The role of Calcium and Vitamin D and How Much Do Patients Need?

The role of Calcium

Calcium is a key structural component of bone and is built into bone as a mineral complex that includes calcium and phosphate. Calcium is a major building-block of bone – the skeleton houses 99% of the body’s calcium stores. 

  • The calcium in bones also acts as a reservoir for maintaining calcium levels in the blood, which is needed for healthy hearts, nerves and muscles.
  • In addition to mineralizing the skeleton, calcium plays a critical role in nerve and muscle function.
  • Inadequate calcium significantly contributes to the development of osteoporosis.
  • In teenage years, more calcium is needed because bones are growing rapidly.
  • At an older age, the body’s ability to absorb calcium declines, which is one of the reasons why seniors also require higher amounts.

The role of Vitamin D

Calcium is absorbed in the small intestine both by passive diffusion and by active absorption regulated by vitamin D. Individuals who have more vitamin D is able to absorb more calcium.

Vitamin D plays key roles in bone health: 

  • It assists in calcium absorption from food in the intestine 
  • It has a downward regulatory effect on parathyroid hormone level resulting in reduced bone loss 
  • It ensures correct renewal and mineralization of bone
  • It has a direct stimulatory effect on muscle tissue and thereby may reduce the risk of falling
  • It increases bone mineral density 

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The amount of calcium you need every day depends on your age and sex.

Recommendations from the Institute of Medicine (IOM)/National Academy of Medicine (NAM) of the US are presented in the table below.

Recommended Calcium intakes

Life-stage group

mg/day

Infants 0 to 6 months

200

Infants 6 to 12 months

260

1 to 3 years old

700

4 to 8 years old

1,000

9 to 13 years old

1,300

14 to 18 years old

1,300

19 to 30 years old

1,000

31 to 50 years old

1,000

51- to 70-year-old males

1,000

51- to 70-year-old females

1,200

70 years old

1,200

14 to 18 years old, pregnant/lactating

1,300

19 to 50 years old, pregnant/lactating

1,000

 

Source: Food and Nutrition Board, Institute of Medicine, National Academy of Medicine.

 

RECOMMENDED VITAMIN D INTAKE

There is no common definition of ‘optimum’ vitamin D intake.

For people with osteoporosis, combined calcium and vitamin D supplements are recommended to ensure that they are getting enough of these important nutrients and to maximize the benefits of osteoporosis treatment. 

The Institute of Medicine recommends no more than 4,000 IU per day for adults. However, sometimes doctors prescribe higher doses for people who are deficient in vitamin D.

 

Recommended Dietary Allowances (RDAs) for Vitamin D

Age

Male

Female

Pregnancy

Lactation

0-12 months*

10 mcg
(400 IU)

10 mcg
(400 IU)

1–13 years

15 mcg
(600 IU)

15 mcg
(600 IU)

14–18 years

15 mcg
(600 IU)

15 mcg
(600 IU)

15 mcg
(600 IU)

15 mcg
(600 IU)

19–50 years

15 mcg
(600 IU)

15 mcg
(600 IU)

15 mcg
(600 IU)

15 mcg
(600 IU)

51–70 years

15 mcg
(600 IU)

15 mcg
(600 IU)

>70 years

20 mcg
(800 IU)

20 mcg
(800 IU)

*Adequate Intake (AI)

 

Osteoporosis Foundation
RACGP AU Guidelines
Osteoporosis Foundation (Vitamin D)
Osteoporosis Foundation (Calcium)
This is for informational purposes only. You should consult your clinical textbook for advising your patients.