Protein Intake, Weight Protein Intake, Weight Loss, and Bone Mineral Loss, and Bone Mineral

Density in Density in Postmenopausal WomenPostmenopausal Women

Wayne W. Campbell and Minghua TangDepartment of Foods and Nutrition, Purdue

University, West Lafayette, IndianaApril 23, 2010

Christy Goff, Danielle Taylor, Ellie Freeman, Julia SimpsonAdvanced 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 Parameters of ParticipantsParticipants

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-ResultsParticipant 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-ResultsBone 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.