Vitamin D for Good Bone Health

Vitamin D is necessary for strong bones and muscles. Without Vitamin D, our bodies cannot effectively absorb calcium, which is essential to good bone health.

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Children who lack Vitamin D develop the condition called rickets, which causes bone weakness, bowed legs, and other skeletal deformities, such as stooped posture.

Today, doctors are seeing an increase in the number of children with rickets. This article focuses on the reasons for the increase, and things 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 it is exposed to good sunlight, Vitamin D is considered a hormone.

How much Vitamin D does the skin make?

Our skin makes a lot of Vitamin D when we spend time in strong sunlight. With about 5-30 minutes of sunlight exposure of head, face, hands, arms, or legs), our skin can make about 1000 IUs of Vitamin D (Vitamin D is measured in units called "International Units," or IUs.) Vitamin D is therefore known as "the sunshine vitamin."
If it is that easy for our bodies to make Vitamin D — at least during the sunny summer months - then why aren't people getting enough of it? Studies show that almost 50% of people in the U.S. – even in Florida – are low in Vitamin D.
Many things affect how much Vitamin D the skin makes.
For example, anything that affects the strength of sunlight reaching the skin can change the amount of vitamin the skin makes, including:

• The time of day
• Season of the year
• How far north you are
• The amount of smog in the air
• How much of your skin is covered with clothes
• The shade of your skin. Darker skin requires more sun to make a given amount of Vitamin D
• Sunscreen use. Sunscreen not only prevents sunburn and skin damage, it also can stop the skin from making Vitamin D

How did we learn about Vitamin D and its importance?

When our ancestors stopped working in the fields and entered factories or schools, rickets began to be a problem—in fact, it was commonly seen during winter months, especially in northern locations.
In about 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.
Today, we are still learning about the different ways our bodies use Vitamin D, and how much of it we need every day — not just to prevent rickets, but for overall bone health.

Why is there an increase in rickets today?

Many aspects of modern-day childhood impact Vitamin D intake.

• Children today spend hours in front of a computer or a television, rather than playing outside in the sun.
• Few children walk to school on a regular basis.
• Many popular sports, such as basketball, volleyball, and gymnastics, are indoor sports.
• Sunscreen use has been vigorously promoted and has become common.
• Milk intake by children has steadily decreased in favor of soda or juice.

For these reasons and others, we are seeing rickets again.
Many children today do not get enough Vitamin D, even those living in sunny climates.

How much Vitamin D do we need?

The government's recommendation from 1997 until 2008 was that 200 IU of Vitamin D would prevent rickets in most children.
New research resulted in doubling that recommendation in 2008, from 200 to 400 IU of Vitamin D.
The American Academy of Pediatrics has recently increased the daily recommended dose of Vitamin D in children to 400 IU, as well.
This is the amount that seems to prevent rickets, not the amount that will result in the healthiest bones.
Recent research supports that the body needs at least 1000 IU per day for good health — depending on age, weight, and growth.
Indeed, many people need much more than 1000 IU to keep Vitamin D levels in a good range.
In general, babies (especially those who are breastfeeding) and small children should intake at least 400 IU of Vitamin D daily.
Children over age 5, adolescents, and adults should get a minimum of 1000 IU of Vitamin D each day.

What are food sources of Vitamin D?

Not many foods naturally contain Vitamin D—it is found in substantial levels only in fish.
Some foods have Vitamin D added to them ("fortification").
For example, milk is fortified, but an 8 ounce glass of milk provides only 100 IU of Vitamin D.
Some other foods, like breakfast cereal, are fortified, but at very low levels.
Eggs can have small amounts of Vitamin D if the chicken was fed the vitamin.
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?

To get 1000 IU of Vitamin D every day, a child needs to do one of the following:

• Be outside between 10 a.m. and 2 p.m. for an average of 15 minutes every day with arms and legs exposed without sunscreen in a sunny climate (in Boston or farther north during the winter, being outside all day is not enough sunshine)
• Eat fish every day
• Drink 10 glasses of Vitamin D fortified milk each day
• Take Vitamin D supplements

What supplements should I give my children?

Because most children do not eat fish every day or drink 10 glasses of milk, they must take a Vitamin D supplement to get enough of the vitamin, at least in the winter time.
Children's multivitamins contain between 60 and 400 IU of Vitamin D.
Taking several multivitamins each day to get more Vitamin D is not a good idea, because too much of other vitamins (such as Vitamin A) can be bad for bone.
Vitamin D is now readily available by itself in child-friendly forms, such as gummy vitamins or liquid.
Unlike calcium supplements, which are not absorbed if taken in doses greater than 500 mg at one time, Vitamin D can be taken all at once, so it need be given only once daily.
Do some children have special Vitamin D requirements?
Some children need extra Vitamin D to maintain good bone health.
These children should have their Vitamin D levels regularly checked, if possible.
Low Vitamin D levels can be easily treated by your pediatrician.

• 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 where it is needed. So, obese children are prone to low Vitamin D levels and need extra Vitamin D intake.
• 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 with disabilities. Children who use wheelchairs or have chronic illnesses often do not play outside in the sun and should take Vitamin D.

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, he or she 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, and more than 150 ng/mL can be harmful.
Most experts suggest that blood levels between 40 and 100 ng/mL would not only prevent rickets, but result in good absorption of calcium for healthy bones.

Can we overdo Vitamin D?

Our skin cannot make too much Vitamin D — it stops when there is enough in the blood —but it is possible to overdose on Vitamin D supplements.
Because too much Vitamin D can be harmful, doses greater than 2000 IU/day should be taken cautiously, as advised by your doctor and based upon the results of blood tests.

Does Vitamin D do more than help us absorb calcium?

Vitamin D is important for good muscle health. People with very low Vitamin D blood levels may be more likely to experience muscle cramps, bone, or joint pain.
Studies suggest that older people who take Vitamin D seem to fall less often, probably due to better muscle function.
Vitamin D is very important in many aspects of our health. Children and adults alike should enjoy outdoor activities, eat Vitamin D-rich foods, such as milk and fish, and take Vitamin D supplements to enjoy good bone health and the other benefits of the sunshine vitamin!