What it is
Calcium is the mineral most people know for bones, but it is also the trigger ion for every nerve signal. Calcium carbonate is the common, stable supplement form.
What it does in Memoclear
When a nerve impulse reaches the end of a neuron, calcium channels open, calcium flows in and that entry releases the neurotransmitter into the gap to the next cell. Calcium contributes to normal neurotransmission. At 18 mg the amount in Memoclear is a small contribution to daily intake, not a calcium supplement, and it should be read that way.
Where it comes from in food
Dairy, sardines, leafy greens, tofu set with calcium, and fortified plant milks.
What the research says
Calcium's role at the synapse is basic neuroscience and not disputed. The NIH Office of Dietary Supplements summarises intake needs. There is no research suggesting 18 mg on its own changes memory or focus; it is here as a supporting nutrient.
Who should be careful
18 mg is well within safe intake for everyone. If you take a separate calcium supplement or certain antibiotics, timing can matter; ask a pharmacist.
Where it sits in the Memoclear formula
Calcium (as calcium carbonate) works alongside L-Arginine (base), L-Arginine AKG 2:1 Extract, L-Citrulline HCl, L-Citrulline Malate, Beta-Alanine, Niacin (Vitamin B3). Together the seven cover nitric oxide, cell energy and nerve signalling in one daily capsule.
Further reading
Calcium fact sheet, NIH ODS. This research is on the ingredient, not on the finished Memoclear product.