MargiAnne Isaia, MD MPH Advanced Nutrition Lipids 3

LIPIDS Essential Fatty Acids 18:2 n-6 and 18:3 n-3 are absolutely needed (essential for development) Functions of EFA –overview: - Growth - Maintenance of skin and hair - Regulation of Cholesterol metabolism - Maintenance of reproductive functions - Membrane integrity

LIPIDS FUNCTIONS of EFFAs -Provide energy PUFA more rapidly oxidized than SFA or MUFA - Are incorporated into structural lipids The major elements in the diet that determine the final distribution of LC PUFA, in cell membrane phospholipids include: - the relative proportion of n-3, n-6, n-9 FA families, - the preformed long chain PUFA vs. their shorter chain precursors. - Eicosanoids synthesis - Regulate gene transcription through PPARs - Membrane function & integrity membrane fluidity, normal function of membrane–bound enzymes, activity of receptors, membrane permeability and transport properties (brain, retina –V LC derivative of n-3 PUFA) - Modulations of cell-cell interactions PPARs = Peroxisome Proliferator Activated Receptor, nuclear hormon receptor, role on the genetic regulation of FA oxidation and lipogenesis

LIPIDS LIPIDS – ESSENTIAL FATTY ACIDS Essential Fatty Acids (C 18:2 n-6 and C 18:3 n-3) provided by diet (the body cannot synthesize them) EFFAs deficiency results in: -reduced growth rate, scaly dermatitis, hair loss, infertility, depressed inflammatory response, -kidney and liver abnormalities, decreased capillary resistance, increased fragility of RBC, reduced contraction of myocardial tissue, poor wound healing.

LIPIDS ESSENTIAL FATTY ACID STATUS EFA adequate:triene/tetraene =/ < 0.4 Eicosatrienoic Acid / Arachidonic Acid (C 20:3 n-9 / C20:4 n-6) EFA deficiency:triene/tetraene > 0.4 Eicosatrienoic Acid (C 20:3 n-9) biomarker of EFA status. Amount of EFA required to keep ratio normal is 1-2% of total energy. An EFA deficient diet for longer than 6 months is required to produce deficiency in adults.

LIPIDS EFA STATUS Total intake of n-3 FA similar among vegans, LOV, omnivores (1-3g/d) Intake of very long chain n-3 FA varies - Vegans negligible - LOV < 5 mg/d EPA and DHA; it varies depending on DHA eggs in the diet) - Omnivores mg/d (it varies based on fatty fish consumption) Intake of n-6 FA higher in vegans and LOV n-6: n-3 ratio higher among vegans (14:1 -20:1) LOV 10:1-16:1, omnivores 10:1 Ideal ratio 4:1

LIPIDS EFA STATUS EPA and DHA in body stores - lower in vegans - Plasma levels - RBC membrane composition (long term) Lactating vegans and LOV had higher Linoleic Acid and a-Linolenic Acid, but less EPA and DHA in the milk than omnivores - Need to take measures to increase intakes - Full term infants have stores of EFA

LIPIDS ACHIVING OPTIMAL STATUS 2 methods - maximize conversion of ALA to EPA and DHA - provide a direct source of EPA and DHA Maximize conversion: - Factors affecting: genetics, age, overall health, diet - Proper calories and protein intake - Optimal status of vit B6, biotin, calcium, magnesium and zinc - Lower SFA and trans FA (avoid processed food with trans FA) - No alcohol intake - Lower n-6 PUFA intake (total PUFA 7-10% energy) ( % should come from n-3 FA, the rest from n-6 PUFA to produce the ratio of 4:1) Avoid cooking oils rich in n-6 PUFA : corn oil, soybean oil, use instead MUFA: olive oil, canola oil. - Increase ALA intake ( g /1000cal/d)

LIPIDS ACHIEVING OPTIMAL STATUS - Provide a direct source of long chain n-3FA - fatty fish or fatty fish oil as a supplement - LOV can include DHA enriched eggs (eggs from chicken fed flax or micro algae) mg DHA/egg - Plant source is micro algae (original source) - direct from seaweeds may not be practical because of low concentration. 100 g seaweeds contains about 100mg Low consumption in US, but higher in Japan. Supplements available EPA will come from retro-conversion of DHA to EPA Conversion of ALA g EPA 5-10% - for vegan population DHA 2-5% Rate of conversion depends on background diet Recommended EPA + DHA intake: mg/day

LIPIDS REQUIREMENTS Pregnancy: EFA required for maternal and fetal needs. Fetal organs (liver, brain, retina) incorporate long chain PUFA during last semester in utero. Maternal EFA consumption : n-6 13 g/d; n-3: 1.4g/d Lactation - 4-5% energy in human milk is 18:2 n-6, 18:3 n-3 - 1% energy as long chain PUFA Efficiency of converting dietary EFA to milk LC EFA not known requirements: n-6 13 g/d; n-3 1.3g/d

LIPIDS REQUIREMENTS Infancy and childhood, adult : n-6 : n-30-6 months: 4.5 g/day: 0.5 g/d 6-12 mo: 5.4 g/day: 0.5 g/d 4-5 years: 7.0 g/day: 0.7 g/d 4-8 years: 10.0 g/day:0.9 g/d 9-13 years: 16.0 g/day: 1.2 g/d 14+ years: 17.0 g/day: 1.6 g/d 51+ years: 18.0 g/day: 1.4 g/d

LIPIDS ESSENTIAL FA Vegetarian diets – lower in total fat, saturated fat and cholesterol than non vegetarians. They provide comparable levels of EFA. Vegetarian (vegan especially) diets - relatively low in ALA company with LA - little, if any EPA and DHA Clinical studies - tissue levels of very long chain n-3 FA are depressed in a vegetarians (vegans) -n-3 cardio-protective effects ALA, EPA, DHA less for ALA than for EPA/DHA Conversion of ALA g EPA < 5-10% g DHA 2-5% Total requirements for n-3FA may be higher for vegetarians Vegetarians - make dietary changes to optimize n-3 FA status

LIPIDS REFERENCES 1. Shils M et al, Modern Nutrition in Health and Disease, 10 th Edition 2. www. Pubmed.org

QUESTIONS?