How Much Calcium Do I Need?

Too much calcium can't be good, right?

When I was volunteering at a senior expo this past weekend, I had the opportunity to get an osteoporosis screening.

To my dismay, my T-score was -1.9, which put me in the osteopenia (low bone mass) range. Even though I am still in my 20s, this should not surprise me.

I have a few non-modifiable risk factors that make me more likely to develop osteoporosis:

I am Asian,
I am female, and
I have a small body frame.¹

In addition, I do not spend too much time doing weight-bearing exercises such as walking, running, or dancing, or muscle-strengthening exercises such as lifting weights or using elastic exercise bands that will help build and maintain bone density.^{1, 2, 3}

The gentleman who did my osteoporosis screening asked if I drink coffee, because this can affect my calcium absorption. Besides caffeine, smoking can increase rates of bone loss and excessive consumption of alcohol, salty foods, or food containing phytic acid (eg, fiber-containing whole-grain products, wheat bran, seeds, and nuts) and oxalic acid (eg, spinach, sweet potatoes, and beans) can reduce calcium absorption.^{1, 2, 3} By introducing fruits and vegetables into the diet, however, calcium excretion will be reduced.²

In addition, vitamin D intake can improve calcium absorption.^{1, 2, 3} Vitamin D can easily be obtained either through sunlight or supplement.

The gentleman told me that I need more calcium and should consider taking calcium supplements. But then I wondered: how much elemental calcium do I need? Too much calcium cannot be good.

According to the Dietary Reference Intakes from the Food and Nutrition Board at the Institute of Medicine of the National Academies, from diet and/or supplements combined, someone in their 20s should have a calcium intake of 1000 mg/day, but not exceed 2500 mg/day.⁴

There are a couple things to remember to ensure that most of the elemental calcium intake is absorbed. First, calcium is best absorbed in smaller amounts (eg, 500 mg or less) throughout the day, and second, most calcium supplements (with the exception of calcium citrate) are absorbed well with food.^2,3

References

1. Osteoporosis. Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/osteoporosis/basics/definition/con-20019924. Accessed Nov. 10, 2015.

2. Calcium. Office of Dietary Supplements. National Institutes of Health. http://ods.od.nih.gov/factsheets/Calcium-HealthProfessional. Accessed Nov. 10, 2015.

3. Clinician’s guide to prevention and treatment of osteoporosis. National Osteoporosis Foundation. http://nof.org/hcp/reserouces/913. Accessed Nov. 10, 2015.

4. Committee to Review Dietary Reference Intakes for Vitamin D and Calcium, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.