Hypertension & Macrominerals: Sodium, "Potassium", Chloride

Question 1

What are some sources of potassium?

Answer 1

potassium is in almost every food
mostly unprocessed foods: bananas, mango, leafy greens, avocado, yams…

sometimes added to food (not as much as Na)
salt substitutes

Question 2

What are potassium?

Answer 2

major INTRAcellular cation (30x more conc. than outside)

Question 3

How are potassium being absorbed from the SI and colon?

Answer 3

> 85% injected absorbed in SI and colon

• across BBM: passive diffusion via membrane channels or K+/H+ ATPase
• across BLM: diffusion via K+ channels

Question 4

How do we metabolize potassium?

Answer 4

Rise in circulation after K+-rich meal
managed largely by insulin: promotes hepatic and muscle uptake
~90% excreted via kidneys

Question 5

What are some functions of potassium?

Answer 5

nerve conduction: K intra- vs. extracellular ratio maintain cell’s resting potenti

muscle contraction

water/fluid balance

w/ Mg: required for activity of pyruvate kinase (glycolysis)

Question 6

New DRIs for potassium?

Answer 6

Decrease over everybody’s I
besides 0-6 months

2005: DIRs based on ppl supp w/ potassium (help lower bP, reduce -ve effect of sodium)
now: number changed as balance study dont support previous AIs (not measured properly)

Question 7

How do we assess the nutrient status of potassium?

Answer 7

assessed by plasma potassium concentrations
(normal 3.5-5 g)

overt deficiencies and toxicities rare: but intakes below AI associated w/ elevated BP in salt sensitive individuals

Hypokalemia: vomiting, diarrhea, thiazide, loop diuretics, refeeding syndrome

Hyperkalemia: impaired renal function

Question 8

What other nutrients interact w/ K+?

Answer 8

dietary K+ intake decreases urinary calcium excretion