Good Fats Bad Fats

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Scientic research into cardiac health

Text of Good Fats Bad Fats

  • Good fats: Bad fats IIProgress on the fats agenda 2006 to 2009

  • This update to the 2006 Good fats: Bad fats briefingpaper summarises the latest evidence and progresstowards supporting healthier fat intake in Cheshire& Merseyside, the UK and beyond. It makes a seriesof recommendations for further policy action tosupport the national fat goals.

    Progress on the dietary fats agenda 2006 to 2009

    Good fats: Bad fats II

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  • Dietary saturated fats powerfully influence bloodcholesterol levels. Dietary saturated fats are bad,they increase levels of bad low density lipoprotein(LDL) cholesterol. The main sources of saturated fatsare butter, other full fat dairy products, processed foods,meat and meat products. It is generally recognisedthat current saturated fat intake levels in the UKpopulation are detrimental to cardiovascular health.

    Industrial Trans Fatty Acids (TFAs) are particularlyharmful. Trans fats are artificially made by hydrogenationof vegetable oils. A small amount of trans fats occurnaturally in ruminant products, for example milk andcheese. Trans fats are considered to be bad fats.Every 1% of our energy obtained from trans fatsincreases our CVD risk by 12%.

    Polyunsaturated and monounsaturated fats are good.They reduce bad LDL cholesterol and raise good highdensity lipoprotein [HDL] cholesterol. Polyunsaturatedand monounsaturated fats are found in vegetables,nuts, avocados and vegetable oils including olive oil,rapeseed oil and sunflower oil.

    Omega 3 oils and oily fish powerfully protect againstCVD through mechanisms which include reducingplaque formation and inflammation, and loweringblood pressure. The Food Standards Agency (FSA)recommends that everyone should eat at least twoportions of fish per week, one of which should be oily,such as trout, mackerel or salmon. Average UK intakesare currently much less. Plant sources of omega 3include flaxseeds, soya beans and walnuts.

    Cardiovascular disease (CVD) includes heart attacks, angina, heart failure and stroke. Although many factors increase CVD risk, there are only three major risk factors whichcan be reduced: cholesterol, blood pressure and smoking. Dietary fats powerfully influence blood cholesterol, and also bloodpressure. The key target is to increase the intake of good fats (whichlower blood cholesterol levels) and reduce the intake of bad fats(which increase blood cholesterol).

    Summary

    Plant sterols (and stanols) substantially lower LDLcholesterol levels in the blood. Clinical trials have shownthat daily consumption of 23g of plant sterols reducesblood cholesterol by about 10%. This will reduce therisk of coronary heart disease (CHD) by about 25%.Fortified margarines (e.g. Benecol, Flora pro.active)and yogurts (e.g. Danacol, Benecol) help meet the 23g per day recommendation for adults.

    Blood cholesterol and coronary heart disease:Our bodies produce two types of cholesterol, high levelsof low density lipoproteins (LDL) are bad cholesterolswhen levels in the blood are high. LDL cholesteroldamages the artery walls resulting in plaques(atherosclerosis) leading to heart attacks and strokes.High density lipoprotein (HDL) is good cholesterol andis increased by exercise, moderate alcohol consumption,and oestrogens.

    Successful population based approaches toreducing CVD: Switching from animal based saturatedfat sources to plant based mono and polyunsaturatedfat sources has been shown to be protective against CHDin several populations. Population based observationalstudies in Australia, Finland, Poland, Norway, Mauritiusand the US have all shown significant reductions in CHDmortality following the introduction of fiscal policieswhich resulted in a reduction in animal fat and anincrease in vegetable fat consumption.

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  • A number of important developments haveoccurred on the saturated fat agenda since 2006.Among them:

    The European Commission introduced a flat rate schoolmilk subsidy in 2006 so schools are no longer financiallydisadvantaged for providing low fat milk

    New school food standards were published in England in 2006 with clear limits for saturated fat, and a ban on the provision of full fat milk

    Trans fats have risen up the political agenda. In 2007 the Secretary of State for Health requested the ScientificAdvisory Committee on Nutrition to undertake a rapid review of the evidence on trans fats, although it failed to recommend a national ban

    The Food Standards Agency (FSA) commenced its saturated fat and energy intake reduction programme in 2008 and launched a saturated fat campaign in 2009.The FSA also relaxed the rules allowing 1% milk to be marketed in the UK (1% milk is a new product that is halfway between semi-skimmed and skimmed milk; it contains 1% fat)

    More retailers have adopted the traffic light food labelling system. Traffic lights make it easier for consumers to spot foods high in saturated fat. Some have also eliminated trans fat from own brand products, and Sainsburys has introduced 1% fat milk

    Some food manufacturers have started to reformulate certain products to reduce the saturated fat content. However, this is a voluntary scheme and currently there are no government levies to promote improvements.

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    Progress on fats 2006 to 2009

  • Further actionneeded on fats

    The Common Agricultural Policy (CAP) needs further reform so expenditure reflects the Eatwell plate balance,i.e there is a shift from funding produce high in saturated fat such as beef and dairy, towards more spending on healthier foods such as fruit and vegetables

    The government should set a timetable for the complete eradication of industrial TFAs

    Urgent action is needed to clarify national nutrition guidelines for young children in relation to low fat milk and other dairy products and also the introduction of nutrient-based standards for food provided in pre-school nurseries

    The FSA should develop saturated fat targets for the food industry, as successfully done with salt. This would encourageproduct reformulation to replace saturated fat currently hidden in processed foods, with good polyunsaturates

    The FSA should also set promotional targets for supermarketswhich reflect the balance of the Eatwell plate. The FSA should consider trans fats labels. Also for levels in cheap imported food products

    The Scientific Advisory Committee on Nutrition should urgently review the population saturated fat and nutritiontargets which were developed by its predecessor, the Committee on Medical Aspects of Food Policy. These were produced in 1991 and are now dated

    All sections of the food industry including manufacturers, retailers and the food service sector need to reformulate mainstream products to reduce saturated fat, provide responsible (i.e small) portion sizes for saturated fat ladenfoods such as cakes, pastries, crisps, chips etc, and adoptresponsible marketing practices which reflect the balanceof the Eatwell plate

    Everyone should switch to using unsaturated fats in cooking,using low fat dairy products, offering healthier snack alternatives such as nuts or chopped fruit and vegetables,and incorporating more foods of vegetable origin, e.g. nuts,beans, pasta, rice, couscous, into main dishes.

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  • However, excessive amounts of cholesterol in the bloodcause serious problems. Spare cholesterol is liable tooxidation. Oxidised cholesterol gets deposited on thewalls of the arteries. In response, the bodys inflammatorysystem attacks the cholesterol deposits in an effort toremove them. This results in scar and fatty tissue in theartery walls, known as plaques. These plaques silentlybuild up over the years, narrowing the arteries. Whenblood flow is seriously reduced, a heart attack orstroke could result.

    Some individuals with CHD may experience pain inthe chest (angina). However for many people the firstsymptom of CHD is a heart attack or sudden death.This happens when an artery becomes completelyblocked, stopping blood from flowing to the heart.Around half of all heart attacks are fatal (see Figure 1)

    Cholesterol levels are powerfully influenced by the type and amount of food we eat. Cholesterol is used in the formation of cell membranes, some hormones and in the production of vitamin D in our bodies.

    Blood cholesterol and childhood obesityThe atheroma process begins in childhood. It worsenswith age and poor diet.1,2 An estimated 20% of obesechildren have raised blood cholesterol levels3 withmore advanced atherosclerosis.

    Types of cholesterolBad low density lipoproteins (LDL) transportcholesterol from the liver through the arteries to therest of the body. When LDL levels in the blood are high,the cholesterol sticks to the artery walls, creatingplaques (atherosclerosis).

    Good high density lipoproteins (HDL) transportcholesterol from the blood to the liver, which thenremoves it from the body. High levels of HDL reducethe risk of plaque formation. HDL cholesterol is raisedby a healthy lifestyle (physical activity, moderate alcoholconsumption, not smoking and consumption of plantsterols /stanols).

    Blood cholesterol andcoronary heart disease

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  • CHD starts early, presents later Hanlon, Capewell et al SNAP 1997

    Atheroma

    Symptoms

    Symptom threshold

    Inflammation and thrombosisSource: Hanlon et al, 1998 4

    Childhood Middle age Old age

    No Symptoms (for survivors)

    Secondary prevention

    Natural

    course

    of CHD

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    Figure 1: The natural progression of coronary heart disease

    Table 1: Effects of different types of fats on cholesterol levels and cardiovascular disease

    Adapted from: Fats & Cholesterol: Nutrition Source, Harvard School of Public Health.

    Type of fat Major dietary sourcesEffect on bad LDLc