Potassium

A review assessing the effects of high dose potassium supplements on serum potassium, after assessing 20 studies, found that there did not appear to be a significant dose dependent effect of supplementation on serum levels in the average range of 1,950-2,925 mg a day (divided doses) with an overall range of 858-5,460 mg.^[1]

When looking at reviews on the association between potassium intake and instances of stroke, meta-analyses on the subject find protective effects such as a 21% reduced risk of stroke (RR 0.79; 95% CI 0.68-0.90) associated with increasing potassium intake by 1.64 grams a day^[2] and 24% reduced risk of incident stroke (RR 0.76; 95% CI 0.66-0.89) associated with dietary levels of potassium near 3,510-4,680 mg;^[3] numerous other meta-analyses find similar effects including the US health professional men^[4] and nurses^[5] cohorts and one 12-year study which found that an increase in potassium as little as 390 mg a day was associated with 40% less death from stroke in adults aged 50-79 in southern California.^[6] This risk reduction appears to be greater in magnitude than the beneficial effects of potassium on cardiac health^[2][3] which is thought to be due to potassium not only influencing blood pressure (main risk factor for stroke) but also direct and independent effects of potassium^[7] as some studies note a protective effect against strokes even when blood pressure is controlled for.^[6]

This beneficial effect does not specifically apply to supplements as a decrease in stroke risk has also been noted with three servings of fruits and vegetable daily, reaching a 22% reduction in the risk of stroke in a manner independent of blood pressure and thought to be due in part due to potassium.^[8]

Potassium appears to be highly protective against strokes when consumed in adequate amounts, although the protective effect does not seem dose dependent as both minor and major increases in potassium intake both confer a powerful protective effect

Potassium intake has been found to have a relation with calcium retention in otherwise healthy adults, with lower intake of potassium being associated with more calcium loss in urine while increasing potassium intake seems to retain calcium and lessen urine losses.^[9]

When supplemented, potassium (as citrate) taken over the course of one year in postmenopausal women with osteopenia appears to be effective in reducing some biomarkers of bone turnover such as u-NTX and P1NP suggesting a protective effect on bone mineral density; no apparent changes were seen in lumbar or hip BMD between the two groups however, thought to be in part due to the relatively short length of the study.^[10]

While not overly potent, potassium seems to have a protective effect on bone mineral density thought to be due to helping retain calcium better

When given to rats sensitive to kidney damage, increasing the potassium concentration of the feed from 0.75% to 2.11%^[11] or up to 2.6-3.8% at a level similar to sodium (4%)^[12] appears to be highly protective against the subsequent renal damage after stroke when compared to lower potassium concentrations; this effect seems to occur without any apparent changes to blood pressure.^[11][12]

The mechanism by which potassium exerts a protective effect against strokes may also influence damage that occurs after a stroke, including kidney damage. It is uncertain if potassium has a direct protective effect outside of stroke-related incidents

Potassium intake is known to reduce calcium loss in urine (via helping the body retain it better)^[9] which has been hypothesized^[7] to be the reason as to why potassium is associated with reduced risk of kidney stones, with half the relative risk when comparing the highest quintile of intake against the lowest.^[13]

Hyperkalemia refers to high blood levels of potassium which can cause symptoms such as cardiac arrythmia or brain damage, with numerous case studies recording such events associated with salt substitutes.^{[14][15][16][17][18]} While some of these cases were associateed with doses of potassium greatly exceeding the RDA, at least one case has noted usage of potassium supplements at 2,730 mg was associated with hyperkalemia in one Afro-Caribbean man on an ACE inhibitor,^[19] although it should be noted a review on the safety of potassium supplements failed to find an association between safety, race, and concomitant usage of pharmaceuticals.^[1]

In a review assessing studies using potassium supplements and whether or not they can induce hyperkalemia, it was found that doses of 50-75 mmol (1,950-2,925 mg) taken in divided doses over the course of the day increased serum potassium in a manner which did not appear dose dependent; no side-effects were reported in the review while biomarkers of renal function (urinary and serum sodium and creatinine) were unaffected.^[1]

Large doses of potassium, taken in forms that can be absorbed rapidly (usually powders such as salt substitutes), can pose a risk for hyperkalemia and cardiac complications. Lower doses, and divided doses, carry less of a risk