2.1. Utrzymanie prawidłowego funkcjonowania układu nerwowo-mięśniowego (ID 320, 386)

The claimed effects are “signal transduction and muscle contraction” and “nerve function”. The Panel assumes that the target population is the general population.
The Panel considers that maintenance of normal muscular and neurological function is a beneficial physiological effect.

2.2. Utrzymanie prawidłowego ciśnienia tętniczego (ID 321)

The claimed effect is “blood pressure”. The Panel assumes the target population is the general population.
In the context of the proposed wording, the Panel notes that the claimed effect relates to the maintenance of a normal blood pressure.
Blood pressure (BP) is the pressure (force per unit area) exerted by circulating blood on the walls of blood vessels. Elevated BP, by convention above 140 mmHg (systolic) and/or 90 mmHg (diastolic), may compromise the normal arterial and cardiac function.
The Panel considers that maintenance of normal blood pressure is a beneficial physiological effect.

3.1. Utrzymanie prawidłowego funkcjonowania układu nerwowo-mięśniowego (ID 320, 386)

Approximately 98% of the total body potassium is located within the cell, where its concentration can be 30 times that of the extracellular fluid. Nevertheless, the concentration of potassium in the extracellular fluid is a critical determinant of neuromuscular excitability (EVM, 2002). Potassium deficiency or hypokalaemia is defined as low (below 137 mg/L or 3.5 mmol/L) plasma potassium concentrations. Hypokalaemia can be the result of either an intracellular shift of potassium, potassium depletion, or both (JHCI, 2003). Signs and symptoms of hypokalaemia owing to changes in the polarisation of cell membranes include muscle weakness, arrhythmia, cardiac arrest, and intestinal ileus. Mental depression and confusion can also develop (SCF, 1992).
The Panel notes that hypokalaemia rarely results from dietary inadequacy, but rather from crash diets, diarrhoea, diabetic acidosis, vomiting, intense or prolonged sweating, body burns and heavy urine losses owing to the use of diuretics (EVM, 2002).
The Panel concludes that a cause and effect relationship has been established between the dietary intake of potassium and maintenance of normal muscular and neurological function.

3.2. Utrzymanie prawidłowego ciśnienia tętniczego (ID 321)

Twenty three references have been provided, all pertinent for the assessment of the claimed effect, including statements from authoritative bodies (IoM, 2005; Lichtenstein et al., 2006, FDA, 2000; Appel et al., 2006), meta-analysis of randomised controlled trials (Capuccio and MacGregor, 1991; Whelton et al., 1997; Geleijnse et al., 2003), large observational studies (Dyer et al., 1994), as well as single studies on the effects of different potassium salts (He et al., 2005; Braschi and Naismith, 2008) or low doses of potassium (Naismith and Braschi, 2003) on BP.
The American Heart Association recommends increasing dietary potassium intakes to 4.7 g/d as a diet-related modification that effectively lowers BP (Appel et al., 2006; Lichtenstein et al., 2006) preferably by increasing consumption of potassium-rich foods (e.g. fruits and vegetables) instead of
supplements. This recommendation is in line with the recommendations from the US Food and Nutrition Board, which has set an intake of 4.7 g potassium per day from food as an adequate intake, mainly based on its blood pressure-lowering effects (IoM, 2005). In this report, data from a large number of observational studies reporting potassium intake (or urinary excretion of potassium as a proxy of intake) from foods were reviewed. Whereas potassium intake generally showed an inverse (and sodium intake a direct) association with BP values and/or the risk of hypertension, the sodium/potassium ratio was a stronger predictor than the intake of either electrolyte alone. Owing to the high colinearity between sodium and potassium intakes, the effects of either one on BP were difficult to estimate.
Most of the intervention studies on the effects of potassium on BP have been conducted with supplements of potassium chloride and have been reviewed in four meta-analysis of randomised controlled trials (RCTs) (Capuccio and MacGregor, 1991; Whelton et al., 1997; Geleijnse et al., 2003; Dickinson et al., 2006), three of them included in the US Food and Nutrition Board report (Capuccio and MacGregor, 1991; Whelton et al., 1997; Geleijnse et al., 2003). Three of the meta-analysis included exclusively trials where the only difference between the intervention and control groups was potassium intake (Whelton et al., 1997; Geleijnse et al., 2003; Dickinson et al., 2006).
The meta-analysis by Whelton et al. (1997) included 33 RCTs (2,609 subjects 18-79 years old), from which 12 trials were on normotensives (1,005 subjects) and 21 in hypertensives (1,560 subjects). Only in four trials subjects received concurrent antihypertensive medications. All but six trials provided potassium chloride as supplements. Systolic and diastolic BP significantly decreased with potassium supplementation as compared to placebo after adjustment for confounders, i.e., the effect size estimates were higher when only trials in non-pharmacologically treated subjects were considered (n=29). The effects were also more pronounced at higher urinary sodium excretions.
In the meta-analysis by Geleijnse et al. (2003), 27 RCTs with a mean duration of six weeks (range 2 to 114 weeks) were included. A significant reduction in systolic and diastolic BP was observed after adjustment for confounders with potassium supplementation as compared to placebo. Age, gender, and initial sodium and potassium excretion did not change the effect size estimates, but the effects were higher in hypertensive subjects.
The meta-analysis by Dickinson et al. (2006) included six RCTs (483 subjects older than 18 years) and observed large (but not significant) reductions in BP following potassium supplementation (8-16 weeks follow-up). The authors concluded that the evidence on the effects of potassium supplementation on BP is inconclusive owing to the large heterogeneity between trials.
The BP-lowering effect of potassium could be mediated by direct vasodilatation, by suppression of the sympathetic nervous system and the renin-angiotensin-aldosterone axis (COMA, 1991), and/or by its natriuretic effects (i.e. it increases urinary excretion of sodium chloride), which is independent of the accompanying ion (EFSA, 2005). This is supported by the observation that moderate potassium deficiency (without hypokalaemia) is characterised by increased BP and salt sensitivity, and that potassium lowers BP more in subjects with high sodium intakes. Potassium intake can also attenuate and even revert the hypertensive effects of sodium chloride in salt-sensitive individuals in a dose- dependent manner (IoM, 2005). Since data from observational studies has been obtained with potassium intakes from foods (as organic acids such as citrate) whereas intervention studies have been mostly conducted with potassium chloride, the effects on BP can likely be attributed to potassium itself independent on the accompanying ion (IoM, 2005).
In weighing the evidence, the Panel took into account that, even if one meta-analysis of RCTs did not observe an effect on BP following potassium supplementation (Dickinson et al., 2006), most observational and most of the RCTs reviewed in three meta-analyses (Whelton et al., 1997; Geleijnse et al., 2003; Dickinson et al., 2006), two of them including well controlled trials and adjustment for confounders, reported a significant association between potassium intake and lower BP. Although not
all bodies agree on this association (JHCI, 2003), European and American professional associations recommend increasing dietary potassium intakes for the prevention and management of human hypertension (Appel et al., 2006; Lichtenstein et al., 2006; Mancia, 2007) and biologically plausible mechanisms for these effects have been proposed.
The Panel concludes that a cause and effect relationship has been established between the dietary intake of potassium and the maintenance of a normal blood pressure.

4.1. Utrzymanie prawidłowego funkcjonowania układu nerwowo-mięśniowego (ID 320, 386)

The Panel considers that the following wording reflects the scientific evidence: “Potassium contributes to normal muscular and neurological function.”.

4.2. Utrzymanie prawidłowego ciśnienia tętniczego (ID 321)

The Panel considers that the following wording reflects the scientific evidence: “Potassium helps maintain normal blood pressure.”.