Institute of Medicine guidelines in 1997 recommended calcium doses of 1,000 mg/day for adults aged 25–50, 1,200 mg/day for older adults, and 1,000–1,300 mg/day for pregnant or lactating women.
Vitamin D supplementation should be at least 800–1,000 IU/day, Dr. Orwoll said. For pure nutritional inadequacy, it may be appropriate to treat with a loading dose of 50,000 IU per week for 2 months followed by 1,000 IU/day, depending on baseline vitamin D levels, he suggested. Vitamin D deficiency due to malabsorption or increased catabolism may require doses as high as 100,000 IU/day.
Lab analyses of vitamin D in serum samples can vary widely, he cautioned. “I would tend to use a well-established reference lab rather than, say, a local lab that doesn't have as much experience with it,” he said.