Vitamin D is essential for adequate absorption and utilization of calcium. Using sunblock is always best so be sure to allow more time. Today, vitamin D is also added to milk products. Magnesium is similarly essential for calcium absorption and is found in many foods. You need 250 to 300 mg daily.
Many supplements are available, even some that combine calcium with magnesium.
Be certain not to take more than 500 mg of supplemental magnesium a day as overdosing can be dangerous. On the other hand, some substances work against strong bones. Alcohol and caffeine can affect our calcium status. Alcohol inhibits absorption of calcium and vitamin D. Caffeine increases excretion of calcium in urine. Be mindful of your intake of both of these substances.