Calcium and Vitamin D

Introduction

Calcium and vitamin D are critical to bone health, especially in children. Children and youth with special health care needs (CYSHCN) may be at increased risk for nutritional deficiencies and bone-related problems like Osteoporosis and Pathologic Fractures. This page discusses when and how to test calcium and vitamin D levels and to counsel families regarding dietary intake and supplementation.

Dietary Recommendations

The American Academy of Pediatrics (AAP) and other health experts recommend that children get their nutrients from a healthy diet. Intake recommendations often contain the following terms:
  • Recommended daily allowances (RDA) - the average daily dietary intake levels needed to meet the nutritional needs of most people
  • Adequate intake - a term used instead of RDA when there is less evidence for the daily dietary intake likely needed for adequate nutrition
  • Upper intake - the limit of routine dietary intake above which most people might be at risk for toxicity, though higher intake may still be indicated for people with unusual needs
Calcium Dietary Intake Recommendations
Calcium Dietary Intake Recommendations
Adapted from DRIs for Calcium and Vitamin D (The National Academies)
Vitamin D Dietary Intake Recommendations
Vitamin D Dietary Recommendations (JPEG imported 300 dpi)
Adapted from DRIs for Calcium and Vitamin D (The National Academies)

Dietary Sources of Calcium

Foods naturally high in calcium include: [Golden: 2014]
  • Milk: An 8-oz glass of cow milk contains about 300 mg of calcium (for lactose-intolerant individuals, tolerance may be improved with use of lactose-free dairy products or lactase enzymes).
  • Yogurt: An 8-oz serving of plain yogurt contains about 275 mg of calcium.
  • Cheese: A 1.5-oz serving of cheese contains about 300 mg of calcium.
Other natural sources of calcium include sardines, salmon, broccoli, beans, leafy greens, and canned tomatoes. Drinks and foods that may be fortified with calcium include “alternative” milk like soy, almond, coconut, and rice beverages, tofu, breakfast cereals, and orange juice. Calcium content is not the same for all products (e.g., not all orange juice is fortified with calcium) and absorption and bioavailability vary. See Calcium Content of Foods (UCSF) for more detail.

Dietary Sources of Vitamin D

Vitamin D is manufactured in the body through skin contact with certain UV wavelengths in sunlight. Dark skin, wearing protective or modest clothing, and sunscreen use increase the risk of inadequate vitamin D production in the body (but decrease the risks of skin damage and skin cancer).
In addition to endogenous production, dietary sources provide Vitamins D2 (plant-derived ergocalciferol) and D3 (animal-derived cholecalciferol): [Golden: 2014]
  • Fatty fish (sardines, salmon, tuna, and cod liver oil): A 3.5-oz serving of fresh, wild-caught salmon contains about 1,000 IU of vitamin D (farmed salmon has about 1/8th the amount of vitamin D).
  • Shitake mushrooms: A 3.5-oz serving of canned shitake mushrooms provides about 1,600 IU of vitamin D.
  • Fortified fruit juices, formulas, cereals, and dairy products: An 8-oz serving of cow milk or baby formula, fortified orange juice, yogurt, or a 3-oz serving of cheese has about 100 IU of vitamin D.
  • Eggs: A hard-boiled egg contains about 20 IU of vitamin D.
As with calcium, vitamin D content varies across products (e.g., not all orange juice, cheese, or yogurt is fortified); reading nutritional labels is essential. See Food Sources of Vitamin D (Dietitians of Canada) for more detail.
Breastfed Infants
Breastfed infants do not get the recommended 400 IU of vitamin D daily unless supplemented; typically, breastmilk contains about 20-25 IU/L. [Institute: 2011]
Once an infant turns 12 months old, fortified cow milk and other dietary sources are usually sufficient to meet the recommended 600 IU daily. Cow milk contains about 100 IU per 8 oz. Limit milk intake to 16-20 oz per day for children ≥1 year (thus contributing up to 400-500 IU of Vitamin D); drinking more milk can reduce iron stores. [Maguire: 2013] For further information, see Vitamin D and Breastfeeding (CDC).

Pearls and Alerts

Risks Factors
Despite consumption of recommended amounts of calcium and vitamin D, children and youth with special health needs may be at risk for deficiencies due to their medical condition, medications, activity level, etc. Risk factors are discussed in more detail in the Portal's Osteoporosis and Pathologic Fractures.
Risk of Overdose
Children are at risk of toxic ingestion of nutritional supplements and may be particularly tempted by tasty chewable formulations (e.g., gummies).
Iron Interacts with Calcium
Calcium ingested at the same time as iron can reduce iron absorption.

Testing Calcium and Vitamin D Levels

Calcium

In the pediatric primary care setting, calcium levels do not require routine laboratory monitoring; however, clinicians may note the calcium levels included in comprehensive metabolic panels. A normal total or ionized level of calcium suggests an appropriate balance among vitamin D, calcium, and the parathyroid hormone in regulating calcium in the body. Normal pediatric total calcium levels range from 8.4 to 10.6 mg/dL with slight variation by age. [University: 2018] Reference range may vary slightly at different labs.

Vitamin D

The recommended test for vitamin D levels is serum vitamin D 25(OH). The following shows concentrations and health status.
Serum 25-Hydroxyvitamin D [25(OH)D] Concentrations and Health* [Institute: 2011]
Testing Vitamin D Levels

Supplementation

For nutritionally vulnerable populations or children who do not meet the RDA with their diet, vitamin and mineral supplements may help meet nutrition needs. Because supplements are not regulated, it is difficult to recommend specific formulations.

Calcium Supplementation

Due to lack of evidence for fracture risk reduction in healthy children and its limited bioavailability, routine calcium supplementation is not recommended for infants, children, or adolescents. Appropriate dietary intake and weight-bearing exercise are strongly encouraged.
Children and Adolescents with Special Health Care Needs
Calcium supplementation (often combined with vitamin D) may be considered for children who have significantly inadequate dietary intake or risk for poor bone health. There is “possible benefit” from supplementing calcium and vitamin D in children with cerebral palsy to increase bone density, but insufficient evidence to show supplementation helps prevent fragility fractures. [Ozel: 2016]Risks of excess calcium supplementation include increased calcium excretion in the urine (which can lead to kidney stones), muscle cramping, bone problems, neurological problems, and heart attack and strokes in older people.
Calcium carbonate (40% elemental calcium) and calcium citrate (21% elemental calcium) are the most commonly used oral/enteral supplements. [Golden: 2014] Calcium carbonate is best absorbed with meals, but calcium citrate can be taken on an empty stomach. [Golden: 2014] Taking calcium supplements between meals can minimize calcium-induced inhibition of iron absorption. Pediatric calcium supplements come in different formulations including chewable tablets, gummies, and drops. Consult with a bone health expert prior to starting calcium supplementation for a low calcium level.

Vitamin D Supplementation

For nutritionally or medically vulnerable populations, multivitamin-mineral supplements can help meet nutrition needs. There is no evidence to support routine vitamin D supplementation in low-risk populations or children with normal vitamin D levels. [Winzenberg: 2011]
Breastfed Infants
Infant Receiving Vitamin D Supplement
Science Photo Library
Vitamin D supplementation is recommended for breastfed and partially breastfed infants until dietary intake is sufficient to meet vitamin D needs. Options include:
  • Oral/enteral supplement for the infant with 400 IU daily of vitamin D (most commonly recommended)
  • Oral supplement for the mothers with 6,000 IU daily to provide adequate vitamin D in the breastmilk
Although breastmilk is preferable, formula can increase vitamin D levels.
Infant formula typically has 100 IU of Vitamin D per 8 oz.; it takes around 32 oz (approximately 1 L) daily to meet the full RDA. Increased sun exposure is NOT recommended to meet vitamin D requirements in babies.
Children and Adolescents with Special Health Care Needs
Children whose bone health is at risk due to obesity, primary or genetic bone disease, or certain medication use (e.g., corticosteroids, antiepileptics, antifungals, or antiretroviral medications) may benefit from consuming 2-4 times the RDA for vitamin D. Testing levels in these groups is advised. Osteoporosis and Pathologic Fractures has more information about medical conditions and medications associated with osteoporosis, testing, and treatment.
Vitamin D supplements include D2 (plant-based ergocalciferol) and D3 (animal-derived cholecalciferol) in varying strengths and formulations and in multivitamins or calcium/vitamin D combinations. The safest and most economical approach is to use oral D3 (cholecalciferol) unless the child has severe kidney disease or some other condition that prevents them from activating it in the body. Infant formulations include liquid 400 IU/mL and drops 400 IU/0.03 mL. For older children, there are liquids, powders, gummies, chewables, capsules, and tablets. Both daily and intermittent regimens work well. [Russo: 2011]
For children >12 months old who are formula dependent, 4 cans (approx. 1 L of PediaSure, Nutren Jr., etc.) are needed to receive 600 IU per day. Of note, some formulas list vitamin D content in micrograms, so be aware of the potential for conversion errors. As a reference, 1 IU of vitamin D2 or D3 = 0.025 mcg, so 400 IU = 10 mcg and 600 IU = 15 mcg. [National: 2018]
The response to vitamin D3 supplementation can be tracked through serial Vitamin D 25-OH serum levels; however, D2 supplementation cannot be tracked this way. [Zaniew: 2012] Serum 25(OH)D levels are expected to rise by about 1 ng/mL (2.5 nmol/L) for every 100 IU of additional vitamin D3 per day. [Heaney: 2008]

Resources

Information & Support

For Professionals

Vitamin D: Fact Sheet for Health Professionals (NIH)
Guidelines and information about sources of vitamin D, its potential interactions with medications, what constitutes excessive amounts, and who is at risk for deficiencies; National Institutes of Health.

Calcium: Fact Sheet for Health Professionals (NIH)
Guidelines and information about sources of calcium, its potential interactions with medications, lactose intolerance, and who is at risk for deficiencies; National Institutes of Health.

Dietary Guidelines for Americans 2015-2020 (HHS & USDA)
Details about healthy eating patterns, limiting calories from added sugars and saturated fats, reducing sodium intake. and shifting to healthier food and beverage choices; U.S. Dept. of Health and Human Services and U.S. Dept. of Agriculture.

Vitamin D and Breastfeeding (CDC)
Information about breast milk and vitamin D content; Centers for Disease Control and Prevention.

For Parents and Patients

Calcium Content of Foods (UCSF)
List of foods, serving sizes, and amounts of calcium (mg); University of California San Francisco.

Food Sources of Vitamin D (Dietitians of Canada)
List of foods, serving sizes, and amounts of vitamin D (IU).

Vitamin D and Your Child (JAMA)
One-page overview focused on children without special needs; JAMA Pediatrics.

Calcium: Fact Sheet for Consumers (NIH)
Learn about the importance of calcium, where to find it in foods and supplements, how much is needed, and how much is too much; National Institutes of Health.

Vitamin D: Fact Sheet for Consumers (NIH)
Learn about the importance of vitamin D, where to find it in foods and supplements, how much is needed, and how much is too much; National Institutes of Health.

Calcium: Fact Sheet for Consumers in Spanish (NIH)
Learn about the importance of calcium, where to find it in foods and supplements, how much is needed, and how much is too much; National Institutes of Health.

Vitamin D: Fact Sheet for Consumers in Spanish (NIH)
Learn about the importance of vitamin D, where to find it in foods and supplements, how much is needed, and how much is too much; National Institutes of Health.

Helpful Articles

Golden NH, Abrams SA.
Optimizing bone health in children and adolescents.
Pediatrics. 2014;134(4):e1229-43. PubMed abstract / Full Text

Authors

Contributing Authors: Meghan Candee, MD - 11/2015
Elizabeth Miller, MS, RD - 6/2018
Content Last Updated: 6/2018

Page Bibliography

Golden NH, Abrams SA.
Optimizing bone health in children and adolescents.
Pediatrics. 2014;134(4):e1229-43. PubMed abstract / Full Text

Heaney RP.
Vitamin D in health and disease.
Clin J Am Soc Nephrol. 2008;3(5):1535-41. PubMed abstract / Full Text

Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium; Ross AC, Taylor CL, Yaktine AL, Del Valle HB, editors.
Dietary Reference Intakes for Calcium and Vitamin D.
The National Academies Collection: Reports funded by National Institutes of Health. 2011. PubMed abstract / Full Text

Maguire JL, Lebovic G, Kandasamy S, Khovratovich M, Mamdani M, Birken CS, Parkin PC.
The relationship between cow's milk and stores of vitamin D and iron in early childhood.
Pediatrics. 2013;131(1):e144-51. PubMed abstract

National Institutes of Health.
Dietary Supplement Ingredient Database.
(2018) https://dietarysupplementdatabase.usda.nih.gov/ingredient_calculator/h.... Accessed on May 2018.

Ozel S, Switzer L, Macintosh A, Fehlings D.
Informing evidence-based clinical practice guidelines for children with cerebral palsy at risk of osteoporosis: an update.
Dev Med Child Neurol. 2016;58(9):918-23. PubMed abstract

Russo S, Carlucci L, Cipriani C, Ragno A, Piemonte S, Fiacco RD, Pepe J, Fassino V, Arima S, Romagnoli E, Minisola S.
Metabolic Changes Following 500 μg Monthly Administration of Calcidiol: A Study in Normal Females.
Calcif Tissue Int. 2011. PubMed abstract

University of Iowa.
Pediatric reference ranges common hematology and chemistry tests.
(2018) https://www.healthcare.uiowa.edu/path_handbook/Appendix/Heme/PEDIATRIC.... Accessed on June 2018.

Winzenberg T, Powell S, Shaw KA, Jones G.
Effects of vitamin D supplementation on bone density in healthy children: systematic review and meta-analysis.
BMJ. 2011;342:c7254. PubMed abstract / Full Text

Zaniew M, Jarmoliński T.
Vitamin D status and bone density in steroid-treated children with glomerulopathies: effect of cholecalciferol and calcium supplementation.
Adv Med Sci. 2012;57(1):88-93. PubMed abstract