Determination of Protein Requirement in Elderly Male Subjects >75 Yrs Old

Study Overview
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Brief Summary
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Minimal data are available on protein requirements throughout the lifespan. Currently available recommendations are based on nitrogen balance data. The limitations of the nitrogen balance method have been well described. Importantly, nitrogen balanced underestimates requirements. The current dietary reference intake (DRI) requirement for healthy adult males is based on the reanalysis of the nitrogen balance date from Young and Scrimshaw. This data was reanalyzed statistically by Rand et al. and he concluded that the protein requirement of healthy adults was 0.65 and 0.83 (mean and RDA) g/kg/day of good quality protein. Using IAAO, our group estimated the protein requirement of young men (mean age 27 years) to be 0.93 and 1.2 g/kg/day (mean and RDA). Currently there are no studies on protein requirement in the elderly. In a recent nutrition survey conducted by national health and nutrition examination survey (NHANES), the authors concluded that adults between the ages of 51 - 70 years old consumed an average on 1.0 g/kg/day (ideal body weight) of protein which represents about 15 % of calories. Depending on the calculations used for ideal body weight some older adults could be getting higher or lower than requirement. There is no scientifically derived protein estimate for older adults. Therefore there is a need to measurer protein requirement in that population. The goal of this study therefore is to measure the protein requirement of male elderly subjects > 75 years using the indicator amino acid oxidation (IAAO) technique. Hypothesis: The investigators hypothesize the protein requirement in elderly male subjects will be lower (0.85-1.05 g/kg/day) than that established in young healthy males ( 0.93 - 1.2g/kg/day).

Conditions
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Healthy

Intervention / Treatment
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* Dietary Supplement: Protein intake


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy elderly males >75 years Willingness to participate in the study Males without a chronic disease or acute illness that could affect protein and amino acid (AA) metabolism eg, diabetes, cancer, liver or kidney disease, HIV, acute cold or flu, hypo or hyperthyroidism, rheumatoid arthritis treated with anti-inflammatory medications. Males with hypertension if well controlled by medications Exclusion Criteria: Presence of disease known to affect protein and AA requirement and synthesis like diabetes, cancer, liver o kidney disease, HIV, acute cold or flu, hypo or hyperthyroidism, rheumatoid arthritis treated with anti-inflammatory medications. On medications known to affect protein and amino acid metabolism like e.g. steroids. Significant weight loss during the past month. Individual on weight reducing diets. Inability to tolerate the diet or unwilling to have blood drawn from a venous access for the purposes of the study. Significant coffee consumption of more than 2 cups/day (400 mg of caffeine/day) Significant Alcohol consumption of more than one drink/day ( 1 beer, ½ glass of wine)

Ages Eligible for Study
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Minimum Age: 76 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: protein<br>varying protein intake in random order from deficient to excess | Dietary Supplement: Protein intake<br>* On the study day, the diet will be provided as free amino acids, with calories made up by a liquid diet and protein free cookies. Protein intakes will be varied as 0.2, 0.5, 0.7, 0.9, 1.0, 1.2, 1.5, 1.8, 2.0 g/kg/day.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Breath samples will be collected on day 3 of the experiment between the 4th and 5th meal and after the 6th and 7th meal. The ratios of carbon 13 to carbon 12 will be measured in breath. |  | 10 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Urine samples will be collected on day 3 of the experiment between the 4th and 5th meal and after the 6th and 7th meal for measurement of the rations of the enrichment of carbon 13 to carbon 12 in urine phenylalanine. |  | 10 months |