (from  -3): down-regulation of inflammation. Action on DNA via transcription factors (NF-kB), cytokine formation. Participate in formation of “Lipid Rafts”: Area where (signal, protein…) uptake through cell membrane may take place. A cell membrane with a lipid raft: higher concentrations of glycosphingolipids, proteins, cholesterol.  II – Categories of Lipids Trans Fatty Acids – a Case of Concern ? Altered structure due to increased linearity of fatty acid Can be produced during strong heating (frying) or (partial) hydrogenation of unsaturated fatty acids (margarine production). Trans-fats behave biologically more like saturated fatty acids. Trans-fats were associated with increased levels of LDL-C, reduced HDL-C, inflammation and CVD. However, some bacterial fermented derived trans-fats were associated with positve health benefits -> type of trans fatty acid important. In the past, content in margerines 5-10%, now 1-2%. Higher conc. may be found in cakes, biscuits, pastry... II – Categories of Lipids Estimated negative effects occur at trans-fatty acid intake of 2-7g/d This may be reached by a single portion of french fries (country dependent !!)  II – Categories of Lipids Excursion: The never ending battle between butter and margarine – a draw ? Which do you prefer ?? Margarine: Butter: less processed  More unsaturated fatty acids  More “natural product”  Often added health beneficial  Less trans-fatty acids compounds (phytosterols…) – Less healthy FA profile  Made from plant fats: sustainable… – Earlier heavy metals (catalysator, Cr…) – Trans-fatty acids II – Categories of Lipids Lipids: a) Triacylglycerides Mostly mixed FA in TGs  II – Categories of Lipids Lipids: b) Phospholipids lecithin phosphate choline 2 fatty acids group Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline. Phospholipids are an integral part of the cell membrane (fluid mosaic model), due to their polar and apolar parts Occurrence in food items: eggs, meat, fish, whole-grains, oilseeds In food industry: often used as emulsifiers Can be synthesized by the human body II – Categories of Lipids Lipids: c) Sphingolipids R If R=H, this would be ceramide No glycerol, but sphingosine (amino-alcohol). Mixture of sphingosine & fatty acids, important in neuronal cells/humen brain. Give additional strength to cell membranes (less easily degraded than TG). Also play a role in apoptosis (signalling cascades). Glycosphingolipids are determinants of blood type. Can be produced by the human body. May accumulate in rare diseases (Nieman-Pick)  II – Categories of Lipids Lipids: d) Sterols - Cholesterol Often esterified with fatty acid Cholesterol is a sterol, an alcohol with a steroid structure (rings A-D) Cholesterol is taken up by food, however, the majority (10.000 subjects. Start: 1958 - Association between CVD and hypercholesterolemia But: -study only with men -subjects not chosen at random -it remains only a correlation !! The Framingham Heart Study. - Epidemiological, longitudinal study with >5000 subjects, start in 1948. - Similar results as in Seven Countries Study: Association for men,not for women between coronary artery disease and cholesterol. IV – Digestion and Transport of Lipids How unhealthy is Cholesterol ?? Low impact for No impact women Inverse relation ! No impact for women, low for men Taken from: Udo Pollmer: Lexikon der populären Ernährungsirrtümer.  IV – Digestion and Transport of Lipids How unhealthy is Cholesterol ?? In conclusion: Cholesterol is essential for the body and synthesized to a large extent by the body itself. Total - cholesterol is associated for men, above 200 mg/dL, with an increased risk of CVD. For women, the correlation is much less strong. Total mortality is also barely effected. V – Metabolism of Lipids Energy Delivery : The following steps are required to yield energy from triglycerides: 1. Cleavage of TG into free FA (fatty acids). 2. Activation of FA in the cytosole. 3. Transfer into mitochondria (carnitine- shuttle). 4. Beta-oxidation in the mitochondria in four recurring steps. 5. Inclusion of acetyl-CoA into tricarboxylic acid (Krebs-) cycle for total oxidative decarboxylation.  V – Metabolism of Lipids 1. Cleavage of TG into free FA : TG intracellular lipase Glycerol + 3 FA lipoprotein lipase 2. Activation of fatty acids in the cytosole. Acyl-CoA synthetase acyl CoA 3. Transfer into mitochondria (carnitine- shuttle). V – Metabolism of Lipids 4. Beta-oxidation in the mitochondria in four recurring steps. 1. Dehydrogenation 2. Hydration acyl-CoA 3. Oxidation (of hydroxyl to keto group) trans-enoyl-CoA acetyl- 4. Thiolysis CoA keto-acyl-CoA hydroxy-acyl-CoA 5. Inclusion of acetyl-CoA into Krebs cycle for total oxidative decarboxylation. Acetyl-CoA is directly further metabolized in the mitochondrion.  V – Metabolism of Lipids Prostaglandins, Thromboxanes, Leukotrienes: Derivatives of arachidonic acid, eicosapentanoic acid, or dihomo- linolenic acid Variety of functions: Inflammation and fever (prostaglandins) Formation of blood clots (thromboxanes) Smooth muscle contraction in lungs (leukotrienes) Smooth muscle contraction in uterus (prostaglandins) EPA (omega-3): rather reducing inflammation Arachidonic acid (omega-6): rather increasing inflammation V – Metabolism of Lipids Storage of Lipids in the Body – Fat tissue Triglycerides can be stored in the adipose tissue. Rather than being a passive storage tissue (sink), this tissue can be metabolically quite active (to be discussed later in course). There are 3 main types of adipose cells: Brown and white and beige fat. Brown Fat White Fat - high in newborns and - less metabolically active than hibernating mammals brown fat - in adults: smaller reserves in - negatively associated with health upper chest and neck - higher number of mitochondria (iron, brown color) - higher number of blood vessels - heat production - positivley associated with health  V – Metabolism of Lipids Lost in adults ? Present in adults V – Metabolism of Lipids Precursors  V – Metabolism of Lipids Brown/beige tissue can produce a lot of heat V – Metabolism of Lipids UCP1 (thermogenin): “a transmembrane uncoupling protein found, in the mitochondria of brown and beige adipose tissue. Generates heat by non- shivering thermogenesis - no ATP is generated.