Magnesium oxide is one of the cheapest forms of magnesium, but it also has the lowest bioavailability among commonly used forms – according to some estimates, only about 4% of the contained magnesium is absorbed, while organic salts such as magnesium citrate or bisglycinate achieve significantly higher absorption (Koc et al., 2025; Merschmann et al., 2025). This means that although the label states 113 mg of magnesium per dose, significantly less actually enters the body. Magnesium oxide also has a more pronounced laxative effect at higher doses. If magnesium is a priority for you, we recommend a product with magnesium citrate, malate, or bisglycinate.

Optimum Electrolyte Powder contains a relatively high dose of sodium (400 mg per dose, which at the recommended dilution in 450 ml of water results in a concentration close to 890 mg per liter) – this is above the typical target range for replacement during exercise (Pérez-Castillo et al., 2024). If you have high blood pressure, heart or kidney disease, or are taking medications such as diuretics or blood pressure medication, we recommend checking with a doctor before regular use, as additional sodium intake may affect your condition. For one-time use during intense exercise with heavy sweating, however, the risk is not the same as with regular, daily use.

The lower price is partly due to the choice of cheaper raw materials – magnesium is in the form of magnesium oxide and calcium in the form of tricalcium phosphate, which are significantly cheaper than organic salts such as magnesium citrate or calcium bisglycinate used in some more expensive competing products. The product also does not contain additional functional ingredients such as coconut water, taurine, or vitamin complexes, which some more expensive products in this category have. This doesn't necessarily mean the product is ineffective – the sodium and potassium doses are solid – but it does mean the compromise lies mainly in the quality and absorbability of the chosen forms of magnesium and calcium.

Based on available product information, the manufacturer does not disclose independent laboratory testing for contaminants, heavy metals, or banned substances. Unfortunately, this is not an exception in this product category – most electrolyte powders on the market do not publicly publish such reports. If you compete in a sport with testing for banned substances, or simply want additional assurance of the product's purity, we recommend checking with the manufacturer whether internal quality certifications exist (e.g., GMP), or choosing a product with a certification such as Informed Sport, which is unfortunately not common in this ingredient category.