Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Human Ecology

Major Professor

Roy E. Beauchene

Committee Members

Rossie L. Mason, Ada Marie Campbell, James N. Liles


This study concerned the relationships among age; physical measurements, protein intake and the urinary excretion of protein-derived matabolites in 125 adult female vegetarians and nonvegetarians. The vegetarian group (AV) included 57 lactoovovegetarians (LOV) and 6 vegans (V). The remaining 62 subjects were nonvegetarians (NV). The subjects ranged in age from 40 to 92 years. The AV were primarily Seventh-Day Adventists who had been recruited through their church groups. The NV were recruited primarily through Jesus Christ of Latter Day Saints and United Methodist church groups as well as Extension Homemakers Clubs. Measurements of height, weight and triceps skinfold thickness, a 7-day dietary record and a 24-hour urine sample were obtained from each subject. Mean daily intakes of energy, total protein, animal protein and vegetable protein were calculated from the dietary records. The urine samples were analyzed for total nitrogen, urea nitrogen, ammonia nitrogen, creatinine, hydroxyproline and inorganic sulfate. Data were adjusted to the mean age of the sample (59.4 years).

Mean (± SEM) heights of the V, LOV and NV groups did not differ and were 162.8 ± 2.4, 162.0 ± 0.8 and 161.1 ± 0.8 cm, respectively. The V (51.0 ± 5.6 kg) weighed significantly less and had a significantly smaller lean body mass (LBM) (39.9 ± 2.1 kg) than LOV (65.8 ± 1.8 and 43.9 ± 0.7 kg, respectively) and NV (66.7 ± 1.6 and 43.7 ± 0.6 kg, respectively). Triceps skinfold thickness and percent body fat for V (19.8 ± 3.6 mm and 14.8 ± 3.9%) were less than those of LOV ( 2 8.5 ± 1.1 mm and 24.1 ± 1.2%). Both vegetarian groups had smaller skinfold thicknesses and percent body fats than NV (32.4 ± 1.0 mm and 28.1 ± 1.1%).

Mean energy intakes for the groups did not differ significantly and were all less than the NRC-RDA. The V consumed 1601 ± 133; the LOV, 1509 ± 42; and the NV, 1524 ± 42 kcal/day. The LOV (54.6 ± 1.3 g) and V (52.2 ± 4.2 g) consumed comparable mean daily amounts of total protein which were significantly less than that consumed by the NV (66.5 ± 1.6 g). The NV consumed 45.8 ± 1.7 g or 68.2 ± 2.2% of total protein from animal sources which was significantly more than the 16.0 ± 1.7 g and 29.5 ± 2.1% of total protein from animal sources consumed by LOV. The V consumed 38.2 ± 3.2 g or 74.8 ± 5.0% of total protein from vegetable sources which was significantly more than the 28.2 ± 1.1 g or 52.1 ± 1.7% of total protein as vegetable protein consumed by the LOV. Both vegetarian groups consumed significantly more vegetable protein than the NV (10.8 ± 1.1 g or 16.4 ± 1.8% of total protein).

There were no significant differences in urinary total nitrogen excretion for the V, LOV and NV groups. The values were 8.50 ± 1.10, 8.49 ± 0.35 and 9.00 ± 0.36 g/day , respectively. Urea nitrogen excretion did not differ significantly; V excreted 7.08 ± 1.09 g; the LOV, 7.24 ± 0.36 g; and the NV, 7.77 ± 0.36 g/day. The LOV excreted 174.6 ± 13.4 mg of ammonia nitrogen/day which was significantly less than the 226.6 ± 15.1 mg excreted by the NV. The 201.2 ± 42 .0 mg of ammonia nitrogen excreted by the V did not differ significantly from that of either other group. The creatinine excretions of groups V and LOV were 1.30 ± 0.14 and 1.33 ± 0.04 g/day, respectively, and were significantly less than the vi 1.54 ± 0.05 g excreted by the NV. Hydroxyproline (HOP) excretion by the V (28.3 ± 4.8 mg/day) was significantly less than the 35.5 ± 1.7 mg excreted by the NV. The 33.2 ± 1.6 mg of HOP/day excreted by the LOV did not differ significantly from that of either other group. Inorganic sulfate excretion did not differ among the groups V, LOV and NV; the values were 1.41 ± 0.22, 1.55 ± 0.07 and 1.57· ± 0.07 g/day, respectively.

Height decreased linearly with age in both the AV and NV groups. Weight and LBM decreased with age in NV; in the AV, the variables increased through age 65 and decreased thereafter. Skinfold thickness and percent body fat were significantly different between the AV and NV and tended to decrease with age in both groups. Energy and protein intakes in the AV decreased almost linearly with age; intakes of the NV increased until the sixth decade and decreased thereafter. Total nitrogen excretion showed approximately the same relationship to age as protein and energy intakes. Ammonia nitrogen and creatinine excretions were significantly different between the AV and NV. Urinary excretions of urea, HOP and inorganic sulfate did not differ between the AV and NV nor did they show a relationship to age.

The most notable differences observed between the AV and NV subjects were in body fat (skinfold thickness), protein intake and urinary creatinine. The 2 groups were similar in height and urinary HOP and inorganic sulfate throughout the age span studied. Regressions of body weight, LBM and body fat on age tended to follow a similar pattern within each group. Energy intake, protein intake and urinary total nitrogen also showed similar relationships to age within each group. The V subjects differed from the NV subjects with respect to body weight, body fat, LBM and urinary HOP and differed from the LOV with respect to body weight, body fat and LBM. It can be concluded that the consumption of a vegan diet may have an effect on selected physical measurements and the intake and metabolism of protein as compared to a nonvegetarian diet while the effect of consumption of a lactoovovegetarian diet is minimal.

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