Q1: Does Costco carry an official Kirkland Signature brand magnesium glycinate?
A1: Through late 2025 and into 2026, Costco has relied on verified national brands like Nature Made to supply magnesium glycinate rather than releasing an in-house Kirkland Signature white-label bottle. Kirkland Signature's primary internal offering remains its high-potency magnesium citrate.
Q2: Why are magnesium glycinate capsules so much larger than other vitamin pills?
A2: Because elemental magnesium makes up only about 14% of the magnesium bisglycinate molecule by weight, manufacturers must pack substantial powder volume into each dose. Achieving a modest 200 mg of elemental magnesium requires over 1,400 mg of total compound, necessitating large vegetarian capsules or multiple pills per serving.
Q3: Can I take Costco's magnesium glycinate in the morning instead of at night?
A3: Yes. While the glycine molecule helps promote mental relaxation, magnesium glycinate is not an over-the-counter sedative or sleeping pill. Taking it with breakfast supports cellular energy production and muscle recovery without causing sudden daytime drowsiness.
