Do You Need Vitamin D3 When Taking Calcium?

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Both calcium and vitamin D have several roles in the body, including cancer prevention and blood pressure regulation, though maintaining bone health is their most important role. Deficiency of either of these nutrients will lead to bone disorders. If you cannot get either of these through natural sources, take supplements. Taking calcium alone may not be sufficient since vitamin D has an important role in bone health and is essential in calcium absorption and maintaining its levels in the blood. And, many people who are deficient in calcium are also deficient in vitamin D.

Bone Health

Your bones undergo continuous processes of building and resorption, or loss of bone matter, throughout your life. While the building process dominates until the age of 30, resorption takes over later on. Older adults, especially after the age of 50, lose bone matter at a higher rate, resulting in lowered bone density and strength. Both calcium and vitamin D are needed to reduce this bone loss.


Osteoporosis is a condition in which bones become thin and brittle, leading to increased risk of fractures. It is most common in the elderly, especially in postmenopausal women. Osteoporosis can be symptomless for many years until a fracture occurs. Contributing factors for osteoporosis include deficiency of calcium and vitamin D, underweight, lack of physical exercise, smoking, alcohol consumption and certain diseases and medications. Osteoporosis can be prevented by avoiding these risk factors. Discuss the risk for osteoporosis with your doctor, who may advise about tests for bone density, blood levels of calcium and vitamin D, to assess the need for supplements.


People who need supplemental calcium include postmenopausal women, lactose intolerant people and vegans. Calcium has many important body functions apart from bone health. Whatever the role of calcium is, vitamin D is needed for its absorption. Though vitamin D is needed for calcium absorption, it is not required to take both at the same time.

Vitamin D

Vitamin D-2, or ergocalciferol, made by plants, and vitamin D-3, or cholecalciferol, made by skin after sun exposure, are the two forms of vitamin D. Both are available as supplements. The National Osteoporosis Foundation, NOF, recommends a daily intake of 400 International Units to 800 International Units of vitamin D, depending on your age. Older people require higher intakes. Natural sources of vitamin D include food such as fish, egg yolks, liver and fortified foods such as milk, and exposure to the sun. Daily exposure for 15 minutes can give enough vitamin D, but the amount varies greatly based on factors such as age, skin color, geographical latitude and use of sunscreen etc. Supplemental vitamin D can be taken alone, as part of multivitamins or along with calcium supplements. According to research done by scientists at Boston University School of Medicine, vitamin D-2 and vitamin D-3 are equally effective.

Vitamin D deficiency

Michael F. Holick, a scientist at Boston University School of Medicine, says, “Vitamin D deficiency is an unrecognized epidemic.” People who take calcium may also need to take vitamin D when there is increased risk of vitamin D deficiency such as being older than age 50, lactose intolerance, veganism, obesity, nursing home residence, lack of adequate sun exposure, intestinal malabsorption and kidney diseases. According to NOF, deficiency of vitamin D is more common than calcium deficiency in elderly people. Without adequate vitamin D, osteoporosis cannot be prevented. Therefore, it is important to ensure adequate intake of vitamin D to maintain bone health.