DIETARY POTASSIUM EFFECTS ON BLOOD PRESSURE AND WHOLE-BODY RETENTION OF POTASSIUM, SODIUM, AND CALCIUM FROM A CONTROLLED FEEDING STUDY IN PRE-HYPERTENSIVE-TO-HYPERTENSIVE ADULTS

2019-10-30T15:34:37Z (GMT) by Michael Steven Stone

Potassium is an essential nutrient, that has been labeled a shortfall nutrient by recent Dietary Guidelines for Americans Advisory Committees. Increases in potassium intake have been linked to improvements in cardiovascular and other metabolic health outcomes. Blood pressure (BP) has often been cited as the primary criterion for determining potassium requirements. Hypertension (HTN), or high BP, is a primary risk factor for cardiovascular disease and other circulatory diseases. Cardiovascular disease (CVD) is responsible for the 31% of deaths worldwide. Findings from the Agency for Healthcare Research and Quality report (which informed the recently released Dietary Reference Intakes for sodium (Na) and potassium) on potassium intake and chronic disease concluded, with a moderate strength of evidence, that increasing potassium intake decreases BP, particularly among those with HTN. Although, of the 18 randomized controlled trials assessed by the AHRQ, only 4 were dietary interventions, the rest involved potassium supplementation. Observational studies also show a consistent bone benefit with increased potassium rich fruit and vegetable intakes in cohorts spanning adolescents to the elderly. In clinical trials, higher potassium intakes through supplementation have been associated with reduced urinary calcium (Ca) excretion and improvement in Ca balance. Although, similar to BP, intervention trials assessing the impact of dietary potassium on bone are lacking. Controlled feeding studies looking specifically at increases in potassium from food are sparse, leaving a large knowledge gap in the field for a nutrient with an important potential health impact. In general, little is known about whole-body potassium retention, with the few studies conducted lacking consistency and rigor in methods and design. What potassium retention means in terms of adequacy, or how higher or lower retention may influence specific health outcomes is understudied and not well understood.

Utilizing a randomized, cross-over, controlled feeding clinical study with complete metabolic balance measures, our research aims to begin filling these gaps, looking specifically at the effects of potassium intake via potato sources and a potassium supplement on BP and vascular outcomes, as well as how the source of potassium may influence potassium, Na and Ca whole-body balance.

This dissertation will discuss the physiology of potassium intake, how this may affect potassium, Na, and Ca retention, and in turn what influence this has on vascular and bone related health outcomes. Overall the goal of this research is to address the question: What is the importance of dietary potassium, and how can it benefit cardiovascular and skeletal health?