Animal source foods in the UK diet:Animal source foods in the UK diet: a nutritional overview a nutritional overview
D Joe Millward D Joe Millward
Nutritional Sciences, Faculty of Health and Medical Sciences
Meat and dairy foods: consumption patterns
95% OF UK ADULTS EAT MEAT95% OF UK ADULTS EAT MEAT99% CONSUME MILK/DAIRY99% CONSUME MILK/DAIRY
Categories of UK vegetarians Categories of UK vegetarians (total 106/2251)* (total 106/2251)*
ASF consumedASF consumed n (% population)n (% population) No meat No meat 100 (5) 100 (5)No fish No fish 48 (2.5) 48 (2.5)No eggsNo eggs 21 (1) 21 (1)No milk/dairy No milk/dairy 15 (0.75) 15 (0.75) None (vegan)None (vegan) 29 (1.50) 29 (1.50)
*2002 NDNS adult sample*2002 NDNS adult sample
Meat and dairy foods: Intakes
%energy intake Meat, meat dishes & meat products 15All 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
The Balance of Good HealthThe 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
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
Eat moderate amounts and choose lower fat versions
Nutrients from meat & dairy foods in the UK adult dietNutrient index = % nutrient intake Good source ≥ 2
% energy intake
Calcium 4.3 43iodine 3.8 38B12 3.6 36Riboflavin 3.3 33SFA 2.4 24phosphorus 2.4 24Fe(non-haem)0.1 1
NI %intakeHaem-iron 5.7 85protein 2.4 36zinc 2.3 34Niacin 2.3 34B12 2.0 30SFA 1.5 22
ASF and protein: intakes: ASF and protein: intakes: Protein intakes increase with ASF intakes. Adult NDNS 19901 %available dietary energyUK omnivores: 12.6UK vegetarians (no meat) 10.2
1 Jackson and Margetts Int J Food Sci Nutr 1993; 44: 95–1042. Millward unpublished 3 Elliot et al Arch Intern Med. 2006;166:79-87 4 top quartile of veg protein intake, bottom quartile of ASF protein intake5. bottom quartile of veg protein intake and top quartile of ASF protein intake
Elderly NDNS 19982
Highest quartile ASF 13.3Lowest quartile ASF 10.0INTERMAP study3
vegetable animal Total%dietary energy
Mainly meat eaters4 5.4 12.0 15.5Mainly vegetarian5 9.1 4.3 10.9
ASF and protein: nutritional issues 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*Millward & Jackson Pub Health Nutr.2004 7(3), 387–405
risk of deficiency (low ASF)** Q1 ASF Q4 ASFadult men: 18-32% 3%adult women: 26-42% 5%
**modelled for men and women, BMI=25, PAL = 25th centile, with available P:E ratio of intake observed for lowest and highest quartiles of non-milk ASF intake in elderly NDNS
Protein deficiency with low ASF intakesProtein deficiency with low ASF intakesDifficulties 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
ASF & Iron: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
ASF & Iron: ASF & Iron: Intakes & vulnerable groupsIntakes & 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)
poorly understoodpoorly understoodHaem iron:Haem iron: generally doesn’t vary much apart generally doesn’t vary much apart
from inhibition by calciumfrom inhibition by calcium
Non-haem iron: Non-haem iron: absorption varies markedly:absorption varies markedly:easily inhibited by phytates, polyphenols, easily inhibited by phytates, polyphenols,
fibre: fibre: also calciumalso calciumoptimised with vitamin C, food optimised with vitamin C, food
preparation, meatpreparation, meatmarkedly up-regulated: low iron stores, markedly up-regulated: low iron stores,
blood lossblood loss
Iron bioavailabilityIron bioavailability::
Prevalencesignificant 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 anemiaIron deficiency anemia
CausesInappropriate feeding practices at weaning:-
unmodified cows milk, unfortified formulaLow iron intakes/poor absorption:
preschool children, older girls and women, elderlyie. <4ys: lowest intake of cereals, Vit C, meat: 13% IDA
highest intake of cereals, Vit C, meat: 6% IDA
ConcernsMental/psychomotor development (children) Work performance in adults.
ASF and iron:ASF and iron:Implications for Implications for
reductionsreductionsDairy foods: not a problemDairy foods: not a problemnot a useful iron source not a useful iron source may be detrimental to absorption. may be detrimental to absorption.
Red meatRed meatcan make a disproportionate contribution to can make a disproportionate contribution to iron supplies in theoryiron supplies in theoryin practice its dietary importance may have in practice its dietary importance may have been overstated been overstated Reduced intakes may have little effect.Reduced intakes may have little effect.Increased fortification is always an option.Increased fortification is always an option.
ASF and Zinc
8.3mg/MJ 34% intake
2mg/MJ 17% intake
25% intake
Essential for normal growth and development in children Essential for normal growth and development in children and maintenance of good health in adults. and maintenance of good health in adults. Problematic nutrient because status is hard to measure.Problematic nutrient because status is hard to measure.Subclinical zinc deficiency is widespread globally and Subclinical zinc deficiency is widespread globally and sstunted growth partly reflects zinc deficiencytunted growth partly reflects zinc deficiencySome controversy as to whether intakes and/or status is Some controversy as to whether intakes and/or status is adequate in UK children, but vegan children tend to be adequate in UK children, but vegan children tend to be shorter, especially boys.shorter, especially boys.
good plant sources: beans, lentils, yeast, nuts, seeds, wholegrain cereals:
but poor bioavailability?
Zinc8.3mg/MJ
34% intake2mg/MJ
17% intake
25% intake
Reductions in ASFReductions in ASF would impact on intakes of the most would impact on intakes of the most bioavailable zincbioavailable zincimplications not clear implications not clear
good plant sources: beans, lentils, yeast, nuts, seeds, wholegrain cereals:but poor bioavailability?.
~1.7 μg/100 kcal6% 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 B12Sources and intakes*
*Adult NDNS
B12: Nutritional consequences of low ASF intakes
Deficiency syndromes Classical (absorption defect)
macrocytic anemiaperipheral neuropathy
Multifactorial disease involvementMultifactorial disease involvement birth defects: limited evidence in the UKbirth defects: limited evidence in the UK
age related cognitive impairment: good evidenceCurrent 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 recommendedIncreased fortification is an option.Increased fortification is an option.
Ca requirements/importance for bone health poorly understood and controversial*Cross-cultural bone fracture rates vary directly with Ca intakesRole of milk/calcium for bone health within countries unresolvedFAO/WHO recommends lower calcium intakes than in many countriesUK 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–37SCounterpoint Lanou AJ 2009 Am J Clin Nutr 89(suppl):1638S–42S
Calcium: intakesCalcium: intakesMainly a function of dairy foodsMainly a function of dairy foods
% intake NDNSmilk/milk products 43Cereal products (white flour fortified) 30white bread 13Whole meal bread 2Meat products 6F&V 7
Alternative sourcescalcium-fortified soymilk
Relative bioavailability unclear apart from inhibition by oxalate (eg spinach)
Although controversial and not fully understood reduced dairy food intakes may not have any serious impact on calcium nutrition
Calcium:Calcium:Implications of Implications of
reduced intakes of reduced intakes of dairy foodsdairy foods
Iodine: and Iodine: and reduced dairy reduced dairy
intakesintakes
UK is normally considered to be iodine sufficient butUK is normally considered to be iodine sufficient butmean intakes for young women was below the RNI mean intakes for young women was below the RNI (97%), when supplements were included: 12%, had (97%), when supplements were included: 12%, had intakes below the LRNI (NDNS)intakes below the LRNI (NDNS)30% of young Surrey women showed mild to moderate 30% of young Surrey women showed mild to moderate iodine deficiency.iodine deficiency.This is worrying in relation to pregnancy outcomesThis is worrying in relation to pregnancy outcomesIodine supplementation is an optionIodine supplementation is an option
Niacin & Riboflavin with reduced ASF
Niacin 34% from meatNot thought to be a problem
Riboflavin: 33% from dairy foodslow 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
General health aspects of General health aspects of milk & dairy foodsmilk & dairy foods
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
ProstateColorectum
MILK, DAIRY PRODUCTS AND THE RISK OF CANCER WCRF REPORT 2007
CONFLICTING PROBABLE: NO RECOMMENDATION for MILK, CHEESE, OTHER DAIRY
PRODUCTS
Milk & dairy foodsMilk & dairy foodsconclusionsconclusions
Milk & dairy foods are a useful package of Milk & dairy foods are a useful package of nutrients especially for growing children and nutrients especially for growing children and the elderly butthe elderly butMost of the human population can’t drink milkMost of the human population can’t drink milkMilk is not recommended for infants<1Milk is not recommended for infants<1Current intakes may be in excess of that needed for Current intakes may be in excess of that needed for optimal bone healthoptimal bone healthDairy foods provide the most potent Dairy foods provide the most potent hypercholesterolemic saturated fat, more so than hypercholesterolemic saturated fat, more so than meatmeatThere is no clear benefit and possible risk for cancer There is no clear benefit and possible risk for cancer
Reductions in dairy food intake are unlikely Reductions in dairy food intake are unlikely to be detrimental for human health to be detrimental for human health butbut questions remain about riboflavin, Bquestions remain about riboflavin, B12 12 and and iodine nutritioniodine nutrition
General health aspects of General health aspects of meatmeat
Convincing
Probable
Limited-suggestive
Exposure Cancer site
Decreases risk
Exposure Cancer site
Increases risk
Red meat ColorectumProcessed meat Colorectum
MEAT AND MEAT PRODUCTS AND THE RISK OF CANCER WCRF REPORT 2007
Red meat ManyProcessed meat sites
Convincing mechanisms through haem (in both red and processed meat) promoting mutagenic carcinogens (N-Nitrosocompound) in colon
Meat: conclusionsMeat: conclusions
Reduced intakes of red/processed meat may be a government recommendationReduced 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