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Animal Source Foods in the UK Diet: A Nutritional Overview - Joe Millward, Professor of Human Nutrition, University of Surrey
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Animal Source Foods in the UK Diet: A Nutritional Overview - Joe Millward, Professor of Human Nutrition, University of Surrey

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During a workshop at the London International Development Centre on 12 June 2009, Joe Millward gave a nutritionist's overview of animal source foods, illustrated from a UK diet perspective.

During a workshop at the London International Development Centre on 12 June 2009, Joe Millward gave a nutritionist's overview of animal source foods, illustrated from a UK diet perspective.

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  • 1. Animal source foods in the UK diet: a nutritional overview D Joe Millward Nutritional Sciences, Faculty of Health and Medical Sciences
  • 2. Meat and dairy foods: consumption patterns 95% OF UK ADULTS EAT MEAT 99% CONSUME MILK/DAIRY Categories of UK vegetarians (total 106/2251)* ASF consumed n (% population) No meat 100 (5) No fish 48 (2.5) No eggs 21 (1) No milk/dairy 15 (0.75) None (vegan) 29 (1.50) *2002 NDNS adult sample
  • 3. Meat and dairy foods: Intakes %energy intake Meat, meat dishes & meat products 15 All dairy products 10 (Liquid milk 5) Meat and dairy foods account for about 25% of energy intakes Current red and processed meat intakes (SACN) ≈ 88g/d for men 52g/d for women
  • 4. The Balance of Good Health UK recommendations for meat & dairy foods Milk and dairy foods About 14% of plate. Important for:- young children >1y<5 (full fat  300mls/d); pregnant women; not babies<1y Eat moderate amounts and choose lower fat versions Meat, fish, eggs, beans & other non-dairy protein sources About 13% of plate. Eat lean meat rather than meat prods. Use smaller quantities of meat in dishes
  • 5. Nutrients from meat & dairy foods in the UK adult diet Nutrient index = % nutrient intake Good source ≥ 2 % energy intake Calcium 4.3 43 iodine 3.8 38 B12 3.6 36 Riboflavin 3.3 33 SFA 2.4 24 phosphorus 2.4 24 Fe(non-haem) 0.1 1 NI %intake Haem-iron 5.7 85 protein 2.4 36 zinc 2.3 34 Niacin 2.3 34 B12 2.0 30 SFA 1.5 22
  • 6. ASF and protein: intakes: Protein intakes increase with ASF intakes. Adult NDNS 1990 1 %available dietary energy UK omnivores: 12.6 UK vegetarians (no meat) 10.2 1 Jackson and Margetts Int J Food Sci Nutr 1993; 44: 95–104 2. Millward unpublished 3 Elliot et al Arch Intern Med. 2006;166:79-87 4 top quartile of veg protein intake, bottom quartile of ASF protein intake 5. bottom quartile of veg protein intake and top quartile of ASF protein intake Elderly NDNS 1998 2 Highest quartile ASF 13.3 Lowest quartile ASF 10.0 INTERMAP study 3 vegetable animal Total %dietary energy Mainly meat eaters 4 5.4 12.0 15.5 Mainly vegetarian 5 9.1 4.3 10.9
  • 7. ASF and protein: nutritional issues Protein quality varies with dietary ASF (digestibility, not AA content)
    • Lower protein intakes: vulnerable groups*:
    • Not infants or children (P:E ratio of requirement is low)
    • Older inactive women and men (P:E ratio of
    • requirement is high)
    *Millward & Jackson Pub Health Nutr.2004 7(3), 387–405 risk of deficiency (low ASF)** Q1 ASF Q4 ASF adult men: 18-32% 3% adult women: 26-42% 5% **modelled for men and women, BMI=25, PAL = 25 th centile, with available P:E ratio of intake observed for lowest and highest quartiles of non-milk ASF intake in elderly NDNS
  • 8. Protein deficiency with low ASF intakes Difficulties and caveats
    • “ Deficiency” = intake <requirement: no objective measure
    • Protein requirements are defined for nitrogen balance equilibrium not for optimal health and low chronic disease risk. This is poorly understood* and controversial
    • Risk of deficiency is model dependent : current models of protein requirement assume habitual protein intakes and requirements are not correlated: ie make no allowance for adaptation.
    • If adaptation is allowed for risk of deficiency with low ASF diets would be low**.
    *Millward DJ (1999), Optimal intakes of protein in the human diet. Proceedings of the Nutrition Society 58: 403-413 **Millward DJ (2003) An adaptive metabolic demand model for protein and amino acid requirements BJNutr 90, 249–260
  • 9. ASF & Iron:
    • Many foods fortified, (flour by law):
    • cereals major source for children and adults -breakfast cereals, white bread etc.
    • haem iron is highly bioavailable
    • Main issue:
    • bioavailability of non haem iron.
    • significant levels of anaemia in several population groups
  • 10. ASF & Iron: Intakes & vulnerable groups Weaning ≥ 6-8mo: cows milk not recommended until >12 mo., only fortified milk feeds, meat recommended (intake unknown) Preschool (NDNS): iron intake marginal: mean =85%RNI, 16%<RNI, Haem iron intake v-low(<5% total iron), 50% report no meat: Older children, adolescents: boys & prepubertal girls: intakes OK: (total and haem iron) Post pubertal girls, young adult women: major problem: 40-50% have intakes <LRNI Institutionalised elderly: low intakes (haem & non-haem iron)
  • 11.
    • poorly understood
    • Haem iron: generally doesn’t vary much apart from inhibition by calcium
    • Non-haem iron: absorption varies markedly:
      • easily inhibited by phytates, polyphenols, fibre: also calcium
      • optimised with vitamin C, food preparation, meat
      • markedly up-regulated: low iron stores, blood loss
    Iron bioavailability :
  • 12.
    • Prevalence
    • significant problem in infancy: 12%NDNS, 25-35% Asians preschool children: 6%NDNS
    • adolescent girls: 10-20%, Asians 25%
    • young women : 8% (NDNS)
    • elderly: 10% free living, 40-50% institutionalised
    Iron deficiency anemia Causes Inappropriate feeding practices at weaning:- unmodified cows milk , unfortified formula Low iron intakes/poor absorption : preschool children, older girls and women, elderly ie. <4ys: lowest intake of cereals, Vit C, meat : 13% IDA highest intake of cereals, Vit C, meat : 6% IDA
    • Concerns
    • Mental/psychomotor development (children)
    • Work performance in adults.
  • 13. ASF and iron: Implications for reductions
    • Dairy foods: not a problem
    • not a useful iron source
    • may be detrimental to absorption.
    • Red meat
    • can make a disproportionate contribution to iron supplies in theory
    • in practice its dietary importance may have been overstated
    • Reduced intakes may have little effect.
    • Increased fortification is always an option.
  • 14. ASF and Zinc 8.3mg/MJ  34% intake 2mg/MJ  17% intake  25% intake
    • Essential for normal growth and development in children and maintenance of good health in adults.
    • Problematic nutrient because status is hard to measure.
    • Subclinical zinc deficiency is widespread globally and s tunted growth partly reflects zinc deficiency
    • Some controversy as to whether intakes and/or status is adequate in UK children, but vegan children tend to be shorter, especially boys.
    good plant sources: beans, lentils, yeast, nuts, seeds, wholegrain cereals: but poor bioavailability?
  • 15. Zinc 8.3mg/MJ  34% intake 2mg/MJ  17% intake  25% intake
    • Reductions in ASF
    • would impact on intakes of the most bioavailable zinc
    • implications not clear
    good plant sources: beans, lentils, yeast, nuts, seeds, wholegrain cereals: but poor bioavailability?.
  • 16. ~1.7 μg/100 kcal 6% intake 1.4 μg/100 kcal  29% intake 0.7 μg/100 kcal  36% intake 3.8μg/100 kcal)  19% intake ~0.4 μg/100 kcal 7% intake ASF and B 12 Sources and intakes* *Adult NDNS
  • 17. B 12 : Nutritional consequences of low ASF intakes Deficiency syndromes Classical (absorption defect) macrocytic anemia peripheral neuropathy Multifactorial disease involvement birth defects: limited evidence in the UK age related cognitive impairment: good evidence Current concerns Prevalence of poor status is underestimated? usual measures of status are inadequate. poor bioavailability from meat cf milk or fish Increased milk intakes are being recommended Increased fortification is an option.
  • 18.
    • Ca requirements/importance for bone health poorly understood and controversial*
    • Cross-cultural bone fracture rates vary directly with Ca intakes
    • Role of milk/calcium for bone health within countries unresolved
    • FAO/WHO recommends lower calcium intakes than in many countries
    • UK vegans: increased fracture rates only if calcium intakes are very low (< 525mg/d: EAR for Ca: 45% of vegan population)
    * Should dairy be recommended as part of a healthy vegetarian diet? Point Weaver CM 2009 Am J Clin Nutr 89(suppl):1634S–37S Counterpoint Lanou AJ 2009 Am J Clin Nutr 89(suppl):1638S–42S Calcium: intakes Mainly a function of dairy foods % intake NDNS milk/milk products 43 Cereal products (white flour fortified) 30 white bread 13 Whole meal bread 2 Meat products 6 F&V 7 Alternative sources calcium-fortified soymilk Relative bioavailability unclear apart from inhibition by oxalate (eg spinach)
  • 19. Although controversial and not fully understood reduced dairy food intakes may not have any serious impact on calcium nutrition Calcium: Implications of reduced intakes of dairy foods
  • 20. Iodine: and reduced dairy intakes
    • UK is normally considered to be iodine sufficient but
    • mean intakes for young women was below the RNI (97%), when supplements were included: 12%, had intakes below the LRNI (NDNS)
    • 30% of young Surrey women showed mild to moderate iodine deficiency.
    • This is worrying in relation to pregnancy outcomes
    • Iodine supplementation is an option
  • 21. Niacin & Riboflavin with reduced ASF Niacin 34% from meat Not thought to be a problem
    • Riboflavin: 33% from dairy foods
    • low intakes/poor status quite widespread in older children and young adults.
    • Poor status tends to reflect milk intake: starts to increase from toddlers through school-age into young adulthood and improves in older adults and the elderly.
    • No obvious deficiency disease but will increase blood homocysteine concentration especially for 10% of the population with a genetic defect in folate metabolism.
    • Increased homocysteine is a risk factor for heart disease and dementia
    • US has responded by fortifying flour
  • 22. General health aspects of milk & dairy foods CONFLICTING PROBABLE: NO RECOMMENDATION for MILK, CHEESE, OTHER DAIRY PRODUCTS Convincing Probable Limited- suggestive Milk Milk Exposure Cancer site Decreases risk Exposure Cancer site Increases risk Colorectum Diets high in calcium Prostate Bladder Milk & dairy products Cheese Prostate Colorectum MILK, DAIRY PRODUCTS AND THE RISK OF CANCER WCRF REPORT 2007
  • 23. Milk & dairy foods conclusions
    • Milk & dairy foods are a useful package of nutrients especially for growing children and the elderly but
    • Most of the human population can’t drink milk
    • Milk is not recommended for infants<1
    • Current intakes may be in excess of that needed for optimal bone health
    • Dairy foods provide the most potent hypercholesterolemic saturated fat, more so than meat
    • There is no clear benefit and possible risk for cancer
    Reductions in dairy food intake are unlikely to be detrimental for human health but questions remain about riboflavin, B 12 and iodine nutrition
  • 24. General health aspects of meat Convincing Probable Limited- suggestive Exposure Cancer site Decreases risk Exposure Cancer site Increases risk Red meat Colorectum Processed meat Colorectum MEAT AND MEAT PRODUCTS AND THE RISK OF CANCER WCRF REPORT 2007 Red meat Many Processed meat sites Convincing mechanisms through haem (in both red and processed meat) promoting mutagenic carcinogens (N-Nitrosocompound) in colon
  • 25. Meat: conclusions
    • Reduced intakes of red/processed meat may be a government recommendation
    • Reduced intakes of all meat could occur without appreciable nutritional risk although questions remain about zinc
    • Nutritional knowledge is not good enough to conduct quantitative risk assessment on reduced meat or dairy