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.