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OptimizingProtein…… inaCarbohydrateWorld

Donald K. Layman, Ph.D.

Professor Emeritus 

Department of Food Science & Human Nutrition

University of Illinois at Urbana‐Champaign

Theconfusedconsumer…

Myth: “Adults eat more protein than they need”

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Recommended Dietary Allowance (RDA)The lowest level of dietary protein intake that will balance the losses of nitrogen from the body … in persons at energy balance with modest levels of physical activity …

Myth: “Adults eat more protein than they need”

Minimum intake to prevent deficiencies

versus

Optimum intake for health

DietaryReferenceIntake

AcceptableMacronutrientDistributionRange

RDA = Recommended Dietary Allowance

SafeRangeofDietaryProtein(DRI)

DietaryReferenceIntake(forprotein)

AcceptableMacronutrientDistributionRange

0.8g/kg~56g/d10%En

>3.0g/kg~225g/d35%En

P P

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Theparadigmshift… from Pyramids to Plates

• avoid fat• eat grains• daily net servings

• vegetables• protein (and dairy)• balanced meals

2010

What’s new in protein research:

health of skeletal muscle critical for long‐term health

age‐related “sacropenia”

• functional mobility  

• metabolic health 

aging reduces efficiency of protein use

meal distribution of protein

A “Muscle‐centric” View of Nutrition

Am J Clin Nutr 2006; 84:475

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Metabolic Advantage of Protein(with reduced carbohydrate intakes)

improves body composition protects skeletal muscle; targets fat loss

increases metabolic rate enhances satiety

reduces snacking 

reverses the Metabolic Syndrome↓ TG, ↑ HDL, ↑ LDL size↓ FBG, ↓ post‐prandial insulin, ↓ BP

Minimum versus Optimum? what are the critical health outcomes?

Growth versus Aging

Protein RDA =    2.2      1.5    1.0     0.8 ……………………………………….. g/kg?

Meal effects on muscle protein balance

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Muscleproteinsynthesisafteramealinyoungversusolderadults

muscle protein syn

thesis

Katsanos et at AJCN 82: 1065, 2005

Meal containing:15 grams of protein

(7 g essential amino acids)

Aging reduces the Efficiency of protein use

Cause (?)

• reduced capillary blood flow

• reduced membrane transport

• reduced metabolic signaling***

Non‐essential Amino AcidsArgAlaAsnAspCysGluGlnGlyProTyr

Essential Amino AcidsLysMetTrpThrLeuPheHisValIle

Limiting AA’s

Why do we need protein = “Amino Acids”

building blocks for new proteins

multiple other metabolic roles

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Non‐essential Amino AcidsArgAlaAsnAspCysGluGlnGlyProTyr

Essential Amino AcidsLysMetTrpThrLeuPheHisValIle

Why do we need protein = “Amino Acids”

= leucine 

= valine= isoleucine

Branched‐chain amino acids

BCAAs

Metabolic signals from amino acids

amino acids

Neurotransmitters(mood, appetite)

gut hormones(GLP1, CCK, PYY)

GCN2(integrated stress response)

SIRT‐1, PGC1(mitochondriabiogenesis)

vascular health(nitric oxide)

Leucine – mTORC1(protein synthesismuscle health)

Aging reduces the efficiency of protein use …… but does not impair the capacity to respond

muscle protein syn

thesis

Katsanos et at AJCN 82: 1065, 2005 Symons et al AJCN 86:451, 20074 oz of beef

~32 g protein~ 15 g EAA

~15 g protein~ 7 g EAA

specifically Leucine

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mTORC1RaptorRagulatorRag A/B

Rag C/DRheb

TSC2 REDD1

Akt

GATOR1

GATOR2Sestrin2

eIF4E‐BP1

rpS6

Muscle protein synthesis

eIF4F

Amino acids(leucine)

Growth hormones(insulin)

Energy(glucose)

TSC1

AMPK

AMPK

Stress(exercise)

S6K1

eEF2

eEF2K

GTP

GTP

GDP

“inhibitor”

“activator”

“regulator”

Regulation of Muscle Protein Synthesis

insulin leucine

mTOR

protein synthesis

Diet Controls Muscle Metabolism

Plateau of muscle protein synthesis(22 yr old subjects)

Moore et al. Am J Clin Nutr 2009; 89:161

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Mealresponseforadultmuscleproteinsynthesis:

0

5

10

15

20

25

30

35

40

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Response to leucine content of meal

Leucine (g)

Protein (g)                      10          20          30          40          50            60     

protein synthesis

“meal threshold”

Meal Patterns:

Breakfast ~10 g protein

Lunch ~20 g

protein

Dinner ~60 g protein

Unbalanced Protein Distribution

Breakfast ~30 g protein

Lunch ~30 g

protein

Dinner ~30 g protein

Balanced Protein Distribution

Maximum Protein Synthesis

Mamerow et al. J Nutr 144: 876, 2014

Balanced Unbalanced

Recommendations:• 30 g of protein per meal• 2.5 g of leucine per meal• 1.2 ‐ 1.5 g protein/kg/day

JAMDA 14:542, 2013

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Leucine content of proteinsProtein source Leucine (%)

whey isolate 11 – 12

milk protein 9.5

egg white 8.8

“meats” 8.6

soy protein 7.8

oat protein 7.8

wheat gluten 6.8

Protein Quality:

*

*meats = 8 g protein/ozfish   =  5 g protein/oz

Metabolic Roles of Leucine and BCAAs

• stimulates mTOR and muscle protein synthesis

• stabilizes blood glucose with recycling of alanine

• enhances fatty acid oxidation thru CPT‐1

• anaplerotic maintenance of TCA cycle

• enhances innate immunity thru glutamine production

• enhances vascular function thru arginine production

acetyl‐CoA

leucine mTOR Protein synthesis

Fatty acids

succinyl‐CoA

alpha‐KG

Val & Ile

glucose pyruvate

alanineglutamate

PDH

BCKAD

BCATalpha‐KIC

CPT‐1

TCAcycle

‐NH3

acyl‐CoA

‐NH3 ‐NH3

Asp

glutamine

arginine

Leucine Metabolism in Skeletal Muscle

‐NH3

mitochondria

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acetyl‐CoA

[Leucine] mTOR Protein synthesis

BCKAD

BCATalpha‐KIC

TCAcycle

‐NH3

Leucine Metabolism in Skeletal Muscle

mitochondria

[ATP]

acetyl‐CoA

leucine mTOR Protein synthesis

glucose pyruvate

alanine

PDH

BCKAD

BCATalpha‐KIC

TCAcycle

‐NH3

‐NH3

Leucine Metabolism in Skeletal Muscle

mitochondria

acetyl‐CoA

leucine mTOR Protein synthesis

Fatty acids

glucose pyruvate

alanine

PDH

BCKAD

BCATalpha‐KIC

CPT‐1

TCAcycle

‐NH3

acyl‐CoA

‐NH3

Leucine Metabolism in Skeletal Muscle

mitochondria

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acetyl‐CoA

leucine mTOR Protein synthesis

Fatty acids

alpha‐KG

glucose pyruvate

alanineglutamate

PDH

BCKAD

BCATalpha‐KIC

CPT‐1

TCAcycle

‐NH3

acyl‐CoA

‐NH3 ‐NH3

Asp

glutamine

arginine

Leucine Metabolism in Skeletal Muscle

‐NH3

mitochondria

‐NH3

acetyl‐CoA

leucine mTOR Protein synthesis

Fatty acids

succinyl‐CoA

alpha‐KG

Val & Ile

glucose pyruvate

alanineglutamate

PDH

BCKAD

BCATalpha‐KIC

CPT‐1

TCAcycle

‐NH3

acyl‐CoA

‐NH3 ‐NH3

Asp

glutamine

arginine

Leucine Metabolism in Skeletal Muscle

‐NH3

mitochondria

DietaryReferenceIntake

AcceptableMacronutrientDistributionRange

(Leucine: minimum vs optimum)

2 g

8‐9 g

> 35 g

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Protein and Exercise (athletes)

Protein for athletes

1.2 up to 2.0 g/kg body weight

Exercise improves efficiency

The “Western Diet”

Is Protein Safe?

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2009;9:311

Nature Reviews Endocrin 2014;10:723

Isn’t protein bad for your kidneys?

Protein enhances kidney functionand efficiency.

Safety of Dietary Protein

Isn’t protein bad for you bones?

Protein is the foundation of bone matrix and essential for bone repair and remodeling.

Solid Bone Matrix

Weakened Bone Matrix

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Doesn’t protein cause cancer?

WhyistheresomuchFakeNewsaboutNutrition?

IJO 39: 1109, 2015

Epidemiology: provides statistical correlations

Correlations do not equal Causation

Surveys in error by ~800 kcal/day       

Carbohydrates:The Good, the Bad, and the Ugly!

• sugar• fructose• whole grains• lactose• fiber• starch• VLCD

Glucose (sugar) is an essential fuel …… but glucose can be toxic to cells (diabetes)

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DietaryReferenceIntake(carbohydrates)

C

130 g/day                          65% kcal

RDA =5 servings of vegetables2‐3 servings of fruit3 servings of grains (15 g each)

Acceptable range

>300 g/d

Carbohydrate needs …

… or tolerance

RDA = 130 g/dayaverage U.S. intake ~ 300 g/day

Glucose as a fuel for muscle: exercise

Factors are: intensity duration training

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Carbohydrate Tolerance (designing diets)

RDA = 130 g/day      RDA meets all nutrition needs(veggies, fruit, fiber, whole grains)

Carbs > 130 g/day are earned with exercise~60 g/hr intense Ex; HR > 100

Meal threshold < 40 g/meal;  minimizes insulin response

Meals > 40 g associated with exercise recovery

Designing Diets:

Designing Diets:

• Diets with higher protein & reduced Carbs are beneficial

• Optimal protein to protect muscle & stimulatemetabolism should be 1.2 to 1.5 g/kg (100 to 140 g/day)

• Evidence supports meal distribution with ~30 g/meal

• The first meal is important for muscle response

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Designing Diets:  carbohydrates?

• Balance protein and carbohydrates at every mealapproximately 1:1 ratio

• Meal with more than 40 g of Carbs have large insulin response(restrict early meals to < 40 g of Carbs)

Email:       dlayman@illinois.edu

Twitter:   @donlayman