The world that we live in is beginning to shift to an "indoor generation," in which people are spending up to 90% of their lives inside.1 In light of this behavioral transition, it should come as no surprise that 42% of Americans have a vitamin D deficiency.2

Vitamin D deficiency can lead to osteomalacia in adults, which is a softening of the bones that can lead to fractures and rickets in children. Pharmacists can play a role by raising awareness and educating patients on prevention strategies.

Pharmacists should be aware of the risk factors and signs of vitamin D deficiency to identify patients who would benefit the most from counseling and education. Risk factors include chronic kidney or liver disease, cystic fibrosis, Crohn disease, and bariatric surgery.3

Obesity and age can also put individuals at an increased risk of deficiency. Obesity has been associated with lower serum concentrations of vitamin D.4 Evidence suggests that obesity may affect the bioavailability of vitamin D; thus, it is important to encourage patients to maintain a healthy weight.4  

Age is also an important factor to consider because as people age, they become less efficient at producing vitamin D.4 Vitamin D deficiency can be difficult to identify, as symptoms include mood changes, bone loss, muscle cramps or weakness, bone pain, joint pain, and fatigue.3 Unfortunately, these signs are common in a variety of other disease states, which makes identifying vitamin D deficiency difficult without lab work.  

Our major source of natural vitamin D is through sun exposure. An individual's vitamin D levels are influenced by multiple factors including where they live and their skin color. Individuals who live further from the equator may have less exposure to the ultraviolet B (UVB) rays needed to synthesize vitamin D from the sun, especially during the winter months.3

It is important to keep in mind the amount of melanin in the skin can affect vitamin D production through sun exposure. Individuals with darker skin have to be exposed to the sun for longer periods compared with individuals who have lighter skin.3 It is also important to inform individuals that they will not receive adequate sun exposure indoors due to the inability of UVB rays to penetrate through windows.5

SPF above 8 can potentially block UVB rays, however some vitamin D synthetization is likely to take place due to insufficient reapplication of sunscreen and other factors.5 Evidence suggests that 5 to 30 minutes of sun exposure between 10 am and  4 pm at least twice a week to 40% of exposed skin should be sufficient enough to maintain adequate levels (serum concentration of >30ng/mL).5-6

Although sun exposure is important to maintain vitamin D levels, prolonged sun exposure can also be harmful. Finding a balance between how much exposure is harmful and how much is beneficial can be difficult to determine.

Individuals who have an increased risk of developing skin cancer should routinely apply sunscreen and always protect their face, arms, and hands when in the sun.7 To prevent sunburn, people should avoid high amounts of unprotected sun exposure.

For some individuals, adequate sun exposure is not an option. Lack of sun exposure can occur due to a variety of reasons, such as covering the skin when in public for religious purposes or being a patient in a long-term care facility.

Fortunately, the sun is not the only source of vitamin D. Some food sources, such as fatty fish, beef liver, cheese, and egg yolks provide vitamin D.5 Fortified foods such as milk, cereal, and some plant-based milk alternatives also contain vitamin D.

Supplemental vitamin D intake is an option and recommended for everyone.5 When discussing vitamin D supplementation with patients, it is important to keep in mind that 40 international units (IU) is equal to 1 mcg and either form (D2 or D3) appears to be equivalent for nutritional purposes.5

The Food and Nutrition Board recommends that healthy adults and children aged 1 to 70 years should receive 600 IU per day and adults older than 70 years of age should receive 800 IU per day.5 These recommendations are based on minimal sun exposure. Vitamin D supplementation is also important for infants, particularly those who are breastfed.

It is recommended that infants who are exclusively or partially breastfed receive 400 IU per day beginning in the first few days after birth. This should be continued unless they begin to receive at least 1 liter per day of vitamin D-fortified formula.8

These recommendations are for the prevention of vitamin D deficiency in healthy individuals. Patients who already have a deficiency may require higher dosing until adequate vitamin D levels are obtained.

Vitamin D deficiency is preventable with adequate sun exposure and supplementation. By educating patients to make small lifestyle changes, pharmacists can have a positive impact on reducing the prevalence of vitamin D deficiency in America.  

  1. What are the trends in indoor air quality and their effects on human health. Updated July16, 2018. Accessed July 30, 2020.
  2. 42% Percent of Americans Are Vitamin D Deficient. Are You Among Them? Published July 1, 2018. Accessed July 30, 2020.
  3. Vitamin D Deficiency. Accessed July 30, 2020.
  4. 6 things you should know about vitamin D. Accessed July 30, 2020.
  5. Vitamin D. National Institutes of Health. Accessed July 30, 2020.
  6. Naeem Z. Vitamin d deficiency- an ignored epidemic. Int J Health Sci (Qassim). 2010;4(1):V-VI. . Accessed July 30, 2020.
  7. Wyatt C, Neale RE, Lucas RM. Skin cancer and vitamin D: an update. Melanoma Management. 2015;2(1): 51-61. Accessed July 30, 2020.
  8. Do infants get enough vitamin D from breast milk? Accessed July 28, 2020.