Vitamin D is a fat-soluble prohormone (precursor of a hormone). Its absorption depends on the gut’s ability to absorb fat. Generally, vitamins are nutrients that the body cannot create, and so a person must consume them in the diet. However, the body can produce Vitamin D. When the skin is exposed to ultraviolet B energy (sunlight), it converts the precursor to vitamin D3. Vitamin D plays an important role in the skeletal system, has many health benefits and very few side effects.

The most important role of Vitamin D is the regulation of the minerals calcium and phosphorus to assist with bone mineralization that maintains proper bone structure. It assists with bone growth and remodeling by osteoblasts and osteoclasts. Vitamin D has other roles in the body including cell growth, neuromuscular and immune function. In addition, it may also protect against a range of diseases and conditions such as rickets, osteomalacia, and osteoporosis. The pathway for Vitamin D is carried in the bloodstream to the liver, where it is then converted into the prohormone calcifediol. Lastly, in the kidneys, it is converted into calcitriol.

History of Vitamin D

In the early 1900’s, Elmer McCollum tested modified cod liver oil to cure sick dogs with bone issues. Cod liver is abundant in Vitamin A and D. The modified version included only Vitamin D. McCollum concluded the modified cod liver oil cured rickets. Several years later, an American biochemist Harry Steenbock demonstrated that Ultraviolet light increased the Vitamin D.

Health Benefits

Vitamin D has multiple benefits…..

  • Supporting immunity
  • Brain and nervous system health
  • Helps regulate insulin levels
  • Supports lung and heart health
  • Promotes skeletal health
  • Cancer

Forms of Vitamin D


  • Cod liver, Salmon, Tuna
  • Egg yolk
  • Orange Juice
  • cheese
  • Milk


Vitamin D is available in two forms

  • D2 (ergocalciferol)
  • D3 (cholecalciferol)

The American Academy of Pediatrics (AAP) recommends that exclusively and partially breastfed infants should receive supplements shortly after birth and until they are weaned.

Symptoms of Vitamin D deficiency

Vitamin D deficiency is very common and most experience little to no symptoms. However, some children can experience the following common symptoms…

  • Bone pain
  • Muscle pain, cramps, weakness
  • Fatigue, low energy
  • Pain- Joint, bone, muscle
  • Frequent illness
  • Weight gain
  • Hair loss
  • Anxiety and irritable

Very low Vitamin D levels can lead to a condition called rickets in children and osteomalacia in adolescents/adults. Rickets in infants cause softening of the entire skull including delayed sitting, crawling and fontanelle closure. Rickets in children cause softer bones which can lead to “bow legs”, walking delays and other structural changes in the skeletal system. Osteomalacia predisposes adults to fractures.

Vitamin D deficiency can cause low calcium levels (also known as hypocalcemia). Low calcium can lead to tetany and seizures in young babies. For this reason, it is so important for pregnant moms to keep their D levels up. Low calcium levels also affect production of the parathyroid hormone which ultimately can result in impaired bone mineralization.  Low parathyroid hormone can cause hyperparathyroidism that increases excretion of phosphate that is essential for bone mineralization. In other words, a lot of phosphate is removed from the body that is needed for balance in the skeletal system.

In addition to Vitamin D levels causing problems with bones and muscle; Low levels is also linked to other health problems such as heart disease/high blood pressure, bowl cancer, decreased immunity and autoimmune diseases such as diabetes.

Risk Factors for Vitamin D Deficiency

  • Milk allergies/intolerance
  • Veganism
  • Born prematurely
  • Minimal sun exposure
  • Breastfed babies
  • Children with dark skin- Dark melanin acts as a natural sunscreen
  • Health conditions affecting absorption and excretion- cystic fibrosis, celiac disease, inflammatory bowel disease

Common Side Effects

Although, Vitamin D toxicity is very rare, the side effects can include…

  • Hypercalcemia (too much calcium)
  • Hyerparathyroidism (over active parathyroid)
  • Kidney stones
  • Hardening of the arteries (atherosclerosis)
  • Renal osteodystrophy- A bone disease that occurs when the kidneys fail to maintain calcium and phosphorus homeostasis (balance).

Drug Interactions

Vitamin D is generally safe to use but can interact with certain medications.

  • Steroids- Prednisone
  • Weight loss drugs
  • Cholesterol lowering medications
  • Seizure medications
  • Aluminum
  • Cardiac medications
  • Diuretics

*Disclaimer- Please seek health advice from your provider before trying any of the above mentioned supplements. Only you and your provider understand your child’s health history. These supplements are not considered cures for any ailments


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