Now with more essential: Vitamin D3 - Assists in the absorption of calcium.† Kirkland Signature Calcium Citrate is scientifically formulated for building a health body. Calcium is essential for strong bones and Vitamin D3 helps the body absorb calcium. Zinc and magnesium assist the body with bone formation.† Calcium Citrate helps maintain and support: Healthy bones and teeth.† Healthy muscle contraction.† Reduces risk of osteoporosis.