Electrolyte Drinks as a daily supplement: A look at the evidence?

Electrolytes are molecules that essentially contribute to the balance of water and salts (or homeostasis) in the body. They are also necessary for a variety of biological and physiological functions, such as nerve function, heartbeat regulation and kidney function. This is due to the fact that they allow for optimal absorption and retention of water molecules in cells and tissues, exchange energy and allow for the low level of electrical impulse that is the basis for nerve cell function.

Should the body's concentration of electrolytes become low or out of balance, it may lead to ill health or neurological symptoms. Adequate hydration - and thus electrolyte balance - is also linked to improved cognitive function. The most common and important electrolytes present in the human body include:

• Calcium (Ca2+)
• Chlorine (Cl-)
• Potassium (K+)
• Sodium (Na+)

Symptoms of imbalances

Adverse effects may be associated with both deficiency and excess of any of these electrolytes. Symptoms of these imbalances may include:

• Confusion
• Dehydration (or, more accurately, a disproportionately high concentration of sodium in relation to that of water)
• Lethargy
• Decreases in muscular performance and endurance
• Feelings of extreme hunger
• Skin dryness and damage
• Heart-rate abnormalities
• Heart failure
• Kidney failure

Where are electrolytes found?

Electrolytes are found in dietary sources, and also in specialised commercial products such as beverages and powders. These products are developed based on observations that a large proportion of electrolyte loss is sustained through perspiration. Therefore, these 'power' or 'sports' products are aimed at those who experience sweating at a high and regular volume, such as athletes and military personnel. These individuals are at a risk of severe dehydration and other symptoms as a result of this acute electrolyte loss, in theory at least.

Sports drinks

Sports or 'power' drinks are also marketed, and available, to the general public. This poses the question of whether non-athletes, or people engaged in an 'average' level of daily activity, also require this level of electrolyte replenishment. For the vast majority of people, physiological processes are constantly enacted within the body to maintain body temperature and other types of homeostasis, which expends electrolytes and water, through the release of sweat and other biological functions. Therefore, these molecules must be replaced in some way, usually through diet.

There is some evidence that electrolyte supplementation may be particularly important to some vulnerable groups, such as infants and the elderly. However, it is not clear if electrolyte-containing products are a more efficient delivery system of these than conventional sources, or if a regular intake of these is beneficial or necessary. The relevant research and literature on this subject will be discussed here.

What the Research Shows

The body of clinical trial evidence on the advantages (if any) of daily electrolyte supplementation in everyday, relatively non-active life is unfortunately thin on the ground.

Most research is conducted on their effects on athletic and/or endurance training and performance. In these cases, the results of independent trials on these subjects tend toward the inconclusive at best.

Some studies conclude that electrolyte drinks do confer an advantage on muscular performance and endurance, which may appear to be due to more efficient water retention.

These effects may be attributed to the carbohydrates and caffeine also included in these products. In fact, there is evidence to suggest that the only beneficial effects associated with these 'energy drinks' are due to the caffeine they provide. Even then, the doses of this drug are often not sufficient for appreciable neuromuscular performance.

Conclusions on the efficacy of electrolyte-containing beverages are also compromised by the variability of their ingredients, to which the electrolytes may be bound. This may affect their availability once in the body, and thus their water-replacing properties.

A trial was conducted in which ten men and ten women were dehydrated (here defined as losing water equivalent to approximately 2% body mass for each subject) and then randomised to an electrolyte/carbohydrate drink, an electrolyte/amino acid drink or flavoured water. The electrolyte/amino acid drink was associated with a significantly more rapid return to normal hydration levels (as measured by its concentration in urine samples) in comparison to the other two treatments. No differences in water retention or urine volume were reported, however.

A crossover trial in which twelve subjects were given an electrolyte drink, a low dose of a novel dipeptide (similar to amino acids) formulation aimed at improving reaction time (RT) and endurance during sport, a high dose of the same, or a placebo in four separate trial periods found that the electrolyte drink elicited an inferior RT test result in comparison with placebo, but a superior one in one type of cognitive test. The study also indicated that both doses of the dipeptide may have improved RT in comparison to the electrolyte drink (although no values of significance were reported).

Other sources of electrolytes

Some other trials appear to question the validity of specialised supplement drinks in their function in balancing electrolytes and water in general.

A trial compared the post-exercise water-retaining properties of cow's milk, soy milk, a milk-based powdered supplement and a popular carbohydrate electrolyte drink. Fifteen male subjects consumed an equal amount of these in separate trials (as above) after an identical cycling regimen.

The electrolyte drink resulted in the lowest water retention (approximately 17%) compared to cow's milk (40%) and soy milk (47%).

However, the powdered supplement, designed to replenish proteins, sodium and energy, was associated with the greatest amount of water retention (65%).

Other studies appear to indicate a negative effect on bodyweight control mediated by the consumption of electrolyte drinks without exercise. In one trial, 25 healthy women and 30 healthy men were randomly assigned to regimens of two days on high-fat or high-carbohydrate meals, or two days on high volumes of water or electrolyte drinks. After a fasting period, body mass was increased significantly in the high-fat, high-carbohydrate and electrolyte drink groups. This should not be taken as a definitive indication of a risk of sport drink consumption, but is interesting nonetheless. In general, it is difficult to define the role of supplementary electrolyte intake in maintaining health and wellbeing.

References

1. Masento NA, Golightly M, Field DT, Butler LT, van Reekum CM. Effects of hydration status on cognitive performance and mood. Br J Nutr.2014;111(10):1841-1852.
2. Bockenhauer D, Zieg J. Electrolyte disorders. Clin Perinatol.2014;41(3):575-590.
3. Casey A, Hughes J, Izard RM, Greeves JP. Supplement use by UK-based British Army soldiers in training. Br J Nutr.2014;112(7):1175-1184.
4. Mora-Rodriguez R, Pallarés JG. Performance outcomes and unwanted side effects associated with energy drinks. Nutr Rev.2014;72 Suppl 1:108-120.
5. Tai C-Y, Joy JM, Falcone PH, et al. An amino acid-electrolyte beverage may increase cellular rehydration relative to carbohydrate-electrolyte and flavored water beverages. Nutr J. 2014;13:47. Accessed 2014.
6. Pruna GJ, Hoffman JR, McCormack WP, et al. Effect of acute L-Alanyl-L-Glutamine and electrolyte ingestion on cognitive function and reaction time following endurance exercise. Eur J Sport Sci.2014:1-8.
7. Desbrow B, Jansen S, Barrett A, Leveritt MD, Irwin C. Comparing the rehydration potential of different milk-based drinks to a carbohydrate-electrolyte beverage. Appl Physiol Nutr Metab.2014:1-7.
8. Androutsos O, Gerasimidis K, Karanikolou A, Reilly JJ, Edwards CA. Impact of eating and drinking on body composition measurements by bioelectrical impedance. J Hum Nutr Diet.2014.