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 Millward unpublished 3 Elliot et al Arch Intern Med. 2006;166:79-87 4 top quartile of veg protein intake, bottom quartile of ASF protein intake5.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