The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.Robert A Gibson, Maria Makrides and Coral G B Colye

Colyer, C.

Gibson, R.

Makrides, M.

The Medical Journal of Australia

Adelaide Research &amp; Scholarship

PUBLISHED VERSION   Gibson, Robert Alan; Makrides, Maria; Colyer, Coral G. B.  Essential role of fats throughout the lifecycle : summary and recommendations Medical Journal of Australia, 2002; 176(11 Suppl):S107-S109  This article is available from the Medical Journal of Australia at:      http://www.mja.com.au/public/issues/176_11_030602/S107-S109.html      PERMISSIONS   This document has been archived with permission from the editor of the Medical Journal of Australia, 26 April 2007.         http://hdl.handle.net/2440/39755 MJA Vol 176 3 June 2002 S107ROLE OF FATSSupplementThe Medical Journal of Australia ISSN: 0025-729X 3 June 2002 176 11 107-109©The Medical Journal of Australia 2002 www.mja.com.auRole of FatsNUTRITION IS NO LONGER just the science of avoidingdeficiencies, but rather is now focused on determining thelevels of dietary nutrients that will optimise physiologicaland health outcomes. Nowhere is this change in the study ofnutrition more evident than in the study of dietary fattyacids.In a few short years we have progressed from the simplemantra “saturates are bad, polyunsaturates are good” to afar more sophisticated understanding of the way that indi-vidual fatty acids in our foods can manifest physiologicalchange. We now know that not all saturated fatty acids causea rise in plasma cholesterol levels — some are moreatherogenic than others, which explains why some food fatscause a larger rise in plasma cholesterol levels than others.So, foods rich in saturates should still be avoided, butdietary advice can now be more targeted.Equally important is that we have also come to realise thatnot all polyunsaturated fatty acids (PUFAs) are equal.Nutritionists now differentiate between omega-6 andomega-3 PUFAs, not only because their chemical structuresdiffer, but also because they elicit different effects. Omega-6PUFAs, for so long a common constituent of a huge varietyof spreads, cooking oils and foods, have proven their worthin numerous studies on cholesterol lowering. However,some key studies conducted over the past 10 years haveshown the potency of foods containing omega-3 PUFAs.The improved survival of people who had already experi-enced a cardiac event when they consumed diets rich inomega-3 PUFAs was remarkable. Whether the omega fattyacids were vegetable in origin1 or were marine oils,2 all-cause mortality rates were reduced by 30%–70% andinduced comparable large reductions in non-fatal sequelae.These results were equivalent to effects seen in statin trials.In addition, the protective effect of the Mediterraneandietary pattern in the Lyon study1 was maintained up tofour years after the first infarction, confirming the previousintermediate analyses and demonstrating the sustainabilityof this type of diet. Major traditional risk factors, such ashigh total blood cholesterol level and raised blood pressure,continued to be independent and joint predictors of recur-rence, indicating that the diet did not alter, at least qualita-tively, the usual relationships between major risk factors andrecurrence, but provided additional protection. Given thelow risk and low cost of this type of intervention, it seemsvital that the usefulness of dietary intervention in secondaryprevention be fully realised.There have also been breakthroughs in the use of omega-3PUFAs in preterm infant nutrition. Because of our limitedability to convert vegetable omega-3 PUFAs to the long-chain PUFA found in marine foods (such as docosahexae-noic acid [DHA]), several clinical trials have tested theeffectiveness on short- and long-term development of sup-plementing formulas with DHA. The results have beenconsistently positive, highlighting the fact that fats areessential to the normal growth and development of children.Here, the mechanism may seem to be self-evident, as DHAis a major component of brain and retina, and the preterminfant is denied the natural flow of DHA from the mother,which is greatest in late pregnancy. However, the actual roleof DHA in these tissues is still being unravelled. Impor-tantly, change has occurred in the market place, and allpreterm infant formulas sold in Australia are now supple-mented with DHA.There are a number of clinical areas where omega-3PUFAs in the diet have shown promising results. Benefitshave been well documented in down-regulating inflamma-tory responses in cells and animals, and these results arebeing translated into an effective treatment for some inflam-matory conditions such as rheumatoid arthritis. Someinconsistencies between trial results may be due to the timebetween disease onset and treatment. Certainly, this diseasehas a lower incidence in fish-eating cultures, and a higherconsumption of omega-3 PUFAs in the national diet mayhelp prevent disease onset.There are a number of challenges for the future. Themechanism of action of many dietary fatty acids is still notfully clear, and their interaction with existing drug therapiesneeds to be defined. There is no doubt that many effects offatty acids are mediated by regulation of gene expression.The real challenge for this decade is to quantify theeffectiveness of primary prevention programs based onincreased omega-3 intakes. After all, this is the area wherethe most public health benefit is to be gained, keepingpeople out of hospitals and ensuring the maximum numberof healthy years to us all.RecommendationsThe following recommendations are provided to guidemedical and allied health professionals working with peopleat all stages of the lifecycle.Summary and recommendationsRobert A Gibson, Maria Makrides and Coral G B ColyerChild Nutrition Research Centre, Child Health Research Institute, Women’s and Children’s Hospital, and Flinders Medical Centre, Adelaide, SA, Australia.Robert A Gibson, PhD, Director (and Associate Professor, Department of Paediatrics, University of Adelaide); Maria Makrides, BND, PhD, Senior Scientist (and Senior Lecturer, Department of Paediatrics, University of Adelaide, SA). Goodman Fielder, Macquarie Park, NSW, Australia.Coral G B Colyer, MSc(Nutr & Diet), APD, Nutrition Services Manager. Correspondence: Associate Professor Robert A Gibson, Child Nutrition Research Centre, Child Health Research Institute, Flinders Medical Centre, Adelaide, SA 5042.S107-S110.fm  Page 107  Wednesday, May 22, 2002  10:58 AMS108 MJA Vol 176 3 June 2002ROLE OF FATS SupplementPregnancy and the first year of life■ The strongest evidence for good developmental out-comes for infants is breastfeeding for at least 6 months.■ Fish-oil supplementation during pregnancy has beentested in several trials, with small positive effects on lengthof gestation.■ There have been no beneficial or harmful effects oncognitive development or growth of infants as a result offish-oil supplementation in pregnancy.■ Preterm infants are at the greatest risk of DHA defi-ciency, and there is evidence for the use of breast milk andDHA-supplemented formulas for positive effects of DHAon visual and cognitive outcomes.■ Debate continues about the importance of DHA supple-mentation for term infants. The current consensus is thatthe benefits of DHA supplementation for term infants aresmaller than for preterm infants.Toddlers to preschool■ Toddlers need to be continually encouraged to try a widerange of foods supplying all types of fats, and with theemphasis on nutrient-dense foods.■ Reduced-fat products are not appropriate for toddlerswhen the particular food forms a substantial part of theirintake.■ No sound evidence exists to support the manipulation ofdietary fat for the treatment of attention deficit hyperactivitydisorder or the prevention or treatment of asthma.Primary school■ Fats are essential to the normal growth and developmentof children.■ Parents need to understand that the most significantinfluence on a child’s eating patterns are their own eatingpatterns and preferences.■ The recommendation of 30% total energy from fat can beachieved by practical changes in eating patterns. This mayinclude limiting high-fat and high-saturated-fat snack foods,like ice cream and potato chips, to occasional or treat items.Adolescence and young adulthood■ Advice supporting regular physical activity, healthy foodchoices and smoking avoidance is definitely warranted inadolescents.■ The amount of dietary fat is important in maintainingenergy balance and the type of fat is important in reducingthe development of heart disease.■ Low fat foods are suitable, but it is also important toavoid sources of “hidden” saturated fatty acids (biscuits andfast foods) and to include sources of polyunsaturated andmonounsaturated fatty acids (oils, margarine, lean meat andpoultry and nuts).Adulthood — preventionCardiovascular disease■ To achieve a more desirable ratio of dietary omega-3 toomega-6 PUFAs, encourage the consumption of fish andomega-3-rich seed oils and spreads, such as canola, soy andflaxseed.■ A diet that is rich in PUFAs, such as omega-3, and low insaturates, should be encouraged. This type of diet is rich infish, whole-grain cereals, fruits and vegetables and low-fatdairy foods. Refer to the Box for a sample menu plan.Rheumatoid arthritis■ There is evidence for preventive and therapeutic effects ofdietary omega-3 fats in rheumatoid arthritis.Diabetes■ Total fat intake is not related to the risk of diabetes.However, polyunsaturated fat reduces the risk, monoun-saturated fat is neutral, and saturated fat may increase therisk. However, body weight is a more critical predictor thanmacronutrients in the diet.■ Putting this into practice for adultsA suggested “healthy fats” meal plan for adults is providedin the Box, which aims to:■ minimise saturated fat intake;■ incorporate monounsaturated and polyunsaturated fatsin moderate quantities from oils, spreads, nuts, seeds andavocado;1: Suggested healthy fats menu plan for adults**Foods in italics are sources of omega-3 fats.BreakfastWedge of rockmelon or paw-pawWholegrain or bran cereal or muesli or oats with low-fat milkSoy and linseed toast with canola spread topped with ricotta and tomato slicesLunchPasta with tomatoes, soy or cannellini beans, capsicum, mushrooms and basil(optional: top with a small can of salmon or tuna)Mixed green salad with flaxseed vinaigrette dressingDinnerFillet of fish, pan-cooked with a little olive oil, herbs and lemonBaked potato wedgesSteamed green beans or zucchini (large serve) with toasted walnutsBetween mealsChoose from:■ Vegetable or minestrone soup■ 2–3 sushi rolls with salmon or tuna or prawn■ Fresh fruit or fruit salad■ ¼ cup walnuts or pecans■ Raisin toast with canola spread■ 2–3 rice cakes with canola spread, sliced banana and honey■ Carton of low-fat fruit yoghurt■ ½ avocado■ Low-fat muesli or breakfast barS107-S110.fm  Page 108  Wednesday, May 15, 2002  3:00 PMMJA Vol 176 3 June 2002 S109ROLE OF FATSSupplement■ include sources of omega-3 fats (see Box);■ be high in fibre; and■ offer generous amounts of vegetables and fruits, wholegrains, and low fat dairy foods.Adulthood — treatmentCholesterol-lowering with plant sterols■ Margarines enriched with plant sterols should be consid-ered for patients with increased cardiovascular risk factors,in whom low-density lipoprotein level reduction is desirable.■ Phytosterol-containing foods are valuable additions toother cholesterol-lowering treatments, including statins.■ Encourage the consumption of an additional serving ofcarotenoid-rich fruit or vegetable (eg, rockmelon, mangoes,carrots, pumpkin) to overcome the possible reduction insome carotenoids in plasma.References1. De Lorgeril M, Salen P, Martin JL, et al. Mediterranean diet, traditional risk factorsand the rate of cardiovascular complications after myocardial infarction. Circula-tion 1999; 99: 779-785.2. GISSI-Prevenzione Investigators. Dietary supplementation with n-3 polyunsatu-rated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Lancet 1999; 354: 447-455. ❏BackgroundThe renaissance of fat: roles in membrane structure, signal transduction and gene expressionGareth S DenyerIN RECENT YEARS, it has become clear that fat has a rolebeyond that of macromolecular energy storage. Indeed, fatparticipates in intracellular processes as diverse and com-plex as membrane fluidity, signal transduction and theregulation of gene expression. Furthermore, as specific fatsare involved in mediating these effects, the profile of dietaryintake assumes vital importance, especially as humans can-not make several of the key lipids themselves.Fatty acids and membrane functionAll cell membranes consist of a bilayer of phospholipids.The membrane is impermeable to charged molecules, so,for communication between cells and compartments tooccur, specific protein transporters or receptors have to beembedded in the bilayer. The bilayer is fluid and flexible,allowing free lateral movement of the proteins and theformation of invaginations to permit the processes of endo-cytosis and exocytosis.Crucially, the length and degree of saturation of the fattyacids in the membrane phospholipids determines the fluid-ity of the membrane. Long (> 16 carbons) and saturatedfatty acyl groups tend to make the membrane less fluid,whereas shorter, unsaturated fatty acids permit greaterflexibility and permeability. The functionality of proteins inthe membrane is critically dependent on membrane fluidity,especially when the proteins have to collide with othermolecules to exert their effects (as in many receptor-mediated pathways) or when the proteins have to be endocy-tosed (such as the ingestion of low-density lipoproteins[LDLs] after binding to the LDL-receptor).It is vital that a variety of fatty acids be available formembrane phospholipid construction. Many of the fattyacids in membranes are unsaturated and cannot be made byhumans de novo. These include alpha-linolenic acid andlinoleic acid. Therefore, the mix of fatty acids in the diet canhave profound effects on the membrane phospholipid fattyacid composition and on the efficiency of membrane-mediated processes. For example, the ability of insulin tocommunicate its signal is strongly impaired when animalsare fed a diet high in saturated fat and this effect can beovercome with omega-3 poyunsaturated fatty acid intake.This, in turn, is probably related to diet-induced changes inmembrane fatty acid profile, as recent studies have shownstrong correlations between membrane phospholipid com-position and insulin sensitivity in humans.1Department of Biochemistry, The University of Sydney, Sydney, NSW, Australia.Gareth S Denyer, BA(Oxon), DPhil (Oxon), Senior Lecturer. Correspondence: Dr Gareth S Denyer, Department of Biochemistry, The University of Sydney, Sydney, NSW 2006.Summary■ The intracellular and intramembrane profiles of fatty acids mirror those of dietary fat intake.■ The properties of transporter and receptor proteins embedded within cell membranes are influenced by the composition of the phospholipid membrane of cells.■ Many cell-signalling pathways involve lipids or lipid-derived molecules.■ Specific fatty acids are increasingly being identified as key regulators of gene expression and tissue differentiation.S107-S110.fm  Page 109  Wednesday, May 15, 2002  3:00 PM

Essential role of fats throughout the lifecycle : summary and recommendations

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Essential role of fats throughout the lifecycle : summary and recommendations

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