How important are calcium and vitamin D for bone health?

Calcium and vitamin D are essential components for building and maintaining strong bones throughout life.  While there has been some controversy in the past few years on how much calcium and vitamin D should be recommended for healthy bones, there are no doubts that too many people in the U.S. and in many other countries, especially elderly, frail people, do not take enough of these nutrients, and this can cause loss of bone and decreased bone strength.


Inadequate calcium significantly contributes to the development of osteoporosis. Many studies show that low calcium intake throughout life is associated with low bone mass and high fracture rates. National surveys have shown that most people do not get the calcium needed to grow and maintain healthy bones.

How Much Calcium Do I Need?  The amount of calcium needed will depend on your age and sex. See table below for details. Remember these daily totals include the calcium you are receiving from your diet and supplements.

Recommended calcium intake

51-70 (male)1000
51-70 (female)1200
70 and older1200

Calcium-Rich Food Sources Food is the best source of calcium. Try to get the daily amount recommended from food and only supplement as needed to make up any shortfall. See the table below for examples of calcium rich foods.

Reading Food Labels –To determine how much calcium is in a particular food, check the nutrition facts panel for the daily value (DV). Food labels list calcium as a percentage of the DV. This amount is based on 1,000 mg of calcium per day. For example: 10% DV of calcium equals 100 mg of calcium.

Calcium Supplements. If you get enough calcium from food, there is no need to take a supplement. There is no benefit to taking more calcium than your body requires, doing so may be harmful.

Calcium supplements are available over the counter and in varying amounts. When choosing a supplement, keep the following in mind:

  • Choose brand-name supplements with proven reliability. Look for labels that state “purified” or have the USP (United States Pharmacopeia) symbol. This means that the USP has tested and found the calcium supplement to meet its standards for purity and quality.
  • Read the product label carefully to determine the amount of elemental calcium, which is the actual amount of calcium in the supplement, as well as how many doses or pills you have to take. When reading the label, pay attention to the “amount per serving” and “serving size.”
  • Calcium is absorbed best when taken in amounts of 600 mg or less. This is the case for both foods and supplements. Try to get your calcium-rich foods and/or supplements in small amounts throughout the day, preferably with a meal.
  • Take (most) calcium supplements with food. The stomach acid aids in the absorption of most calcium supplements.
  • Side effects from calcium supplements, such as gas or constipation may occur. If increasing fluids in your diet does not solve the problem, try another type or brand of calcium. It may require trial and error to find the right supplement for you.
Vitamin D

The body needs vitamin D to absorb calcium. Without enough vitamin D there is insufficient calcium absorption from the diet. Then the body must take calcium it stores in the skeleton, which weakens existing bone and prevents the formation for strong, new bone. You can get vitamin D in three ways: through the skin from sunlight exposure, through diet and supplements. Recommended dietary intake for vitamin D: 1000-1200 international units (IU) daily for both males and females of any age.

Vitamin D Deficiency: Are You at Risk?

Vitamin D deficiency occurs when you are not getting the recommended level of vitamin D over time. In the long term, vitamin D deficiency can cause rickets, in growing children, or osteomalacia, in adults, leading to low bone mass and bone deformities. In the past, nutritional deficiency of vitamin D was frequent in people living in areas with low sunlight irradiation during the winter, typically at northern latitudes. Widespread use of vitamin supplements has greatly reduced these problems. Sadly, however, we still see a significant proportion of people living in sunny areas, such as the Midwestern U.S., with vitamin D deficiency or insufficiency because of poor dietary and lifestyle habits. The following are the most common situations that can lead to vitamin D deficiency:

  • People who spend little time in the sun or those who regularly cover up when outdoors;
  • People living in nursing homes or other institutions or who are homebound;
  • People with medical conditions that affect the ability to absorb vitamin D from the gut.
  • People taking medicines that affect vitamin D levels such as certain anti-seizure medicines
  • People with very dark skin
  • People who are very overweight or obese

If you have osteoporosis and also have a vitamin D deficiency, your healthcare provider may prescribe a short course of high dose of vitamin D to bring you up to a healthy level. Regardless, it is always important to continue taking enough daily vitamin D to keep your levels in the desired range.


Your skin makes vitamin D when exposed to sunlight.  How much vitamin D your skin can produce depends on time of day, season, latitude, skin pigmentation, and age. As we age, our skin loses its ability to generate vitamin D. Furthermore, older people, particularly nursing home residents may spend too little time outdoors, allowing very little vitamin D to be produced by the skin. Of note, sunscreens commonly used to prevent skin cancer also reduce vitamin D synthesis – sunscreens with an SPF as low as 8 reduce vitamin D production by 95 percent.

Vitamin D in Food

Vitamin D is found in very few foods. See table below.

Vitamin D Supplements

Vitamin D supplements should be used by anyone who cannot take enough vitamin D from dietary sources and sunlight exposure. Therefore, not everyone must take vitamin D supplements; supplements are intended to correct a dietary shortfall. There are two types of vitamin D supplements, vitamin D2 and vitamin D3. Both are equally beneficial to your bone health.

You can download these Bone Health Program tables (pdf) to help you determine how much calcium and vitamin D comes from your typical diet, and thus, how much supplement you should consider taking.

Before buying a vitamin D supplement, check to see if any of the other supplements, multivitamins, or medications you take contain vitamin D. Many calcium supplements do, for example.

Are calcium and vitamin D supplements safe?

In recent years, there has been some controversy about the safety of calcium supplements.  Some researchers found a slight but significant increase in heart attacks in patients who were taking calcium (not vitamin D) supplements[i].  However, other studies have not confirmed such findings[ii]; others even concluded that calcium and vitamin D supplementation if anything, reduces the risk of atherosclerosis[iii].  Our recommendations are consistent with guidelines published by major professional organizations and reflect decades of clinical practice.  The bottom line is that if you follow the recommendations noted above and take the amount of calcium and vitamin D supplements that is right for you, you will meet your daily needs of these vital nutrients without any risks.

If you want to know more about calcium and vitamin D, you can visit The National Osteoporosis Foundation website, which contains additional useful tips and tools on these topics.

We recommend that you always contact your health care provider before making decisions on over the counter medications or supplements, or if you have diseases or conditions that may affect your calcium and vitamin D intake, or that may contraindicate your taking such supplements.


[i] Bolland et al. British Medical Journal 342:d2040; 2011

[ii] Alcantara Cunha Lima et al. Archives of Endocrinology and Metabolism 60:252-263;2016

[iii] Thiele et al. Atherosclerosis 241:743-751; 2015

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