Retention of Potassium From Potatoes and Potassium Gluconate, and the Effect on Blood Pressure.

Purdue University

Status and phase

Unknown

Phase 2

Phase 1

Conditions

Hypertensive Disease

Treatments

Dietary Supplement: French Fries Diet

Dietary Supplement: Potassium control diet

Dietary Supplement: Potato Diet

Dietary Supplement: Potassium gluconate diet

Study type

Interventional

Funder types

Other

Identifiers

NCT02697708

1511016780

Details and patient eligibility

About

This study is designed to compare the effect of different dietary potassium sources on uptake and retention of potassium, as well as to determine the effect of potassium intake on blood pressure and acid-base balance. The study will compare three different sources of potassium given as a supplement, potatoes or French fries.

Full description

Potassium is a shortfall nutrient according to the 2010 Dietary Guidelines for Americans. Only 3% of Americans meet the recommended Adequate Intake of 4700 mg/d for potassium. Average potassium intake is approximately half of the Recommended Dietary Allowance (RDA), with potatoes providing the highest percentage (19-20% of potassium) in the American diet. Recommended dietary potassium intakes were determined primarily to optimize protection against hypertension and secondarily to protect against stroke and coronary heart disease. In setting requirements for most minerals, bioavailability is usually considered. However, little is known about bioavailability of potassium and what is known is from supplements rather than food. Recently, we performed a potassium bioavailability study on white potatoes looking at 35 healthy, normotensive men and women at 3 levels of potassium intake as potatoes or potassium gluconate supplements. Bioavailability of potassium was determined from AUC of serial blood draws and cumulative urinary excretion. Serum potassium Area Under the Curve (AUC )increased with dose (P<0.0001) and did not differ due to source (p=0.52). Cumulative 24 h urinary potassium also increased with dose (p<0.0001) and was greater with potato than supplement (p<0.0001), concluding that bioavailability of potassium is as high from potatoes as from supplements. These data allow us to evaluate the quality of the food as a source of potassium. However, a remaining question is whether retention of potassium from potatoes is higher than from the salt, which requires a metabolic balance study to determine. The effects of potassium rich foods on blood pressure have also been recently accessed. A controlled feeding study would properly capture potassium retention and balance, as well as adequately control for any positive benefit potassium may have on blood pressure and other vascular outcomes.

Increasing potassium citrate decreased titratable acidity and improved calcium retention in a dose response manner in postmenopausal women. There is one Randomized Controlled Trial (RCT) of potassium on bone, in postmenopausal women, showing a benefit of a supplement of potassium chloride on protecting against bone loss. Similar studies have not been performed with food sources of potassium.

This study is designed to evaluate the effect of added potassium (K) from potatoes in the diet on K retention , blood pressure, and parameters related to bone health including calcium retention and acid base balance.

Enrollment

40 patients

Sex

All

Ages

21+ years old

Volunteers

Accepts Healthy Volunteers

Inclusion criteria

Age 21 and above
Subjects able to adhere to the visit schedule and protocol requirements and be available to complete the study.
Pre-hypertensive, (SBP: 120-159mmHg).

Exclusion criteria

Subjects taking more than one medication to treat hypertension
Subject is taking medication to treat hypotension, or medication known to affect electrolyte metabolism or contain high levels of potassium or sodium, smoke cigarettes, use illegal drugs, or excessive alcohol intake.
Current use systemic corticosteroids, androgens, phenytoin, erythromycin, thyroid hormones, lipid-lowering medication.
Subjects who have hypertension (SBP > 160 mmHg), hypotension (SBP < 120mmHg) or diseases known to affect potassium metabolism (kidney disease or malabsorption disorders). History of myocardial infarction, diabetes mellitus, renal disease, gastrointestinal disease, pancreatitis, cholestatic liver disease, cancer.
Subjects who are pregnant.
Allergy or intolerance of intervention foods.
Unwillingness to refrain from dietary supplements.
Weight loss > 3kg in the past 2 months.
Subjects with liver and/or lipid abnormalities (elevated alanine amino transferase (ALT) and aspartate amino transferase (AST), dyslipidemia).

Trial design

Primary purpose

Prevention

Allocation

Randomized

Interventional model

Crossover Assignment

Masking

None (Open label)

40 participants in 4 patient groups, including a placebo group

Control Diet

Placebo Comparator group

Description:

Control (no additional potassium added to diet): Arm will consist of a 16 day balance period with a basal diet set at \~2340mg K/day; based on average American intake.

Treatment:

Dietary Supplement: Potassium control diet

Potassium Supplement Diet

Active Comparator group

Description:

Potassium gluconate: Arm will consist of a 16 day balance period with the basal (control) diet plus the addition of 1000mg of K/day from potassium gluconate (12 tablets).

Treatment:

Dietary Supplement: Potassium gluconate diet

Potato Diet

Experimental group

Description:

Potato diet: Arm will consist of a 16 day balance period with a basal (control) diet with an addition of 1000mg of K/day from white potatoes.

Treatment:

Dietary Supplement: Potato Diet

French fries Diet

Experimental group

Description:

French fry diet: Arm will consist of a 16 day balance period with a basal (control) diet with an addition of 1000mg K/day from French fries.