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Vitamin D for Kids

Whether we’re talking about infant feeding, introducing solids, or picky eating, vitamin D is an important part of the conversation. Vitamin D is a vitamin that we can technically make ourselves, but most of us do not make enough. There are also not that many good food sources of vitamin D, meaning that many people need to supplement.

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The Sunshine Vitamin

Vitamin D is also known as calciferol. It is a fat soluble vitamin that is needed for several systems in the body, including bone health. Vitamin D helps your body absorb calcium and helps with bone development, making it crucial for babies and kids who are still growing and need the extra calcium for bone development.

Vitamin D also plays a part in the immune system, glucose regulation, and reduction of inflammation (1). Many tissues on the body have vitamin D receptors. Your muscles use it to move and your nerves use it to send signals throughout the body.

Where can you get vitamin D?

There aren’t many foods that provide vitamin D. Some foods are fortified to help people meet their needs. Fortification will vary depending on the brand, so you’ll need to check labels for specifics. Much of the vitamin D intake in the United States is from fortified foods, like milk.

Vitamin D Containing Foods

  • Salmon
  • Tuna
  • Trout
  • Sardines
  • Egg yolk
  • Cheese (varies greatly on the cheese)
  • Mushrooms exposed to UV light
  • Cod liver oil
  • Beef liver

Fortified Foods

  • Cow’s milk and many milk alternatives
  • Breakfast cereals
  • Orange juice
  • Yogurts
  • Infant formula


UVB light can be used to create previtamin D3 which can then become vitamin D. This light is unable to go through glass, so you must be outside in order to make it. There are many factors that can affect vitamin D synthesis:

  • season
  • time of day
  • length of day
  • cloud cover
  • smog
  • skin color (melanin content)
  • sunscreen
  • subcutaneous fat levels
  • age
  • latitude

Because there are so many factors that can affect vitamin D production along with individual responsiveness to radiation, it’s difficult to determine exact guidelines for sun exposure. Some recommendations states 5-30 minutes between 10 AM and 4 PM twice weekly to daily to the face, arms, hands, and legs without sunscreen may be enough to maintain blood levels (1).

However, it is also important to limit skin exposure to sunlight to prevent skin cancer. Sunscreens with an SPF of at least 8 will probably block UVB (1). That being said, many people do not apply sufficient sunscreen, cover all exposed skin, or reapply regularly, so they may be getting some vitamin D, even with sunscreen.

Recommended Intakes

AgeRecommended Amount
Babies 0-12 months10 mcg (400 IU)
Children 1–13 years15 mcg (600 IU)

IU or mcg?

You may see vitamin D listed as IU or mcg. IU is short for international unit. While many labels do list both, if you are trying to convert yourself, you can simply do some math: 2.5 mcg=100 IUs.

What if you don’t get enough vitamin D?

Most people in the US do not eat enough foods with vitamin D, however true deficiency isn’t as common as you may expect. Many people are still able to get some vitamin D from the sun and many people take supplements as well.

We generally see a deficiency when intake is low and there is lack of access to sunlight, the kidneys aren’t able to convert vitamin D properly, or absorption is impaired.

Groups at highest risk for deficiency include breastfed infants not receiving supplemental vitamin D, older adults, people with limited sun exposure, people with darker skin, and people with altered absorption of nutrients.


Rickets is the name of a vitamin D deficiency in children. Bone tissue will not mineralize properly resulting in soft bones. You may have seen images of young children with severely bowed out legs. In more severe cases, it can lead to failure to thrive, developmental delays, seizures due to low calcium levels, as well as heart and teeth problems.


A vitamin D deficiency in older children and adults is called osteomalacia. This is when bones are either incompletely or defectively mineralized while remodeling which leads to weak bones. It can also lead to bone deformities, pain, seizures due to low calcium, and teeth problems.

Signs of a Vitamin D Deficiency

  • bone deformities
  • bone pain
  • seizures due to low calcium
  • spasms
  • failure to thrive
  • cardiomyopathy
  • dental abnormalities

Can you get too much?

Vitamin D is a fat-soluble vitamin, so if you take in too much, your body won’t just pee it out like with water soluble vitamins. Because it increases calcium absorption, excess vitamin D can lead to high calcium levels which can cause nausea, vomiting, muscle weakness, neuropsychiatric disturbances, pain, loss of appetite, dehydration, polyuria, excessive thirst, and kidney stones.

In very extreme cases, it can cause renal failure, calcification of soft tissues (like heart valves and blood vessels), cardiac arrhythmias, and even death. These serious side effects have occurred due to excessive levels in supplements due to manufacturing errors or when people were taking excessive amounts either taken inappropriately or incorrectly prescribed.

It’s rare to see signs and symptoms of toxicity at daily intake levels below 250 mcg (1000 IU), however the tolerable upper limits were set well below this number due to the possibility of adverse health effects over time. For infants 0-6 months, the upper limit is 25 mcg (1000 IU). The upper limit for infants 7-12 months is 38 mcg (1500 IUs). For children 1-3 years, the upper limit is 63 mcg (2500 IUs). Lastly, the upper limit for children 4-8 years is 75 mcg (3000 IUs).


It is recommended to provide supplementation of 400 IU to all infants receiving < 32 ounces/day of formula. Formulas in the US are fortified, so if your baby is taking at least 32 ounces/day, they will be meeting their needs. There have been some studies that show that if mom takes high levels of vitamin D (as high as 6400 IUs which is technically above the tolerable upper limit of 4000 IUs), there will be enough vitamin D in the breast milk for baby, however more research is definitely needed in this area. If this is something you are interested in, speak with your doctor.

For anyone not an infant, it is recommended to get bloodwork done prior to starting supplementation. Based on the results of your vitamin D levels, your doctor can recommend an appropriate level of supplementation for you. They should be taking into account your levels as well as your geographic location and sunlight exposure.

Best Vitamin D Drops for Baby

There are many great options for vitamin D drops for your baby. The best drops for you are going to be the ones that you have access to and that your baby takes. Some things to keep in mind for any supplement:

  • Make sure that it is 3rd party tested: this means that the supplement has what it says it has and it doesn’t have anything else in it
  • Know what dose you should be getting: more is not better
  • Consider the form: there are single drop options that may work well for a baby feeding directly at the breast whereas if baby is drinking from a bottle, a 1 ml form may not be a problem and may be more affordable

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