University Times

• Breastfed infants

Human milk ordinarily does not meet babies’ vitamin D requirements, so it is recommended that breastfed infants receive supplements of 400 IU of vitamin D each day.  However, the amount of vitamin D in milk is related to the mother’s own levels, so women who take high doses of vitamin D may have high amounts of vitamin D in their breast milk.

• Older adults

Older adults are at increased risk for several reasons. As people age, skin synthesizes vitamin D less efficiently. Additionally, older people tend to spend more time indoors and may have inadequate intakes of the vitamin.

• People with limited sun exposure

People who are homebound or whose occupations prevent sun exposure are at risk, as are women who wear long robes and head coverings for religious reasons. Sunscreen use also may play a role, although many people don’t use enough sunscreen, so the impact remains unclear.

• People with dark skin

The skin pigment melanin, which in high levels creates darker skin, cuts the skin’s ability to make vitamin D from sun exposure.

• People with fat malabsorption

Fat malabsorption (associated with some forms of liver disease, cystic fibrosis and Crohn’s disease) could put some people at risk because vitamin D, as a fat-soluble vitamin, needs some dietary fat for absorption.

• People who are obese

A body mass index of 30 or above is associated with lower serum 25(OH)D levels and obese people may need greater intakes of vitamin D to reach blood levels comparable to non-obese individuals. Greater amounts of fat beneath the skin alter the release of vitamin D into the circulation.

• People who have had gastric bypass surgery

Because part of the small intestine where vitamin D is absorbed is bypassed, people who have had this surgery may become deficient over time.

Source: NIH Office of Dietary Supplements