Dietary Protein and Bone Health
Transcript of Dietary Protein and Bone Health
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Dietary Protein and Bone HealthEmphasis: Animal Protein
Z.K. (Fariba) Roughead, PhD, RDResearch Nutritionist
USDA-ARSGrand Forks Human Nutrition Research Center
USDA-ARS Human Nutrition Research Centers
15 Senior Scientists135 support staff2 metabolic kitchensService labs: clinical lab, mineral analysis
2 DXAs, Whole body counter
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Osteoporosis affects 200 million worldwide
20% of elderly with hip fx die within the first year
Risk Factors for Osteoporosis
• Age• Gender• Genetics• Sedentary life style• Smoking• Alcohol• Low calcium / Vitamin D • High protein intake (NIH Consensus Statement, 2000)
The Controversy
High protein diets are a risk for osteoporosis…
Especiallyif source is animal protein
andcalcium intake is low
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The Evidence• Purified sources of protein
increased urinary calcium loss (Linkswiler et al 1970s)
• common sources of proteindid not (Spencer et al,1978; Hunt, et al 1995)
Phosphorus Effect?
Observational EvidenceFeskanich et al (1996): Animal protein associated
with increased risk of forearm fracturesMunger et al (1999): Animal protein associated
with reduced incidence of hip fracturesHannan et al (2000): Lower total and animal protein
intake associated with increased bone lossWengreen et al (2004): Increased total protein
intake associated with reduced hip fx in “younger” elderly
Bone• Composition:
– 70% mineral (40% calcium; 99% body Ca)
– 25% organic (>90% protein)
– 5-8% water• Function
– Structure, locomotion, hematopoesis, growth factors
– Acid-base balance
Renal Mechanisms for Acid-Base Balance
Animal Protein Intake
Sulfur Amino Acid Intake
Osteoclastic activity Bone Resorption
Renal Net Acid Excretion
Glomerular Filtration Rate
Bone Mineral Density
Renal Reabsorption of Calcium
Bone Resorption
Bone Mineral Density
Net Endogenous Acid
Research Questions …
Does increased animal protein intake decrease calcium retention? Does replacing animal protein with plant protein improve calcium retention? Do dietary calcium and protein interact in a dose-dependent manner?
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Design Considerations
• Purified vs. Common protein• Equalized P vs. Variable P• Urinary Ca vs. Ca retention• Balance vs. Tracer methodology
(absorption vs. retention)
• Short-term vs. Long-term feeding• Few subjects vs. Statistical power
Protocol• Volunteers: - healthy post-menopausal
women • Design: - randomized crossover• Diets: - weighed diets; 7-8 wk • Calcium Retention:
- wk 3-4: labeled entire 2-d menu with 47Ca (constant specific activity)
- whole body scintillation counting for 4 wk
Diet Composition1
Low Meat High Meat
Meat (beef, chicken, turkey, pork), g 65 112Protein, % of energy 12 20
g/kg bw 0.94 1.62
Fat, % of energy 30 31Carbohydrate, % of energy 58 49Calcium, mg 700 (594.2 ± 19.3) 698 (574.1 ± 18.4)
Phosphorus, mg 1214 (1218.2 ± 87.0) 1659 (1616.4 ± 104.1)
Potassium, mg (2803 ± 339) (2184 ± 290)1Per 2200 Kcal. Data in parentheses are analyzed values (mean ± SD)
Observed
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Time (days)
Cal
cium
Ret
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) High MeatLow Meat
Modeled
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Time (days)
Cal
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High MeatLow Meat
Calcium Retention in Postmenopausal Women Consuming High and Low Meat Diets for 8 wk each
(Mean ±SEM)
Roughead, Johnson, Lykken & Hunt, (2003) J. Nutr. 133:1020
Diet: P = 0.09
High Meat Low Meat High Meat Low Meat
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45Titratable AcidityDiet: P <0.0001Diet*Time: P <0.05
AmmoniumDiet: P <0.0001
week3 5 8 3 5 8 3 5 8 3 5 8
Roughead, Johnson, Lykken & Hunt, (2003) J. Nutr. 133:1020
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Diet did not Affect Biomarkers of Bone Metabolism
Blood:• Tartarate-resistant acid phosphatase, Bone-
specific alkaline phosphatase, Osteocalcin, 25-OH Vitamin D
Urine:• Calcium, N-telopeptide
Roughead, Johnson, Lykken & Hunt, (2003) J. Nutr. 133:1020
Protein Intake
Sulfur Amino Acid Intake
Osteoclastic activity Bone Resorption
Renal Net Acid Excretion
Glomerular Filtration Rate
Bone Mineral Density
Renal Reabsorption of Calcium
Bone Resorption
Bone Mineral Density
Net Endogenous Acid
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Plantvs.
AnimalProteins?
ObjectivesIn healthy postmenopausal women, determine if daily substitution of 25 g of soy protein for meat protein1) improves calcium retention2) affects biomarkers of bone metabolism
Diet Composition1
CONTROL SOY
Meat (beef, chicken, pork), gMeat (beef, chicken, pork), g 170 55Soy Protein Isolate, g* --- 30Protein, % of energy 15 16
g/kg bw 1.32 1.33Fat, % of energy 30 30Carbohydrate, % of energy 55 55Calcium, mg 690 (653 ± 40) 746 (740 ±27)Phosphorus, mg 1505 (1563 ± 207) 1533 (1601 ± 178)Phytate, mg 1673 21501Per 2200 Kcal. Data in parentheses are analyzed values (mean ± SD)*Soy protein: 2.28 mg *Soy protein: 2.28 mg aglycone/gaglycone/g proteinprotein
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Observed Modeled
Diet: NS (n=12)
Consuming 25 g of Soy Protein Substituted for Meat Protein for 8 wkConsuming 25 g of Soy Protein Substituted for Meat Protein for 8 wk did not Affect Calcium Retention in Postmenopausal Women did not Affect Calcium Retention in Postmenopausal Women
(Mean + SE)(Mean + SE)
Cal
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Ret
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of d
ose)
Observed Modeled
Roughead et al (2005) J. Clin. End. Met., in press
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Initial Absorption
Soy: 27.0 + 7.0Control: 26.1 + 7.0
NS
CONTROL SOY CONTROL SOY
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week3 5 7 3 5 7 3 5 7 3 5 7
Ammonium(Diet: NS)
Titratable Acidity(Diet: P = 0.03)
Roughead et al (2005) J. Clin. End. Met., in press
The bottom line…
No evidence of adverse effects from animal protein intake on calcium metabolism even when calcium intake is low
What about whenCa intake is high?
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Urine BloodUrine
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Urine Urine BloodUrine
BloodUrine
Whole body Counting(28 days)
Controlled Diets(HC:1500 mg/d or LC: 600 mg/d)
47Ca
Note: Participant consumed either a Low or High Protein diet for 7 weeks; after a 2-wk washout, consumed the alternate diet for 7 weeks.
n=27
wk 1 wk 2 wk 3 wk 5 wk 70
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Ca: NS Pro: P < 0.0001Ca x Pro: NS
A high protein diet increased total renal acid excretion regardless of calcium intake
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wk 1 wk 2 wk 3 wk 5 wk 750
100
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250HCHPHCLPLCHPLCLP
Ca: P < 0.0001Pro: P < 0.01Ca x Pro: NS
Both dietary calcium and protein independentlyinfluenced urinary calcium loss
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High Ca, High ProteinHigh Ca, Low ProteinLow Ca, High ProteinLow Ca, Low Protein
Calcium: P < 0.001Protein: P<0.02Ca x Pro: P <0.05
A high protein intake enhanced calcium retention from a low calcium diet
HCHP HCLP LCHP LCLP0
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A high protein intake enhanced calcium bioavailabilityfrom a low calcium diet
Calcium: P < 0.001Protein: P<0.02Ca x Pro: P <0.05
HCHP HCLP LCHP LCLP0.0
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Ca: NSPro: P < 0.001Ca x Pro: NS
A high protein intake reduced bone resorption as indicated by urinary Dpd excretion
HCHP HCLP LCHP LCLP0
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A high protein diet increased serum IGF-1 by ~27%, regardless of calcium intake
Ca: NSPro: P< 0.01Ca x P: NS
ng/m
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20% Meat
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In ovx rats, the efficiency of calcium retention was highest when protein intake was high (especially from animal protein)
Source: P< 0.003Quantity: P <0.01Interaction: NS
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10% 20% 10% 20%0
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Source: NSQuantity: P = 0.02Interaction: NS
Serum IGF-1 was higher in the rats fed the high protein diets regardless of protein source
P Protein???
KMg
Milk Constituents
Ca
Vitamin D
Lactose
Dairy Protein and Bone?
• Isolated Casein and Lactalbumin have been shown to be calciuric
• Isolated Whey Protein may reduce bone resorption
Milk and Bone Health• Milk supplementation, 12 mo: increased spine and total
BMD in young girls (Chan, 1995)• Milk supplementation, 18 mo: increased serum IGF-I and
lumbar BMD and total BMC in young girls (Cadogan, 1997)• Milk supplementation, 3 y: prevented vertebral bone loss
in pre-meneopausal women (Baran, 1990)• High Ca milk supplementation 24 mo: decreased bone
loss in femoral neck, lumbar spine and total hip in postmenopausal women (Chee, 2003)
• Milk Supplementation 12 wk: increased serum IGF-I and decreased urinary N-telopeptides in older men and women (Heaney, 1999)
Protein Intake
Sulfur Amino Acid Intake
Acid Excretion
Increased urine Ca loss
Bone Mineral Density
Bone Resorption
↓ Calcium Retention
√
√
X, ?
X
X
↓
Bone Mineral Density
Serum IGF-1
?
?
Future Directions
Carefully controlled feeding trials are needed to assess:
• Effects of dairy proteins provided as food (milk, cheese, yogurt, etc) on calcium retention and bone health
• Effects of dairy proteins per se on calcium retention and bone health
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“As we analyze a thing into its parts and properties, we tend to magnify these, to exaggerate their apparent independence and to hide from ourselves the essential integrity and individuality for the composite whole. We may study them apart but it is a concession to our weakness and the narrow outlook of our minds.”
(D’Arcy Thompson, 1942)
Acknowledgments- Janet Hunt, PhD, RD - Bonnie Hoverson, RD- Glenn Lykken, PhD - Debbie Krause, RD - LuAnn Johnson - Brenda Hanson, RD- Carol Zito - Angela Scheett, RD- Jennifer Hanson - Emily Neilsen, RN• Jackie Nelson• Aldrin Lafferty• Study Volunteers• Primarily supported by USDA• Partial support: National Cattlemen’s Beef Association,
North Dakota Beef Commission• Solea Company (soy protein isolate)