Vitamin D - How Does Vitamin D Affect Your Child's Growth and Development?

Posted on June 04 2021, By: Dr. Aqsa Ph.D. Scholar in Nutrigenomics

Vitamin D - How Does Vitamin D Affect Your Child's Growth and Development?




Vitamin D is a fat-soluble vitamin that is naturally present in some foods and available in supplements. Many people refer to it as the sunshine vitamin because our bodies create vitamin D when ultraviolet (UV) rays from the sun strike the skin’s surface. (1)

What does vitamin D do? This vitamin is crucial for bone and teeth health in humans. It aids the body in absorbing calcium, which is a building block of strong bones. Alongside calcium, vitamin D protects the human body from developing several diseases such as osteoporosis (a disease that makes the bones weak and increases the risk of bone break) and rickets (softening and weakening of bones in kids). (1)

Additionally, vitamin D performs many significant functions in your child’s body. For example, muscles need this vitamin to move, and the nerves use it for sending messages from the brain to the rest of the body. The defense system also requires vitamin D to fight against invading viruses and bacteria. (2)

How Does Vitamin D Function in Your Child’s Body?

Vitamin D is crucial for a child’s health, and its primary function is to support proper growth and development in children. This vitamin promotes adequate calcium absorption in the gut, which aids the digestive system. It also maintains healthy phosphorus and calcium levels in the blood serum, enabling normal bone mineralization in kids. Having healthy serum levels of calcium and phosphorus prevents the risk of hypocalcemic tetany (a condition in which there is an involuntary contraction of muscles that leads to spasms and cramps). Additionally, vitamin D promotes proper bone growth through the production of bone cells. It reduces inflammation and regulates glucose metabolism, immune functions, and cell growth in kids. (2)

Vitamin D is obtained from sun exposure, food, and supplements. It is biologically inert, meaning that it needs to undergo two hydroxylation (oxidation reaction) processes in order for it to become active in the human body. The first hydroxylation process takes place in the liver, during which vitamin D is converted to calcidiol (a pre-active form of vitamin D). The second hydroxylation process occurs in the kidney, converting calcidiol to calcitriol (an active form of vitamin D) through enzymatic reactions. After activation, vitamin D is absorbed into the small intestine by means of intestinal carrier proteins and passive diffusion. The presence of fats in your child’s gut can enhance vitamin D absorption because it is a fat-soluble vitamin. However, some dietary forms of vitamin D do not require fat for absorption. (2)

Why Do Children Need Vitamin D?

Micronutrients (vitamins and minerals) play a vital role in children’s growth and development. The body cannot create its own micronutrients, so it is essential that your child receive an adequate amount of vitamins and minerals through diet and supplementation every day. Remember, the body can also produce vitamin D via sunlight exposure! No matter how your child received vitamin D, the vitamin offers several health benefits to your child.

Some vitamin D benefits include:

  • Maintains bone health
  • Reduces the risk of infections
  • Maintains heart health
  • Promotes proper growth and development

Maintains bone health:  Vitamin D plays a promising role in the regulation of calcium and maintenance of phosphorus levels in the blood. Both these minerals are essential for fostering bone health in children. Research has depicted that vitamin D is required to allow your intestine to absorb calcium and reclaim calcium that your kidneys would otherwise excrete.

Studies have also claimed that a lack of vitamin D increases the risk of rickets in children, leading to a bow-legged appearance due to softening bones. For adults, a vitamin D deficiency can lead to osteomalacia, resulting in muscle weakness and poor bone density. (2)

Reduces the risk of infections:  According to health experts, Vitamin D boosts immune functions in kids and reduces the risk of infections. A review of multiple studies has depicted that an adequate vitamin D intake protects your child from the influenza virus.

One study found that vitamin D boosts immune functions by increasing the pathogen-fighting effects of macrophages and monocytes (white blood cells). It also reduces inflammation in the body, further helping to lower the risk of infections.

The American Academy of Allergy Asthma and Immunology (AAAAI) has found that children who are not taking an adequate amount of vitamin D are at high risk of allergic sensitization. The AAAAI conducted another study on egg intake among kids, given that eggs are a major source of vitamin D. The results revealed that children who started eating eggs after 6 months are at higher risk of food allergies in comparison to kids who started from 4 months. Thus, children who received vitamin D earlier in life showed better health benefits than their counterparts. (3)

Maintains heart health:  Vitamin D is also beneficial to children’s heart health. Health professionals claim that a lack of vitamin D is strongly linked with high blood pressure in children. In 2018, a study demonstrated that a vitamin D deficiency contributes to this high blood pressure as a result of stiffness in the arterial walls of children. (4

Promotes proper growth and development:  Vitamin D not only maintains bone and teeth health, but it also plays a significant role in regulating growth hormones in children. One study found that vitamin D enhances the release of growth hormones and its mediators (insulin-like growth factor IGF-1), which leads to proper growth and development in kids. Another research study found that supplementation of vitamin D in children increased their height over six months. Moreover, a different study demonstrated yet another benefit of obtaining vitamin D by eating eggs: they are associated with more height gains in children. (3)

What Happens When Your Vitamin D Is Low?

Vitamin D deficiency can occur due to several reasons, including:

  • Skin type: Children with darker skin tones have less ability to absorb UV rays from the sun, and the absorption of sunlight is mandatory to synthesize vitamin D. (2)
  • Sunscreen: According to research, sunscreen with a sun protection factor (SPF) of 30 decreases the production of vitamin D by 90% in the human body. This is why health experts suggest exposing kids to sunlight for 15 minutes daily without applying sunscreen to their skin. (5)
  • Breastfeeding: Infants who are breastfeeding require vitamin D supplements, especially if they have darker skin that is rich in melanin pigments. The American Academy of Pediatrics suggests that breastfed children should receive 400 IU of vitamin D daily. (6)
  • Geographical location: If you live in northern latitudes, there is a high risk of vitamin D deficiency in your children due to less sun exposure. It is often necessary to supplement your child’s diet with vitamin D products if you live in regions with less sun exposure. (1)

    Vitamin D deficiency in kids can cause several health issues, such as cardiovascular diseases and rickets. A lack of this vitamin in children can also cause autoimmune diseases, like type 1 diabetes, rheumatoid arthritis, and Crohn’s disease, at a later age. (2)

    The common signs and symptoms of vitamin D deficiency in kids include:

    • Frequent illnesses and infections
    • Tiredness and fatigue
    • Slow wound healing
    • Muscle pain

    Frequent illnesses and infections:  One of the significant roles of vitamin D is to support immune function in children as it aids in fighting off bacteria and viruses that lead to illness and infections. If your kid often gets ill, especially with flu or cold, low vitamin D levels can be a leading cause. Several observational studies have found a strong association between vitamin D deficiency and respiratory tract infections in kids, like bronchitis, cold, and pneumonia. (7)

    Tiredness and fatigue:  Tiredness and fatigue in kids can have several causes, including a vitamin D deficiency. A study found that children who often complain of headaches and fatigue have low levels of vitamin D. In 2014, a different study demonstrated that individuals with fatigue consuming vitamin D supplements for five weeks experienced significant improvement in fatigue symptoms. (8)

    Slow wound healing:  If your child’s wounds take longer than usual to heal, it can be a sign of vitamin D deficiency. The results of an in-vitro study found that vitamin D is important in wound healing because it regulates growth factors that form new tissues. (7)

    Muscle pain:  Research has shown that vitamin D deficiency is a potential cause of muscle pain in adults and children. In one study, researchers gave a single dose of vitamin D to 120 deficient children experiencing high muscle pain, and it was found that their pains cores were significantly reduced by 57%. This study demonstrates vitamin D’s essential role in contributing to muscle health. (8)

    How Much Vitamin D Does Your Kid Need per Day?

    Vitamin D is used to prevent or treat several health issues such as rickets, osteomalacia, osteoporosis, and vitamin D deficiency. Oral intake of vitamin D2 is also effective in treating muscle diseases, also caused by a deficiency. (9)

    Dosing recommendations for vitamin D are given in the Dietary Reference Intake (DRI) developed by the Food and Nutrition Board (FNB). DRI describes the optimal amount of nutrients a person needs per day. (2)

    According to the Center for Disease Control and Prevention, all children require vitamin D after birth. For infants 0 to 12 months of age, the recommended dietary allowance (RDA) of vitamin D is 400 IU per day, and children above 1 year require 600 IU daily. A further breakdown of recommended daily doses of vitamin D is listed below. It is always recommended you consult with a medical doctor to establish the best routine of supplements for your child’s specific needs. (2)(10

     Age Recommended Daily Amount in micrograms (mcg)
    0-12 months* 10 mcg
    1-13 years 15 mcg
    14-18 years 15 mcg
    19-50 years 15 mcg
    51-70 years 15 mcg
    70+ years 20 mcg

    *Adequate Intake (AI) 

    Should You Give Vitamin D Supplements to Your Kid?

    Focusing on healthy food sources of vitamin D is always a good start to ensuring you have adequate nutrients. However, supplementation of vitamin D products is common and heavily relied upon for people who live in regions of the United States that get less sun. If you notice above symptoms that might be reflective of a vitamin D deficiency in your child, you might opt to have your physician check their blood for nutrient deficiency. Another common use of vitamin D supplements is for babies who only takes breast milk or drink less than 32 ounces of milk-based formula per day. If your child falls into this category, ask your health professional about giving vitamin D supplements to them. Children who do not get 600 IU of vitamin D daily through their diet must receive supplements to fulfill the requirement, and supplements should always be taken with the guidance of a medical professional. (11)

    What Foods Are Highest in Vitamin D?

    How can I boost my vitamin D? Major dietary sources of vitamin D include fish liver oils and fatty fish (tuna, trout, mackerel, and salmon). Egg yolks, cheese, and beef liver also contain vitamin D, although in lesser amounts. In the United States, most people get vitamin D from fortified foods such as ready-to-eat breakfast cereals, fortified orange juice, and other food products.

    Below is a list of foods that are rich in vitamin D: (2)

     Food Name Serving Size International Units (IU) per serving
    Cod liver oil 1 tablespoon 1360
    Salmon, cooked 3 oz 570
    Herring, fresh 3.5 216
    Sardines 3.8 oz can 177
    Oat milk, fortified 1 cup 100-144
    Orange juice, fortified 1 cup 100
    Egg 1 large egg 44
    Cheddar cheese 1 oz 12
    Chicken breast, roasted 3 oz 4


    Risks and Side Effects of Vitamin D

    Children do not experience side effects of vitamin D unless too much is given. Some common negative outcomes of excessive intake include stomach cramps, loss of appetite, weakness, sleepiness, fatigue, and vomiting.
    Research has revealed that excessive intake of vitamin D that leads to calcium build-up in blood leads to frequent urination, dizziness, confusion, and extreme thirst. Another study shows that mega doses of this vitamin can also disturb the absorption of other vitamins in the body, such as vitamin K2, which affects bone health. Although vitamin D is also mandatory for proper bone health, excessive intake will instead lead to problems by interfering with the absorption of vitamin K2. You should always follow dosing guidelines as recommended dosage by health professionals and your child’s physician to avoid the negative side effects of improper vitamin D dosing. (12


    Vitamin D can be remembered by its common nickname, the sunshine vitamin, referencing the human body’s ability to synthesize the vitamin via sunlight. Vitamin D is crucial for child health and it performs several vital functions, such as helping proper growth and development, boosting immune functions, and supporting bone health. On the other hand, a lack of vitamin D results in various health issues in children, such as rickets, high risk of infections, fatigue, tiredness, and many more. It is crucial that you try to give an adequate amount of vitamin D to your children through healthy sun exposure and diet. Supplements should be given to infants taking only breast milk after the approval of your child’s doctor. Vitamin D supplements are also commonly used in regions with less sun exposure. With everything vitamin D has to offer, it is in your best interest to be mindful of including it in your child’s care so that they can live healthier and happier lives! 




    Disclaimer: The content of this blog post is intended for informational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. You should not use this information for diagnosing or treating a health problem or disease, or prescribing any medication or other treatment. Always seek the advice of your physician or other qualified health provider before taking any medication or nutritional, herbal or homeopathic supplement and with any questions you may have regarding a medical condition.