Protein Intake, Weight Loss, and Bone Mineral Density in
Postmenopausal Women���������
Wayne W. Campbell and Minghua Tang���Department of Foods and Nutrition, Purdue University,
West Lafayette, Indiana���April 23, 2010
Christy Goff, Danielle Taylor, Ellie Freeman, Julia Simpson!Advanced Macronutrients, Dr. Koutoubi 2011!
Presentation Outline • Purpose/Objective of the study
• Background Information
• Who and What is being studied
• Methods
• Results
• Limitations
• Future research
• Personal opinions
Background Information
• Many studies have examined the relationships between increasing protein intake and bone mineral density and bone turnover markers
• Produced conflicting results • Different age groups
• Types of protein given (dairy vs mixed protein)
• Percentage of protein consumed in a calorie restricted diet
Purpose and Objective of this
study • To see if higher protein diets have an effect
on Bone Mineral Density (BMD) during weight loss in overweight and moderately obese postmenopausal women
• And if different sources of protein diets have an effect on BMD
Parameters of Participants Study One:
-Only Women -Age >20 years old -BMI between 25-37 -NO clinically abnormal kidney, liver or heart function -NO clinically abnormal protein or hematological status -NO Diagnosed diabetes mellitus or receiving insulin replacement therapy -NO smokers
Study Two:
-Only Women -age 50-80 years old ->2 years postmenopausal -BMI between 25-34 -NO Clinically abnormal kidney, liver, or heart function -NO Clinically abnormal protein or hematological status -NO Diagnosed diabetes mellitus or receiving insulin replacement therapy -NO Smokers
Methods • 2 randomized controlled feeding studies conducted
• Study 1: 28 women – Consumed a 750kcal/day energy deficit diet – Randomly assigned to high protein or normal protein groups
• Study 2: 54 women – Consumed 1250kcal/day – Randomly assigned to habitual diet (control), or one of 3 energy
restricted groups (carb, chicken or beef)
Measurement Methods • STUDY 1
– Blood samples were taken post intervention and analyzed for blood urea nitrogen
• STUDY 2 – Fasting state venous blood samples were collected at baseline and post interventions – Measurements of serum bone alkaline phospatase parathyroid hormone and IGF 1 were
made – Urine samples were also taken every 24 hrs at baseline and post intervention
• Measurements of bone resorption rate, creatinein, calcium, phosphorous and total nitrogen were measured.
• Micronutrient intakes were estimated for both using Nutrition Data System for Research
• Potential renal acid load (PRAL) was evaluated for each of the conditions as well
Study 1
• Diet – Randomly assigned to either 18% protein (from vegetarian
sources) or 30% protein (with 40% coming from pork) – Comparable amounts of protein from dairy
• Study not intended to compare sources of animal protein (meat vs. dairy)
– All participants consumed a multivitamin & 2 calcium citrate tablets
• Timeline: 1 week baseline, 12 week dietary intervention with energy restriction
Study 1-Results ���
Text
Study 2- Methods • Diet- Either habitual (control) or restricted to 1250 kcal
– 1250 consisted of • 1000 kcal/day same lacto-ovo vegetarian basal diet • 250 kcal
– CARB- shortbread cookies and sugar-coated chocolates – CHICKEN- cooked chicken breast + 10 g of butter – BEEF- beef tenderloin
– CARB group received 16% protein, CHICKEN and BEEF received 26% protein control continued to consume usual diets
– 29 of the 54 used calcium supplements
• Timeline- 2 week baseline, 9 week dietary intervention
Study 2-Results ���Participant Body Composition
• At baseline there was no difference among the 4 groups in – Age – Height – Body mass – BMI – Body composition
• At the end of the study the Carb, Chicken and Beef groups lost body mass, fat mass, fat-free mass, and decreased their BMI compared to the control
Study 2-Results ���Bone Parameters
• At baseline BMD, bone mineral content, and bone area was similar in 4 groups
• After weight loss – Bone mineral content and
bone area was unchanged
Research Conclusions
• During energy restricted weight loss programs, overweight postmenopausal women lost more BMD when consuming a high protein diet vs. a normal diet
• Overweight postmenopausal women consuming an energy restricted high protein diet containing protein from animal flesh sources lost more BMD than those consuming a diet with protein from non animal flesh sources
Limitations
• Length of Study – Relatively short-term; possible that changes in BMD
were due to normal cycles of bone remodeling
• Equipment – Dual energy x-ray absorptiometer can be insensitive
to slight changes in BMD and/or affected by changes in body water levels.
Limitations
• Source of protein: dairy vs. meat • Study not meant to distinguish between the two but
the difference in Ca2+ could influence degree of BMD loss.
• Exercise • Not documented at all; could vary widely among
participants
• Number of Participants
Future Research Possibilities • Same study and population
– Document women’s protein intake prior to study
• Repeat study among: – Other age groups – Men – Athletes – Normal weight population (no energy-restriction)
• Study effects of calcium: high animal protein diet across all groups in study – Control Group: no added calcium; no dairy foods in diet – Group #1: + dairy – Group #2: + calcium supplement – Group #3: + dairy and calcium supplement
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Personal Opinion on Applicability
• Prevent rising rates in osteoporosis • Effects of high protein diets in people trying to
lose weight
• Applies to our future practices
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References
• Campbell, W.W. and Minghua Tang. “Protein Intake, Weight Loss, and Bone Mineral Density in Postmenopausal Women”. Journal of Gerontology. Biol Sci Med Sci. 2010. 65A(10): 1115-1122.