Algas calcareas, also known as Lithothamnion calcareum, is a type of red marine algae that accumulates significant amounts of minerals, particularly calcium and magnesium, in its cell walls. This ingredient is widely marketed as a natural source of these minerals and is often included in supplements intended to support bone health and the skeletal system.

The scientific rationale for its use is that calcium and magnesium are essential minerals for bone formation and maintenance. Several studies have examined mineral-rich algae such as Lithothamnion calcareum for their bioavailability and effects on bone metabolism. Animal studies have shown positive effects on bone mineral density and strength when algal calcium is compared to other sources of calcium. Some small human studies suggest that algas calcareas may be as effective as traditional calcium supplements in maintaining bone mineral density, particularly in populations at risk of osteoporosis; however, these human studies are limited in number and scope.

Overall, the use of algas calcareas to support the skeletal system is supported by the known importance of its mineral content and some preliminary clinical data. However, more robust, long-term human trials are needed to confirm its efficacy compared to conventional calcium sources. Thus, while there is scientific basis for its use, the evidence is moderate rather than strong.