Staying Healthy
Vitamin D for Good Bone Health
Vitamin D is necessary for strong, healthy bones and muscles.
- Without Vitamin D, our bodies can absorb only 10 to 15% of the calcium we consume.
- Children who lack Vitamin D develop a condition called rickets, which causes bone weakness, bowed legs, and other skeletal deformities.
Today, doctors are seeing an increase in the number of children with rickets and Vitamin D deficiency. This article focuses on the reasons for the increase and what parents can do to improve their children's bone health — as well as their own.
What Is Vitamin D All About?
Vitamin D is really not a vitamin. Vitamins are special nutrients that the body needs but cannot make, so they must be obtained from what we eat or by supplements. Because our bodies can make Vitamin D in our skin when the skin is exposed to sunlight, Vitamin D is considered a hormone.
How did we learn about Vitamin D and its importance?
When people stopped working in the fields and started spending most of their days in factories or schools, rickets began to be a problem — in fact, it was commonly seen during winter months in areas with heavy smog blocking the sun, and especially in northern locations far from the equator.
Around 1920, people noticed that children who took cod liver oil rarely got rickets. This led to the discovery of Vitamin D and the beginning of Vitamin D supplementation of the diet.
Why is there a new focus on Vitamin D today?
Recent research has stressed the importance of Vitamin D, not just for good bone health, but also for:
- Brain development
- Improving immunity
- Possibly preventing chronic disease when we are older.
It has been linked to:
- Brain and heart health
- Obesity
- Mood
- Autoimmune and immunologic disorders
- Infections, like the flu and COVID-19
Yet, many children today are not getting enough Vitamin D. There are several reasons for this, including the fact that very few foods contain substantial levels of Vitamin D. Even the healthiest of diets will probably not provide a child with adequate Vitamin D, especially as kids get bigger. As a result, current recommendations are for children to take a daily Vitamin D supplement.
Changes in lifestyle have also played a part. Several aspects of modern-day childhood impact Vitamin D intake:
- Children today spend hours in front of a computer or on phones or tablets, rather than playing outdoors. It is well documented that fitness levels among children are on the decline and obesity levels are rising.
- Children should be getting at least 35 to 60 minutes of moderate physical activity every day to build healthy bodies and bones.
- Many popular sports, such as basketball, volleyball, and gymnastics, are played indoors.
- Milk intake by children has steadily decreased.
- When playing outside, children often wear sunscreen to block harmful ultraviolet (UV) rays. However, sunscreen also blocks the body's ability to make Vitamin D from the sun. (Note: The American Academy of Dermatology cautions against overexposure to UV radiation from the sun or from indoor tanning beds, which can lead to the development of skin cancer.)
If a healthy diet and playing outside will not provide children with enough Vitamin D, how do we make sure they get it?
The best way for today's children to safely get the Vitamin D their bodies need is to take Vitamin D supplements.
How Much Vitamin Do We Need?
There is not currently one accepted recommendation for how much daily Vitamin D is needed. Vitamin D is measured in units called international units, which is shortened to "IU."
According to the Institute of Medicine–Food and Nutrition Board, and the National Institutes of Health–Office of Dietary Supplements, the recommended daily allowances (RDA) for Vitamin D among children is:
- 400 IU/day for children ages 0 to 12 months*
- 600 IU/day for children ages 1 to 18 years*
*These are the lowest amounts that seem to prevent rickets in the general population, not the amounts that will result in the healthiest bones or each child. As a result, these are considered the minimum recommended daily amounts of Vitamin D for children.
Recent research shows that higher levels of Vitamin D are needed for good health and healthy bones. The amounts needed can depend on a person's age, weight, and growth.
The Endocrine Society has published ranges for daily requirements of Vitamin D that include both the lower limit and the upper limit (the highest amount that is considered safe). A dosing range is a good way to think about how much Vitamin D to consume because the specific amount that is right for each person will vary.
What Are Food Sources of Vitamin D?
Not many foods naturally contain Vitamin D — it is found in substantial levels only in certain fish:
- Farmed rainbow trout contains 645 IU per 3-ounce serving.
- Sockeye salmon contains 570 IU per 3-ounce serving.
Some foods have Vitamin D added to them (fortification). For example:
- Milk is fortified, but an 8-ounce glass of any cow's milk (skim, 2%, whole) or other non-dairy fortified milk provides only 100 IU of Vitamin D.
- Some other foods, like breakfast cereal, are fortified, but at even lower levels.
- Eggs and liver can also have small amounts of Vitamin D.
Other dairy products — such as yogurt and cheese — are typically not fortified with Vitamin D.
How Do I Make Sure My Child Gets Enough Vitamin D?
Taking a Vitamin D supplement is the most effective way for your child to get enough Vitamin D every day. In fact, the 2024 Endocrine Society Clinical Practice Guideline recommends daily Vitamin D supplementation.
The form of Vitamin D used for supplementation is called Vitamin D3 on labels.
Which supplements should I give my children?
Children should be given a daily multivitamin. Children's multivitamins contain between 200 and 600 IU of Vitamin D3. Taking several multivitamins each day to get more Vitamin D is not a good idea, however, because too much of other vitamins can be bad for the body.
Children should be given daily Vitamin D3 supplementation. Vitamin D is readily available by itself in child-friendly forms, such as gummy vitamins or liquid drops. These supplements may be found on adult vitamin shelves, but they are also acceptable for children since the amount of Vitamin D is based on size, not age.
- Birth to 90 pounds can be given 1000 IU daily.
- 90 to 150 pounds can be given 2000 IU daily.
- 150 pounds and greater can take 4000 IU daily.
These amounts are consistent with the numbers listed in the chart above using upper limits for higher weights for healthy children.
- Vitamin D supplements can be given alongside multivitamins that have up to 600 IU of Vitamin D3.
- If the multivitamin has more than 600 IU of Vitamin D, then the Vitamin D can be counted toward the suggested amount of Vitamin D for the person's weight. For example, a child who weighs 100 pounds can take a multivitamin with 600 IU of Vitamin D3 plus a Vitamin D supplement that contains 1,400 IU of Vitamin D for a total of 2000 IU.
Children should be given calcium daily. Ideally, this should be broken up into amounts no larger than 500 milligrams (mg) at a time so the body can absorb it. Starting at age 3 years, a child's minimum calcium intake should be at least 1,000 mg and up to 1,500 mg each day. The minimum amount is roughly equal to consuming three 8-ounce cups of dairy or non-dairy milk, orange juice with calcium, or yogurt.
There is not a lot of calcium in multivitamins, so even if your child is taking a multivitamin, they should still aim to get the recommended daily amount of calcium from other sources (food or Vitamin C supplements).
Note: Vitamin D and calcium should always be taken together because calcium is needed to carry the Vitamin D into the bones. Without calcium in the body, the Vitamin D cannot help the bones grow stronger.
Do some children have special Vitamin D requirements?
Everyone is at risk for Vitamin D deficiency, but some people may need more Vitamin D than others. This includes those who:
- Have darker skin
- Live far away from the equator
- Have a higher BMI
- Have certain health conditions
- Take certain medications
Children who fall into any of the below categories need extra Vitamin D to maintain good bone health. These children should have their Vitamin D levels regularly checked, if possible.
- Obese children. Heavier children require extra Vitamin D. This is because Vitamin D goes straight to body fat and accumulates there. The more fat tissue the body has, the less Vitamin D there is in the bloodstream and the bones, where it is needed. So, obese children are prone to low Vitamin D levels and need to take more Vitamin D than non-obese kids.
- Children who are prone to seizures. Medicines that are taken to prevent or treat seizures increase the body's need for Vitamin D, so children who take anti-seizure medicines must increase their daily Vitamin D intake.
- Children who take certain medications, including glucocorticoids, antiretrovirals, and antifungals. These medications can block the absorption of Vitamin D or negatively affect bone health. These children should have Vitamin D levels checked and may need to take higher amounts of Vitamin D.
- Children with disabilities. Children who use wheelchairs or have chronic illnesses should take Vitamin D supplements.
Low Vitamin D levels can be easily treated by your pediatrician.
How Do Doctors Test Vitamin D Levels?
The best way to know a person's Vitamin D status is to have a blood test which checks the level in the blood. It is important that the correct blood test is done: The "25 hydroxy Vitamin D test" shows the level in the blood from both diet and sunlight.
When your doctor knows the exact level of Vitamin D in your bloodstream, they can make a more accurate recommendation of how much Vitamin D to take.
- A blood level less than 20 ng/mL can result in rickets.
- A blood level of higher than 150 ng/mL can be harmful.
- Most experts suggest that blood levels between 40 and 70 ng/mL and up to 100 ng/mL would prevent bone problems.
Can We Overdo Vitamin D?
Our skin cannot make too much Vitamin D when exposed to the sun — it stops when there is enough in the blood — but it is possible to take too many Vitamin D supplements. If there are any concerns about taking too many supplements, your doctor should order a blood test to check your or your child's Vitamin D level.
Last Reviewed
October 2024
Contributed and/or Updated by
Peer-Reviewed by
AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.