Masters Theses

Date of Award

3-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

Nina L. Marable

Committee Members

Majorie P. Penfield, Jean D. Skinner

Abstract

Normotensive (11) and medicated hypertensive (6) female subjects ages 23 to 58 participated in blood pressure measurements, blood sampling (2 days) following a 10-hour fast, for the determination of maximum ouabain binding, and dietary assessment using 7-day records and/or food frequency forms. Maximum ouabain binding, an index of Na+,K+-ATPase activity, was measured using a tritiated ouabain binding technique in which the number of ouabain binding sites per cell are determined. The number of enzyme units (Na+,K+-ATPase units) was calculated from the number of binding sites per cell because the two are directly proportional.

Stepwise regression procedures in the Statistical Analysis System (SAS) (SAS Institute, 1982b) were used to analyze the relationships among mean systolic blood pressure taken prior to blood sampling (dependent variable, MBP1S), maximum ouabain binding (MBMAX), dietary intake, body mass index (BMI), and age. MBP1S and MBMAX were directly related when data from 15 of the 17 subjects were analyzed. Arthritis medications taken by two of the subjects may have an effect on the blood pressures of the subjects. For this reason, subsequent data analysis excluded these two subjects. Age and BMI were not related to either MBP1S or MBMAX.

Total Inhibition Scores and Total Vanadium Indices, indicators of the consumption of foods containing in vitro Na+,K+-ATPase inhibitors and/or vanadium, were calculated per subject (17) from food frequency data. No associations were found among MBP1S, MBMAX, and the consumption of foods containing in vitro Na+,K+-ATPase and/or food containing vanadium (an inhibitor of Na+,K+-ATPase activity). The lack of associations may be due to the scarcity of published data on in vitro Na+,K+-ATPase inhibitors or vanadium contents in foods, and/or the possible inabilities of subjects to determine the quantities and frequencies of consumption. Food frequency forms are not the best method to use when quantitative data are needed.

Enery and nutrient intake means were calculated for the 15 subjects who kept 7-day dietary records. Mean energy intakes ranged from 1002 to 2262 kcal/day, the principal source of calories for most subjects being carbohydrates. Calcium and iron intakes for several subjects were ≤ 70% of the 800-mg RDA. All medicated hypertensive subjects' calcium intakes were low (≤ 80% of the RDA). None of the subjects consumed ≤ 70% of the RDA for vitamin C, thiamin, riboflavin, and niacin. One subject's mean vitamin A intake was < 70% of the RDA.

Of the dietary variables analyzed using PROC STEPWISE (SAS Institute, 1982b) (energy, protein, carbohydrate, crude fiber, calcium, iron, vitamin A, vitamin C, thiamin, riboflavin, niacin, and cholesterol), only crude fiber was related to MBP1S. A negative relationship was found between MBP1S and crude fiber intake only when MBMAX was included in the regression equation. MBMAX and crude fiber intake also were inversely related. Crude fiber may appear as a proxy for other variables that independently do not significantly alter blood pressure: including cholesterol, thiamin, niacin, and carbohydrate. Multiple vitamins taken by several subjects may have obscured the relationship between MBP1S and some of the dietary variables. This should be a consideration in future research studies conducted with a larger number of subjects.

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