Nutraceutical Ingredients: The Benefits of Fully Reacted Mineral Salts in Dietary Supplements

Jost Chemical

Daily intake of several minerals, including calcium, iron, copper, magnesium, manganese, and zinc as well as several other trace minerals, is necessary for the proper function, growth, and overall health of the human body. Increasing consumer interest and a willingness to spend more on mineral supplement products are expected to contribute to a compound annual growth rate in the mineral supplement market of 5.1 percent over the next 5 years, with the market reaching $14.53 billion by 2025¹.

In October 1994, the US Congress passed the Dietary Supplement Health and Education Act (DSHEA), which called for the establishment of current Good Manufacturing Practices (cGMPs) for dietary supplements. However, many widely used mineral salts still lack published monographs, and instances of non-compliance with established dietary supplement monographs reinforce the need for good chemistry and accurate content disclosure. This can leave supplement manufacturers wondering whether the ingredients they buy are of good quality and safe for their intended use and how those ingredients are affecting the quality of their finished products. 

Manufacturers can safeguard against these and other concerns by using fully reacted mineral salts. Fully reacted salts are manufactured by a reaction of an acid and a base in an aqueous solution and the precipitation of a salt compound. A dry blend of an acid and a base often results in a partially reacted product. The acid and base might mix completely, but the reaction may not proceed to completion, causing performance and stability issues if the partially reacted mineral salt is used in a formulation. It takes skilled chemists, chemical engineers, and production operators to drive reactions to completion, resulting in quality mineral salts. Manufacturers can differentiate between a fully reacted mineral salt and a blend of reactants using infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermal gravimetric analysis, or numerous other analytical techniques. 

To illustrate the problems blended and partially reacted salts can cause mineral supplement product manufacturers, let’s consider magnesium. The magnesium supplement market is forecast to grow at a compound annual rate of 7.1 percent through 2025 [1]. While it’s important for everyone to achieve the recommended daily intake of magnesium, supplementation can be especially beneficial for heart patients and diabetics. Magnesium helps regulate heart rate and blood pressure, reducing the risk of several cardiovascular diseases, and also helps control blood glucose levels. 

Using partially reacted magnesium can reduce a supplement’s quality and effectiveness. For example, most fully reacted salts have a fairly neutral pH, while blended products might exhibit an acidic or alkaline pH. A partially reacted blend can be unstable because the alkaline minerals will continue to slowly react with any acidic ingredients in the formula. This instability can cause the blend to harden or the tablets to disintegrate over time. A blended product might be low or high in pH because of an imbalance in the acid-base stoichiometry. The pH imbalance can lead to problems with the product’s integrity. Structure and content uniformity can suffer if a product contains a mineral blend with a partially reacted salt. In compounding operations, blends can separate based on differing physical characteristics. 

Depending on the mineral salt, the addition of an acid to a sample can demonstrate the presence of unreacted mineral carbonate, as effervescence of the acid will occur. Putting a partially reacted hydrated magnesium citrate tribasic in water will cause a reaction and temperature increase. An exothermic reaction will occur if an unreacted acid and excess hydroxide/oxides react post blending upon rehydration. Additionally, if such a blend is exposed to water during wet granulation or if the product is added to a consumer’s drink, a reaction might occur at an inopportune time and damage the product’s integrity. 

Besides creating an unstable end product, formulations that contain blended mineral ingredients may also have a misstated ingredient label. For example, a magnesium citrate product may list the magnesium content at 20 percent, but this is not possible based upon the stoichiometry of a fully reacted salt. Per the USP monograph, magnesium citrate tribasic can only offer 11.2 to 12.0 percent magnesium on the “As-Is” basis in the hydrated form. 

Table 1 shows the fully reacted mineral content of several mineral supplement products. Products that claim higher magnesium content levels than those listed are likely blends. Appropriate labeling should list the ingredients comprising a “blend” such as magnesium citrate and magnesium oxide, so that the finished product complies with the FDA ingredient declaration mandates. 

Higher mineral content is a marker for an adulterated product, typically as an oxide, hydroxide, or carbonate. Stability and performance issues increase as the level of adulterant increases. Furthermore, product labeling compliance will be an issue if the added adulterant does not appear on the ingredients list. By using fully reacted mineral salts, dietary supplement manufacturers can ensure stability, consistent performance, and good bioavailability and avoid product labeling compliance issues. 

Reference 

1. www.grandviewresearch.com/industry-analysis/ mineral-supplements-market