Vitamin D Deficiency and Sources

By Gilliant Tan Zhi Lei

October 21, 2020

Vitamin from the Sun?

Vitamin D is a fat soluble vitamin, which means it is only dissolved in oil. Vitamin D comes in two main forms, Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is obtained from the UV irradiation of the yeast sterol ergocalciferol when UVB light strikes the human skin.

How does Vitamin D work?

Vitamin D is unique as it can be made naturally through the sunlight exposure. Vitamin D that comes from the skin or diet is biologically inert and requires going through first hydroxylation in the liver by the vitamin D-25 hydroxylase to 25-hydroxy vitamin D3. However, 25-hydroxy vitamin D3 requires a further hydroxylation in the kidneys in order to from the biologically active form of 1.25 dihydroxy vitamin D3.

Vitamin D is important in bone growth by maintaining blood level of calcium and phosphorus. There is only 10-15% dietary calcium and about 60% of phosphorus is absorbed without Vitamin D. Calcium and phosphorus absorption increase by 30-40% and 80% respectively with the sufficiency of Vitamin D. Besides, Vitamin D plays an important role in the prevention and treatment of diseases as Vitamin D receptors are found throughout the body including in the immune system, nervous system, cardiovascular system and endocrine system. The lesser the sunlight exposure, the lesser the Vitamin D in the body and results to lower immunity and more illness.

Most of the research shows that Vitamin D3 is the preferable form as it is found to be more effective in raising blood levels of calcifediol when compared to Vitamin D2. Besides, Vitamin D2 is more sensitive to humidity and degrade over time.

Vitamin D Deficiency:

Almost 50% of the population worldwide experienced Vitamin D insufficiency. An estimated 1 billion people worldwide, across all ethnicity and age groups, have a Vitamin D deficiency (VOD).

Who are at risk of Vitamin D Deficiency?

1.Breastfed Infants






Breast milk is an ideal form of nourishment for a newborn. However, a woman’s breast milk contains only 25IU/L to 78IU/L which could not meet infant Vitamin D requirement. Vitamin D content of breast milk is related to the mother’s Vitamin D status. In other words, if lactating women is supplemented with high doses of Vitamin D, the level of Vitamin D in the breast milk will be higher too.

2. People with dark skin

People with dark-colored skin have large amount of melanin in the epidermal layer that makes them less able to make as much Vitamin D as those with fair-colored skin. People with natural dark skin tone require at least 3-5 times longer exposure to sunlight in order to get the same amount of Vitamin D as those with fairer skin tone.

3. People with Fat Malabsorption.

Vitamin D is fats soluble. Hence, it requires some dietary fat in the gut for absorption. Vitamin D supplement might be needed for those who are unable to absorb dietary fat. Fat malabsorption is associated with a variety of medical conditions including some forms of liver disease, cystic fibrosis and Crohn’s disease.

4. Older Adults







Age can also be a factor for Vitamin D deficiency. The skin’s ability to make Vitamin D is reduced as the age increases. Older adults are likely to spend more time indoors and have inadequate intake of vitamins.

5. Obese or Gastric Bypass Surgery

Obese people with a BMI value of ≥30 is associated with lower serum 25-hydroxyl compared with non-obese individuals. Obese people may need larger intakes of Vitamin D to achieve 25-hydroxyl level which is same as those of normal weight. Patient with gastric bypass surgery (weight loss surgery) that removes part of the upper small intestine have a higher chance to get Vitamin D deficiency over time due to the reducing size of the organ for Vitamin D absorption.

Recommended Intake of Vitamin D

Infants 0-6 months: 400IU; Upper Level Intake: 1000IU

Infants 0-12 months: 400IU; Upper Level Intake: 1500IU

Children 1-3 years: 600IU; Upper Level Intake: 2500

Children 4-8 years: 600IU; Upper Level Intake: 3000

9-70 years: 600IU; Upper Level Intake: 4000

Over 70 years: 800IU; Upper Level Intake: 4000

Pregnant and Lactating Women: 600IU; Upper Level Intake: 4000






Symptoms Of Vitamin D Deficiency:

  • Getting sick or infected more often
  • Fatigue
  • Painful bones and back
  • Depressed mood
  • Impaired wound healing
  • Hair loss
  • Muscle pain

Sources of Vitamin D






COD liver oil, swordfish, salmon, tuna, orange juice fortified with Vitamin D, milk, sardines, egg yolk are good source of Vitamin D.

However, absorption of Vitamin D can vary. Should you have any signs and symptoms as per above speak to a healthcare professional for further assistance and information.

In order for you to get your daily Vitamin D requirements, get Powerlife Vitamin D3 1000IU as Vitamin D3 is the most preferable form as it is more effective in raising blood levels of calcifediol when compared to Vitamin D2.





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